text:
\section{Introduction}
\label{sect:intro}
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  \footnotesize \textsf{D.~Flamm \textit{et al.}, "Structured light for ultrafast laser micro- and nanoprocessing," Opt. Eng. 60(2) 025105 (24 February 2021); \url{https://doi.org/10.1117/1.OE.60.2.025105}.}
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   © 2021 Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited. \url{https://doi.org/10.1117/1.OE.60.2.025105}.}
\end{textblock*}
Miniaturization---the trend to manufacture ever smaller products and components while retaining their function and quality---is a process that sooner or later affects all established technologies. The prospect of products with reduced sizes and weights and, therefore, costs, leads manufacturers to develop novel tools and processing strategies. Ultrashort pulsed lasers represent unique, industry-ready tools for machining in the micro- and nanometer scale. Pulse durations from $\sim\unit[100]{fs}$ up to $\sim \unit[10]{ps}$ and corresponding extreme peak intensities lead to interaction processes with all conceivable materials, independent of the state of matter or absorption behavior\cite{feng1997theory, nolte1997ablation, couairon2007femtosecond}. \par
Transparent and brittle materials, such as glasses or sapphire, can be found in almost every optoelectronic device and represent particularly challenging examples for processing mainly due to extreme mechanical or chemical properties. Especially here, ultrashort pulsed lasers show enormous potential, acting as subtle tools for a controlled energy deposition at the surface or inside the volume. At the same time, desired optical properties or implemented optical functionalities of non-processed, adjacent areas remain unaffected due to a marginal thermal diffusion\cite{chichkov1996femtosecond, nolte1997ablation}. A single, nearly diffraction limited Gaussian focus distribution usually provided by this class of lasers represents the ideal focus form for a certain laser machining process only in exceptional cases. More sophisticated spatial distributions become especially attractive when considering efficient, industry-compatible concepts intended to yield high throughputs\cite{Tillkorn2018,Flamm2019,jenne2020faci, pang2020focal}. Thus, in addition to the remarkable temporal properties of ultrashort pulsed lasers there is a need for tailored focus distributions in all spatial degrees of freedom \cite{Kumkar2014, Flamm2015, Flamm2019}. \par
Recently, the term ``structured light'' has been used to cover advanced beam shaping concepts in which all spatial and temporal properties of laser radiation are manipulated to achieve tailored light states.\cite{rubinsztein2016roadmap, forbes2020structured}. In the present case, temporal characteristics are determined by the industrial ultrafast laser platforms used with band limited pulses of $\sim\unit[1]{ps}$ duration (or pulse trains thereof, \textcolor{black}{see, e.g. Refs.\,\citenum{herman2003burst,kerse2016ablation} for the beneficial use of burst modes}).\footnote{Simultaneous spatial and temporal focusing (SSTF) concepts\cite{Kammel2014} are not part of this review, since applied pulses exhibit durations of $>\unit[100]{fs}$.} The spatial properties, on the other hand, are determined by efficient and power-resistant concepts based on, e.g., diffractive-optical elements (DOEs)\cite{cumme2015regular, brodsky2019adjustable}, free-form optical elements (ROEs)\cite{wu2013freeform, cumme2015regular} or geometric phase holograms (GPHs)\cite{kim2015fabrication} (stationary or adaptive versions) illuminated single or multiple times. Together with the focusing unit (used NAs up to $0.5$)\cite{Flamm2019}, the beam shaping elements form the processing optics\cite{Flamm2019} usually fed with free-space or fiber-guided pulses \cite{wang2013hollow, baumbach2020hollow}, see Fig.\,\ref{sschool}.
\par
The broad accessibility of liquid-crystal-based spatial light modulators has attracted the attention of the laser processing community, too \cite{mauclair2013ultrafast, Flamm2019, Jenne2018, jenne2020faci, Bergner2018, lazarev2019beyond}. There is ongoing progress regarding the display's ability to resist high peak and average powers, so that these devices may be part of future industrial processing optics forming ultrashort pulsed optical radiation in the kilowatt and tens-of-millijoules class\cite{sutter2019high, saraceno2019amazing, muller202010}.
\par Equally conceivable are concepts where the laser system itself is able to provide structured light. Such systems based, for example, on intra-cavity beam shaping\cite{naidoo2016controlled, forbes2017controlling}, amplified transverse fiber modes\cite{lin2020high, lin2020reconfigurable} or on coherent beam combining\cite{shekel202016kw, prossotowicz2020coherent,prossotowicz2020dynamic} enable complex focus shaping up to highly dynamic focus scanning and splitting. In the future, these concepts could replace the classical processing optics. Currently, however, the required degrees of freedom in focus distribution or the available (peak) power of the laser systems are still lacking.
\par
The paper will review strategies for the micro- and nano-processing of transparent materials such as cutting (Sec.\,\ref{sec:cutt}), selective laser etching (Sec.\,\ref{sec:SLE}) or welding (Sec.\,\ref{sec:weld}) as well as surface ablation and drilling of metals (Sec.\,\ref{sec:drill}) that become possible or attractive for industry by spatiotemporal beam shaping.
\begin{figure*}
    \centering
    \includegraphics[width=1\textwidth]{sschool-Seite001.jpg}
    \caption{Modular concept for ultrashort pulse processing optics. Free space or fiber-guided pulses (a) are illuminating beam shaping elements (b) and propagate in free space or are transformed into their respective far-fields (c). After further possible beam shaping and propagation steps (d) the resulting optical fields are focused/imaged by an objective onto or into the workpiece (e). Alternating beam shaping and beam propagation/far-field transformation steps may be realized by single illuminating multiple elements or by illuminating single elements multiple times, cf. Sec.\,\ref{sec:drill}. Focusing/imaging units may be realized, for example, as $f$-$\theta$-objectives or as microscope objectives.\cite{Flamm2019}.}
    \label{sschool}
\end{figure*}

\section{Laser cutting of transparent materials}\label{sec:cutt}
There are different processing strategies known for cutting of transparent materials using ultrashort pulsed lasers\cite{nisar2013laser, Kumkar2014, kumkar2014cutting}. The concept presented in the following is based on a spatially controlled energy deposition into the volume of the workpiece.
\begin{figure*}
    \centering
    \includegraphics[width=1\textwidth]{meinbess-Kopie2-Seite001.jpg}
    \caption{Menu of diffracting, non-diffracting and quasi non-diffracting beams designed for transparent materials processing\cite{Flamm2019}. All cases show the propagation behavior (cross section, top) and corresponding transverse intensity profile at a selected propagation distance (bottom). Gaussian focus distribution (for direct comparison) (a). Fundamental Bessel-Gaussian beam (b). Non-diffracting beams with elliptical central spots (c)\cite{chen2019generalized, jenne2020faci}, higher-order Bessel-Gaussian beams (d)\cite{vasilyeu2009generating, Flamm2017, xie2015tubular}, multi-focus distributions (e)\cite{chen2019generalized}, quasi non-diffracting beams exhibiting longitudinal homogenization (f)\cite{Flamm2015}, ``bottle-beams'' with on-axis modulation as superposition of quasi non-diffracting beams (g)\cite{Du2014, Flamm2015}, and propagation along tilted (h)\cite{Jenne2018a} or accelerating trajectories, also called second type of non-diffracting beams  (i)\cite{woerdemann2012structured, baumgartl2008optically,Chremmos2012, mathis2012micromachining}, as well as an example of an aberrated Bessel-like beam\cite{Jenne2018}. Here and in some of the following figures, we make use of David Green's color scheme representation.\cite{Green2011}}
    \label{bess00}
\end{figure*}
Induced micro explosions cause weakened areas characterized by voids, cavities and increased stress\cite{glezer1997ultrafast}.
\begin{figure}
    \centering
    \includegraphics[width=.48\textwidth]{JZC.jpg}
    \caption{Examples of diffractive inverse axicons (central details). Ideal height profile (a) and  height profile measurement of a corresponding element fabricated via grey-tone lithography in fused silica using a laser scanning microscope (b). Here, the diffraction efficiency is above $\unit[99]{\%}$ with a zero-order power amount of $<\unit[0.5]{\%}$\cite{Flamm2019}. Please note the almost perfect axicon tip. \textcolor{black}{This diffractive solution represents a prime example for the realization of efficient and power resistant phase-only beam shaping elements shown throughout the manuscript as phase modulations, see e.g. Figs.\,\ref{bess} and \ref{fig:3dfoc}.}}
    \label{czj}
\end{figure}
A second process step applies external stress (e.g., thermal, mechanical, chemical) to these areas acting as breaking layer. The first step of the concept is achieved particularly efficient using an optical setup and a corresponding laser platform allowing to modify the entire substrate thickness with a single pulse. For this purpose, sufficient pulse energy is required on the one hand, and on the other hand a focusing optic, which creates an elongated focus distribution. Bessel-like beams represent a remarkable beam class for the controlled deposition of energy in a certain working volume\cite{McGloin2005, Flamm2015, bhuyan2010high}. They come to the fore with aspect ratios of longitudinal to transverse dimensions than can easily reach factors of higher than $10000$\cite{McGloin2005}, see Fig.\,\ref{bess00}\,(a), (b). Thus, the exact length of the processing beam can be adapted to the thickness of the transparent material enabling single-pass processing strategies\cite{Kumkar2014} for glasses of thicknesses $>\unit[10]{mm}$\cite{Flamm2019}. Further remarkable properties should only be mentioned here in brief: self-healing\cite{McGloin2005}, simple and efficient generation\cite{McGloin2005} and---particular interesting for the processing of transparent materials---a natural resistance to spherical aberrations\cite{Jenne2018, Flamm2019}. Figure \ref{bess00} provides a menu of non-diffracting beams tailored for various processing strategies \cite{Jenne2018a, Flamm2019, jenne2020faci}. \par
First reports on Bessel-like beam generation were based on ring-slit apertures (far-field generation)\cite{Durnin1987}. However, for efficiency reasons, the axicon-based generation (near-field)\cite{McGloin2005} is preferred. An axicon is a conically ground lens and, by design, completely defined by axicon angle $\gamma$ and refractive index $n$. Using holographic axicons (both, digital and conventional) non-diffractive beams can be generated in very high qualities, as there arise no problems with manufacturing the axicon tip\cite{Brzobohaty2008, Flamm2019}, see diffractive element depicted in Fig.\,\ref{czj}. Here, a radial-symmetric transmission according to $T^{\text{axi}}\left(r\right)=\exp{\left[\imath\Phi^{\text{axi}}\left(r\right)\right]}=\exp{\left(\imath k_r r\right)}$ needs to be realized. In thin element approximation the radial component of the wavevector $k_r$ allows to directly assign a holographic axicon to its refractive counterpart via $k_r = 2\uppi \left(n-1\right)\gamma\lambda$ \cite{Leach2006, Flamm2019}. Illumination of these holograms by fundamental Gaussian beams generates Bessel-Gaussian beams of zero order. It is well known that minor modifications of $T^{\text{axi}}$ such as the multiplexing of phase vortices or $\uppi$-phase jumps allow the generation of Bessel-like beams of higher-order or superposition thereof \cite{vasilyeu2009generating, Bergner2018a, Flamm2019}. Here, the required phase modulation $\Phi$ is no longer radial symmetric but exhibits additional azimuthal dependencies such as, e.g., constant azimuthal slopes $\Phi\left(r, \phi\right) = k_rr+\ell\phi, \ell \in \mathbb{Z}$ \cite{vasilyeu2009generating, Flamm2019}. \par
We use a generalization of this concept to generate non-diffracting beams with arbitrary transverse intensity profiles\cite{chen2019generalized, jenne2020faci}. Now, the generalized axicon-like phase transmission $T^{\text{gen}} = \exp{\left(\imath\Phi^{\text{gen}}\right)}$ is characterized by a phase modulation with arbitrary azimuthal dependencies $\Theta\left(\phi\right)$ and, thus,
\begin{gather}
\Phi^{\text{gen}}\left(r,\phi\right) = k_rr+\Theta\left(\phi\right).
\end{gather}
In principle, there are no restrictions regarding the exact dependency of $\Theta\left(\phi\right)$\cite{chen2019generalized, flamm2020generalized}. Continuous functions are as conceivable as those containing discrete jumps. The beam profiles created in this way are characterized by an enormous diversity regarding the transverse intensity profile while remaining almost all well-known beneficial features of Bessel-like beams ensured by the constant radial slope $\nicefrac{\partial\Phi^{\text{gen}}}{\partial r}=k_r$ given by the holographic axicon carrier.\cite{McGloin2005,jenne2020faci,chen2019generalized}
\begin{figure}
    \centering
    \includegraphics[width=.48\textwidth]{A1.jpg}
    \caption{Shaping of non-diffracting beams with generalized axicons\cite{chen2019generalized}. For each example the sag profile of a refractive axicon (left), its holographic counterpart as phase-only transmission function (middle) and measured transverse intensity profile is depicted (right). Classical axicon shaping the fundamental Bessel-Gaussian beam (a). Generalized axicon generating an elliptical Bessel-like beam (b). Generalized axicon for shaping a non-diffracting beam exhibiting two spatially separated, elliptical intensity maxima (c). \cite{chen2019generalized, jenne2020faci}}
    \label{bess}
\end{figure}
Examples are provided in Fig.\,\ref{bess} where the measured transverse intensity profile of the fundamental Bessel-Gaussian beam (a) can directly be compared to an elliptical (b) and a twofold split non-diffracting beam (c), respectively, optically realized using generalized axicons. The implemented azimuthal fan segments, see $\Phi\left(x,y\right)$ in Fig.\,\ref{bess}\,(b), disturb the constructive on-axis interference of the fundamental Bessel-like beam resulting in an elliptical on-axis intensity maximum\cite{chen2019generalized}. For the particular case shown in Fig.\,\ref{bess}\,(b), the sag difference of the azimuthal segments results in azimuthal phase jumps of $\uppi$ which corresponds to a height difference of $\unit[1]{\upmu m}$ (at $\lambda = \unit[1]{\upmu m}$ wavelength) when realized as refractive version. For this reason, we prefer the diffractive realization, similar to the example depicted in Fig.\,\ref{czj}\,(b).\cite{Flamm2019}
\par
Throughout this work several phase profiles are shown, cf. Figs. \ref{bess},\,\ref{fig:3dfoc}, for the realization of which there are various options. One variant is based on an etched microstructure in fused silica, see example depicted in Fig.\,\ref{czj}. Particular efficient DOEs may be achieved by applying an adapted anti-reflection nano-texture\cite{hobbs2013contamination} exhibiting pulsed laser damage resistances which are typically several factors higher than conventional thin-film anti-reflection coatings and, thus, close to the thresholds of the unprocessed surface\cite{hobbs2007high}. Diffractive elements similar to the one depicted in Fig.\,\ref{czj} have been subjected to long-term ultrashort laser pulse high-power and high-energy tests. For pulse durations of $\sim\unit[1]{ps}$ we applied average powers above $\unit[1]{kW}$ as well as pulses in the order of tens-of-millijoules\cite{dietz2020ultrafast}. At resulting fluences of $\sim\unit[0.1]{J/cm^2}$ and peak intensities of $\sim\unit[1 \times 10^{11}]{W/cm^2}$ no signs of degradation at the DOE's surface or optical functionality were apparent.
\par
The realization of the concept as processing optics is explained by means of Fig.\,\ref{sschool}. The collimated raw beam is illuminating the axicon-like DOE [Fig.\,\ref{sschool}\,(b)]. A subsequent telescopic setup is imaging the non-diffracting beam into the workpiece with a well-defined (de-)magnification factor [Fig.\,\ref{sschool}\,(c),\,(e)]. For this purpose, long-working distance microscope objectives with NAs up to $0.5$ are available.\cite{Flamm2019, grossmann2020scaling}.
\par
As mentioned in the beginning of this section, the modification step is only one part of the entire cutting process. The actual separation process remains challenging especially if comparatively thin $<\unit[0.3]{mm}$ and thick glasses $>\unit[2]{mm}$ need to be separated. In the first case, already smallest deviations from the laser induced modification layer, such as, e.g., local micro cracks, are sufficient to separate the material not along the intended contour. In the second case, for mm-scaled glass substrates, the required force necessary for separation exceeds $\unit[1]{kN}$\cite{jenne2020faci} which makes controlled cutting with high quality equally difficult. For these reasons, very recently, there is ongoing research for facilitated cutting of glasses using asymmetric Bessel-like beams to control the formation of cracks. Tailored transverse intensity profiles of non-diffracting beams can cause modifications with preferential direction reducing the necessary breaking force. Established concepts make use of spatial frequency filtering or controlled aberrations \cite{hendricks2016, Meyer2017, Dudutis2018} but come at the expense of significant power loss or reduced process stability. Our concept using generalized axicons which allows to shape non-diffracting beams with an elliptical on-axis intensity profile, cf.~Fig.\,\ref{bess}, represents a promising approach to further reduce the necessary breaking force of thick glass substrates and to control the separation along predefined contours of ultra-thin glasses, respectively. More details about this facilitated glass separation concept are provided in Ref.\,\citenum{jenne2020faci}. Selected processing results are depicted in Fig.\,\ref{fig:faci} highlighting the successful glass cutting for two extreme glass substrate geometries.
\begin{figure}
    \centering
    \includegraphics[width=.48\textwidth]{faci03.pdf}
    \caption{Processing results of facilitated separation of ultra thin ($<\unit[0.05]{mm}$) and thick glass substrates ($>\unit[10]{mm}$) (a). For the latter case the TOP Cleave cutting optics and a TruMicro Series 5000 laser source providing pulse energies of $\unit[1.5]{mJ}$ was used. Permanent material modifications at the glass surface from single ultra short pulses spatially shaped as elliptical non-diffracting beam, similar to the example depicted in Fig.\,\ref{bess}\,(c). The orientation of cracks is controlled by rotating the central beam shaping element in $30^{\circ}$ steps (b)\cite{chen2019generalized, jenne2020faci}. Modifications directly connected by cracks may well be $\unit[100]{\upmu m}$ apart (c). \textcolor{black}{So far, the concept for full-thickness crack orientation control by rotating asymmetric elongated beam profiles is restricted to amorphous materials.}}
    \label{fig:faci}
\end{figure}
\par
Based on the developed processing strategies for perpendicular glass cutting, recently, there is an increased demand for customized glass edges, such as, e.g., chamfer or bevel structures. Apart from visual benefits, this is due to the increased edge stability and a reduction of potential edge fractures. Additionally, substrate geometries are becoming more complex and there is interest in cutting glass with curved surfaces, such as tubes, syringes and ampoules as required in large quantities in medical technology. The challenge for both cases is that the applied non-diffracting focus distributions require sensitive aberration corrections to compensate phase disturbances caused by the beam transition through tilted or curved interfaces. Figure \ref{fig:zaxicon} illustrates this concept (for details, see Refs.\,\citenum{Jenne2018, Jenne2018a}) at the example of processing glass tubes with given diameter.
\begin{figure}
    \centering
    \includegraphics[width=.48\textwidth]{zaxicon.jpg}
    \caption{Cutting of glass tubes with complex inner and outer contours. The aberrated (a) and aberration-corrected (b) elongated beam profile is depicted in terms of simulated intensity cross-sections $I\left(x,z\right)$ and $I\left(x,y\right)$ (see subsets), respectively. The cylindrical surfaces (radius, z-position) are sketched only schematically. A processed glass tube (diameter $\sim\unit[10]{mm}$, wall thickness $\sim\unit[1]{mm}$) with mechanical outer contour separation is depicted in (c). The complex inner contours of the sample depicted in (d) were achieved using a selective etching strategy, cf. Sec.\,\ref{sec:SLE}. Processing results were achieved using a modified TOP Cleave cutting optics in combination with $\unit[100]{\upmu J}$-pulses emerged from a TruMicro 2000 series laser.}
    \label{fig:zaxicon}
\end{figure}
The propagation of a Bessel-Gaussian beam behind a cylindrical glass surface is simulated in Fig.\,\ref{fig:zaxicon}\,(a) where a complex interference pattern is obtained with reduced peak intensities especially for larger propagation distances $z$. Now, we virtually apply the aberration correction and achieve the almost undisturbed profile of the well-known Bessel-Gaussian beam, see Fig.\,\ref{fig:zaxicon}\,(b). Processing samples are depicted in (c),\,(d) proving the efficacy of the concept for single-pass cutting of glass tubes of diameter $>\unit[1]{mm}$ with complex inner and outer contours. \textcolor{black}{Structured light concepts in this and the following sections (Secs.\,\ref{sec:SLE} and \ref{sec:weld}) were applied to transparent materials (glasses and crystals) with refractive indices below $2$ at the laser processing wavelength. For processing high refractive index transparent materials ($n>2$) such as, e.g., silicon, silicon carbide or diamond, the processing strategies presented, for example with regard to single-pass cutting using non-diffracting beams, cannot be applied as is. Significantly reduced processing thresholds at the surface as well as inside the volume prevent a spatially controlled energy deposition. Comparatively low intensities already lead to surface ablation perturbing the propagation of optical fields into the volume. The handling of the high index mismatch is equally challenging for the optical design as the strong refraction and Fresnel reflections prevent certain beam shaping concepts. However, space-time structured light concepts \cite{Kammel2014}, especially techniques providing radially chirped simultaneous spatial and temporal focusing\cite{meier2015application} represent promising potential solutions. Radial symmetric grating structures, similar to the one depicted in Fig.\,\ref{czj} but with higher spatial frequencies, generate a well-defined radial dispersion resulting in Gaussian or Bessel-Gaussian field distributions exhibiting short pulses and, thus, high intensities only in the focal region where energy is intended to be deposited. In the areas located immediately before or after the spatial focus, pulse durations are significantly longer and intensities as well as unwanted material defects are reduced.}

\section{Selective laser etching of transparent materials}\label{sec:SLE}
The combination of ultrashort pulsed volume modifications and subsequent selective chemical etching of dielectrics, known as selective laser etching (SLE), enables rapid fabrication of 3D glass structures of arbitrary shape with smallest structural features down to the $\unit[10]{\upmu m}$ scale\cite{wortmann2008micro, hermans2014selective, Kumkar2016}. The remarkable 3D fused silica articles provided by, e.g., LightFab\cite{LF3dptint} convince with extreme geometries, including micro tunnels, cavities or mounted moving parts. Usually, the corresponding processing strategy is based on 3D-scanning a single Gaussian focus distribution into the transparent workpiece to spatially control the nonlinear energy deposition. The concept presented in the following focuses on the efficient fabrication of high-quality 2D geometries ranging from mm-scaled complex inner contours down to nano-channels in transparent materials. The key to the efficient and industry-ready processing concept is to generate selectively etchable elongated modifications connected by cracks provided by spatially shaped ultrashort pulses using the concepts on non-diffracting beams presented in Sec.\,\ref{sec:cutt}. The employed beam profiles thus generated are length adapted by the processing optics allowing for full-thickness, single-pass modifications of the substrate. Our approach is thus remarkable efficient, allows for throughput scaling and to exploit the complete pulse energy performance of the respective laser platform \cite{Flamm2019}.\par
\begin{figure}
    \centering
    \includegraphics[width=0.48\textwidth]{yakuf2.jpg}
    \caption{Fused silica wafer ($\unit[4]{in}$) with thickness of $\unit[350]{\upmu m}$ with high-quality glass vias of diameters between $\unit[0.25]{mm}$ and $\unit[6]{mm}$ fabricated by selective laser etching (a). Microscope images of the laser entrance glass side confirm high-quality edge contours (b). Taper-free glass vias proven by SEM image (c)\cite{flamm2020structured}.}
    \label{fig:yakuv}
\end{figure}
During the laser process, elongated modifications, which extend from the beam entrance to the exit side of the material to be processed, are arranged sequentially along a contour. The modified volume shows typically a $100$ times higher etching rate compared to the base material. Depending on the respective material to be processed, adapted pulse energies, durations and a controlled spatio-temporal energy deposition strategy enable the fabrication of high-quality, taper-free 2D-geometries with high etching rates. Figure \ref{fig:yakuv}\,(a) depicts a processed fused silica wafer of $\unit[350]{\upmu m}$ thickness into which high-density through glass vias (TGVs) of different diameters (between $\unit[0.25]{mm}$ and $\unit[6]{mm}$) were etched. By applying $30$\,wt.-\% KOH etch solutions in an ultrasonic bath at a temperature of $\unit[80]{^\circ C}$ etching rates of about $\unit[20]{\upmu m/min}$ were achieved.
\par
Besides an increase of throughput there is a demand for further miniaturization of the etched geometries. Using a non-diffracting beam in combination with the single pass contour modification strategy described above, allows to generate crack-free microholes down to $\unit[50]{\upmu m}$ in diameter, see Fig.\,\ref{fig:yakuv}\,(b). The smallest possible aspect ratio of hole diameter to material thickness is about $1:10$---almost independent of the processed transparent material. We provide an SEM image of a cut TGV profile proving that there is no taper angle at hand, see Fig.\,\ref{fig:yakuv}\,(c).
\begin{figure}
    \centering
    \includegraphics[width=0.48\textwidth]{nanchann.jpg}
    \caption{Nanochannels in fused silica fabricated by single-pulse modifications from a non-diffracting beam and ultrashort pulses. The high aspect channels exhibit diameters of $\unit[500]{nm}$ without visible taper angles and without applying subsequent etching (a). An additional etch step enables to increase the channel diameter. From left channel to right: no etching, $\unit[5]{min}$, $\unit[10]{min}$, and $\unit[15]{min}$ etching in $30$\,wt.-\% KOH etch solution (b).\cite{flamm2020structured}}
    \label{fig:nannchnn}
\end{figure}
\par
In addition to the presented complex contours and microholes another innovation in laser processing is the generation of hollow nanoscale channels in glass and sapphire. The processing strategy is again based on using a non-diffracting beam and a TruMicro laser platform enabling the formation of hollow modifications in glasses using a single pulse only, without subsequent etch steps. Depending on optical configuration and pulse specifications, nanochannels of desired length and diameter can be achieved.
In Fig.\,\ref{fig:nannchnn}\,(a) nanochannels along a glass thickness of $\unit[350]{\upmu m}$ are shown. The high aspect channels exhibit diameters of $\unit[500]{nm}$ without visible taper angles. In the case of glass, a fine adjustment of the nanochannel's diameter is possible by an additional selective etching step. For example, as shown in Fig.\,\ref{fig:nannchnn}\,(b) a short etching time in KOH solution allows the channels to be expanded to a diameter of $\unit[1]{\upmu m}$.
\begin{figure}
    \centering
    \includegraphics[width=0.48\textwidth]{nanchann2.pdf}
    \caption{Scanning electron microscope image of an array of nanochannels etched into ultrafast laser modified sapphire. For size comparison, on the upper left, a human hair is microscoped.\cite{flamm2020structured}}
    \label{fig:nannchnn2}
\end{figure}
In the case of processing sapphire, elongated modifications filled with an amorphous phase instead of hollow nanochannels appear after the modification process.\cite{kaiser2019selective}. An additional selective etching step to open the amorphous phase is required resulting in $\unit[200]{nm}$-diameter hollow channels, see Fig.\,\ref{fig:nannchnn2}. \textcolor{black}{Therefore, controlling the channel diameter by varying etching parameters, similar to glass (cf.~Fig.\,\ref{fig:nannchnn}), is not straightforward for crystals.} We demonstrate highest reproducibility with a fabricated array of nanochannels that can be compared to the dimensions of a human hair (see left hand side in Fig.\,\ref{fig:nannchnn2}).
\begin{figure*}
    \centering
    \includegraphics[width=1\textwidth]{corrsss.jpg}
\caption{Efficient SLE of large glass volumes based on spatial crack control. Cross-like transverse intensity profile of the non-diffracting beam (a) and phase modulation of the corresponding generalized axicon (b)\cite{chen2019generalized}. Microscope image of surface modifications with cross-like crack orientation (c), (c*). Plurality of surface modifications on a Cartesian grid connected by perpendicular running cracks (d). Resulting large-volume trench efficiently removed via selective etching of the crack-modified volume (e)\cite{kaiser2019selective}.}
    \label{fig:corrsss}
\end{figure*}
\par
For the case that comparatively large volumes need to be etched efficiently, beam shaping again proves to be particularly useful. In Fig.\,\ref{fig:corrsss} a non-diffracting beam with cross-like transverse intensity distribution is depicted (a) that generates volume modifications with cross-like crack orientations (b). A plurality of such modifications on a Cartesian grid connected by perpendicular running cracks (d) allows to efficiently etch a large volume trench (e).
\par
At this section's end we would like to point out that the complex inner contours from glass tubes, see Fig.\,\ref{fig:zaxicon}\,(d), were removed using a selective etching strategy, too. Thus, discussed concept can be applied to curved glass articles.

\section{Laser welding of transparent materials}\label{sec:weld}
The short pulse duration and subsequent nonlinear absorption within the focal region in combination with heat accumulation from pulse to pulse enables local melting of transparent materials within a confined region that allows for permanent joining. Even though first reports of this technology were already published in 2001 by Tamaki \textit{et al.} \cite{tamaki2005welding} the technology is only gradually transferred to industrial applications so far. This is due to the high surface preparation requirements, i.e. low roughness and flatness in order to reduce potential gaps close to zero. On the other hand, the size of the gap that can be closed strongly depends on the glass properties that limit the weld seam dimension and laser power that can be applied. In glasses with low thermal diffusivity such as fused silica, thus large weld seams can be induced that allow for the bridging of gaps up to a few $\upmu$m \cite{richter2015toward, cvecek2015gap}. Moreover Chen \textit{et al.} reported on the formation of a melt pool using high-scan speeds which allows to accumulate melt and bridge significant larger gaps, see Ref.\,\citenum{chen2019picosecond}. However, crack formation inside the melt and reduced optical quality of the seams are obtained. \textcolor{black}{A detailed study about spatial and optical properties of weld seams including SEM images is provided in Ref.\,\citenum{richter2011bonding}.} \par
In our approach temporal and spatial beam shaping is used to overcome basic limitations while keeping the stability of the joints high (up to the volume material) and generate high-transparency seams. Details of the method can be found in Ref.\,\citenum{zimmermann2019situ}. The basic idea is to enlarge the laser-induced seam based on an elongated beam shape. By this the absorption region is distributed over an elongated region resulting in homogeneous melting during ongoing illumination. In addition, the induced stress is strongly reduced allowing for larger modifications and crack-free welding. \textcolor{black}{We refer to Jenne \textit{et al.}\cite{Jenne2018b} for a detailed study on the material's absorption and stress response to pulses shaped as Gaussian foci and elongated focus distributions, respectively.}
\begin{figure}
    \centering
    \includegraphics[width=0.43\textwidth]{flixxscheiass-Seite001.jpg}
    \caption{Measured shear strength of welded Gorilla glass (Corning) in dependence of the focal position relative to the interface for standard focusing and elongated beam shape (TOP Weld optics) (b). Encapsulated liquid (c) made of three individual glass layers whereas the middle glass exhibits a rectangle shaped cavity (fabricated by laser modifying and etching). The microscope images show the weld seams (above) and the etched contour (below).\cite{flamm2020structured}}
    \label{fig1}
\end{figure}
\par
The TRUMPF ultrashort pulse welding portfolio consists of an ultrashort pulse laser source (TruMicro 2000 series) and the TOP Weld optics. The focus distribution thus generated leads to much higher process performance as shown by the measured shear strength in Fig.\,\ref{fig1}\,(a). The focal tolerance of about $\unit[230]{\upmu m}$ in $z$-direction is about three times higher compared to state-of-the-art focusing (Gaussian beam shape) while keeping the breaking stability as high as the volume material.
\par
By using temporal pulse energy modulation the weld performance can even be improved. As shown by Nakamura \textit{et al}. the temporal modulation of the pulse energy can reduce permanent stress in and around the weld seam and allows for larger seam dimensions \cite{nakamura2017suppression}. Adding this technique, which can directly be set in the laser control of the TruMicro 2000 series, the focal tolerance shown in Fig.\,\ref{fig1}\,(a) can be increased up to $\unit[300]{\upmu m}$ for Gorilla glass. Another important feature for welding in industrial environment is the bridging of gaps. As mentioned above state-of-the-art techniques are limited to about $\unit[3]{\upmu m}$. By using the TOP Weld optics gaps up to $\unit[7]{\upmu m}$, together with pulse energy modulation gaps even up to $\unit[10]{\upmu m}$ can be bridged. By this, real world applications in the field of consumer electronics, bio medicine or encapsulation for MEMS devices can be addressed.
\par
One of the main challenges for encapsulation denotes the gas and liquid tightness of welded devices. To test the resulting tightness after welding protection caps of laser light cables were characterized (see Ref.\,\citenum{kaiser2016} for details). By this a hermeticity to the power of $-9$ could be measured confirming the feasibility for encapsulated devices such as microfluidics. This has further been demonstrated by encapsulating a blue liquid shown in Fig.\,\ref{fig1}\,(b). The article is made of three individual glass layers (each $\unit[30]{mm} \times \unit[50]{mm} \times \unit[0.55]{mm}$) whereas the middle glass exhibits a rectangle shaped cavity that has been fabricated by laser scribing (using the same laser setup) and etching (contour shown in the inset). Several weld seams (10) were inscribed in a parallel manner around the cavity (see inset). The encapsulated device showed high stability without leakage of the liquid.
\par
Since femtosecond laser pulse welding around $\unit[1]{\upmu m}$ wavelength of transparent materials requires moderate pulse energies $<\unit[10]{\upmu J}$\cite{tamaki2005welding} concepts for throughput scaling are becoming increasingly important\cite{Kumkar2016, Flamm2019,flamm2020structured}. This becomes even clearer if one considers the recent progress in pulse energy and average power of today's ultrafast laser platforms\cite{sutter2019high}. We use a structured light concept based on a diffractive 3D-beam splitter to discuss the potential of parallel processing for particularly efficient welding of transparent materials\cite{Kumkar2017, Flamm2019}. \par
One way to displace a focus from its original position behind a lens is achieved by introducing phase modifications into the wavefront of the illuminating optical field. In terms of Zernike polynomials\cite{Noll1976}, a proper choice of tip/tilt modes in combination with a defocus allows to control the transverse $\left(\Delta x, \Delta y\right)$ and longitudinal $\Delta z$ displacement, respectively. We extend this simple concept for the manipulation of a single focus to a 3D-beam splitting concept by exploiting the linearity property of optics and multiplex the corresponding holographic transmission functions\cite{Flamm2012, Forbes2016, silvennoinen2014parallel} (one for each focus to be placed in the working volume).

Transverse displacement for the focus of order $j$ is achieved by setting a linear blaze grating with spatial frequency $\mathbf{K}_j = \left( K_{x,j}, K_{y,j}\right)$ in the front focal plane of a lens with focal length $f_{\text{FL}}$. The corresponding transmission function then reads as
\begin{equation}\label{eq:grat1}
	T_{j}^{\text{trans}}\left(\mathbf{r}\right) = \exp{\left[-\imath\left(\mathbf{K}_j\mathbf{r}+\phi_j\right)\right]}
\end{equation}
and yields a transverse displacement according to $\Delta x_j = f_{\text{FL}}\tan{\left[\sin^{-1}{\left(\lambda K_{x,j}/2\uppi\right)}\right]}$ (straightforward for $\Delta y_j$). Longitudinal displacement $\Delta z_j$ of the $j$th-order focus is realized by introducing the defocus ``aberration'' using, e.g., a holographic lens transmission with focal length $f_j$
\begin{equation}
T_{j}^{\text{long}}\left(\mathbf{r}\right) = \exp{\left[-\imath\uppi r^2/\left(\lambda f_j\right)\right]}.
\end{equation}
Then, the longitudinal shift is directly deduced from $\Delta z_j \sim -f_{\text{FL}}^2 / \left(f_{\text{FL}}+f_j\right)$. Combinations of both shifts are achieved by multiplying both transmissions $T_j = T_{j}^{\text{trans}}T_{j}^{\text{long}}$. Multiplexing these $j_{\text{max}}$ transmission functions will yield the total transmission according to
\begin{equation}\label{eq:tot}
T^{\text{tot}}\left(\mathbf{r}\right) = \sum_j^{j_{\text{max}}} T_{j} = \sum_j^{j_{\text{max}}} T_{j}^{\text{trans}}\left(\mathbf{r}\right)T_{j}^{\text{long}}\left(\mathbf{r}\right).
\end{equation}
In general, this multiplexing scheme will result in a complex valued transmission $T^{\text{tot}}\left(\mathbf{r}\right) = A^{\text{tot}}\left(\mathbf{r}\right) \times \exp{\left[\imath\Phi^{\text{tot}}\left(\mathbf{r}\right)\right]}$. Different approaches exist to realize such a transmission as phase-only hologram, see, e.g., Davis \textit{et al.~}\cite{Davis1999} or Arriz{\'o}n \textit{et al.~}\cite{Arrizon2007}. However, a particularly efficient and simple solution represents $A^{\text{tot}}\left(\mathbf{r}\right) = \mathbbm{1}$, thus setting the amplitude modulation to unity and directly use $T^{\text{tot}}\left(\mathbf{r}\right) =\exp{\left[\imath\Phi^{\text{tot}}\left(\mathbf{r}\right)\right]}$ as phase-only transmission. This approach will yield optical powers in unwanted diffraction orders, but, nonetheless, will be significantly more efficient than aforementioned phase-coding techniques. However, it has negative impact on the uniformity of the split spots. To restore equal power distribution a set of constant phase offsets $\left\{\phi_j\right\}$ in the grating representation of Eq.\,(\ref{eq:grat1}) can be found by an iterative optimization routine. Here, the optical field in the working volume and the optical power of the $j_{\text{max}}$ spots have to be simulated for each iteration\cite{Leutenegger2006}. This iterative Fourier-transform algorithm \cite{Wyrowski1988} is expanded to all three spatial dimensions (3D-IFTA) and yields the phase offsets $\left\{\phi_j\right\}$ until a desired uniformity is reached. The deduced set of $\left\{\phi_j\right\}$, finally, completely determines the total phase-only transmission $T^{\text{tot}}$ for each spot placed in the working volume by $\left\{\mathbf{K}_j, f_j\right\}$. Examples for 3D-focus distributions (intensity cross sections) and corresponding phase modulations $\Phi^{\text{tot}}\left(\mathbf{r}\right)$ are depicted in Fig.\,\ref{fig:3dfoc}.
\begin{figure*}
    \centering
    \includegraphics[width=0.9\textwidth]{3dfoc.jpg}
    \caption{Selection of 3D-focus distributions [intensity cross sections, $I\left(x=0, y, z\right)$, top row, $z$-axis corresponds to propagation direction] with corresponding phase-only transmission functions ($\arg{\left[T^{\text{tot}}\left(x,y\right)\right]}$, bottom row) for beam generation. The Gaussian-foci are arbitrarily distributed within the working volume. Regular longitudinal focus arrangement (a). Combination of regular longitudinal and transversal beam splitting (b). Focus arrangement along a $45^{\circ}$-straight line (c). Focus arrangement along a $90^{\circ}$-angle (d). Focus arrangement along an accelerating trajectory (half circle) (e).\cite{Flamm2019}}
    \label{fig:3dfoc}
\end{figure*}
\par
We designed a diffractive optical element capable to split the illuminating fundamental Gaussian beam into $13$ copies, see Fig.\,\ref{fig:scheiss2}\,(a)\cite{Flamm2019}. Referring to the schematic shown in Fig.\,\ref{sschool}, the collimated raw beam illuminates the beam shaping DOE [Fig.\,\ref{sschool}\,(d)] which forms a $2f$-arrangement with the focusing unit [Fig.\,\ref{sschool}\,(e)]. Each focus exhibits a well defined longitudinal and transverse distance with respect to the respective neighbour, see simulated intensities in Fig.\,\ref{fig:scheiss2}\,(b) ($z$-axis corresponds to propagation direction). The successful energy deposition into the volume of a transparent workpiece is proven by transverse pump-probe microscopy, for details see Refs.\,\citenum{Bergner2018, Bergner2018a, Grossmann2016}. The measured optical depth $\tau\left(x, z\right)$ in non-strengthened Corning Gorilla$^\text{\textregistered}$ glass from a single laser burst with $4$ pulses (pulse energy of $\unit[30]{\upmu J}$) emitted from a TruMicro 2000 with a pulse duration of $\unit[5]{ps}$ is provided in Fig.\,\ref{fig:scheiss2}\,(c).
\begin{figure}
    \centering
    \includegraphics[width=0.5\textwidth]{scheiss1.pdf}
    \caption{Measured optical depth $\tau\left(x, z\right)$ for a multi-spot focus distribution, see inset, inside the volume of borosilicate glass using transverse pump-probe microscopy \cite{Bergner2018, Jenne2018b}. The beam propagates from negative to positive $z$-direction. The absorption projection is composed of $13$ single zones and clearly indicates that energy is deposited spatially controlled by the beam splitting concept.\cite{Jenne2018b, Flamm2019}}
    \label{fig:scheiss2}
\end{figure}
Here, $\tau\left(x, z\right)$ at a probe delay of $\unit[5]{ns}$ indicates the optical losses due to, e.g., absorption or scattering on a transient temporal scale. For each of the 13 foci a single absorption zone is observed starting at the geometrical focus and expanding in direction of the incoming laser pulse. The behavior well known from focusing single Gaussian beams into transparent materials\cite{Grossmann2016, Bergner2018} is multiplied here due to the beam splitting concept. Intriguingly, the spatial distribution of induced modification corresponds to the simulated focus positions and even at this small lateral and longitudinal spot separation of $\unit[3]{\upmu m}$ no shielding or inhomogeneities in between the individual spots is obtained. This denotes a precondition for advanced material processing in particular for scaling throughput in the field of welding, material functionalization or cutting.

\section{Laser surface structuring and percussion drilling}\label{sec:drill}
Drilling processes by ultrashort laser pulses meet the demand for high-end applications in the display and electronics industry. Especially the manufacturing of microstructures requires highest accuracy and minimal damage of the workpiece. Although the materials to be processed are very diverse---from highly absorbent to transparent\cite{chichkov1996femtosecond, furusawa1999ablation, shah2001femtosecond, Kumkar2016}---the process strategy is usually based on a Gaussian focus (single spots or multiple copies\cite{Kumkar2017, Flamm2019}) being directed over the workpiece using scanner optics or axis systems. Although, as mentioned, high quality machining results are usually obtained, industry requirements regarding efficiency and process speed often cannot always be met.  Additionally, a variety of applications, like the production of blind holes in multi-layer stacks or through holes in metal foils demand specific processing constraints. For example, the application of fine metal masks (FMMs) for the fabrication of OLED displays requires exact rectangular hole shape as well as tailored taper angles and minimized residual particle contamination. Decisive for a realization with ultrashort pulsed laser platforms, finally, is the achievable throughput.\cite{Kumkar2017, Flamm2019, kudryashov2019high, pavlov201910}.
\par
The optical concept described in the following, is realized with a liquid-crystal-on-silicon-based spatial light modulator (SLM) as central beam shaping element in a multi-illumination configuration, see Fig.\,\ref{fig:guenn1}.\footnote{For reasons of flexibility, this setup comprises an SLM. In consequence, the power performance is limited. A final processing optics may also consist of stationary beam-shaping components such as DOEs, ROEs or elements for geometric phase manipulation\cite{sakakura2020ultralow} mounted or fabricated on a single or multiple substrates and illuminated single or multiple times, cf.\,Fig.\,\ref{sschool}. Equally conceivable would be the use of unimorph deformable mirrors\cite{verpoort2020fast}. For the experiment conducted with the ultrashort pulsed laser operating at $\unit[257]{nm}$ wavelength, cf. Fig.\,\ref{fig:guenn8}, no SLM was used. Here, a setup with stationary beam shaping elements was developed.}
\begin{figure}
    \centering
    \includegraphics[width=0.5\textwidth]{guenn1.jpg}
    \caption{Optical setup for shaping multiple beam properties. Ultrashort laser pulses emerging from a TruMicro 2000 and externally frequency converted to a wavelength of $\unit[515]{nm}$ are illuminating the SLM in a double-pass configuration; half-wave plate (HWP), quarter-wave plate (QWP), thin-film polarizer (TFP). In this configuration, the SLM's left-hand side in combination with QWP and TFP acts as amplitude modulator and imprints and amplitude mask to the illuminating field \cite{Flamm2019}.}
    \label{fig:guenn1}
\end{figure}
Starting from a conventional field-mapping concept for shaping a rectangular flattop distribution \cite{Dickey2000} (for alternatives, see Refs. \citenum{banas2014gpc, laskin2012variable, jiang2018liquid, kuang2015ultrafast, liu2018dynamic}), the SLM displays the required phase modulation at a well-defined subsection---in the present case the SLM's right hand side, see Fig.\,\ref{fig:guenn1}. The optical concept is designed in such a way that the flattop is generated at a second subsection of the SLM. This second beam shaping step enables to manipulate a further field property of the flattop, thus, in general, a well-defined spatial amplitude-, phase- or polarization distribution, see Fig.\,\ref{fig:guenn2}. By creating a plane phase distribution, for example, the propagation behavior can be manipulated to achieve maximum depth of field\cite{Pal2018, Scholes2020}. For the applications discussed in the following, such as laser drilling of thin foils, however, the amplitude distribution, in particular with regard to contour accuracy and edge steepness, will be decisive. Therefore, in the setup depicted in Fig.\,\ref{fig:guenn1}, the SLM's second illumination area in combination with quarter-wave plate (QWP) and thin-film polarizer (TFP) acts as amplitude modulator. In other words, the SLM imprints an amplitude mask to the illuminating optical field.
\begin{figure}
    \centering
    \includegraphics[width=0.35\textwidth]{sd.jpg}
    \caption{Two-step beam shaping of multiple beam properties. First step: phase-only shaping of flat-top beams.\cite{Dickey2000}. Potential second step: Tailored amplitude distribution using an amplitude mask or tailored polarization distribution using local quarter-wave or half-wave plates or tailored propagation properties based on phase manipulation. One possible setup to realize this concept is depicted in Fig.\,\ref{fig:guenn1} and employs a SLM as central beam shaping element.\cite{grossmann2020scaling}}
    \label{fig:guenn2}
\end{figure}
Without using a complex Fourier coding\footnote{The advantages in comparison to a classic phase-only IFTA\cite{Wyrowski1988} are in particular that no favorable initial transmission has to be found (an IFTA is only as good as its starting transmission) and that undesired diffraction orders and vortices are completely suppressed. We also see advantages in terms of homogeneity and edge steepness of the shaped profiles. The efficiency situation must be assessed on a case-by-case basis. Please note that for the present amplitude-mask concept local amplitude damping always comes at the expense of a direct reduction of available optical power at the workpiece.} such as iterative Fourier transform algorithms\cite{Wyrowski1988} almost any intensity profile can be generated. The required micrometer-scaled dimensions at the workpiece are finally achieved using the beam delivery system depicted in Fig.\,\ref{fig:guenn1} with adapted telescopic setups and middle- to high-NA focusing objectives.\cite{Flamm2019}.
\par
Exemplary processing results of a micrometer-scale marking process and corresponding measurements of the intensity profiles are depicted in Fig.\,\ref{fig:guenn3b}. Here, letters of $\unit[10]{\upmu m}$-dimensions were directly marked onto the substrate's surface---no scanning system was required.
\begin{figure}
    \centering
    \includegraphics[width=0.30\textwidth]{guenn3b_df.jpg}
    \caption{Direct marking of micrometer-scaled letters (microscope images, right column) from tailored intensity profiles (camera measurement, left column). The two-step beam shaping approach, cf. Fig.\,\ref{fig:guenn1}, enables simple realization of arbitrary amplitude distributions without applying Fourier coding techniques, see (and please scan) measured QR-code at the bottom.\cite{grossmann2020scaling}}
    \label{fig:guenn3b}
\end{figure}
An other challenging application which can benefit from appropriate beam shaping flexibility is the percussion drilling of rectangular holes in thin metal foils (FMMs).
Exemplary machining results with lateral dimensions below $\unit[20]{\upmu m}$ on an Invar foil with a thickness of $\unit[10]{\upmu m}$ are demonstrated in Fig.\,\ref{fig:guenn6b}. The accuracy regarding contour, edges and taper is a decisive factor of this process (a). Depending on the applied laser pulse parameter the exact geometry can be adjusted (b). With additional scaling by means of beam splitting, large scale samples with highly reproducible  holes can be achieved (c). Accordingly, the resulting pixel density or resolution, respectively can be $>\unit[1000]{ppi}$.
\begin{figure*}
    \centering
    \includegraphics[width=0.8\textwidth]{guenn6b_df.jpg}
    \caption{Drilling result using the flat-top beam profile depicted in Fig.\,\ref{fig:guenn6}. Direct drilling of quadratic-shaped holes in thin metal sheets with dimensions of $\sim\unit[10]{\upmu m}$ (a), different taper geometries and achieved hole density of $>\unit[1000]{ppi}$ (b), (c).\cite{grossmann2020scaling}}
    \label{fig:guenn6b}
\end{figure*}
To achieve even further degrees of freedom, regarding the hole geometry, advanced beam shaping methods can be applied. In this context, the efficacy of the double stage shaping concept is demonstrated by means of controlled taper-angles for the drilled holes.
\begin{figure*}
    \centering
    \includegraphics[width=0.9\textwidth]{guenn6_df.jpg}
    \caption{Controllable taper angles of drilled rectangular holes in invar foil with a thickness of $\unit[10]{\upmu m}$ for FMM applications. The additional adjustability is achieved using intensity graded flat-top-like beams on a $\upmu$m-scale at a wavelength of $\unit[515]{nm}$ (left-hand side).}
    \label{fig:guenn6}
\end{figure*}
Local intensity gradients of circularly-polarized flat-top-like beams enable to control the 3D hole geometry.  Figure\,\ref{fig:guenn6} shows SEM-images of details of laser-drilled holes in metal foils of $\sim\unit[20]{\upmu m}$-thickness with different entrance and exit hole dimensions. Please note, that the propagation behavior of the shown flat-top examples is similar due to approximately similar phase distributions, cf.\,Fig.\,\ref{fig:guenn2}. Taper angles are mainly controlled by the structured amplitude and resulting local intensity gradients.
\par
The application of liquid-crystal-on-silicon-based SLMs shows several limitations regarding beam shaping performance and applicable laser parameters. Extensive diagnostic systems are provided to monitor the behavior of the beam shaping device during the application of high average powers. Using the telescopic setup, the SLM's second illumination step is imaged onto sensors for laser beam characterization, cf.~Fig.\,\ref{fig:guenn1}. Beam diagnostics may base on field reconstructions from caustic- \cite{merx2020beam, pang2020focal} or wavefront measurements\cite{sheldakova2007beam, Schulze2013} as well as from modal analysis\cite{flamm2013, pinnell2020modal}. In the simplest case a camera monitors the actual focus quality at a fixed $z$-position. In general, the flat-top's uniformity and contour accuracy will deviate from the ideal situation, cf. Fig.\,\ref{fig:guenn2}, for example, if a large number of mirrors is used for free-space beam delivery and wavefront aberrations exceed $\sim \lambda/10$ (p-v-error). Using the flexible SLM, the displayed phase and/or amplitude transmission can be adapted to the situation of the illuminating optical field. Simple control loops may compensate for potential wavefront aberrations using sets of Zernike modes\cite{Noll1976} or radial basis functions\cite{merx2020beam} until certain focus specifications, such as, e.g. homogeneity or edge steepness, are achieved.
\par
The phase-shifting performance of the SLM while exposed to high intensities or high average powers is usually only roughly known. To characterize the display spatially resolved interferometric techniques\cite{beck2010application} are used as well as global measurements of the diffraction efficiency. Possible applied laser parameters (wavelength, pulse durations, repetition rate, burst modes, etc.), however, are  manifold requiring a spatially resolved \textit{in situ} characterization technique. To achieve best beam shaping quality we calibrate the complete phase shifting performance of each pixel by spatially resolved polarization measurements.
\par
By irradiating the SLM with $45^\circ$ linear polarization and neglecting constant phase shifts the polarisation of the resulting electrical field $\mathbf{E}$ can be written as,
\begin{equation}\label{eq:pol1}
  \mathbf{E}(x,y) = \frac{1}{2} \begin{pmatrix} \sin \left(k d \left(n_{\text{e}}\left(x,y,U\right)-n_{\text{o}}\right)\right) \\ \imath \cos\left(k d\left(n_{\text{e}}\left(x,y,U\right)-n_{\text{o}}\right)\right) \end{pmatrix},
\end{equation}
with $k=2 \uppi/\lambda$ and the thickness of the liquid crystal layer $d$. The local polarization depends on the liquid crystal refractive index on both axis $n_{\text{e}}$ and $n_{\text{o}}$, respectively. In consequence, an applied $8$-bit pixel value corresponds to a specific voltage $U$ which changes the local phase retardation.
By evaluating the intensity in one polarization state for each pixel, the exact phase modulation for each applied voltage can be calibrated.
With these measurements we can assess the necessary phase correction for each pixel at different laser parameters. In Fig.\,\ref{fig:guenn7}, the measured phase performance for selected SLM pixels is shown. With moderate laser parameters different pixels primarily exhibit a relative phase shift to each other which can be corrected directly by the spatially resolved measurement. These correction masks are shown in the corresponding graphic for different laser parameters, see bottom of Fig.\,\ref{fig:guenn7}. Thereby a substantial increase in phase shifting error for higher average laser powers can be observed. Especially with an increased thermal load the local additional phase shift becomes prominent. However, as long as the measured intensity profile over all pixel values is just shifted, a direct correction for beam shaping applications is possible. With a further increased laser power, additional errors start to occur, which can no longer be compensated by a simple pixel shift correction and indicate an approach to the damage threshold of the device.
\begin{figure}
    \centering
    \includegraphics[width=0.48\textwidth]{guennSLM-Seite001.jpg}
    \caption{\textcolor{black}{Novel SLM characterization technique for \textit{in situ} measurement of the phase-shifting performance during display illumination with high optical powers or energies. Based on the setup depicted in Fig.\,\ref{fig:guenn1}, the beam shaping performance with pixel-resolved phase-shift-performance measurement at different pulse parameters is optimized. This method enables a direct measurement of necessary laser parameter-depended phase-correction masks for high quality beam shaping applications. The bottom row depicts exemplary phase correction maps (in arbitrary grey value units) for varying laser parameters.}}
    \label{fig:guenn7}
\end{figure}
\par
In specific applications, which require highest power or short wavelength, beam shaping has to be realized with more suitable components. With an appropriate optical setup this can also be realized with multiple optical components. In Fig.\,\ref{fig:guenn8}, a measurement of an exemplary optimized beam shape is shown generated at a wavelength of $\lambda = \unit[257]{nm}$. The designed setup similar to the double illumination concept of Fig.\ref{fig:guenn1} was realized solely with static and wavelength-suitable components. Here, no SLM was used, since conventional liquid crystal displays show significant absorption below $\unit[400]{nm}$ wavelength. To demonstrate the capabilities of beam shaping this ``exotic'' laser parameter an additional microscope image of a processed silicon wafer is shown. This workpiece was processed with several beam split flat-top focus distributions of $\unit[20]{\upmu m}$ dimensions and $\sim\unit[2]{ps}$ ultra short laser pulses at $\lambda = \unit[257]{nm}$. We employed an externally frequency-converted TruMicro 5270 laser based on the established industrial ultrafast laser platform TruMicro Series 5000\cite{Quentin2020, Haefner2021}.\par
By using a rectangular-confined spatial energy distribution instead of a round-shaped Gaussian focus with a slowly decaying amplitude, rectangular patterns can be realized that are used in a variety of applications like drilling of masks or for example laser lift off. Here, the combination of energy absorption in the DUV regime paired with ultra-short temporal energy deposition, enables a minimum thermal damage to functional layers made of, e.g., isolators or semiconductors. Adapting the flat-top dimensions to the feature size of the semiconductor and applying beam splitting, cf.~Fig.\,\ref{fig:guenn8}, parallel processing, single-shot lift-off strategies can be realized that meet the throughput demands of industrial production lines. \par
\textcolor{black}{The broad accessibility of liquid-crystal displays makes their use in industrial-grade processing optics more and more conceivable. The steadily increasing refresh rates up to several hundred Hertz may even allow the display's use as adaptive components during the actual machining. For example, too much energy is usually deposited at the reversal points of a scanning process for ablation or marking applications. One could use the SLM to switch the beam shape during scanning to adapt intensities and to achieve particularly homogeneous processing results. Especially here, \textit{in situ} diagnostics of the phase-shifting performance is of importance, as demonstrated by the direct measurement of pulse-energy dependent phase correction masks, cf.~Fig.\,\ref{fig:guenn7}. For the further industrial dissemination of adaptive beam shaping concepts based on liquid-crystal displays---not only with regard to laser materials processing---, the effort in calculating the required phase masks needs to be reduced. Usually, complex Fourier algorithms are used for this purpose which require advanced knowledge in the field of wave optics. We would like to emphasize once again, that using the presented double-illumination concept, cf.~Fig.\,\ref{fig:guenn1}, where the SLM acts as both phase and amplitude modulator, no sophisticated phase-coding algorithms are necessary.}
\begin{figure}
    \centering
    \includegraphics[width=0.5\textwidth]{guenn8.jpg}
    \caption{Splitting a flat-top focus distribution into multiple copies for parallel processing (top). The employed laser providing ps-pulses and operating at $\unit[257]{nm}$ wavelength is realized by an externally frequency converted TruMicro 5270. The processed silicon wafer exhibits rectangularly shaped patterns of $\unit[20]{\upmu m}$ dimensions (bottom) fabricated with fluences of $\sim\unit[1]{J/cm^2}$ showing the potential for drilling of masks and single-shot $\upmu$LED laser lift off, respectively.}
    \label{fig:guenn8}
\end{figure}

\section{Conclusion}
Structured light concepts as enabler for advanced ultrafast laser materials processing have been demonstrated. Based on selected challenging application examples, such as cutting of glass tubes or drilling of fine metal masks, relevant for medical application and consumer electronics, respectively, we reviewed the generation and beneficial use of customized focus distributions. Several optical concepts were introduced for shaping a variety of beam classes ranging from tailored non-diffracting beams to adapted 3D-beam splitters operating in the near infrared down to the deep ultraviolet. As a matter of principle, concepts were examined that can withstand high average and peak powers showing potential to be central parts of future processing optics forming ultrafast focus distributions with tens-of-millijoules pulse energies and kilowatt-class average powers. \textcolor{black}{Finally, conceptual solutions were discussed in which adaptive optics based on liquid-crystal displays can act as central beam shaping elements in future industrial-grade processing optics.}

\subsection*{Disclosures}
The authors declare no conflicts of interest.

\footnotesize

redpajama_set_name: RedPajamaArXiv


text:
Home Latest News Lucas ALARIO or Marco RUBEN could be called as replacement
Lucas ALARIO or Marco RUBEN could be called as replacement
Lucas Alario River Plate
One of Lucas ALARIO or Marco RUBEN could be called as a replacement for Lucas PRATTO.
As we reported, Lucas PRATTO suffered a broken nose during Sao Paulo's match against Palmeiras. It was reported that should he play, he would need a protective mask. However, per a report by TyC Sports, should PRATTO not be able to take part in Argentina's upcoming World Cup Qualifying matches, it would be one of Lucas ALARIO or Marco RUBEN who would get called as a replacement.
Marco Ruben of Rosario Central could be called to the Argentina National Team.
No Mauro ICARDI
This happening after Argentina National Team coach Edgardo BAUZA stated a few times that if something were to happen to Gonzalo HIGUAIN or Lucas PRATTO, it would be Inter's Mauro ICARDI who would get called to replace one of the players.
It now appears to not be the case. It would be either River Plate's Lucas ALARIO or Rosario Central's Marco RUBEN.
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Istiaque March 14, 2017 At 1:57 pm
What is surprising to me that y'all seems surprised! Come on guys, its Bozo, who probably has kid as his assistant lol.
NoHateOnlyLove March 14, 2017 At 3:28 pm
vik March 14, 2017 At 10:40 am
This is how you would take the piss!
You get being told your watched and on the radar. Which make's you feel good about things and urges you to work even harder…I don't know…maybe score a hattrick….then get told your getting the shaft because there are 2 blind men both sharing a leg who are deemed fitter and more capable than you are.
I don't know about you folks but I would be upset! Lol. Bollocks this ain't funny anymore. It's eye-twitching, gut-wrenching annoying.
He can shag who he likes for all I care as long as he's putting the ball in the net for our shirt.
And if Messi and Mascherano have a problem with that…then sorry they ain't done much in terms of trophies for our team. They need a serious reality check.
pablo.d March 14, 2017 At 2:29 pm
vik: great to hear from you as always and sadly for us all the great afa led drama show rolls on and on and on …….
vik March 14, 2017 At 2:48 pm
I've been away but always read up on everyone's posts and displeasure on how this team is slowly fading away into the oblivion. It's a huge shame and depressing. But it's you guys who don't give up that keeps me ticking too. It's thanks to you Pablo and all my albiceleste brothers for keeping the faith and posting on.
muchas gracias mi amigo
vis March 14, 2017 At 9:56 am
Whhat is this traitor nonsense? If a deserving player is not selected by a coach the coach is the traitor,not the player. Any person on this website who talks against a deserving player is also a traitor. This holier than thou attitude is destroying our chances. With this screwball of a coach it will be tough for us to win the world cup
Lucas PRATTO talks his injury and Argentina status - Mundo Albiceleste March 14, 2017 At 7:17 am
[…] we reported, there had been rumors that if PRATTO cannot make it, one of Lucas ALARIO or Marco RUBEN would be […]
Dollon Biswas March 14, 2017 At 6:23 am
I still believe Tata martino is hundred miles better than bazua… I miss Tata martino…
miskan March 14, 2017 At 9:05 am
Dont miss him dude…he dont miss u
NoHateOnlyLove March 14, 2017 At 12:02 pm
chalz March 14, 2017 At 4:09 am
Worst of the Worst – Edgardo Bauza.
Icardi is in exile, forget about him already, he will never be call up no matter who the coach is. Icardi done messed up already, nobody wants a traitor sharing the same locker room with them. Not worth bringing his shame inside the dressing room. Maybe after every single one of these guys retire then maybe Icardi will come out of exile. If you ask me, who do you rather on the team, Messi, Masche etc. or Icardi? The answer is clear, I stick with the former! To quote Maradona, the guy is a traitor. How can you trust a team mate with this kind of personality?
are you really using maradona as a moral compass to life…wow…
guled March 13, 2017 At 10:17 pm
Saint maradona 😄
pablo.d March 14, 2017 At 12:46 am
hes my foot balling hero and always will be but…… lets just say the devil will be busy with his charge sheet when its time to take maradona away lol
CrazyArg March 14, 2017 At 6:18 am
I have to disagree with u kid. actually I am not clear u using the word traitor. what do you mean by that, to me being a drug addict and getting ban from football in the middle of a world cup is a work of traitor, he make cry the whole nation along with all his supporter.
answer me a question, was riquelme a traitor, why did he ignore him in 2010, that cost us a world cup, to me this is a work of traitor
Richard March 14, 2017 At 6:38 am
What is this traitor bullshit? We need a spirit of rebellion in the dressing room. There are way too many players that lost three finals and let their heads hang if we fall behind or someone is sent off. We need fighters! Just because he fell in love with a woman who was married to another player does not make him a bad man. Millions of wives and husbands cheat on their partner. Just look at the Ashley Madison hack and the hundreds of websites all over the world that enable people to look for a new or second partner. Who are we to judge on people's behavior in their spare time? Icardi is a must now Pratto (who completely failed in Italy) is out. The Argentine league was postponed and has just started. Alario and Ruben haven't played many matches and can't be as fit or sharp as Icardi.
Bang on….condition and form is the real issue. And neither of the rumoured possibilities are that in comparison to Icardi
EnganChe March 13, 2017 At 6:48 pm
It's clear as day Icardi is not getting a call, ever, or at least not until he is 28 or something. Alario is a promising player but not in the best form right now. Then again, form alone does not seem to be the only criteria for Bauza.
miskan March 13, 2017 At 6:42 pm
He look change his mind so fast as well…he came to icardi told him the chance with national team then aliby not include him moment later..stated to whole people that icardi was what heppen with pratto and higuin…then sooner he avoid it…this only took 2 months..to show us he is heavy weight liar champion
chris March 13, 2017 At 6:17 pm
This is such a shame.. the kid comes in the game and within 9 min scores a hat trick..
any other country he would've been a starter..
Clearly this is personal, I still have trouble understanding what the hell pratto is doing on be NT..
AFA is a mess, the coach is a mess, the whole damn country is a mess.. we will never learn..
I'm praying for icardi to start getting his chance..
I understand whatever he might've done is wrong, but that's all his personal business leave it alone,
guled March 13, 2017 At 3:37 pm
Player power and shitty coaches are ruining argentina.
Richard March 13, 2017 At 3:19 pm
If true, we should start an investigation if Bauza is still being paid by Brazil to miss qualification.
"bozo stated a few times that if something were to happen to Gonzalo HIGUAIN or Lucas PRATTO, it would be Inter's Mauro ICARDI who would get called to replace one of the players"
ive been misquoted says bozo I meant "icardi will never get called up and mark my words ill play striker before I call him up"
His big lie get caught here but he will find another excuse something like alario is already integrated with the team so we opted for him.
glued: sadly true
Insider March 14, 2017 At 6:20 pm
Bauzo…what a $h!t coach…man…he's swallowing his words now. Actually, he was cheating Argentina by not calling Icardi at the first place. Now he's running away…! What Messi is thinking…3 final loss is not enough? He's waiting for another Higuain miss ?? Another final loss? If nobody in the team is blocking Icardi….as captain Messi should come out and speak with Bauza for Icardi.
Dfox1942 March 13, 2017 At 2:51 pm
oh FOR GOD'S Sake, call the man ALREADY.
I honestly and for the first time believe that he will NEVER be called up no matter who is injured………..was she worth it? I guess
argentuban March 13, 2017 At 1:55 pm
Bozo the Clown.
Gonzalo March 13, 2017 At 12:52 pm
Though Dario Benedetto is best No. 9 in Primera

redpajama_set_name: RedPajamaCommonCrawl


text:
Gustav Herglotz (2. února 1881 Volary – 22. března 1953 Göttingen) byl německý fyzik a matematik českoněmeckého původu. Studoval ve Vídni, Mnichově a Göttingen, kde se také později stal profesorem aplikované matematiky. Nejznámější jsou jeho příspěvky k rozvoji teorie relativity, učinil však objevy také v jiných oblastech matematiky a fyziky.

Reference

Externí odkazy

Němečtí matematici
Němečtí geofyzici
Matematici 20. století
Seismologové
Čeští Němci
Členové Göttingenské akademie věd
Vyučující na Vídeňské univerzitě
Vyučující na Lipské univerzitě
Absolventi Mnichovské univerzity
Narození v roce 1881
Narození 2. února
Narození ve Volarech
Úmrtí v roce 1953
Úmrtí 22. března
Úmrtí v Göttingenu
Muži

redpajama_set_name: RedPajamaWikipedia


text:
Out Traveler
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DOMA UNCONSTITUTIONAL; CALIFORNIA BAN ON MARRIAGE DEAD
The Supreme Court made history today by deciding two landmark cases on LGBT equality today with far-reaching implications.
By Advocate.com Editors
June 26 2013 10:10 AM EDT Updated November 17 2015 10:28 PM EST
With the Supreme Court's rulings today, the part of the Defense of Marriage Act that prevented federal recognition of same-sex marriages is no more. And the Proposition 8 law that barred same-sex couples from marrying in California is once again overturned, clearing the way for the return of marriage equality to the state.
California attorney general Kamala Harris, who along with Gov. Jerry Brown refused to defend Prop. 8 in court, urged the lower court to lift its stay and allow same-sex marriages to resume in California "immediately," according to the Los Angeles Times. But the Ninth Circuit Court of Appeals, which issued a stay of district judge Vaughn Walker's 2010 decision striking down Prop. 8 as unconstitutional while the appeal wound its way to the nation's highest court, is expected to take the allotted 25 days to formalize the Supreme Court's ruling and lift the stay, allowing same-sex couples to marry in California by the end of next month.
The Supreme Court's decision that section 3 of the U.S. Defense of Marriage Act is unconstitutional means that legally married same-sex couples can begin claiming a litany of federal benefits immediately, according to The New York Times. Section 3 prevented the federal government from recognizing these marriages.
In a 5-4 decision written by Justice Anthony Kennedy, the nation's highest court ruled that DOMA denies equal protection to a group of people protected by the Fifth Amendment for no other reason than the group's political unpopularity.
"By seeking to injure the very class New York seeks to protect, DOMA violates basic due process and equal protection principles applicable to the Federal Government," writes Kennedy in the majority decision, which was joined by justices Elena Kagan, Ruth Bader Ginsburg, Sonia Sotomayor, and Stephen Breyer. "The Constitution's guarantee of equality 'must at the very least mean that a bare congressional desire to harm a politically unpopular group cannot' justify disparate treatment of that group. … DOMA cannot survive under these principles."
While the death of DOMA does not establish marriage equality nationwide, it does mean that any federal statute that refers to "marriage" or a "spouse" must apply with equal force to legally married same-sex couples, according to SCOTUSBlog. That will have major implications for married same-sex couples, who can now file joint federal tax returns, as well as members of the military who are married to same-sex spouses; these couples can now be recognized by the Department of Defense to receive the same benefits and protections offered to the spouses of straight soldiers.
The decision also clears the way for binational couples to sponsor their foreign-born same-sex spouses for U.S. citizenship, according to Immigration Equality.
"DOMA singles out a class of persons deemed by a State entitled to recognition and protection to enhance their own liberty," the opinion said in ruling it unconstitutional.
Chief Justice John Roberts made clear, though, that the court did not consider in its DOMA ruling whether states have the right to use "the traditional definition of marriage."
On Proposition 8, the Supreme Court ruled by dismissing the appeal by those who challenged the decision overturning it. The majority ruled the Prop. 8 proponents did not have "standing" to challenge a federal judge's decision in the case. The ruling in Proposition 8 was less clear-cut than the one in DOMA, with Chief Justice Roberts siding with the 5-4 majority. Then the dissenters were Sonia Sotomayor, Anthony Kennedy, Clarence Thomas, and Samuel Alito.
The Supreme Court declined to rule on the constitutionality of Proposition 8, but did conclude that the ballot proponents should not have been allowed to defend the case in court in the first place. The nation's highest court ordered the lower courts to reconsider the case, with instructions to dismiss it for lack of standing.
Proposition 8 is a state constitutional amendment banning same-sex marriage approved by California voters in 2008 after the state Supreme Court briefly legalized such unions. Shortly after the vote, a new activist group, the American Foundation for Equal Rights, funded a legal challenge with famed lawyers Ted Olson and David Boies — the two attorneys who argued opposing sides of Bush v. Gore in 2000.
The federal lawsuit against Prop. 8 contended that the measure violates the U.S. Constitution's Fourteenth Amendment guarantees of due process and equal protection of the laws. The plaintiffs were two California couples, Kris Perry and Sandy Stier, and Paul Katami and Jeff Zarrillo. Two sets of California governors and attorneys general declined to defend Prop. 8, so the measure's supporters took up the defense.
In December 2010, U.S. district judge Vaughn Walker found Prop. 8 unconstitutional "because California has no interest in discriminating against gay men and lesbians, and because Proposition 8 prevents California from fulfilling its constitutional obligation to provide marriages on an equal basis."
Then in 2012 an appeals court agreed that the measure is unconstitutional, but ruled in a more narrow fashion, so that its decision could not be applied to other states. And it's at this step that the justices said the supporters of Prop. 8 did not have standing to make an appeal to the Ninth Circuit.
"We have never before upheld the standing of a private party to defend the constitutionality of a state statute when state officials have chosen not to. We decline to do so for the first time here," the majority opinion stated, according to SCOTUSblog.
(RELATED: A Detailed Timeline on How The Proposition 8 Case Unfolded)
On DOMA, the court ruled that Edie Windsor will get her money back. The 83-year-old from New York was forced to pay more than $360,000 in estate taxes because the federal government did not recognize her marriage to her wife spouse, Thea Spyer. And the ruling could have far-reaching consequences for couples in a myriad of circumstances caused by DOMA's ban on federal recognition of same-sex marriages.
In 1996, when a court case in Hawaii appeared to be paving the way for legal same-sex marriage in that state, Congress had passed DOMA and President Clinton signed it into law, in what some critics considered a cynical election-year move to appeal to conservative voters. The law not only prevents the federal government from recognizing same-sex marriages but allows any state to deny recognition of such marriages performed in other states. The Windsor case dealt with only the former section.
Marriage equality never came to Hawaii; the first state to establish it was Massachusetts, in 2004. The first court challenge to DOMA, Gill v. Office of Personnel Management, originated there in 2009. In that and other cases, several federal trial and appeals courts ruled that section 3 violated the U.S. Constitution.
But the case the Supreme Court decided to hear was Edie Windsor's. Windsor, who had been with Spyer for decades, married her in Canada after same-sex unions became legal there. After Spyer's death, Windsor ended up liable for estate taxes that she would not have owed had the federal government considered the two women legally married. Windsor's suit was filed in 2010, and trial and appeals courts found in her favor in 2012.
The Obama administration had declined to defend the law, and the Republican-led Bipartisan Legal Advisory Group, consisting of congressional leaders, took up the defense and hired lawyer Paul Clement. As the Supreme Court prepared to hear the case, more than 40 friend of the court briefs were filed in support of Windsor, and Bill Clinton announced that he was now opposed to DOMA and believed it should be struck down.
When the case was argued before the Supreme Court March 27, Justice Kennedy pointed out several times that regulation of marriages was generally left to the states, not the federal government. All four of the liberal members of the court questioned the law's constitutionality, with Justice Ruth Bader Ginsburg saying it created "two kinds of marriage: the full marriage, and then this sort of skim-milk marriage."
Justice Elena Kagan cited a report from the time of the law's enactment that member of Congress saw it as a way to "express moral disapproval of homosexuality." Clement responded that "just because a couple legislators may have had an improper motive" was not by itself a reason to invalidate the law. However, Roberta Kaplan, Windsor's lawyer, told the court DOMA resulted in "discrimination for the first time in our country's history against a class of married couples."
(RELATED: A Complete Timeline of the Defense of Marriage Act)
Check back for updates and reaction throughout the day at Advocate.com.
Tags: Marriage Equality, Prop 8, DOMA, 2013 Supreme Court Decision, American Foundation for Equal Rights, Prop. 8 Majority
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for Kokobilly Music Recordings ~ A subsidiary of FRONT ROOM MUSIC ~ U.S.A.
Rick Stricklan ~ lead vocals, rhythm & flat-picked lead guitar, and banjo on "I'll Fly Away," and "John Henry."
Jim Stricklan ~ lead & backing vocals, rhythm and finger-picked guitar.
Doug Taylor ~ bass and vocals, mandolin on "Lost and Found," and lead vocal on "Wayfaring Stranger."
Greg Lowry ~ dobro, harmonica, snare drum, bass on "Red Wing;" banjo on "Nine Pound Hammer," "I Find Jesus," and "Where the Soul Never Dies;" mandolin on "Wayfaring Stranger," and backing vocals.
After my cousin Jim Stricklan had his battle with throat cancer and I had my heart attack, we thought we would record something together just cuz we wanted too. I have to say that the "Just Cuz" CD wasn't just an average project for me, it was an experience. It was my first studio recording and I am so thankful to have the opportunity to record with my cousin Jim Stricklan who has always been a musical inspiration in my life. I am also thankful to have top shelf professional musicians Doug Taylor and Greg Lowry who played and sang from the depths of their hearts. The Peaceful setting of the Parrot Tracks Studio in Manchaca Texas was awesome with the high quality technical experience and directing of studio owner George Coyne... it don't get any better. I am thankful to all four of you for being so patient with me. Greg was on the end of his cancer treatments and Doug was diagnosed with colon cancer and had surgery and chemo treatments throughout the duration of the sessions and still gave it all they had. There is no doubt that the Lord had his hand on this. Because He spoke to me and inspired me through each song, I pray He will speak to and be an inspiration to all who hear "Just Cuz".
I often wish that my dad, Clarence Stricklan, could've lived to enjoy these gifts that have come along in my life. I think he would've liked hearing most of the music I've made all these years. Mama, God rest her soul, heard a lot of it and was always so encouraging. She's the reason I made "An American Family Album" several years ago. Without the love and confidence expressed by my wonderful friends and family, I might not have continued along the challenging road of making music that I'm still on today. My cousin Rick Stricklan has been on that road with me since the Route 66 signs went up! We've both survived a lot of pot-holes and detours along life's journey. I can still recall us playing our Teisco del Ray guitars in Aunt Etta's wash room as teenagers...daring to dream where it all might eventually lead. Well, for the past couple of decades, it's enriched our lives by sharing songs at the annual Stricklan family reunions, from Albuquerque to Austin and Buchanan to Buffalo Gap. And now, praise God, it's blessed us with the opportunity to bring together a pair of beautiful Martin guitars, the talents of our pals Doug Taylor and Greg Lowry, and a bunch of our favorite songs—-into the recording studio. "Just Cuz" is the humble, heartfelt result. We sincerely hope this music lifts you up, as it never fails to do for us!
To a battle far away.
Mills adapted the music from Robert Schuman's 1848 piano composition "The Happy Farmer, Returning From Work" from his Album for the Young, Opus 68.


text:
Selection criteria for indexing journals/proceedings:
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Acknowledgements is also strongly recommended. Not only do they help create a greater context for the journal, they also function as a confirmation of the importance of the research presented.
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However, when a journal publishes articles online one at a time rather than collecting articles for release as an 'issue' we take a different approach. In these cases, the editor looks for a steady flow of articles over a nine-month period. The appropriate number of articles for the journal will be determined by the norms for its particular Web of Science category.
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We are also interested in excellent regional Journals and are able to include a relatively small proportion of these each year. Regional journals often target a local, rather than an international, audience requiring less emphasis on extensive international diversity. Citation analyses may also play a different role in the evaluation of regional Journals whose citation impact is characteristically modest. Otherwise, the selection criteria for regional journals are the same as for international journals. The importance of a regional journal is measured more in terms of the specificity of its content. Will it enrich our coverage of a particular subject or provide studies with a specific regional perspective? All regional journals selected must be publishing on time, have English-language bibliographic information (title, abstract, keywords), and be peer reviewed. Cited references must be in the Roman alphabet.
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Wolfe City Rail Trail now has a primitive overnight camp ground!
This beautiful park is located at the city lakes which is right off the trail.
Trail users passing thru now have a spot to stop and rest for the night. They can safely pitch a tent while biking, packing, or hiking along the North East Texas Trail.
The campsite has been named in memory of Wolfe City police officer Tom Ellis White who gave his life in the line of duty July 8th, 1975.