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INTERNATIONAL SYMPOSIUM ON PHOTOELECTRONIC DETECTION AND IMAGING: TECHNOLOGY AND APPLICATIONS 2007 | 9-12 SEPTEMBER 2007
International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing
Editor(s): Liwei Zhou
Opto-electronic System Design, Manufacturing and Testing (77)
INTERNATIONAL SYMPOSIUM ON PHOTOELECTRONIC DETECTION AND IMAGING: TECHNOLOGY AND APPLICATIONS 2007
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 662401 (12 March 2008); doi: 10.1117/12.792915
This PDF file contains the front matter associated with SPIE Proceedings Volume 6624, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
Opto-electronic System Design, Manufacturing and Testing
Simultaneous 360° viewing optical system with the lenses of the compound eyes from the dragonfly
Seong-Weon Kim, R. S. Ramakrishna
We present an optical system with four lenses that imitate the eyes of a dragonfly. With these lenses, an attempt is made at simultaneous 360° viewing without any translation, rotation, or scaling. The viewed image will be projected onto a 2D image. The dragonfly eye system inspired earlier work by Luke and others. They achieved a wide viewing range through compound eyes. However, their work fell short of a perfect 360° circular viewing field. In this paper, a simultaneous 360°-wide vision system and representation of the simple still image is attempted. This is done through appropriate combinations of the compound eyes' hemispheres and the location settings at 45°, 135°, 225°, and 315° on the sphere. This covers the entire visual volume that includes the observer. The observed subject can be represented as a simple planar image. The result shows that within the circular imaging area, the four ellipses along each edge of the lozenge, composed of the four points of the compound eyes at 45°, 135°, 225°, and 315°, provide outer vision areas and the remaining regions constitute the inner visual field. By proper adjustment of the initial positions of the lenses, a doughnut shape is produced. Our approach is computational in nature. The proposed optical system can be an effective tool in medical or military applications.
Evaluating the viscoelastic properties of glass above transition temperature for numerical modeling of lens molding process
Tianfeng Zhou, Jiwang Yan, Tsunemoto Kuriyagawa
Glass molding process has emerged as a promising way to produce complex optical elements with high precision. Glass material shows explicit viscoelasticity at molding temperature, therefore studying the viscoelastic properties of glass at elevated temperature is important for the molding process. In this paper, Young's modulus and viscosity of glass were tested by compressing cylindrical glass gobs above the transition temperature, and obtained by curve fitting using the Burgers model of viscoelastic deformation. Based on the viscoelastic parameters obtained from experiments, a numerical model was developed to simulate the glass molding process with the help of a commercial finite element method software package. The simulation results provide an easy way to analyze and understand the molding process in detail, such as temperature distribution, stress, strain and strain rate, which are difficult or impossible to measure in experiments. A good agreement between the calculated pressing loads and the experimental results verified the validity of the numerical model, which can be applied to predict the pressing load during complex-shape glass lens molding process.
Cobalt chloride doped polymer film for relative humidity measurement
Pabitra Nath, Monubrat Datta, Abdul Barik, Azahar Ali, Hidam K. Singh, Apurba K. Kalita, Pranayee Datta
We report a simple approach to measure relative humidity with high dynamic range and fast response time using Cobalt chloride (CoCl2) doped polymer thin film. Anhydrous Cobalt chloride exhibits high absorption at low humidity level in the wavelength range 550-700 nm while possess very low absorption at high humidity level present in the environment. Thin CoCl2 doped polymer films of different thickness were fabricated on thin cover slides using dip coating technique. Expanded light from a diode laser source (680 nm) was allowed to transmit through the sensing film of the slide. The variation in intensity of the transmitted light with the moisture level present in the environment was monitored using silicon photodiode and finally the detector signal was taken through a computer. As large area of the sensing region is exposed to the environment, high sensitivity of the sensor is achieved. Further, sensor response was investigated in terms of chemically synthesized film thickness on the slides. A high dynamic range of the sensor is obtained with fully reversible and repeatable behavior. The advantage of the system is its simplicity and is a very low cost technique to monitor relative humidity present in environment.
Preexposure effect on the fabrication of continuous relief microstructure and advanced method
Duoshu Wang, Chongtai Luo, Hongkai Liu, Ziyu Ye
The principle and application of the preexposure in the fabrication of the continuous relief microstructure of diffractive optical element with polar coordinate Laser Direct Writing method were described in the paper. The paper also studied the rule of preexposure effect during the fabrication of continuous relief microstructure. We gave a substitute method of preexposure used in fabrication process of the microstructure and fabricated one kind of continuous relief microstructure successfully with the new method in the end.
Research on the NO gas-sensitive effect of long-period fiber gratings coated with film
Yong Peng, Min Sun
The spectral characteristics of long period fiber grating (LPFG) coated with sensitive film whose refractive index is higher than that of cladding is analyzed based on four-layer-step geometrical model both theoretically and experimentally. It is pointed out that the resonant wavelength of LPFG has a regular variation with the refractive indices of both ambience and the film besides film thickness. Blue shift appears due to the increase of film thickness. Optimal film thickness corresponding to the maximum values of both sensitivity and the change rate of resonant wavelength merely depends on ambient refractive index when the refractive index of the film is a constant. According to above theories, the new LPFG sensors sensitive to refractive index of chemical medium with higher sensitivities and wider range of application will be designed. Five LPFG sensors with different film thicknesses have been prepared by coating 2-6 layers SiO2-WO3 nanoscale multiforamen films on five claddings of LPFG respectively. When we put them in NO with 2% volume fraction, some changes happened only on the LPFG coated with three layers, whose resonant peak red shift 4.77nm, the loss change from -9.93db to -8.53db, the gas sensitivity, response time and recovery time also reached to 3%, 10s and 20s respectively.
The optimization of incoherent fiber laser beam combination
Jie Xu, Shanghong Zhao, Shengbao Zhan, Rui Hou, Jili Wu, Yongjun Li, Shaoqiang Fang
With the continuous increase of output power of double cladding fiber lasers, the researches of the techniques of fiber laser beam combination have become a new focus. With the inherent characters of small volume, light weight, good beam quality and system stability. Once the high power output laser was achieved, there would be broad applications in industry, scientific researches and military field. Incoherent beam combination is much easier to be realized compared with coherent beam combination, and with better system stability, thus it became an promising technique to achieve small volume and high power laser source. In an incoherent fiber laser beam combination system, the transform lens and diffractive grating play an important role in determining the coupling efficiency. Through theoretic analysis and numerical simulations, it has been proved that the optimum focal length of transform lens should be around 20cm in order to ensure a high system coupling efficiency under some selected simulation parameters. Also the lower frequency of diffractive grating is preferred, and a contradiction is present that is the higher frequency of diffractive grating is favorable in the consideration of maximum fiber array width, thus a moderate value was chosen as 200mm-1 with comprehensive consideration. The lower grating thickness is helpful in improving the diffractive efficiency, while it faced the problem of heat resistance and manufacturing difficulty, therefore the grating thickness between 2mm and 4mm is preferred. Under such optimized parameters, the coupling efficiency would be 70% or even higher with small deviation angle and wavelength. An example of effective jamming distance of combined fiber laser to visible light silicon CCD has been given, whose results had proved the application foreground of combined fiber laser.
Laser diode transmitter for laser radar based on FM ranging principles
Wen-jin Yang, Ji-guang Zhao, Xiao-ping Du, Zhao-yang Zeng, Qiao Wang
The purpose of this paper is to present the prototype of the laser diode transmitter for the laser radar based on frequency-modulated (FM) ranging principles. It belongs to the time-of-flight measurement category. In this case, the time-of-flight is converted to a beat frequency proportional to the range to be measured. This conversion is realized with intensity modulation of the laser power by a linear FM continuous wave. FM ranging theory and the principle of operation are described to show the application of FM radar principles in laser radar. The design of laser diode illuminator and the key techniques in the transmitter are discussed, including the generation technique of the wideband radio-frequency (RF) chirp signal, design of the transmitter module and the laser beam collimation optics. The possible factors that may limit the performance the laser radar system are discussed.
The fractal character of micromirror for metal MEMS optical switch
Yi Zhang, Yuan Luo, Xiaodong Xu
In this paper, the topographies of various micro-mirror surfaces are measured by Scanning Tunneling Microscope (STM) based on the NiCrAu MEMS optical switch unit which is desined and fabricated by ourselves. Fractal theory and Weierstrass-Mandelbrot function is applied to analyze and simulate the topography of different surfaces. The result shows that the surface of MEMS micromirror which fabricated by metal sputter has low anisotropism and the W-M function is very efficient in creating models and is very useful in analysis the topography of MEMS surface.
Annular sub-aperture stitching interferometry for testing of large aspherical surfaces
Xiao-kun Wang, Li-hui Wang, Li-gong Zheng, Wei-jie Deng, Xue-jun Zhang
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240A (12 March 2008); doi: 10.1117/12.791061
Annular subaperture stitching interferometric technology can test large-aperture, high numerical aperture aspheric surfaces with high resolution, low cost and high efficiency without auxiliary null optics. In this paper, the basic principle and theory of the stitching method are introduced, the reasonable mathematical model and effective splicing algorithm are established based on simultaneous least-squares method and Zernike polynomial fitting. The translation errors are eliminated from each subaperture through the synthetical optimization stitching mode, it keeps the error from transmitting and accumulating. The numerical simulations have been carried on by this method. As results, the surface map of the full aperture after stitching is consistent to the input surface map, the difference of PV error and RMS error between them is -0.0074 λ and -0.00052 λ (λ is 632.8nm), respectively; the relative error of PV and RMS is -0.53% and -0.31%; and the PV and RMS of residual error of the full aperture phase distribution is 0.027 λ and 0.0023 λ, respectively. The results conclude that this splicing model and algorithm are accurate and feasible. So it provides another quantitive measurement for test aspheric surfaces especially for large aperture aspheres besides null-compensation.
Effect of gaps and piston on image quality for large segmented telescope
Jixiang Yan, Yan Wen, Xin Yu, Xiaofang Zhang
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240B (12 March 2008); doi: 10.1117/12.791062
For a segmented primary mirror consisting of 7 segments organized in 1 concentric hexagonal band around the central segment, of which the point spread function (PSF) is represented by the product of the grid function (GF) and the PSFj of an individual segment. The system PSF and Strehl ratio given for the cases of the gaps or piston errors are present.
Study on optical design of all-reflective Fourier transform imaging spectrometer
Min-yong Liang, Ning-fang Liao
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240C (12 March 2008); doi: 10.1117/12.791063
The Fourier Transform Imaging Spectrometer (FTIS) used for remote sensing has been developed rapidly in the past two decades. Most of the Temporarily Modulated FTIS and the Spatially Modulated FTIS include a beam splitter structure, such as Sagnac prism or double refraction crystal beam splitter. The material of the beam splitter which is optical glass, crystalline materials or plastic optical materials all have the transmission limitation, so the spectrum range would be limited; the transparent material also would cause the chromatic aberration. We presented an all-reflective optical structure based on the Fresnel double mirror interference structure that could overcome these two shortcomings. The three-mirror anastigmat (TMA) telescope is employed to realize all-reflective fore-optics, it has a compact structure, wide field of view (FOV) and competent modulation transfer function (MTF). An abaxial parabolic-cylindrical mirror has been designed to focus the interference fringes onto the plane focal array (FPA) which would increase the signal to noise ratio (SNR).
Testing the large aperture optical components by the sub-aperture stitching interferometer
Yong He, Zhao-xuan Wang, Qing Wang, Bo Ji
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240D (12 March 2008); doi: 10.1117/12.791064
Nowadays many large aperture optical components are widely used in the high-tech area, how to test them become more and more important. Here describes a new method to test the large aperture optical components using the small aperture interferometer, deduce how to get the aperture number and the concrete process of the stitching parameter in a systematic way, finally get the best plan to choose the sub-aperture of the square and circular optical plane. To specify the stability of the method we operate an experiment, the result shows that the stitching accuracy can reach λ/10, it meet the need of the inertia constraint fusion etc, that is good enough to be used in the high-tech area.
Studies on LSPR effect of assembled gold nanoparticles film
Dandan Du, Xin Hong
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240E (12 March 2008); doi: 10.1117/12.791065
In the paper, gold nanoparticles film is fabricated based on nanolithorgraphy. The nanostructure and the optical properties are studied by SEM and spectroscopy. We design a spectroscopy acquisition system, gain the peak absorption wavelength by fitting the data collected, then we analyze its localized surface plasmon resonance effect by experiments of sucrose with different concentration. It shows a red-shift of peak absorption wavelength when the refractive index of external medium of gold nanoparticles film changes.
A new method of realizing the super light space zoom reflector
Kunyu Tao, Sen Fu, Xiaotong Qu, Boshu Sun, Yanping Zhou
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240F (12 March 2008); doi: 10.1117/12.791066
Space zoom reflector (SZR) is a key component in many applications of intending super-range deep space optical communication in interstellar task, laser antimissile etc. In this article, the demand of SZR has been analyzed, and a new plane machining method has been brought forward, which uses load on edge flexural torque to adjust the focal length and micrometer mechanisms to implement the precise closed-loop control. Firstly the study discusses the feasibility of using entire distortion to obtain steady focus in mechanics of elasticity, and then advances the techniques of its realization and methods of space combination and unfolding. Finally it describes the methods on how to adjust the SZR's focus, control tracking and pointing directions and increase its precision. Compared with SZRs made in other methods, this SZR is easier to machining, to adjust the focus and to be applied in the space combination with lower cost. All these merits give it a very good prospect.
Optical measuring system for defects of artillery lumen
Wenjuan Zhu, Chunguang Xu, Dingguo Xiao
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240G (12 March 2008); doi: 10.1117/12.791067
At present, some method to measure the defects of artillery lumen has less automation and objectivity, and the other is designed complicatedly and has low efficiency. So the optical measuring system for defects of artillery lumen is developed. The system is made up of a cone-shaped lamp-house, a CCD camera and a mechanism to center and support them, and so on. Whereas the imaging system is nonlinear, there exists geometric distortion on the original image of the artillery lumen. So the pixel coordinate transformation and brightness interpolation are introduced to rectify the geometric distortion of the image and the non-distortion image of the whole artillery lumen surface is gotten. Then the methods such as segmenting, distilling, and area calculating are employed to measure the defects on the rectified image. The experiments prove that the system can measure the defects effectively and rapidly. The precision can be advanced more if the error factors are ameliorated and the methods to compensate the errors are adopted. The measuring precision of the defects area can reach 0.5 mm2.
Study on the polarization dependency of diffraction efficiency of perfectly conducting blazed gratings
Shuping Li, Tiantong Tang, Jingping Zhu
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240H (12 March 2008); doi: 10.1117/12.791068
The diffraction properties for blazing -3 order of the perfectly conducting blazed gratings in the Littrow mounting under the polarized incident beam is investigated by numerical simulation. The diffractive electromagnetic fields for S and P polarized incident lights are calculated numerically using TDFD method. The field distribution of the electromagnetic field in the near groove area is analyzed, and the polarization dependency of diffraction efficiency is studied. The spectral characteristics in 1530~1566 nm range is given. It is proved that the efficiency for S polarized incident light is higher than that of P polarized one and it is not sensitive to the blazed angle. The spectral characteristic is flat within the fiber communication spectrum range.
Design and research of zoom optic system applied in micro-processing using 248nm KrF excimer laser
Xun Liu, Tao Chen, Tie-chuan Zuo
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240I (12 March 2008); doi: 10.1117/12.791069
The content of this paper is a design of zoom optic system applied in 248nm KrF excimer laser micro-processing. Due to the characteristic of KrF laser and the applied requests of micro-processing, it was determined that the maximal field of view is 1.2°, the optical material is fused quartz (JGS1) and the value of working distance is greater than 30mm. On the premise that the system has stable image surfaces and good imaging qualities under each different focal length, the goals of design include the continuous zoom ratio Γ=1~3.5 and the minimal magnification M≈0.1. In addition, the mechanically compensated method was employed to compensate image surface, so as not to change the position of the image plane in the whole range of focal lengths or magnification. The zoom optical system was composed of three parts: the front fixed group, the zoom group and the compensated group. After perfect optical calculation, the correlation of zoom ratio and focal length was obtained. The maximum of focal length is 129.2308mm and minimum is 39.92926mm when M=0.1. For continuous improvement of imaging quality, the initial configuration has been optimized by making use of ZEMAX. The result of design can achieve the goal of zoom ratio. During the zoom process, the total length of system is about 290.7065mm with the deviation Δ=±0.0403mm and the minimum of working distance is 59.3094mm. The whole system has good imaging quality and effective etching capability.
The theoretical and experimental research on endoscopic confocal imaging system
Huayong Ge, Baohua Wang, Qiushi Ren
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240J (12 March 2008); doi: 10.1117/12.791070
A novel endoscopic confocal imaging system is presented by modifying the conventional laser confocal scanning microscope. Based on point spread function and Fourier optics, the coherent transmission function of the system is derived and the influence of fiber on axial resolution is investigated in detail. It is shown that the system acts as a coherent imaging system and the axial resolution of the system decays with increasing fiber radius A. Finally, an endoscopic confocal imaging system was built, and the in-focus and out-of-focus images of glass grating are obtained, which show good lateral resolution.
New design techniques and alignment methods for CGH-null testing of aspheric surface
Guo guo Kang, Jing-hui Xie, Yi Liu
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240K (12 March 2008); doi: 10.1117/12.791080
The entire process of designing the test setup with a computer-generated hologram (CGH), fabricating the CGH with a laser direct writing system and performing the CGH-null test of an asphere will be described in detail. New considerations in designing the null corrector with calculating CGH's phase function, filtering off unwanted diffraction orders and aligning CGH to the interferometer are discussed. A laser writing machine is used to fabricate designing patterns onto plane substrate and substrate figure error, pattern distortion, etching and duty cycle variations that influence the reconstructed wavefront are quantitatively analyzed in theory and corresponding error equations are obtained. The CGH used for measuring a paraboloid mirror is designed and fabricated. Experimental results of interferometric CGH-null test are presented.
Methodology on zoom system design and optimization
Quanxin Ding, Hua Liu
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240L (12 March 2008); doi: 10.1117/12.791081
For aim to establish effective methodology in research to design and evaluate on typical zoom sensor system, to satisfy the system requirements and achieve an advanced characteristics. Some methods about system analysis, especially task principle and key technique of core system, are analyzed deeply. Base on Gaussian photonics theory, zoom system differential equation, solves vector space distribution and integrated balance algorithm on global optimization system is studied. Dominate configuration of new idea system design and optimization, with which consecutive zoom and diffractive module equipped by great format photonics device, is established. The results of evaluated on a kind of typical zoom sensor system is presented, and achieves remarkable advantages on some criterions, such as Modulation Transfer Function (MTF), Spot Diagram (RMS) and Point Spread Function (PSF) etc., and in volume, weight, system efficiency and otherwise.
Research and application of ergonomics to optical microscope
Xue-kun Jiang, Ze-xin Xiao, Jie Zhang
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240M (12 March 2008); doi: 10.1117/12.791082
The characteristics of the human and the microscope, and their integrated characteristic have been studied respectively in this paper. Our results indicated that the correspondence of (i) focusing installment with human body arm, (ii) the height of ocular with eyes, (iii) visual characteristic with illuminative condition of the optical microscope, should obey the theory of the ergonomics. This was reflected in the structural design and the produce of the product, and therefore, improved the property of the amenity of the machine.
New method for detecting the piston of segmented mirrors: a modification of the peak ratio technique
Dan-dan Qu, Yue-jin Zhao, Li-quan Dong, Rongrong Chen
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240N (12 March 2008); doi: 10.1117/12.791083
Large segmented mirrors require efficient co-phasing techniques in order to avoid the image degradation due to segments misalignment. Detecting the piston error in high precision is critical to phasing the segmented mirrors. The energy ratio method, compared with the peak ratio technique, is presented in this paper to detect the piston. It focuses on a single quadrate intersegment subaperture which straddles two segments .This method provides a way to extracting some information on piston error. The details of the diffraction-interference pattern formed by the subaperture are sensitive to the piston when observed on the image plane. This method has several advantages compared with the peak ratio technique. The simulation results show that. the energy ratio method is good in detecting the piston error and is better than the peak ratio technique in robust and reliability.
Sampling pulses with symmetric Mach-Zehnder interferometer optical switch
Yi Yang, Zheng Zheng, Zheng Li
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240O (12 March 2008); doi: 10.1117/12.791085
The all optical window equivalent-time sampling method using SMIOS and a numerical algorithm used for waveform recovery are present. A system model based on SOA dynamic model was founded to analyze sampling process. The pulse broadening in low bandwidth PIN and its response are discussed too. The relationships between sampling windows and sensitivity due to SOA bias current, aptitude of control pulse and input measured signal wavelength are analyzed theoretically. The results have shown that the SMIOS sampler system combined with numerical algorithm can measure short pulses with low error.
Performance analysis of Brillouin optical time domain reflectometer using Golay complementary sequence
Xiao-wei Cheng, Yong-qian Li
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240P (12 March 2008); doi: 10.1117/12.791086
A distributed optical fiber sensing system using Golay complementary sequences as the probing pulses has been presented. By applying Golay complementary sequences to Brillouin optical time domain reflectometer (BOTDR), the system performances such as signal-to-noise ratio and dynamic range can be improved greatly without degrading spatial resolution. This paper has researched the constitution and frequency performances of Golay complementary sequences. Based on the study of applying bipolar sequence to optical system, the idea of applying Golay complementary sequences to BOTDR system has been presented, and the performance improvement on SNR and dynamic range of the system have been calculated. At last, a BOTDR system based on Golay complementary sequences has been presented and the simulation results have demonstrated the feasibility of this method.
Estimation of the measurement uncertainty based on quasi Monte-Carlo method in optical measurement
Hui Jing, Mei-fa Huang, Yan-ru Zhong, Bing Kuang, Xiang-qian Jiang
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240Q (12 March 2008); doi: 10.1117/12.791087
Because measurement uncertainty is an important parameter to evaluate the reliability of measurement results, it is essential to present reliable methods to evaluate the measurement uncertainty especially in precise optical measurement. Though Monte-Carlo (MC) method has been applied to estimate the measurement uncertainty in recent years, this method, however, has some shortcomings such as low convergence and unstable results. Therefore its application is limited. To evaluate the measurement uncertainty in a fast and robust way, Quasi Monte-Carlo (QMC) method is adopted in this paper. In the estimating process, more homogeneous random numbers (quasi random numbers) are generated based on Halton's sequence, and then these random numbers are transformed into the desired distribution random numbers. An experiment of cylinder measurement is given. The results show that the Quasi Monte-Carlo method has higher convergence rate and more stable evaluation results than that of Monte-Carlo method. Therefore, the quasi Monte-Carlo method can be applied efficiently to evaluate the measurement uncertainty.
Golay3 sparse aperture systems designed on a spherical surface
Feng Wu, Quanying Wu, Lin Qian
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240R (12 March 2008); doi: 10.1117/12.791088
High resolution imaging from space telescope for surveillance and astrometry is currently limited by launch vehicles and systems cost. The weight of the telescope is one of major factors which limits the vehicles to be placed in orbit. Sparse aperture optical system uses a reduced aperture area to synthesize the optical performance of a filled aperture. It is more promising in virtue of its light weight, low cost and larger synthetic aperture. The sparse aperture optical system has two types, i.e. the multiple-mirror telescope (MMT) and the multiple-telescope telescope (MTT). A MMT of Golay3 sparse aperture optical system is investigated that three sub-mirrors are located on a spherical primary mirror. Three sub apertures of Golay3 are elliptic that in fact the circular sub-mirrors of spherical primary mirror are projected on the entrance pupil. The relationships between fill factor, radius of sub-mirrors and F number of the primary mirror are presented. The analytical formula is also completed, which shows that the maximum fill factor is limited by F number of the primary mirror. When the aperture radius is equal to curvature radius of the primary mirror approximately, the shape of sub-apertures exhibits to be elliptic obviously. The maximum fill factor reaches the largest one at that time. Modulation Transfer Function (MTF) of Golay3 system is studied. MTF is the correlation of three elliptic sub-apertures. The sub-MTFs are different from those of sub-mirrors located on a plane. The formula is verified by designing two Cassegrain telescopes which primary mirror is made up of three sub-mirrors of Golay3 configuration with Zemax optical program. Three sub-mirrors of primary mirror share a common asphercial secondary mirror. The errors caused by tilt and piston of three sub-apertures are also given out. Because of the loss of MTF for the sparse aperture optical system, the image quality is decreased. Wiener filter technique is utilized to improve the image quality for the sparse aperture system.
Application of conformal optical design in star sensor
Yan Li, Lin Li, Yifan Huang, Jiaguo Liu
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240S (12 March 2008); doi: 10.1117/12.791089
Star sensor is a special high accuracy photoelectric instrument. It is often used in navigation of aircraft, cruise missiles, and ballistic missiles, so the imaging quality of the optical system in a star senor is very important. The spherical windows with a small impact to imaging performance are usually used in traditional star sensors. However, the spherical surfaces are not ideal aerodynamic surfaces and would cause problems such as high drag. In this paper the conformal window whose outer shape is neither spherical nor flat is used in a star sensor. Unfortunately, the conformal shape introduces amounts of aberration which may lead to low imaging resolution. The various correctors can be used to eliminate the aberrations, for example, the fixed corrector, the arch, Zernike wedges, and the deformable mirror. The fixed corrector method is selected to decrease aberrations from the conformal window in this paper. The surface of the conformal window in the star senor is described as the Von Karman equation. The field of view is 17.6°×13.5°, and the size of the CCD pixel is 6.45 um×6.45um. The optical design program ZEMAX is used to design this system. After the optimization, under the max frequency of 77.52lp/mm, the MFT can almost achieve 30%. The design results show that the aerodynamic requirements can be satisfied by the application of the conformal window in the star sensor, and the aberrations can be corrected by proper ways.
Analysis on the interferogram of a low coherence interferometric system for measuring the dispersion of chirped fiber grating through Fourier spectrometry method
Qingshan Chen, Naiguang Lu, Xinzhu Sang
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240T (12 March 2008); doi: 10.1117/12.791090
Analyzes the interferogram of a system for measuring the dispersion of CFBGs (chirped fiber Bragg grating) through Fourier spectrometric method. Theoretical representation of the interferogram is provided. A numerical model for simulating the interferogram is established under the common cognition that the recorded interfogram during the scanning of OPD (optical path difference) along the light beam axis is the sum of separate symmetrical interferogram of all quasi-monochromatic light components according to power. This analysis method will facilitate the analysis of interferogram of several interferometric systems in which the light transmits via a dispersive medium.
Research of the application of low-precision large aperture nonimaging optics in free-space optical communication system
Jia Wang, Xin Yu
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240U (12 March 2008); doi: 10.1117/12.791094
A novel receiving antenna using low precision large aperture nonimaging optical apparatus in free-space optical (FSO) communication system has been proposed. The receiving optical antenna of FSO communication system is usually a conventional imaging optical system such as Newton system, Green system or Cassegrain system. It is ineffective to use a large aperture receiving antenna in FSO communication system because the precision imaging optical apparatus will be very expensive with aperture increase, so that, in order to reduce the difficulty of pointing and tracking between transmitter and receiver, the beam divergence has to be increased with the cost of lost part of the transmitted power. Since in the field of FSO communication system, the receiving optical antenna is used not to image but to concentrate optical signal as much as possible, the novel concept of using low precision large aperture nonimaging optical apparatus as receiving optical antenna to replace the conventional imaging optical system was proposed. Several nonimaging apparatus including spherical reflector, elliptical reflector, compound parabolic concentrator (CPC) and conical barrel concentrator are analyzed by ray tracing. Their gain and the transmission rate limitation due to wave-front aberrations are discussed, and their merit used in FSO communication system has been proved.
Designed achromatic quarter wave plates of subwavelength grating structure
Jun Zhang, Shu-hua Yan, Chun-lei Zhou, Shao-wei Shen, E Li, Hui-peng Tong
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240V (12 March 2008); doi: 10.1117/12.791095
We presented the design of an achromatic quarter wave plates based on subwavelength grating structure and considered the dispersion of material in design. The refractive indices of most material become small with the light wavelength increasing, and the dispersion of effective refractive indices of TE and TM polarized waves in the subwavelength structure increase with the light wavelength. Using this feature, we can design a quarter wave plates whose phase retardation is maintained at π/2 for a larger wavelength range. A design method using the effective medium theory is described, and the transmittance of TE and TM polarized waves are evaluated by numerical calculation with the rigorous couple wave theory. The results showed that phase retardation of the quarter wave plates had maintained retardation errors at ±1° for a ±9.85% change in wavelength, and the transmittance of both TE and TM waves were more than 94%. We also designed an achromatic quarter wave plates applied to visible light wavelength range using the method whose phase retardation maintained at ±2° in the 0.47 μm ~ 0.63 μm wavelength interval, and there also had a transmittance of more than 94% for the TE and TM waves.
Design of multi-layer diffractive lenses to correct secondary spectrum
Hui Xing, Wumei Lin, Jianmei Feng, Zhijie Liao
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240W (12 March 2008); doi: 10.1117/12.791096
Diffractive optical elements (DOEs) are more flexible and powerful than tradition refractive-reflective optical elements in correcting chromatic aberration of an optical system. In this paper the principle of correcting secondary spectrum is described. In order to compare the effect of DOEs on correcting secondary spectrum, we use CODE V to design a refractive telephoto system with different strategies: (I) All surfaces are spherical; (II) One surface is diffractive in the system; (III) Two or more surfaces are diffractive (Multi-layer diffractive system). It is found that multi-layer diffractive elements used in a telephoto system can easily correct secondary spectrum without high dispersion glasses, such as calcium fluoride, at the same time high diffraction efficiency and broad spectral bandwidth can be obtained. And the most important of all, the length of the telephoto system can be shortened by about 30%, and the weight can be greatly cut.
Image based measurement for the center position error of micro-sphere in micro-target
Ting Wang, Zurong Qiu, Jinjiang Wang, Bingzhen Wang
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240X (12 March 2008); doi: 10.1117/12.791097
Micro-sphere is the key element in ICF (Inertial Confinement Fusion).The relative position between micro-sphere and cylindrical gold hohlraum is required to be critically accurate so that the motivation energy and transition efficiency of the ICF can be significantly improved. Accurate detection of micro-target assembly (especially the center position error) is necessary and indispensable to ascertain the qualities of ignitions. The micro-sphere and cylindrical gold hohlraum have tiny dimensions and are flimsy and easy to deform. To resolve such problems, a non-contact method based on digital image progressing is proposed to detect the center position error of micro-sphere in this paper. Canny operator is employed to detect the gray-level gradient image. After removing the fake edge points, the images are transformed into binary images by a dual-threshold. To increase the operation speed, a region of interest (ROI) containing only parts of the detected target is selected by alternating manual work. A Hough transform is then selectively applied to the chosen sub-area. The equations of the target circles and the lines can be gotten by fitting these edge points. The center position error of micro-sphere can be obtained based on axial and radial position errors of micro-sphere. Experimental results show that the proposed method is independent of binary thresholds and robust to additional noises. The standard deviation of the center position error is about 2μm, and the maximum error (3σ) is less than 6μm.
Polarization aberrations caused by fold mirrors in optical systems
Ying Zhang, Lin Li, Huijie Zhao
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240Y (12 March 2008); doi: 10.1117/12.791098
A unified discussion of the polarization aberration theory is presented and Jones arithmetic is studied to calculate the polarization aberrations caused by coated fold mirrors in optical systems. The factor |t| is presented, which affects the polarization aberrations introduced by mirrors. It is proved that the magnitudes of the polarization aberrations increase quadratically with the linear increase of the angle of incidence. The method of character matrix is given to calculate the thin films properties. ZEMAX software is used to analyze the polarization aberrations caused by the fold mirrors in the primary optical system of the resource satellite. Two designs are presented for the coatings of the mirrors and polarization effects are analyzed respectively. According to the results of the study, polarization properties of coated fold mirrors are confirmed and two methods to control the properties have been found. One effective way is to decrease the incident angles on the fold mirrors. Another effective way to control the polarization aberrations is to design appropriate coatings on fold mirrors. It can be seen that coating design plays an important role in polarization aberrations. Therefore, optical thin film designs should be considered carefully while designing optical systems.
Design of the scanning mode coated glass color difference online detection system
Weihong Bi, Yu Zhang, Dajiang Wang, Baojun Zhang, Guangwei Fu
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240Z (12 March 2008); doi: 10.1117/12.791099
A design of scanning mode coated glass color difference online detection system was introduced. The system consisted of color difference data acquirement part and orbit control part. The function of the color difference data acquirement part was to acquire glass spectral reflectance and then processed them to get the color difference value. Using fiber for light guiding, the reflected light from surface of glass was transmitted into light division part, and the dispersive light was imaged on linear CCD, and then the output signals from the CCD was sampled pixel by pixel, and the spectral reflectance of coated glass was obtained finally. Then, the acquired spectral reflectance signals was sent to industrial personal computer through USB interface, using standard color space and color difference formula nominated by International Commission on Illumination (CIE) in 1976 to process these signals, and the reflected color parameter and color difference of coated glass was gained in the end. The function of the orbit control part was to move the detection probe by way of transverse scanning mode above the glass strip, and control the measuring start-stop time of the color difference data acquirement part at the same time. The color difference data acquirement part of the system was put on the orbit which is after annealing area in coated glass production line, and the protected fiber probe was placed on slide of the orbit. Using single chip microcomputer to control transmission mechanism of the slide, which made the slide move by way of transverse scanning mode on the glass strip, meanwhile, the color difference data acquirement part of the system was also controlled by the single chip microcomputer, and it made the acquirement part measure color difference data when the probe reached the needed working speed and required place on the glass strip. The scanning mode coated glass color difference online detection system can measure color parameter and color difference of each transverse point on glass strip, it can also measure lengthways color stability on glass strip. Furthermore, the measuring results can be transmitted to coated control room through intranet, so it is very useful to improve producing technique in time. In addition, equipping necessary marking machine, this system can classify glass board automatically based on the measuring result.
Beaming of light from metallic surface plasmon polaritons nanostructure
Guo-ting Zhang, Juan Liu, Chuan-fei Hu, Fang Sun, Xiao-xing Su
We investigate the beaming of light formed by a metallic nanostructure through the coupling of a metallic nanoparticle and a metallic nanoslit flanked with periodic sinusoidal grating on one surface. We employ the boundary element method (BEM) to simulate the transmission resonant spectrum and the optical field distribution. The numerical results show that beaming of light are formed from the metallic nanoslit system. Such device can be used for miniature optical antennas in the optical regime, which can transmit or receive light along a specific direction for a given wavelength. Potential applications include the coupling light in or out of fibers and the achieving the miniature optical source.
A combination of BIM and BEM for efficiently analyzing optical elements
Fang Sun, Juan Liu, Guo-ting Zhang, Chuan-fei Hu, Xiaoxing Su
We propose the revised boundary integral method (RBIM) that combines the boundary integral method (BIM) and the boundary element method (BEM) together. It is well known that the boundary integral equations are cast into matrix form for ease of computer implementation, and the points on the diagonal line of the matrix present the superposition of the observation and the source points. The points are called singularity points which can cause the big error bar. Thus, we consider replacing the BIM by the BEM at the diagonal line, comparing the numerical results by using the RBIM, the BIM, the BEM, and the analytical method, and find the error bar caused by the RBIM is smaller than that of the BIM. It indicates that the RBIM is not only faster than the BEM, but also it is preciser than BIM.
A novel algorithm of wave front time domain testing
Lei Tang, Qun Hao, Qiudong Zhu
In order to achieve the surface testing of entire caliber large-aperture optical elements, the distance between the tested piece and the interferometer is often several meters to tens of meters. In such long optical path the impact of environment vibration and air turbulence are inevitable, which seriously affects the accuracy of the interferometry and also limits the possibility of processing and testing large optical system. This paper presents a novel algorithm of wave front time domain detection, which needn't equal interval phase shifting and precise calibration of the phase-shifting step, just by means of using the environment vibration and air turbulence as phase shifters. On basis of enough interfergrams light intensity vs time curves of each point can be achieved. Light intensity vs phase curves of each point can be figured out by proposed algorithm. Then, we can gain the phase value of each point in terms of the light intensity, and also the wave surfaces corresponding to each interfergram by the unwrapping calculation. As result, we can obtain the stable wave surface wiping off random vibration and air turbulence under taking of average on all wave surfaces. Compared to conventional phase shifting interferometry algorithms, this algorithm can effectively decrease the impact of vibration and air turbulence within the interferometric measurement, enhance its ability of anti-jamming, and improve the adaptability, particularly in real-time detection of 1arge-aperture mirror.
ZnO/Ag/ZnO multilayer films deposited at room temperature
Jinliang Yan, Xueqing Sun, Youliang Zhu, Yinnv Zhao
Transparent conductive ZnO/Ag/ZnO multilayer films were prepared by simultaneous RF magnetron sputtering of ZnO and DC magnetron sputtering of silver at room temperature. A silver film with nanoscale thickness was used as intermediate metallic layers. The crystal structure of the ZnO/Ag/ZnO film was analyzed by X-ray diffraction. The electrical property of the ZnO/Ag/ZnO film was investigated by a linear array four-point probe. The transmittance spectra of the ZnO/Ag/ZnO films were measured using spectrophotometer. A strong ZnO (002) peak is seen for ZnO/Ag/ZnO film, indicating polycrystalline nature and wurtzite structure of ZnO film. Silver has (111) orientation, addition of underlayer ZnO enhances the polycrystallinity of silver layer in ZnO/Ag/ZnO multilayer film. The transmittance decreases in the short wavelength as well as in the long wavelength regions as the thickness of the silver layer is increased. The peak transmittance shifts toward the long wavelength region when the thickness of the two ZnO layers is increased. The electrical and optical properties of the ZnO/Ag/ZnO films depend strongly on the silver film thickness. ZnO/Ag/ZnO multilayer films having high transmittance of 92.5% and low sheet resistance of 4.2Ω/sq. are successfully fabricated and can be reproduced by controlling the preparation process parameters properly.
A convertible aerial camera system integrated with film and CCD image sensor
Lei Yan, Shi-hu Zhao, Zhou-hui Lian
It is the coexisting time between film and digital imaging. Both film aerial camera and digital one have their particular imaging principles, characteristics and complementarities between them. In this paper, a new convertible aerial camera is developed to integrate film and CCD sensors, named as twice-imaging scheme. Some experiments have been carried out for the feasibility of the scheme. This convertible aerial camera system has both film and digital advantages. It can be used in different aspects of aerial remote sensing, surveying and mapping.
Fiber point diffraction interferometer in measurement of spherical lens
Shuo Wu, Tao geng Zhou, Jia ming Lin, Lin feng Chen, Liang Nie, Ding guo Sha
An advanced fiber point diffraction interferometer (FPDI) is built for measuring spherical mirror surface and spherical lens wave front aberration with high precision. This new interferometer is based on point diffraction technique. Using short coherence length laser as light source, the perfect spherical wave diffracts from fiber point resource as reference wave. And the spherical wave is interfered with object wave to achieve higher accuracy. A phase shifting point diffraction interferometer with one single-mode-optical-fiber is built for measuring concave spherical mirror surface. A concave spherical mirror is measured by the experimental facility. The interferograms are collected by CCD and analyzed by computer. The PV values and RMS values of resulted surface error are compared with the result acquired by digital wave front interferometer. The measured surface is fitted and represented by Zernike polynomials. The results compared with Zygo GPI interferometer are proximately the same. Finally the differences between them are discussed in detail. To measure the aberration of spherical lens, a two single-mode-optical-fibers point diffraction interferometer is built by adding another single mode optical fiber. A convex lens is measured. The interferograms is presented.
Design of a compact wide field of view HMD optical system using freeform surfaces
M. M. Talha, Yongtian Wang, Dewen Cheng, Jun Chang
The design of a compact optical system with good image quality for head mounted display (HMD) is particularly demanding since the aberrations, weights, and center of gravity of the display are always critical. One more critical requirement is its wide field of view. We are presenting two designs of an HMD optical system, which have good optical performance while maintaining the compactness. The comparison of their optical performance and other parameters is also presented. Freeform optical surfaces are employed in one of these designs while one aspheric and some spherical surfaces are used in the other design. Freeform surfaces provide more degrees of freedom to design an optical system with less number of elements and hence to reduce the weight of the overall system. Generally, HMD optical systems are tilted and decentered in their nature; it is difficult to get rid of all the aberrations without adding extra optics in such systems. However, freeform optics also provides enough degrees of freedom in this aspect and facilitates the designer to overcome such limitations without additional optics. It is also mentioned that the fabrication technologies of freeform optics are developing now and hence allow the designers to employ such optics elements in their designs. The designing characteristics and results of the two proposed models are also discussed in this paper.
Form error automatic measurement system based on optical fiber sensing array
Shan Jin, Yong Lv, Qing Shan Chen
A novel high accuracy form error optical measurement system based on reflective intensity modulation optical fiber sensor is presented. Combing the optical fiber sensor technology and optical fiber communication technology, the system is developed by using optical switch to realize the Time Division Multiplex (TMD) of optical fiber sensing array, improve the system efficiency, reduce cost and suppress errors caused by the movement of optical fiber. SNR (signal noise ratio) and accuracy of the system are enhanced through lock-in amplifier. The intensity fluctuation of the reference light is adopted to correct the effects of the power variation of light source and so as to improve stability of the system. The experiment results show that the resolution of the system is up to 0.1μm and repeatability is about 0.5%. The architecture of the system is very simple that it can be used in multiple form error measurement of mechanical parts of different shapes by changing the number and layout of the optical fiber sensor array flexibly.
Closed loop high precision position control system with optical scale
Cheng-liang Ge, Yuan Liao, Zhong-wu He, Zhong-xiang Luo, Zhi-wei Huang, Min Wan, Xiao-yang Hu, Guo-bin Fan, Zheng Liang
With the developments of science of art, there are more and more demands on the high resolution control of position of object to be controlled, such as lathe, product line, elements in the optical resonant cavity, telescope, and so on. As one device with high resolution, the optical scale has more and more utility within the industrial and civil applications. With one optical scale and small DC servo motor, one closed loop high resolution position control system is constructed. This apparatus is used to control the position of the elements of optical system. The optical scale is attached on the object or reference guide way. The object position is sampled by a readhead of non-contact optical encoder. Control system processes the position information and control the position of object through the motion control of servo DC motor. The DC motor is controlled by one controller which is connected to an industrial computer. And the micro frictionless slide table does support the smooth motion of object to be controlled. The control algorithm of system is PID (Proportional-Integral-Differential) methods. The PID control methods have well ROBUST. The needed data to control are position, velocity and acceleration of the object. These three parameters correspond to the PID characters respectively. After the accomplishments of hardware, GUI (Graphical user interface), that is, the software of control system is also programmed. The whole system is assembled by specialized worker. Through calibration experiments, the coefficients of PID are obtained respectively. And then the precision of position control of the system is about 0.1μm.
Analyses of test glass edge-effect on coatings monitoring
Hua-qing Wang, Jing Heng, Wei-qiang Lu, Xia Li, Wei Xue
During optical coatings monitoring, the test glass edgy-effect often makes the monitoring curve falseness and thin films thickness control inaccurate. The thin films edge-effect makes the films thickness different from the test glass centre to the edge, and the edge-effect gets distinctly with coating layers increasing. NBBF (narrow band pass filter) is fabricated, and its monitoring curve and spectrum curve are analyzed. The results show that the edge-effect comes from material deposition angle when test glass does not rotate, temperature and electric field different distributing on the test glass surface. Several methods are used to minish the test glass edge-effect, such as, rotating the test glass to reduce the films thickness difference caused by material deposition angle, using quartz and other glass alike material as a link between test glass and the fixture to lessen temperature and electric field different distributing, making beam size small monitor the test glass centre field, where can be considered having no thickness different. The above methods make the thickness symmetrical over the test glass, and then the experiment monitoring curve is close to the theory curve. The results are important for the thin films automatic monitoring, especially for NBBF coatings.
Ion beam sputter deposition of zirconia thin films
Weihua Jin, Chunshui Jin, Lei Liu, Hongli Zhu, Huaijiang Yang
We determined the optical constants (the refractive index n and the extinction coefficient k) of ion beam sputter deposited zirconia thin films with spectroscopic ellipsometry (SE). First, we obtained the structure information (the layer thickness, surface roughness and layer diffusion) by fitting the grazing x-ray reflection (GXRR) spectra. The fitted surface roughness is verified by atomic force micrometer (AFM) measurement. Second, based on the acquired structure information, the measured ellipsometry spectra are fitted in the range of 240-800nm at an incident angle of 70.25 degree. The optical constants are solved based on the Tauc-Lorentz dispersion. The optical band gap extracted by SE is 4.79eV. Finally, the optical band gap is verified by Tauc plot method, which is well consistent with that of SE.
Optical characteristic of ion beam sputter deposited aluminum thin films
Weihua Jin, Chunshui Jin, Hongli Zhu, Lei Liu, Huaijiang Yang
Aluminum is a typical active metal very easy to oxidize. An oxide surface layer of about 2~6nm quickly formed in air which adds difficulty to the optical constants determination. An ex-situ method is used to determine the optical constants of aluminum thin films. First, alumina (Al2O3) thin film is deposited by ion beam sputter deposition. The optical constants and thickness are determined by spectral ellipsoemtry (SE). The thickness is verified by grazing x-ray reflection (GXRR) fitting method; Second, Al thin film with an Al2O3 cap layer on top is deposited. This cap layer is of the same deposition condition with the first step. By fitting the GXRR spectra, the structure information (the thickness of the aluminum and the cap layer, surface roughness and the diffusion between Al-Al2O3) is obtained; Third, based on the acquired structure information, the ellipsometric spectra are fitted. The optical constants of the aluminum layer are extracted with the aid of the Drude model. Finally, an induced transmission filter (ITF) is designed and deposited.
Design of absorbency photometer used in a fully automatic ELISA analyzer
Ningning Dong, Lianqing Zhu, Mingli Dong, Shouwei Niu
Absorbency measurement is the most important step in the ELISA analysis. Based on the spectrophotometry, absorbency photometer system used in a fully automatic ELISA analyzer is developed. The system is one core module of the fully automatic ELISA analyzer. The principle and function of the system is analyzed. Three main units of the system, the photoelectric transform unit, the data processing unit and the communication and control unit, are designed and debugged. Finally, the test of the system is carried out using the verification plate. The experiment results agree well with the requirements.
Fisheye supplementary lens for liquid crystal projector
Zhenyu Jiang, Lin Li, Yifan Huang
In some applications the large field-of-view projector is demanded for special purpose. However, currently available liquid-crystal-projectors generally have a field-of-view of 40 degree. These ordinary projectors can't meet the special requirements. The ordinary method for solving the problem is to remove the original projection lens and design a new fisheye lens whose field-of-view is large enough to meet the requirement. However, most current advanced projector's lenses are integrated with the circuit controllers or circuit boards. In many situations it is impossible to replace the lenses. In this paper, a new method, designing a new supplementary lens for the original projector without destroying its structure, is presented. The field-of-view of the new system can be expanded to 180 degree. Since the exit beam of the original projector lens is similar to parallel beam, the entrance beam of the supplementary lens is also parallel beam. That means, both the entrance and the exit beams of the supplementary lens are parallel beams. So the supplementary lens can be treated as a telephoto system. In this paper, the focal length of the original projector lens is 16.4 millimeter, the field-of-view is 42 degree, and the required field of view is 180 degree. The new designed supplementary lens is a reverse Galilean telephoto system. The software Zemax is used to design the system. Results show that the system is well designed and it can meet the actual requirements.
A novel verification device for optical aiming equipments
Zhi Zhu, Xiaosong Guo, Hongquan Ding, Lipei Ding
The main components of the device are three optical tubes. The upper tube and lower tube are two mini autocollimators. The middle tube is a mini autocollimator with two-dimensional small angle synchronous measurement function. The optical configuration of each tube and the processing circuit of the middle tube have been described in detail. In order to simplify the design of the middle tube, we proposed a double-lamp and double-reticule measurement mode and place all the reticules on refraction routes to improve recognition precision of the CCD acceptor. The principle of two-dimensional angular measurement using "N" reticule and one linear CCD has been introduced. We also proposed a subdivision method of small angle measurement to control the ultimate error within 0.5". Using the middle tube itself or combining it with the other two tubes, we can verify all the main performance parameters of the existing optical aiming equipments. The measurement uncertainties have been evaluated at the end of the paper. The results show that the measurement uncertainties of the device can fully meet the requirements of verification work. The device has the advantages of small volume, high automation, convenient verification operation and good reading repeatability. It has been used in some measurement stations successfully.
Optimization control based on hierarchical coordination for a space-based telescope
Baiwei Guo, Zaozhen Liu
The performance of a space-based telescope with a segmented primary mirror is seriously decreased due to thermal deformation of its optical components, deployment procedure, and manufacturing procedure. To achieve diffraction-limited imagery, the telescope usually has multiple wave-front correctors, such as deformable primary mirror segments and a MEMS mirror. A control archtecuture of hierarchical coordination is established for such a space-based telescope in this papar. The initial wave-front errors are decomposed by wavelet transformation, then low- frequency errors are corrected by the primary mirror segment, and high-frequency errors are corrected by the MEMS mirror. A simple coordination control method and an optimization control method are applied to diliver the wave-front errors to the two corrctors. The simulation results show the optimization control can result in better correction effect.
The measurement and system error analysis of diopter and optical parallax in optical pointing system
Weiguo Cao, Changxi Xue, Lijuan Li, Zhiyong An
The measurement of diopter and optical parallax of optical system is preceded traditionally with collimating device or diopter cylinder, the result of which is influenced largely by subjective operator. In order to increase the pointing accuracy of the telescope system, a high resolution CCD is adopted and the image of which is processed by computer, then the result of measurement is outputted by latter. The measuring method which is processed in the paper increase the degree of accuracy, cancel the influence of subjective factor and simplified the manipulation. Principle of test and measurement of diopter and optical parallax is represented and computation formula is deduced also. Then, error analysis of the test and measurement system is presented in the paper.
The research for EO imaging system simulation
Hao-ming Yang, Ling-jie Wang, Zhi-liang Fang, Jian-ping Zhang, Xin Zhang
Electric-Optical (EO) imaging systems are modern systems, especially the one consists of aspheric optics and image processing called wavefront coding system. The design concept of this kind system is totally different from the traditional image system. The trade-off between the complexity of the image deconvolution and the depth of focus extended should be considered. So we establish a simulation model consisting of optical optimization design, system signal-to-noise ratio analysis and recovered image evaluation. The data can be exchanged among them. This simulation tools will be very useful in system design process.
Application of a high-precision interferometric measuring system as phasing the segmented primary mirrors of the next generation of ground-based telescope
Helun Song, Hao Xian, Wenhan Jiang, Changhui Rao, Jian Huang
Optical telescope systems with segmented mirrors require precise coalignment of their segments to achieve the desired full near-diffraction-limit performance. The segment vertical misalignment (piston error) between the segments must be reduced to a small fraction of the wavelength (<100nm) of incoming light. We have considered an interferometric piston error measurement system based on a high-aperture Michelson interferometer layout for accomplishing such objectives, The piston error between the segments can be extracted from the interferometric fringes mismatching, The innovation introduced in the optical design of the interferometer is the simultaneous use of monochromatic light and two-wavelength combination white-light source in a direct method for improving the central fringe identification in the white-light interferometric phasing system. We find that this two-wavelength combination technique can greatly increase the visibility difference between the central fringe and its adjacent side fringes, and thus it offers an increased signal resolution. So make the central fringe identification become easier, and enhance the measure precision of the segment phasing error. As a result, it is suitable for high-precision measurement purpose and application in the segment piston error phasing system.
A binary beam-splitter for lidar beam-shaping in laser imaging application
Guoxing Zheng, Song Li, Hui Zhou
In three-dimensional laser imaging system, multi-channel laser transmitting and receiving can increase the coverage area and provide better surface information and roughness than traditional single channel. The multi-channel laser beams can be realized by a diffractive beam-splitter, and in this paper the problem of designing a binary beam-splitter that produces 8×8 uniform intensity beams from a Gaussian-profile input beam is considered. To produce spots with even number, each period of the beam-splitter is divided into four phase-inverse parts to compress the even diffractive orders and reserve the odd orders. Simulated annealing algorism is applied in the beam-splitter design and in the numerical simulation, fabrication error tolerance, environmental issues, input field fluctuation and other factors are considered. The simulated results show that the performance of the device is quite insensitive to the amplitude fluctuation of input laser beam, the diffractive efficiency exceeds 77% and the uniformity between spots is about 0.12%, which confirm the efficiency of the design. This device will be fabricated in our lab soon.
Design of an inflatable and deployable space reflecting concentrator
Benxin Wang, Zhao Yang, Bingjing Mao, Tianxiang Zhang, Yukun Feng
An inflatable and deployable reflecting concentrator has been designed based on the Advanced Technology of Inflatable and Deployable Space Structure to concentrate solar energy. Around the focal area, a conversion plate made of thermoelectric semiconductor is set to convert the solar energy gathered into electricity to drive various spacecrafts. The whole system will be made mainly of polyester membrane. In pursuit of steady performance, solidify-technology is applied to solidify the structure after it is deployed. The membrane structure boasts the following advantages: lightweight, high efficiency, easy deployment and low cost. Those are of great importance in resolving the contradiction of launch vehicle's limit capability and the growing size of space equipments. Its efficiency and manufacturability have been analyzed and proved. The result shows that it has great business value. Several plans of its application in the aerospace engineering are also presented in this paper.
Optical properties of porous anodic alumina films implanted with ZnO nanoparticles
Porous anodic alumina (PAA) films with highly ordered pore arrays were prepared by a two step anodization process in 0.3M oxalic acid solution at 0°C. ZnO nanoparticles were loaded into the nanopores of PAA films by soaking the PAA films in an aqueous solution of zinc acetate and then annealing them at 500°C. The PAA films and ZnO/PAA composites were characterized by scanning electron microscope, X-ray diffraction, ultraviolet-visible spectrophotometer and fluorescent spectrometer. The highly ordered PAA films are amorphous, the PAA films have a high optical transmissivity in visible range and a wide blue photoluminescence band in the wavelength range of 350~550nm. The photoluminescence intensity and peak position depend strongly on the excitation wavelength. ZnO nanoparticles loaded into PAA films display a pure wurtzite ZnO phase, the average diameter of ZnO particles is 10.8nm. The transmissivity of PAA films declines after ZnO is loaded in. The photoluminescence of ZnO/PAA films exhibits intense and broad emission spectra in the wavelength range of 350-600nm. There is only one strong photoluminescence peak at 430nm when excited at 340nm wavelength, the photoluminescence peak divides into two peaks of 410nm and 460nm while excited at 380nm wavelength. The oxygen vacancies, F+ centres, are responsible for the photoluminescence of ZnO nanoparticles loaded into PAA films.
Hybrid phase-diverse phase retrieval algorithm in wavefront sensing for segmented optics
Heng Mao, Xiao Wang, Dazun Zhao
Wavefront sensing of the segmented optics usually includes two steps. The first step is to sense and correct each segment's position error (co-phasing error) and figure error (aberration), and the second step is to sense the residual wavefront error over the whole aperture. However, due to the limited correction capability and accuracy of the figure sensing and co-phasing sensing in the first step, the original fine wavefront sensing (WFS) algorithm in the second step, the Modified Baseline algorithm, would be failed once the absolute figure difference at nearby edges of nearby segments exceeds λ/2. Thus a Hybrid Phase-diverse Phase Retrieval (HPDPR) algorithm, which adds the Levenburg-Marquardt (LM) algorithm to eliminate each segment's residual position error for decreasing the absolute figure difference, is proposed. Simulations have proven the validity of the HPDPR algorithm, and shown its robustness and high WFS accuracy.
Summarize of conformal optics
Nan Zhao, Jun Chang, Zhihui Sun, Yongtian Wang
The state of conformal optics is described in this article, it explains the concept of the conformal optics and its application in both military and daily life, the difficulties and solutions to them in the design, also together with the developing of the tools and techniques which make the use of conformal optics into reality is included. And in the last part of the article, the comparison of some testing methods of aspheric surface is described.
The preparation of AZO films with RF sputtering
Zhinong Yu, Jin Xu, We Xue, Xia Li, Jinwei Li
ZnO:Al is a kind of N type semiconductor material with low resistance and high transmittance in the visible region. Using ZnO mixed with Al2O3 (2 wt %) as target, ZAO thin films were deposited on glass substrate by RF magnetron sputtering. Orthogonal experiments were used to analyze the effects of main factors (oxygen flux, argon pressure, substrate temperature, RF power) on the properties (transmittance, resistance) of the film. The results showed that the optimal parameters in the room temperature are: the partial pressure of argon without oxygen is 0.1 Pa, RF power is 400w. After vacuum annealing at 220°C, the deposited film exhibits visible transmittance of above 82% and minimum sheet resistance in 3.36 × 10-3 Ω • cm.
The effects of process parameters on the properties of ITO films grown by ion beam-assisted deposition using 90In-10Sn (wt%) alloy
Zhinong Yu, Longfeng Xiang, We Xue, Huaqing Wang, Weiqiang Lu
ITO films have been grown by ion beam-assisted deposition (IBAD) using 90In-10Sn (wt%) alloy. The electrical and optical properties of these films have been investigated as a function of oxygen flux, evaporation rate, ion energy and substrate temperature during deposition. The films with resistivity as low as cm Ω 2.4 × 10-3 Ω • cm (at room temperature) and 8 × 10-4 Ω • cm (at 150°C) have been deposited, and the transmittance of all samples in the visible range is above 82%. The deposited films at room temperature are polycrystalline with a preferred orientation of (222) and the size of crystal particle is about 21nm, and the surface roughness for the ITO films grown at room temperature is Ra=5.32nm.
An integrated measurement system for LED thermal, optical and electrical characteristics
Xiyong Zou, Xiaoming Zheng, Shangzhong Jin, Kai Ni, Huaming Zhou, Xianqi He
Thermal, optical and electrical parameters are main characterization of light-emitting diodes (LEDs). Consumers are often concerned about the explicit properties such as luminous intensity, luminous flux and color. But Manufacturers may pay more attention to the thermal characteristic. Excess heat at the junction directly affects the LED performance in terms of color shit, light output and life. To measure all these parameters of LED accurately and simultaneously, we designed an integrated system, product number SSP8112, which was based on a new developed thermal, optical and electrical measurement instrument and a specially-made integrating sphere with temperature controller. The thermal measurement segment of the instrument was developed in accordance with JESD51-1 standard; it can automatically record the transient response curve of heat with a 50μs time resolution and a 0.5mV voltage resolution. And the integrating sphere, which has high light reflectivity, good thermal insulation and tolerance to high temperature, was used to achieve the optical response during the experiment. The principle and structure of this system were introduced and discussed, and at the end an application example was presented.
Characteristics of the photoinduced current pulses of the optically addressed photorefractive BSO spatial light modulators
Xiujian Li, Wenhua Hu, Hui Jia, Jiannan Zhang, Juncai Yang
Along with the development of parallel optical computing, more and more two-dimensional optical modulating and transforming devices with high response speed are needed. As the response times of most of the photorefractive crystals are very short, optically addressed photorefractive BSO spatial light modulators are the most important devices which have been successfully used in many two-dimensional optical information processing systems. However, the response time is still too large for optical computing applications. In order to achieve adequate contrast ratio, a majority of the operation process of the photorefractive spatial light modulators have to account for the accumulating of the photoinduced charges so as to build up a strong internal electric field. The experiment results show that, the photoinduced currents through the external circuits which provide the applied voltage behave with the characteristics of pulses. The properties of the current pulses vary with the wavelength of the write-light, the direction of the external field, the value of the applied voltage, the thickness of the BSO films and the properties of the external circuits. The analysis of the photoinduced current pulses is useful for optimizing the structure, the operation modes and the performance of the photorefractive spatial light modulators. Furthermore, the analysis can provide some useful information for choosing appropriate materials and devices for optical computing applications, and building up efficient all-optical architecture for the future parallel optical computers.
Design of a three field-of-view IR system
Jun Chang, Zhicheng Weng, Yongtian Wang, Huilin Jiang, Xiaojie Cong
The design method and result are described for an infrared zoom system with three fields of view. Its zoom ratio is 9, and the corresponding field of view is 3°~27°. The working waveband is from 3μm to 5μm, and its total length is required to be no more than 400mm. The final optical system consists of 9 elements, with two aspheric surfaces and a diffractive optical element. It achieves diffraction-limited imaging at the middle infrared waveband. From the last result we can know using the diffractive optical elements can eliminate the color aberration and helps to reduce the cost of the system; and using the rotated elements in the system it is easy to change the field-of-view and satisfied the cooled detector requirements.
Compressed infrared mirror-lens system design
Tao Ren, Jun Chang, Zhi-cheng Weng, Huilin Jiang, Xiaojie Cong
In the special optical system such as the infrared optical system, the compressed construction and mini module is necessary. In this paper, a kind of compressed infrared lens design is proposed. The total length and focus length ratio is no more than 0.6 and this type system is accessible of temperature, the key step in this design is how to make the system actable. The parasitic light is also analyzed. The couple efficient of cool stop is 100%.
Superprism structure with linear spatial dispersion based on thin film Gires-Tournois cavity
Weige Lv, Dawei Zhang, Jiabi Chen
A periodic multi-layer thin film stack, which behaves as one-dimensional photonic crystal, exhibits "superprism effect", or high spatial dispersion, which can be used for wavelength multiplexing and demultiplexing. For application purposes, thin-film stacks of multi-cavity Gires-Tournois structure are more suitable to design linear spatial shifts than periodic multi-layer structures. Using the modified design procedure for all-pass filters, a mathematical model of the spatial dispersion with normalized frequency is set up to simulate the designed spatial dispersion at given wavelength band. As a simulated result, the all-pass polynomial coefficients, and reflectivity coefficients of reflectors are obtained. According to the calculation based on resonate theory, the spatial dispersion of the designed structure is in accordance with the required dispersion. Then, this structure is implemented in thin film stacks, with layers of different periodical numbers as different reflectors and materials of high or low refractive index as cavity materials. Adjusting the cavity lengths also performs optimization. In our design, a linear spatial shift of 25μm caused by dispersion is designed at 850nm and 1550nm, and implemented in thin film stacks. Comparisons are made between designs of different center wavelength, different cavity lengths, and different number of cavities.
Computer-aided alignment for the segmented mirrors of three-mirror optical system
Yifan Huang, Lin Li
Computer-aided alignment (CAA) is a significant technique to correct errors which are caused by the misalignment of each element in an optical system. It is especially important in such areas as space remote sensing optical systems, since manual adjustment is impossible when it operates in orbit. In this paper, a three-mirror optical system is adopted as an example to perform CAA. Principle of this system is introduced. And based on the CAA algorithm, the method of CAA for the segmented mirror is expatiated in detail. A numerical simulation of CAA has been performed for the segmented mirror to verify the ability and accuracy of the method. Comparisons of the image qualities between the pre-alignment and post-alignment systems are also presented. These results indicate that the CAA method is feasible.
Research on blue emitting BaAl2S4: Eu phosphor layers of TFEL
Zhao Ding, Zhinong Yu, Wei Xue
Europium-doped barium thioaluminate based on BaAl2S4: Eu is currently the most efficient blue phosphor for inorganic thin film electroluminescence. Many researchers and experts have been investigating on this material and have also got great achievements. The phosphors exhibit EL luminescence up to 900cd/m2, peak efficiency over 1 lm/W, and long life time of 30 thousand hours, which is sufficient to TV display application. In this work we will review the experimental research process of the fabrication on the BaAl2S4:Eu phosphor layers, introduce the four main methods of fabricating the blue emitting phosphors: two targets pulse electron beam evaporation; four targets pulse electron beam evaporation; two targets sputter deposition and one target sputter deposition. Finally we will also summarize the principal conclusions drawn from those experiments mentioned above, which will be beneficial to our research in the future.
Study on the laser beam transformation and its measurement in laser processing
Ruifang Ye, Yuanqing Huang, Zihua Weng, Tianlin Hu, Shufen Lin, Huangping Yan, Zhaoxi Wu
The shape and energy distribution of laser beam directly define its applications in laser processing. In order to cater for different laser processing requirements, the input beam always needs to be transformed. The transformation between the solid beam and ring beam can be realized by the axicon-based optical devices. A beam transformation optical system, which uses a pair of positive axicon and negative axicon is designed and analyzed. The novelty of the optical system is not only that they can focus the laser beam on a ring pattern or solid beam pattern, but also that they can change the diameter of patter easily by adjusting the separation of the two conical lenses. The optical system is analyzed based on the geometry optical theory. By adjusting the separation of the convergent conical lens and the divergent conical lens, different shapes and the energy distributions are gained. At last, a measurement method of the beam profile is introduced which based on charge coupled device (CCD) The results show that the axicon-based beam transformations raise the effectiveness of laser and have a wide application prospect in laser processing field.
Study of wavefront error and polarization of a side mounted infrared window
Jiaguo Liu, Lin Li, Xinqi Hu, Xin Yu
The wavefront error and polarization of a side mounted infrared window made of ZnS are studied. The Infrared windows suffer from temperature gradient and stress during their launch process. Generally, the gradient in temperature changes the refractive index of the material whereas stress produces deformation and birefringence. In this paper, a thermal finite element analysis (FEA) of an IR window is presented. For this purpose, we employed an FEA program Ansys to obtain the time-varying temperature field. The deformation and stress of the window are derived from a structural FEA with the aerodynamic force and the temperature field previously obtained as being the loads. The deformation, temperature field, stress field, ray tracing and Jones Calculus are used to calculate the wavefront error and the change of polarization state.
Application of virtual optical assembly in research and development of special optical instrument
Ze-xin Xiao, Zheng Sun
Embarks from the virtual assembly definition, unifies author's practice and exploration in special optical instrument research and development application, the concept and content of virtual optical assembly is proposed. According to our preliminary practice, virtual optical assembly can be applied to the optical path which has high-precision requirements of the optical surface location and the special optical system that has strictly symmetrical optical path, and also can be used to identify or verify the tolerance of optical parts and components. In the article the author will give the cases which are experienced.
Optical design of a confocal scanning laser ophthalmoscope based on adaptive optics
Jing Lu, Yudong Zhang, Xuejun Rao, GuoHua Shi, HanSheng Yang, Can Wang
The optical design of a confocal scanning laser ophthalmoscope based on adaptive optics (AOSLO) is described in this paper. Spherical mirrors are used for pupil relay and astigmatism compensation. The main optical system achieves diffraction-limited performance through the entire scanning angle (6mm pupil, 3 degree on pupil plane).
Contamination effects of oil paint on the space optical system
Chun-lian Lu, Yan-ping Zhou, Yi Sang
Space environment in which the space optical system exposed includes space vacuum, cryogenics, and energetic particles and etc. The contamination effects on the space optical system, so the optical damage occurs. And the image quality of the system will be affected. In this paper, the effects of contamination to optical system were discussed, and the contamination source and its space distribution were analyzed. An experiment was designed to determine the effect value. Numeral fitting method was used to analyze the relationship of the optical damage factor (Transmissivity decay factor) and the contamination degree of the optical system. In the experiment, the contamination degree was expressed by mass thickness with the unit μg/mm2. Oil paint was used as the contamination source. Comparison between previous and present researches was given.
The design of the CMOS wireless bar code scanner applying optical system based on ZigBee
Yuelin Chen, Jian Peng
The traditional bar code scanner is influenced by the length of data line, but the farthest distance of the wireless bar code scanner of wireless communication is generally between 30m and 100m on the market. By rebuilding the traditional CCD optical bar code scanner, a CMOS code scanner is designed based on the ZigBee to meet the demands of market. The scan system consists of the CMOS image sensor and embedded chip S3C2401X, when the two dimensional bar code is read, the results show the inaccurate and wrong code bar, resulted from image defile, disturber, reads image condition badness, signal interference, unstable system voltage. So we put forward the method which uses the matrix evaluation and Read-Solomon arithmetic to solve them. In order to construct the whole wireless optics of bar code system and to ensure its ability of transmitting bar code image signals digitally with long distances, ZigBee is used to transmit data to the base station, and this module is designed based on image acquisition system, and at last the wireless transmitting/receiving CC2430 module circuit linking chart is established. And by transplanting the embedded RTOS system LINUX to the MCU, an applying wireless CMOS optics bar code scanner and multi-task system is constructed. Finally, performance of communication is tested by evaluation software Smart RF. In broad space, every ZIGBEE node can realize 50m transmission with high reliability. When adding more ZigBee nodes, the transmission distance can be several thousands of meters long.
Design of optical elements for imaging the Earth's plasmasphere
Li-hui Wang, Xiao-kun Wang, Bo Chen
Studying the distribution of He+ in Earth's plasmasphere by detecting its resonantly-scattered emission at 304Å will record the structure and dynamics of the cold plasma in Earth's plasmasphere on a global scale. EUV imaging systems usually utilizes near normal incidence optics including multilayer mirror and filter. In this paper, the space condition of the Earth's plasmasphere to confirm the expected performance of mirror and filter for this task were analyzed and some guidelines for the design of the optical elements were introduced. In order to achieve higher response at 304Å and reduce 584Å radiation for the optical system, a new multilayer coating of Mo/Si with UOX (x=2~3) was developed, and it is indicated that promising filter material is Al/C with a nickel mesh. In addition, we compute the reflectance of multilayer mirror based on optical constants and the transmission of the filter based on atomic scattering factor. The results show the multilayer mirror has high reflectance of 26.27% at 304 Å and low reflectance of 0.60% at 584Å. Finally, the conversion efficiency of mirror coupled with filter is 6.88% at 304Å and 0.01% at 584Å.
Antireflection coatings of broad angle range for ultraviolet band designed by rugate coatings
Guanliang Peng, Jiankun Yang, Shengli Chang, Hongwei Yin, Juncai Yang
Rugate coatings are usually defined as optical coatings that present a continuous variation of refractive index in the direction perpendicular to the film plane. Such kind of optical coating has optical and mechanical properties that differ from those of conventional high-low-index stacks. Especially, the broad angle range and the low optical scatter level make them superior to traditional stacks. Antireflective (AR) coatings have found increasing applications. In this paper, the principal aspects of rugate coatings theory are discussed and the emphasis is focused on polarization effect of the incident light. The reason accounting for difference of the transmissivity was analyzed in the case of polarization and board angle incidence. To eliminate polarization effect, a method of designing antireflection coatings using rugate coatings was demonstrated. Antireflection coatings for the ultraviolet spectral region in the wavelength range 300-400 nm and incidence angle from 0 to 80 degree were designed. Then the implementation of optimization recurred to optimac and conjugate gradient. It shows that the result of optimization is ideal. For AR coatings, this design method can enhance the ratio of utilization of optical energy.
Influence of the size dispersion on the emission spectra of the hydrogen passivated Si nanoparticles in SiNx
Wenge Ding, Zhongxiu Hao, Wei Yu, Jiangyong Zhang, Yachao Li, Guangsheng Fu
The influence of the size dispersion on the emission spectra of the hydrogen passivated silicon nanopaticles (Si NPs) in silicon nitride thin films, which are grown by helicon wave plasma-enhanced chemical vapor deposition (HWP-CVD) technique with SiH4, H2 and Ar-diluted 6.25% N2 as the reactant gas sources, have been investigated. Transmission electron microscopy examination shows that Si NPs are isolated from the others by silicon nitride barriers and the sizes of Si NPs in silicon nitride matrix are distributed within a wide range. The luminescent due to quantum confinement effect of Si NPs embedded in the SiNx matrix was guaranteed by adding H2 into film deposition process. The emission correlated to the defects such as excess silicon voids and nonradiative recombination centers have been suppressed and a strong PL with a wide band was observed. The photoluminescence (PL) spectra were investigated under different excitation energy (Eex). It is shown that both the PL peak energy and their full width at half maximum (FWHM) show a decrease trend with decreasing the Eex, and no obvious PL can be observed when the Eex lower than a certain Eex. And at high excitation energy contribution of the smaller particles in size becomes remarkable larger, thus it may be extremely difficult to correlate the PL spectra with the mean size of the Si NPs. These results are explained by quantum confinement effect model taking into account there existing a size distribution of Si NPs in the SiNx matrix.
Influence of hydrogen dilution on bonding configurations and optical absorption properties of a-Si/SiNx composite films
Wei Yu, Ya-chao Li, Wen-ge Ding, Jiang-yong Zhang, Yan-bin Yang, Guang-sheng Fu
Infrared absorption and optical transmission combined with the optical absorption model have been used to study the influence of hydrogen dilution on bonding configurations and optical absorption properties of nano-sized amorphous silicon embedded in silicon nitride thin films (a-Si /SiNx). The amount of bonded hydrogen was investigated by the N-H and Si-H infrared absorption bands. The optical band gap and sub-gap absorption coefficient were obtained by optical absorption spectra. It is shown that the film deposited at 20 sccm hydrogen flow rate, which contains the highest bonded hydrogen content, has the maximum optical band gap and the lowest density of defects. Furthermore, the optical band gap and mean size of a-Si nano-grains in SiNx matrix were obtained through simulating the optical absorption data using an optical absorption model. The simulated optical band gap was in good agreement with the experiment results. These results suggest that appropriate hydrogen dilution in the precursor is beneficial to improving the microstructure and optical properties of the a-Si /SiNx composite films.

redpajama_set_name: RedPajamaCommonCrawl


Pope Francis has rightfully earned a reputation for advocating for the world's marginalized. Now he's coming out with a major message that will urge the world to tackle climate change. In it, he also shares his concerns about maintaining biodiversity.
Stephanie Kirchgaessner and John Hooper (@john_hooper) wrote this piece for The Guardian.
This will likely place the Pope at odds with many U.S. politicians, prior to his visit to the U.S. to attend a United Nations meeting and to address a joint meeting of Congress. The pope will also reportedly call for a new "global political authority" to address key environmental issues, which he regards as a critical social justice issue.
A must read, and a story that we will continue to follow.


On Sunday, March 24th, Macy's Herald Square launched its 45th annual two-week long Flower Show, Journey To Paradisios, celebrating the arrival of spring with discovery, color, and wonder.
The opening revealed spectacular floral designs made up of more than 5,000 types of plants, trees, and flowers that transported visitors into a mufti-dimensional world of space and adventure through flora and eccentrically landscaped gardens blasting off into the wonder and mystery of the planet Paradisios.
The Journey To Paradisios theme brings to life the cosmic tale of Space Flight Director Lucy Ryder and her discovery of the planet Paradisios – a pristine exoplanet, untouched by human technology and filled with resplendent plant life. Ryder and R.H. Macy IV, (a pilot-turned-cosmonaut, and the great-great-great grandson of Macy's founder) set out on the adventure of a lifetime as they discover the planet's extraterrestrial beings and fantastic flora.
Throughout opening day, guests were invited to explore a host of themed in-store events and observed seven fashion pods throughout the main floor featuring looks designed by FIT students who were challenged to create original designs inspired by the Journey to Paradisios theme. Visitors walked through several intergalactic creations featuring a space ship launching into outer space through the roof into a star-filled night sky and colorful inhabitants, floating cities, alien technology, and whimsical plant life of planet Paradisios.
The two-week show is in full bloom and closes on Sunday, April 7th.