- 标题
- 摘要
- 关键词
- 实验方案
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Fast Calculation of Computer Generated Holograms for 3D Photostimulation through Compressive-Sensing Gerchberg–Saxton Algorithm
摘要： The use of spatial light modulators to project computer generated holograms is a common strategy for optogenetic stimulation of multiple structures of interest within a three-dimensional volume. A common requirement when addressing multiple targets sparsely distributed in three dimensions is the generation of a points cloud, focusing excitation light in multiple diffraction-limited locations throughout the sample. Calculation of this type of holograms is most commonly performed with either the high-speed, low-performance random superposition algorithm, or the low-speed, high performance Gerchberg–Saxton algorithm. This paper presents a variation of the Gerchberg–Saxton algorithm that, by only performing iterations on a subset of the data, according to compressive sensing principles, is rendered significantly faster while maintaining high quality outputs. The algorithm is presented in high-efficiency and high-uniformity variants. All source code for the method implementation is available as Supplementary Materials and as open-source software. The method was tested computationally against existing algorithms, and the results were confirmed experimentally on a custom setup for in-vivo multiphoton optogenetics. The results clearly show that the proposed method can achieve computational speed performances close to the random superposition algorithm, while retaining the high performance of the Gerchberg–Saxton algorithm, with a minimal hologram quality loss.
关键词： optogenetics,spatial light modulators,computer generated holograms
更新于2025-09-23 15:23:52
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Recent Trends in Compressive Raman Spectroscopy Using DMD-Based Binary Detection
摘要： The collection of high-dimensional hyperspectral data is often the slowest step in the process of hyperspectral Raman imaging. With the conventional array-based Raman spectroscopy acquiring of chemical images could take hours to even days. To increase the Raman collection speeds, a number of compressive detection (CD) strategies, which simultaneously sense and compress the spectral signal, have recently been demonstrated. As opposed to conventional hyperspectral imaging, where full spectra are measured prior to post-processing and imaging CD increases the speed of data collection by making measurements in a low-dimensional space containing only the information of interest, thus enabling real-time imaging. The use of single channel detectors gives the key advantage to CD strategy using optical filter functions to obtain component intensities. In other words, the filter functions are simply the optimized patterns of wavelength combinations characteristic of component in the sample, and the intensity transmitted through each filter represents a direct measure of the associated score values. Essentially, compressive hyperspectral images consist of 'score' pixels (instead of 'spectral' pixels). This paper presents an overview of recent advances in compressive Raman detection designs and performance validations using a DMD based binary detection strategy.
关键词： Chemometrics,multivariate data analysis,digital light processor (DLP),digital micromirror device (DMD),optimal binary filters,spatial light modulators (SLM),Raman spectroscopy,chemical imaging,compressive detection
更新于2025-09-23 15:22:29
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Transmissive flexoelectro-optic liquid crystal optical phase modulator with 2 <b>??</b> modulation
摘要： In this paper, we demonstrate analog phase modulation in a transmissive configuration using the flexoelectro-optic effect in short-pitch chiral nematic liquid crystal (LC) devices. Two different modes are considered, both of which are shown to generate full 2π phase modulation at 1 kHz switching frequency. The first configuration that is considered consists of a half-wave plate that is placed between two flexoelectro-optic LC devices that are subjected to electric fields that are applied in phase. Second, we demonstrate that a similar phase modulation response can be observed by removing the half-wave plate and subjecting the two flexoelectro-optic LC devices to electric fields whereby the polarities are out of phase. Both configurations demonstrated herein are promising for the development of next-generation LC spatial light modulators, particularly when reflective geometries are challenging or impractical.
关键词： spatial light modulators,flexoelectro-optic effect,liquid crystal,phase modulation,transmissive configuration
更新于2025-09-23 15:21:01
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Relative limitations of increasing the number of modulation levels in computer generated holography
摘要： Phase and amplitude spatial light modulators (SLMs) capable of both binary and multi-level modulation are widely available and offer a wide range of technologies to choose from for holographic applications. While the replay fields generated with multi-level phase-only SLMs are of a significantly higher quality than those generated by equivalent binary phase-only SLMs, evidence is presented in this letter that this improvement is not as marked for amplitude SLMs, where multi-level devices offer only a small benefit over their binary counterparts. Heuristic and numerical justifications for this are discussed and conclusions drawn.
关键词： Computer generated holography,Amplitude holography,Phase holography,Spatial light modulators
更新于2025-09-19 17:13:59
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Photonic Discrete-time Quantum Walks and Applications
摘要： We present a review of photonic implementations of discrete-time quantum walks (DTQW) in the spatial and temporal domains, based on spatial- and time-multiplexing techniques, respectively. Additionally, we propose a detailed novel scheme for photonic DTQW, using transverse spatial modes of single photons and programmable spatial light modulators (SLM) to manipulate them. Unlike all previous mode-multiplexed implementations, this scheme enables simulation of an arbitrary step of the walker, only limited, in principle, by the SLM resolution. We discuss current applications of such photonic DTQW architectures in quantum simulation of topological effects and the use of non-local coin operations based on two-photon hybrid entanglement.
关键词： time-multiplexing,quantum walks,spatial-multiplexing,spatial light modulators
更新于2025-09-10 09:29:36
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A review of complex vector light fields and their applications
摘要： Vector beams, and in particular vector vortex beams, have found many applications in recent times, both as classical fields and as quantum states. While much attention has focused on the creation and detection of scalar optical fields, it is only recently that vector beams have found their place in the modern laboratory. In this review, we outline the fundamental concepts of vector beams, summarise the various approaches to control them in the laboratory, and give a concise overview of the many applications they have spurned.
关键词： hyper-entanglement,vector beams,vector vortex modes,hybrid entanglement,polarisation,spatial light modulators,geometric phase
更新于2025-09-10 09:29:36
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Electrically programmable multi-purpose nonvolatile metasurface based on phase change materials
摘要： We propose an electrically programmable nonvolatile metasurface working at near-IR frequency (λ=1550 nm) based on ITO/Ge2Sb2Te5-ITO/Au crossbar structure. The proposed metasurface can dynamically change its optical function by modulating the crystallization level of Ge2Sb2Te5, which is a phase change material, at each pixel position individually by controlled electrical pulses. We design and optimize the metasurface by using finite-difference time-domain simulations and numerically demonstrate various optical functions including beam steering devices, flat lenses, optical vortex generators, and metasurface holograms with a single device geometry.
关键词： metasurfaces,phase change materials,spatial light modulators,reconfigurable metasurfaces,programmable metasurfaces
更新于2025-09-10 09:29:36
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Terahertz two-pixel imaging based on complementary compressive sensing
摘要： A compact terahertz (THz) imaging system based on complementary compressive sensing has been proposed using two single-pixel detectors. By using a mechanical spatial light modulator, sampling in the transmission and re?ection orientations was achieved simultaneously, which allows imaging with negative mask values. The improvement of THz image quality and anti-noise performance has been veri?ed experimentally compared with the traditional reconstructed image, and is in good agreement with the numerical simulation. The demonstrated imaging system, with the advantages of high imaging quality and strong anti-noise property, opens up possibilities for new applications in the THz region.
关键词： image reconstruction techniques,terahertz imaging,spatial light modulators
更新于2025-09-09 09:28:46
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Thermally-induced nonlinear spatial shaping of infrared femtosecond pulses in nematic liquid crystals
摘要： An optically-induced thermal non-linear effect in a nematic liquid-crystal (E7) cell is evidenced through weak light-absorption by the ITO coating of an infrared pulsed femtosecond laser (λ0 = 1.5 μm). Strong spatial self-phase modulation is generated, thus a multiple-ring pattern is observed in the far-field. The sign of the nonlinearity is changed depending on the laser polarization. The refractive index and thermal gradients are measured as a function of the laser intensity and we observe that the temperature can increase close to the nematic phase transition. The fidelity and stability of the process open new prospects for spatial shaping devices and delimits the operating wavelength range for ultrafast liquid-crystal based electro-optic application.
关键词： liquid crystal,spatial light modulators,ultrafast laser
更新于2025-09-09 09:28:46