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Efficiently shaping femtosecond, transverse Gaussian laser beams to flat-top beams with flat wavefronts is critical for large-scale material processing and manufacturing. Existing beam shaping devices fall short either in final beam homogeneity or efficiency. We present an approach that uses refractive optics to perform the majority of the beam shaping and then uses a fine-tune device (spatial light modulator) to refine the intensity profile. For the beam that we selected, circularly asymmetric with intensity fluctuations, our method achieved a uniformity of 0.055 within 90% of the beam area at 92% efficiency. The optimization involved an iterative beam shaping process that converged to optimum within 10 iterations.

In the fast‐growing field of integrated photonics, quantifying the dispersive characteristics of the optical components integrated on chip is of key importance. The short length of on‐chip components, however, makes it challenging to measure their dispersive properties. Hence, experimental data are relatively scarce, especially at wavelengths close to the zero‐dispersion wavelength (ZDW) where the dispersion‐length product becomes very small. Ideally, the dispersion should be characterized with a technique that, besides being highly sensitive, “directly” yields the dispersion value without frequency derivative calculations nor the addition of dedicated on‐chip measurement structures. To fulfill these requirements, a dispersion characterization technique is presented relying on femtosecond‐resolution time‐of‐flight measurements combined with advanced spatial light modulator (SLM) technology. With this new “direct” technique, suitable for measuring dispersion‐length products down to 5 × 10−5 ps nm−1, the dispersion of mm‐length silicon nitride waveguides is characterized, both in the weakly dispersive (close to the ZDW) and strongly dispersive regimes. Furthermore, dispersion data are presented for sub‐mm‐length trident couplers and inverted taper couplers connected to the waveguides. The resulting insights into the waveguides’ and couplers’ dispersive properties, and the wide applicability of the technique, will benefit the development of advanced photonic integrated circuits (PICs) in silicon nitride and other waveguide material platforms. [ABSTRACT FROM AUTHOR]

At present, there is a large number of aspherical surfaces in the optical systems. However, making separate compensators to detect each aspherical surface is costly, lack versatility, and faces processing challenges. To solve the problem that different compensators are needed for various aspherical surfaces with different parameters, a method of interferometric surface test put was forward by using spatial light modulator (SLM) as a null-test compensator. This method combined a polarizing beam splitter and waveplates to construct a testing optical path, so as to achieve the measurement of aspheric surface errors. The interferometric testing method was validated by simulating the testing optical path of a field lens with concave aspherical surfaces on both surfaces on ZEMAX. In the meantime, the wavefront modulation error of SLM was simulated and analyzed through MATLAB. The simulation results indicate that the method can test different aspheric surface errors, and the wavefront modulation accuracy within the designed optical path reaches up to 0. 008 3λ. [ABSTRACT FROM AUTHOR]

In this work, we propose a structured-illumination lensless digital holographic microscopy (SI-LDHM). SI-LDHM illuminates a sample with 24 structured illuminations (8 orientations × 3 phase shifts) and records the defocused interferogram formed by two copies of object waves along the ±1st diffraction orders of each SI. The reconstructed object waves under different illumination orientations are respectively propagated to the sample plane along the +1st diffraction order and then averaged, thus yielding a clean image without the artifact of twin images. Experimental results demonstrated that thanks to the multi-oriented SI strategy, the twin image in SI-LDHM is sevenfold reduced compared to conventional DHM, while the spatial resolution is 1.15 times higher. [ABSTRACT FROM AUTHOR]

The continuous miniaturization of semiconductor devices has increased the demand for advanced process control technologies. This process requires real-time measurement systems to monitor manufacturing parameters to ensure efficiency and high quality. This study introduces a novel optical module that uses a spatial light modulator to extract key-point intensity distributions from diffraction images in scatterometry. The efficacy of this method is demonstrated on a grating target with a pitch of 855 nm using a feature extraction algorithm that identifies key point locations based on calculated diffraction images. A particularly designed off-axis extraction pattern facilitates the acquisition of key-point intensity distributions. Moreover, incorporating a cylindrical lens into the optical setup reduces the image feature dimensionality, thereby decreasing the data storage space and enabling the output in a streamlined vector format conducive to further analysis. Experimental data on the development of this scatterometry-based optical module and the subsequent validation of the key-point extraction method indicate a maximum mean absolute error of 0.0080 and a cosine similarity consistently above 0.9999. This study integrates image analysis and measurement techniques by optics, providing a more efficient pathway for key-point extraction in diffraction images, offering the potential for improving real-time process monitoring in the semiconductor manufacturing industry. [ABSTRACT FROM AUTHOR]

Earth observation (EO) is crucial for addressing environmental and societal challenges, but it struggles with revisit times and spatial resolution. The EU-funded SURPRISE project aims to improve EO capabilities by studying space instrumentation using compressive sensing (CS) implemented through spatial light modulators (SLMs) based on micromirror arrays (MMAs) to improve the ground sampling distance. In the SURPRISE project, we studied the development of an MMA that meets the requirements of a CS-based geostationary instrument working in the visible (VIS) and mid-infrared (MIR) spectral ranges. This paper describes the optical simulation procedure and the results obtained for analyzing the performance of such an MMA with the goal of identifying a mirror design that would allow the device to meet the optical requirements of this specific application. [ABSTRACT FROM AUTHOR]

In order to solve the problems of high processing difficulty and limited spectral application range of specific spectra device in traditional quadriwave lateral shearing interferometry system, dividing incident light beam into four beams of lateral shearing coherent wavelets was proposed by using a spatial light modulator instead of a spectro grating. The diffraction efficiency of wavelets was adjusted flexibly by adjusting the refractive index of grating to adapt to the illumination light source, and the optical path difference distribution reflecting the height information and refractive index of the sample was reconstructed according to the interference effect between two wavelets, so as to realize accurate measurement of surface topography in a wide spectral and large dimensions range. In this study, the effect of incident light wavelength on the reconstruction accuracy of optical path difference was investigated by combining the Fourier transform method, and a wide spectrum quadriwave lateral shearing interferometry system from the visible to near infrared was built using a spatial light modulator. The results show that the system measured the etching depth of a standard quartz sample at 209.39 nm ± 1.72 nm, which is basically consistent with its nominal value of 210.83 nm ± 2.39 nm and the measurement value of 212.92 nm ± 1.35 nm by white light interferometer, which verifies the effectiveness of the surface topography measurement method proposed. This study can provide a theoretical reference for the extended application of quadriwave lateral shearing interferometry in the field of surface topography measurement. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, we propose a structured-illumination lensless digital holographic microscopy (SI-LDHM). SI-LDHM illuminates a sample with 24 structured illuminations (8 orientations χ 3 phase shifts) and records the defocused interferogram formed by two copies of object waves along the ±1st diffraction orders of each SI. The reconstructed object waves under different illumination orientations are respectively propagated to the sample plane along the +1st diffraction order and then averaged, thus yielding a clean image without the artifact of twin images. Experimental results demonstrated that thanks to the multi-oriented SI strategy, the twin image in SI-LDHM is sevenfold reduced compared to conventional DHM, while the spatial resolution is 1.15 times higher. [ABSTRACT FROM AUTHOR]

Diode-pumped multi-mode graded-index (GRIN) fiber Raman lasers provide prominent brightness enhancement both in linear and half-open cavities with random distributed feedback via natural Rayleigh backscattering. Femtosecond laser-inscribed random refractive index structures allow for the sufficient reduction in the Raman threshold by means of Rayleigh backscattering signal enhancement by +50 + 66 dB relative to the intrinsic fiber level. At the same time, they offer an opportunity to generate Stokes beams with a shape close to fundamental transverse mode (LP01), as well as to select higher-order modes such as LP11 with a near-1D longitudinal random structure shifted off the fiber axis. Further development of the inscription technology includes the fabrication of 3D ring-shaped random structures using a spatial light modulator (SLM) in a 100/140 μm GRIN multi-mode fiber. This allows for the generation of a multi-mode diode-pumped GRIN fiber random Raman laser at 976 nm with a ring-shaped output beam at a relatively low pumping threshold (~160 W), demonstrated for the first time to our knowledge. [ABSTRACT FROM AUTHOR]

In recent years, the single-pixel imaging technique which uses a detector without spatial resolution and spatially modulated illumination patterns to reconstruct an object image has been finding its application for imaging objects in visibility obstructing conditions such as smoke or fog. The unifying feature of the studies published so far is the proof of workability of the methods proposed by the authors to improve the quality of single-pixel imaging images at their chosen scattering medium parameters without revealing the limits of applicability. This work experimentally demonstrates the influence of the number of scattering particles in the medium on the contrast of single-pixel images, and also compares the results with images obtained with a CCD camera, which allows not only to compare imaging methods under varying conditions, but also to evaluate the influence of losses introduced by the presence of a scattering medium on the contrast of single-pixel images. This work uses the classical experimental scheme of single-pixel imaging in which the single-pixel detector and focusing lens were replaced by a CCD camera to obtain images for comparison. A cuvette containing milk solution of different concentrations was placed between the object and the detector. For each concentration, an image of the object was reconstructed using the single-pixel imaging method and then recorded on the CCD camera until the concentration of the scattering agent was reached at which no image could be obtained by either method. The contrast was then calculated for each image obtained. It is shown that the single-pixel imaging method for milk concentrations up to 1/150 has an average contrast of 0.21, which does not decrease as the scattering increases. At the same time for CCD camera the contrast in the absence of scattering is 0.70, and with increasing milk concentration monotonically decreases to 0.07. The main feature of images obtained by single-pixel imaging through scattering media is the preservation of contrast as the concentration of the scattering medium increases indicating that the relationships between all the recorded on a single-pixel detector intensities used in the construction of the correlation function are preserved. A single-pixel image ceases to be reconstructed only when information about the object does not reach the detector due to multiple scattering and absorption produced by a milk solution. The considered features show the prospect of using single-pixel imaging for the construction of remote sensing systems with pattern recognition, as they allow obtaining similar images at different scattering coefficients of the scattering medium.

A high-throughput laser micro-machining system has been developed using a programmable multi-spot modulated line beam capable of >30x throughput enhancement over a single-spot system. While commercially available lasers have been rapidly growing in output energy and power, single-spot scanning systems cannot take full advantage of these advancements. This system provides high throughput, high resolution micro-processing on a variety of surfaces (stainless steel, aluminum, and polymer). This high productivity system is enabled by a high-power MEMS spatial light modulator called the Planar Light Valve (PLVTM). The PLV is a 1088-pixel device in a linear configuration capable of 10-bit, 100 kHz amplitude modulation. The PLV supports pulse energies of ~1 mJ (1064 nm, 10 ps) and has been used at pulse widths down to 300 femtoseconds. The system can resolve features as small as 10 µm with an edge placement resolution of 2.5 µm. Large area processing is done by scanning and stitching this line beam across the media using X-Y stages and a unique relay galvo scanner has been incorporated into the system to allow for faster scanning over a 15 x 15 mm area. [ABSTRACT FROM AUTHOR]

Wavefront distortions pose a significant limitation in various optical applications, hindering further advancements in optical system performance. In this study, a novel generic calibration model based on Zernike‐fitting neural network (ZFNN) is proposed, which enables insitu wavefront correction with just a single‐shot measurement. The experimental setup follows a standard or equivalent focal‐field imaging optical path, allowing calibration without the need to remove any components from the optical system. The ZFNN, a physics‐informed neural network, offers the advantage of not requiring prior training, eliminating the need for extensive labeled data. With a fully connected network architecture and a modest number of neurons (469), the ZFNN achieves exceptionally fast optimization speed and meets the basic requirements for real‐time calibration. Consequently, this approach holds great potential for applications such as rapid calibration of optical systems, high‐precision light field modulation, and various advanced imaging techniques. [ABSTRACT FROM AUTHOR]

Copyright of Rare Metals is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article considers the use of digital holography in reconstructing object images from different 3D scene cross-sections. This reconstruction enables the study of different materials, characterization of microparticles in a medium, and analysis of microplastic content in water bodies. A method is proposed for reconstructing object images from digital off-axis holograms using a generative adversarial network (GAN). The generative adversarial network is used to reconstruct 3D scene cross-sections in which off-axis objects are present. The application of neural networks is shown to improve the speed and quality of reconstruction, as well as to reduce image noise. The proposed method was tested on numerically synthesized and optically measured digital holograms. By means of this method, eight 3D scene cross-sections were reconstructed using a single synthesized hologram. An average structural similarity index measure of at least 0.73 was obtained. In the study, the authors experimentally recorded sets of digital off-axis holograms of phase objects displayed on spatial light modulators to form the cross-sections of the 3D scene. In the reconstruction of object images using optically registered holograms, the average structural similarity index measure for the cross-sections of the scene amounted to 0.83. The proposed method enables a high-quality reconstruction of object images and will be useful in the analysis of micro- and macro-objects, including in biomedical applications, metrology, as well as characterization of materials, surfaces, and volume media. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to its complex spatial distribution, the higher-order Hermite–Gaussian mode possesses significant application in fields such as precision measurement and optical communication. The spatial light modulator, with its capability to modulate the complex amplitude distribution of the incident light field, finds extensive applications in optical information processing and adaptive optics, thus making it an indispensable tool in these fields. Using cascaded spatial light modulators can efficiently and superbly generate a higher-order Hermite–Gaussian mode; however, the experimental system is challenging, and there are many influencing factors, such as the misalignment between the optical field on the plane of the second spatial light modulator and the hologram loaded onto it, as well as the spot size of the optical field on the plane of the second spatial light modulator. In this paper, we analyzed the influence of the above factors on the quality of generating a higher-order Hermite–Gaussian mode, providing a reference for the efficient and high-quality generation of the higher-order Hermite–Gaussian mode. [ABSTRACT FROM AUTHOR]

The paper demonstrates a method for calculating spiral beams of a given configuration based on a linear combination of displaced Gaussian beams. A new method for generating spiral beams is implemented. The effect of scaling the phase distribution on the quality of the generated light fields is experimentally investigated. The synthesized fields are tested in an experiment on optical manipulation of ensembles of single microparticles. [ABSTRACT FROM AUTHOR]

We clarified that a ferroelectric liquid crystal (FLC) has high resolution display capability as small as 1 × 1 μm pixel pitch using an FLC pixel array with a two‐layer electrode, which has a 1 × 1‐μm‐checkered apertured electrode and a plane electrode separated by an insulation layer. By applying +2 V to the apertured electrode and −10 V to the plane electrode in the two‐layer electrode and 0 V to the transparent common electrode, a checkered pattern was clearly observed, which indicates the successful individual pixel driving with a pixel pitch of 1 × 1 μm. When fabricating 1 × 2‐μm‐pitch rectangular FLC pixels, we elucidated that the liquid crystal alignment direction should be along the shorter side of the pixels to avoid asymmetric transmittance distribution in each pixel. Moreover, we successfully reconstructed a 3D holographic image using 10 × 10 k FLC pixel array with a pitch of 1 × 1 μm driven by the two‐layer electrode with hologram‐patterned apertures. We showed that FLC is a strong candidate material for realizing spatial light modulator with extremely small pixel pitches, which is essential for holographic displays with wide‐viewing‐zone angles. [ABSTRACT FROM AUTHOR]

This paper presents the development of liquid crystal on silicon (LCOS) technology aimed at enhancing the image quality and reliability of projectors. Additionally, we introduce an 8K LCOS panel with a pixel pitch of 2.6 μm. Furthermore, we discuss the application prospects of the developed phase‐only spatial light modulator. [ABSTRACT FROM AUTHOR]

Diffractive Optical Elements (DOEs) are indispensable tools across numerous technological domains due to their capacity to manipulate light with sophistication and versatility. Their compact dimensions, lightweight nature, and compatibility with diverse materials render DOEs as prime candidates for integration into various optical systems, spanning from consumer electronics to state‐of‐the‐art scientific devices. Thus, DOEs stand as essential catalysts in technological advancement, facilitating innovation and unlocking new applications across a broad spectrum of disciplines. In this comprehensive review paper, Numerous types of DOEs widely acknowledge for their efficacy in both free space optics and imaging applications are delved. Beyond mere enumeration, their practical applications, elucidating their transformative impact on these fields are carefully examined. Furthermore, the challenges encountered in their implementation are dissected, paving the way for insightful discussions on future trajectories and advancements. [ABSTRACT FROM AUTHOR]

The application of non-uniform spiral gratings to control the structure, topological parameters and propagation of orbital angular momentum (OAM) beams was studied experimentally with coherent near-infrared light. Adapted digital spiral grating structures were programmed into the phase map of a high-resolution liquid-crystal-on-silicon spatial light modulator (LCoS-SLM). It is shown that characteristic spatio-spectral anomalies related to Gouy phase shift can be used as pointers to quantify rotational beam properties. Depending on the sign and gradient of spatially variable periods of chirped spiral gratings (CSGs), variations in rotation angle and angular velocity were measured as a function of the propagation distance. Propagation-dependent self-torque is introduced in analogy to known local self-torque phenomena of OAM beams as obtained by the superposition of temporally chirped or phase-modulated wavepackets. Applications in metrology, nonlinear optics or particle trapping are conceivable. [ABSTRACT FROM AUTHOR]

In this work, we study the polarization properties of diffraction gratings recorded in thin films of the azopolymer PAZO (poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt]) using digital polarization holography. Using two quarter-wave plates, the phase retardation of each pixel of the SLM is converted into the azimuth rotation of linearly polarized light. When recording from the azopolymer side of the sample, significant surface relief amplitude is observed with atomic force microscopy. In contrast, recording from the substrate side of the sample allows the reduction of the surface relief modulation and the obtaining of polarization gratings with characteristics close to an ideal grating, recorded with two orthogonal circular polarizations. This can be achieved even with a four-pixel period of grating, as demonstrated by our results. [ABSTRACT FROM AUTHOR]

Holographic display enabled by performing both amplitude modulation (AM) and phase modulation (PM) in a single Liquid Crystal on Silicon (LCoS)‐based Spatial Light Modulator (SLM) is introduced. Light propagation is manipulated in two different directions to perform both AM and PM via liquid crystals alignment layer which can be based on technologies by using photoalignment, nano‐imprint lithography (NIL), or unique over‐driving across Liquid Crystal (LC) layer of Vam‐Vpm method which are described and proved to be effective to tune incident light, control the polarization and propagation of the light entering the liquid crystals of a single LCoS‐based SLM (LCoS‐SLM) device. These methods enable holographic display and to alleviate the issues in using two separated SLMs trying to achieve the same. Further, the design techniques and methods to suppress adjacent pixels' crosstalk due to fringe field effect (FFE) [1] in 2D array are amenable to ensure higher resolution with pixel pitch down to 1¼m for compact size and higher pixel numbers beyond 8K×4K. It mitigates to reduce chores of pixel‐to‐pixel alignment, and to enhance image clarity and quality within a single LCoS‐SLM. It will be applicable to enable holographic display with such unique LCoS‐SLM particularly for AR/VR/MR smart glasses applications [18] [19] [20] once being fabricated in the future. [ABSTRACT FROM AUTHOR]

Bessel beams have multiple applications owing to their propagation-invariant properties, including particle trapping, optical coherence tomography, and material processing. However, traditional Bessel-beam shaping techniques require bulky components, which limits the development of miniaturized optical systems for integration with other devices. Here, we report a novel femtosecond laser direct writing strategy for fabricating mesoscale (from submicrometer to subcentimeter) binary optical elements with microscale resolution. This strategy utilizes femtosecond beams with a long focal depth to increase throughput while reducing the constraints on critical sample positioning. As a demonstration, we manufactured and characterized a 2.2 mm diameter binary axicon. The experimentally measured quasi-Bessel beam intensity distribution and the numerical results were remarkably consistent, demonstrating a suitable tradeoff between the overall size, efficiency, and structural fidelity. Furthermore, a compact Bessel lens containing binary axicons was constructed and successfully used for femtosecond laser mask-less ablation of periodic grating-type surface plasmon polariton excitation units. The demonstrated approach shows significant potential for fabricating customizable integrated optical components.

Realizing a spatial phase modulation (SPM) from 0 to 2π is vital for achieving precise light field manipulation, when the phase-only spatial light modulator (SLM) is driven by the voltage. However, insufficient bias voltage degrades the quality of the generated structured light. Here, we propose a superpixel method that consists of 2 × 2 adjacent pixels to equalize the imperfect SPM response, when the bias voltage is insufficient. Meanwhile, a look-up table (LUT) is established between the target light field and the superpixel equalized light field, for reducing the computational complexity of phase hologram generation. When the phase modulation depth is reduced from 2π to 1.67π, we can generate the vortex beams with better quality by the superpixel technique. Characterizing the spatial phase distribution of vortex beams through interferometry verifies the correct function of the superpixel enabled SPM equalization method. In addition, the peak signal-to-noise ratio (PSNR) is used as the metric to quantitatively evaluate the quality of the generated vortex beam. Compared with the phase modulation distortion caused by the insufficient bias voltage, the PSNR after the superpixel enabled SPM equalization is improved by 4.5 dB. Our results would facilitate various applications mediated by power-efficient phase modulation utilizing the SLM.

Earth observation (EO) is crucial for addressing environmental and societal challenges, but it struggles with revisit times and spatial resolution. The EU-funded SURPRISE project aims to improve EO capabilities by studying space instrumentation using compressive sensing (CS) implemented through spatial light modulators (SLMs) based on micromirror arrays (MMAs) to improve the ground sampling distance. In the SURPRISE project, we studied the development of an MMA that meets the requirements of a CS-based geostationary instrument working in the visible (VIS) and mid-infrared (MIR) spectral ranges. This paper describes the optical simulation procedure and the results obtained for analyzing the performance of such an MMA with the goal of identifying a mirror design that would allow the device to meet the optical requirements of this specific application.

Diode-pumped multi-mode graded-index (GRIN) fiber Raman lasers provide prominent brightness enhancement both in linear and half-open cavities with random distributed feedback via natural Rayleigh backscattering. Femtosecond laser-inscribed random refractive index structures allow for the sufficient reduction in the Raman threshold by means of Rayleigh backscattering signal enhancement by +50 + 66 dB relative to the intrinsic fiber level. At the same time, they offer an opportunity to generate Stokes beams with a shape close to fundamental transverse mode (LP01), as well as to select higher-order modes such as LP11 with a near-1D longitudinal random structure shifted off the fiber axis. Further development of the inscription technology includes the fabrication of 3D ring-shaped random structures using a spatial light modulator (SLM) in a 100/140 μm GRIN multi-mode fiber. This allows for the generation of a multi-mode diode-pumped GRIN fiber random Raman laser at 976 nm with a ring-shaped output beam at a relatively low pumping threshold (~160 W), demonstrated for the first time to our knowledge.

The orbital angular momentum (OAM) associated with structured singular beams carries vital information crucial for studying various properties and applications of light. Determining OAM through the interference of light is an efficient method. The interferogram serves as a valuable tool for analyzing the wavefront of structured beams, especially identifying the order of singularity. In this study, we propose a modified Mach–Zehnder interferometer architecture to effectively determine the topological charge of Bessel–Gaussian (BG) beams. Several numerically generated self-referenced interferograms have been used for analysis. Moreover, this study examines the propagation property and phase distribution within BG beams after they are obstructed by an aperture in the interferometer setup. [ABSTRACT FROM AUTHOR]

We propose a method for creating parallel Bessel-like vortical optical needles with an arbitrary axial intensity distribution via the superposition of different cone-angle Bessel vortices. We analyzed the interplay between the separation of individual optical vortical needles and their respective lengths and introduce a super-Gaussian function as their axial profile. We also analyzed the physical limitations to observe well-separated optical needles, as they are influenced by the mutual interference of the individual beams. To verify our theoretical and numerical results, we generated controllable spatial arrays of individual Bessel beams with various numbers and spatial separations by altering the spectrum of the incoming laser beam via the spatial light modulator. We demonstrate experimentally how to implement such beams using a diffractive mask. The presented method facilitates the creation of diverse spatial intensity distributions in three dimensions, potentially finding applications in specific microfabrication tasks or other contexts. These beams may have benefits in laser material processing applications such as nanochannel machining, glass via production, modification of glass refractive indices, and glass dicing. [ABSTRACT FROM AUTHOR]

An oblique-incidence interferometric measurement method is proposed to measure and adjust optical surfaces with a liquid-crystal-on-silicon spatial light modulator (LCoS-SLM). The optical system only consists of an interferometer and an LCoS-SLM with precision mounts. It could reduce the measuring cost and time consumption due to the programmable function of the LCoS-SLM and offer the ability to align the optical system. The oblique-incidence measurement theory and optical system adjustment method are established based on an off-axis paraboloid model. The ray-tracing program to calculate the compensation phase map in the measurement is proposed with math models. In the optical alignment step, the off-axis paraboloid model is used to apply the LCoS-SLM as a phase compensator to generate a focusing spot or light spot array to adjust the measured optical surface. And in the interferometric measurement step, the calculated compensation phase map from the ray-tracing calculation is loaded on the LCoS-SLM using the same optical setup as the optical alignment step without any mechanical adjustment. Two interference measurement experiments of typical optical surfaces were carried out to verify the accuracy of the measuring system. [ABSTRACT FROM AUTHOR]

The field of simulation and machine learning models for ultra-short pulse (USP) ablation manufacturing has seen significant advancements. These models utilize advanced algorithms and mathematical techniques to predict ablation during material interaction or optimize process parameters, resulting in improved precision and efficiency. However, the integration of these systems into production is lacking due to the monolithic design of control software. This design, characterized by tightly coupled components and limited modularity, makes it difficult to incorporate new technologies and updates. Additionally, the computational power required for simulations and machine learning algorithms exceeds the capabilities of traditional shopfloor computers. To address these challenges, a microservice-oriented software design is proposed. Microservices allow for the flexible inclusion of data-driven models by deploying and scaling individual components independently. This enables quick adaptation to changing processes, materials, and business requirements. Moreover, microservices offer the flexibility to use multiple models and algorithms, resulting in a more agile system. However, the infrastructure requirements of a microservice-style architecture are higher compared to a monolithic architecture. The authors will discuss the general architecture, software components, and advantages and disadvantages of controlling USP production machines with a microservice-style architecture. [ABSTRACT FROM AUTHOR]

The increasing enhancement in the modulation accuracy of spatial light modulators has garnered significant attention towards real-time control technology for light fields based on these modulators. It has been demonstrated that this technology possesses a remarkable capability to generate vector beams with arbitrary complex amplitude distributions. Nevertheless, past studies indicate that the generation of only one vector beam at a time has been observed. The simultaneous generation of numerous vector light fields can give rise to several challenges, including compromised picture quality, limited single-mode operation, and intricate optical path configurations. In pursuit of this objective, we present a novel methodology that integrates the coding methodology of modified off-axis interferometric holography with the idea of optical superposition. This technique facilitates the concurrent generation of several vector beams. In this study, we present a demonstration of the simultaneous creation of twelve vector beams using a single spatial light modulator (SLM) as a proof of concept. Significantly, this technology has the ability to generate an unlimited quantity of vector light fields concurrently under the assumption that the resolution of the SLM does not impose any limitations. The findings indicate that the imaging quality achieved by this technology is of a high standard. Furthermore, it is possible to separately control the beam waist radius, topological charge, polarization order, and extra phase of each beam. [ABSTRACT FROM AUTHOR]

Today, the development of tools for analyzing the spatio-temporal properties of optical radiation is a hot topic because of the increased interest in multimode optical technologies. The determination of mode composition and of intermode phases of optical beams is particularly important in the context of studies of new nonlinear effects in multimode waveguides. However, the mode decomposition methods being developed have some limitations that affect their accuracy. This paper is devoted to the study of the impact of recording camera noise in the process of mode decomposition of optical radiation by the correlation filtering method. A significant impact of intensity noise on determining the position of the center of correlation response, a key step in mode decomposition. In order to improve the accuracy of the method, it is proposed to use the Jensen-Shannon metric that allows to effectively determine the center of correlation response of noisy signal. The proposed approach is resistant to a noise level of around 7%. [ABSTRACT FROM AUTHOR]

Complex RGB spatial light modulators are required to produce full-color holographic displays. In particular, complex spatial light modulation, which modulates the amplitude and phase of incident light is essential for noiseless dynamic computer-generated hologram synthesis. The feasibility of full-color holographic image generation through the dual-layer in-plane switching liquid crystal plane is theoretically validated and experimentally demonstrated. [ABSTRACT FROM AUTHOR]

Earth observation (EO) payload performances in the infrared spectral region from geostationary platforms are often limited by spatial resolution. In this paper, we investigate an instrumental concept leveraging a compressive sensing paradigm and super-resolution architecture to implement an EO payload from a geostationary platform aimed at the monitoring of wildfires with a nominal spatial sampling distance of 500 m. The core device of the instrument is a European-technology-based micromirror array under study for space applications. Besides payload specifications and working principles, the main critical aspects and the expected impact on EO applications are discussed. [ABSTRACT FROM AUTHOR]

In this paper, studies have been carried out on the formation of complex structured Laguerre-Gauss vector beams. For the first time, a digital method of intensity moments was used, which allows one to determine the mode composition using a single intensity distribution in each polarization component in the focal plane, either of a spherical lens, or in the plane of double focus of a cylindrical lens. [ABSTRACT FROM AUTHOR]

Whispering-gallery mode microresonators have gained wide popularity as experimental platforms for different applications, ranging from biosensing to nonlinear optics. Typically, the resonant modes of dielectric microresonators are stimulated via evanescent wave coupling, facilitated using tapered optical fibers or coupling prisms. However, this method poses serious shortcomings due to fabrication and access-related limitations, which could be elegantly overcome by implementing a free-space coupling approach; although additional alignment procedures are needed in this case. To address this issue, we have developed a new algorithm to excite the microresonator automatically. Here, we show the working mechanism and the preliminary results of our experimental method applied to a home-made silica microsphere, using a visible laser beam with a spatial light modulator and a software control. [ABSTRACT FROM AUTHOR]

We developed two types of liquid-crystal spatial light modulators: an improved device by modifying each layer of the device and a large active area for industrial infrared lasers to demonstrate innovative manufacturing and fabrication techniques in smart manufacturing. The reconstruction of computer-generated holograms was demonstrated to prove the concept of the proposed device in the IR region. The incident phase performance characteristics of the device under high-power laser irradiation were obtained using a 1030 nm ultrashort pulse laser. [ABSTRACT FROM AUTHOR]