Reflective LaRocca Refractive Desired Device Binocular System Monocular System FOV 10 degrees 7 degrees 7 degrees Handheld No Yes Yes Probe/scanner Ideally <20 pounds ~50 pounds 94 grams weight Must be <50 pounds Cost N/A N/A <$35,000 #scanning mirrors 2 1 2 (one for each eye) Battery Powered No No Yes Wavelength (nm) 840 840 852 Table 1: Comparison of the two devices that are motivation and the device that needs to be designed. System Overview Design Constraints/Performance The system needs to be able to generate a 512x512 pixel image Wavelength: 852 nm Retinal scan ± 3.5 degrees Diffraction limited imaging Device Layout Figure 3: Device Schematic showing the optical components required for imaging both eyes simultaneously. The components are all labeled and the key can be found in the lower left corner. Identical components are labeled with the same abbreviations. In the current system, we have a Keplerian telescope with a 3.5x magnification, that expands the beam it is incident on the MEMS scanner and expands the beam diameter. The magnification was determined by the clear aperture (CA) of the MEMS scanner and the desired 3 mm beam diameter at the surface of the eye. Though the CA of the MEMS is 1.2 mm, the usable portion is about two thirds of the total CA as the MEMS is positioned at a 45 angle to the incident beam. The MEMS is placed at the entrance pupil of the telescope as it allows the angle of the beam incident on the eye to be controlled. The angle at which the light enters the telescope is equal to the angle exiting the telescope. There is also a fold mirror at the intermediate image plane allowing for another degree of freedom when aligning the system for retinal tracking as it can be used to reposition the beam on the retina. While it is not shown in the above schematic, we have made the decision to add an aperture prior to the beam splitter to clip the beam rather than using the MEMS to clip the beam as light could reflect from the area surrounding the MEMS introducing stray light to the system.
Reflective Binocular System LaRocca Refractive Monocular System Desired Device FOV 10 degrees 7 degrees 7 degrees Handheld No Yes Yes Probe/scanner weight ~50 pounds 94 grams Ideally <20 pounds Must be <50 pounds Cost N/A N/A <$35,000 #scanning mirrors 2 1 2 (one for each eye) Battery Powered No No Yes Wavelength (nm) 840 840 852 Table 1: Comparison of the two devices that are motivation and the device that needs to be designed. System Overview Design Constraints/Performance The system needs to be able to generate a 512x512 pixel image Wavelength: 852 nm Retinal scan ± 3.5 degrees Diffraction limited imaging Device Layout Figure 3: Device Schematic showing the optical components required for imaging both eyes simultaneously. The components are all labeled and the key can be found in the lower left corner. Identical components are labeled with the same abbreviations. In the current system, we have a Keplerian telescope with a 3.5x magnification, that expands the beam it is incident on the MEMS scanner and expands the beam diameter. The magnification was determined by the clear aperture (CA) of the MEMS scanner and the desired 3 mm beam diameter at the surface of the eye. Though the CA of the MEMS is 1.2 mm, the usable portion is about two thirds of the total CA as the MEMS is positioned at a 45 angle to the incident beam. The MEMS is placed at the entrance pupil of the telescope as it allows the angle of the beam incident on the eye to be controlled. The angle at which the light enters the telescope is equal to the angle exiting the telescope. There is also a fold mirror at the intermediate image plane allowing for another degree of freedom when aligning the system for retinal tracking as it can be used to reposition the beam on the retina. While it is not shown in the above schematic, we have made the decision to add an aperture prior to the beam splitter to clip the beam rather than using the MEMS to clip the beam as light could reflect from the area surrounding the MEMS introducing stray light to the system.
Tracker_FinalDDD.docx