Search

Localisation microscopy of individual molecules allows one to bypass the diffraction limit, revealing cellular organisation on a nanometric scale. This method, which relies on spatial analysis of the signal emitted by molecules, is often limited to the observation of biological objects at shallow depths, or with very few aberrations. The introduction of a temporal parameter into the localisation process through a time‐modulated excitation was recently proposed to address these limitations. This method, called ModLoc, is demonstrated here with an alternative flexible strategy. In this implementation, to encode the time‐modulated excitation a digital micromirror device (DMD) is used in combination with a fast demodulation approach, and provides a twofold enhancement in localisation precision. Layout: Nowadays, we can use an optical microscope to observe how proteins are organised in 3D within a cell at the nanoscale. By carefully controlling the emission of molecules in both space and time, we can overcome the limitations set by the diffraction limit. This allows us to pinpoint the exact location of molecules more precisely. However, the usual spatial analysis method limits observations to shallow depths or causing low distortion of optical waves. To overcome these restrictions, a recent approach introduces a temporal element to the localisation process. This involves changing the illumination over time to enhance the precision of localisation. This method, known as ModLoc, is showcased here using a flexible and alternative strategy. In this setup, a matrix of micrometric mirrors, working together with a fast demodulation optical module, is used to encode and decode the time‐modulated information. This combination results in a twofold improvement in localisation precision. [ABSTRACT FROM AUTHOR]

Perovskite quantum dots (PQDs) are inherently unstable under environmental conditions, making it difficult to form patterns using conventional techniques. Herein, a unique approach is reported for patterning PQDs by the nonuniform photopolymerization of the liquid monomer. The demonstrated approach employs a PQD‐dispersed photocurable liquid, which is illuminated with the patterned light formed using a digital micromirror device (DMD). As the monomers are photopolymerized, the PQDs in the solution are patterned by diffusion (migration), and eventually, their pattern is imprinted on the film after photopolymerization. The migration process of the PQDs is in situ observed using an inverted‐type confocal microscope, and the patterning principle is examined by fine‐tuning the spatial distribution of the light intensity using the DMD. These findings will promote the generation of clear nanocrystal patterns with high contrasts and narrow line widths on films. [ABSTRACT FROM AUTHOR]

We propose a single-pixel imaging (SPI) method to achieve a higher-resolution image via the Hadamard transform matrix. Unlike traditional SPI schemes, this new method recovers images by correlating single-pixel signals with synchronized transformed patterns of Hadamard bases that are actually projected onto the digital micromirror device. Each transform pattern is obtained through the inverse Fourier transform of the pattern acquired by Gaussian filtering of each Hadamard basis in the frequency domain. The proposed scheme is based on a typical SPI experimental setup and does not add any hardware complexity, enabling the transformation of Hadamard matrices and image reconstruction through data processing alone. Therefore, this approach could be considered as an alternative option for achieving fast SPI in a diffraction-limited imaging system, without the need for additional hardware. [ABSTRACT FROM AUTHOR]

INdian Spectroscopic and Imaging Space Telescope (INSIST) is the next-generation UV-Optical space mission proposed by the Indian Astronomical community motivated by the great success of India's first multi-wavelength Astronomical satellite (ASTROSAT) where Ultra Violet Imaging Telescope (UVIT) was one of the main payload launched in 2015 by Indian Space Research Organisation. INSIST is primarily designed for photometry observation in three bands (g-[400 nm–550 nm], u-[300 nm–400 nm] and UV-[150 nm–300 nm]) simultaneously over 0.25 sq.degree field of view. INSIST is equipped with a low resolution [ R ∼ 5 0 0 ] spectrograph for multi-Object slitless spectroscopy over the imaging field of view and also has a medium resolution [ R ∼ 2 0 0 0 ] spectrograph for multi-object slit spectroscopy in UV-band over ∼6 sq.arcmin sky. MEMS-based Digital Micromirror Device [DMD] is used to form configurable slits for the selection of objects at the focal plane of the telescope for multi-object slit spectrograph. Multi-Object spectrograph with DMD as a re-configurable slit for INSIST is designed and the performance of the spectrograph is presented. [ABSTRACT FROM AUTHOR]

Single-pixel imaging (SPI) can capture images using a single-pixel detector. However, conventional SPI schemes only provide a magnitude image of the object, where the phase information is completely lost. Here, we present a dual-modal SPI (DMSPI) system capable of simultaneously capturing the real-part and magnitude images. Since the real-part image fuses the phase distribution, DMSPI has a strong information acquisition capability for all types of objects. The DMSPI system utilizes the two reflection arms provided by the digital micromirror device (DMD) to perform zero-frequency detection in one arm and bucket detection in the other to achieve dual-modal imaging. Benefiting from the unique modulation characteristics of DMD, the DMSPI system is simple and efficient, with high spatial resolution and fast imaging speed. Thus, it might find broad applications in biomedical diagnostics and industrial inspection. [ABSTRACT FROM AUTHOR]

We present a super sub-Nyquist Hadamard single-pixel terahertz (THz) imaging system in which the THz waves are modulated by a digital micromirror device and a laser driver. Spatial coding of the THz radiation is performed using the cake-cutting (CC)-order Hadamard basis. THz images are reconstructed from a series of coding sequences of the measurement intensity. We prove that with the use of super sub-Nyquist sampling, single-pixel THz imaging with 87% fidelity and a signal-to-noise ratio of more than 23 dB can be achieved using 10% of the CC-order Hadamard basis patterns. The total variation regularization algorithm is shown to have higher robustness to noise than the Hadamard transform and thus offers a good technical solution for single-pixel THz imaging. [ABSTRACT FROM AUTHOR]

Single-cell screening, which has revolutionized the life sciences, is an important method for detecting, separating, or treating specific cells based on desired characteristics. Previously, single cells of interest were manually identified in an image, which required human labor and time. We developed an automated photopolymerization system to encapsulate suspended single cells in approximately 50-µm photo-crosslinkable hydrogel squares. An image was captured, and single cells were selected from grouped cells based on image processing. A generated image was transferred to a digital micromirror device (DMD), and in parallel, target-suspended single cells were encapsulated in gelatin methacryloyl (GelMA) hydrogels. We built a data transfer platform based on a Power Automate Desktop (PAD), completed the data transfer, and projected the processed image onto a sample in 10 s, ensuring a minimum alignment error of 6.2 µm. [ABSTRACT FROM AUTHOR]

We report on the achievement of continuous wave bi-frequency operation in a membrane external-cavity surface-emitting laser (MECSEL), which is optically pumped with up to 4 W of 808 nm pump light. The presence of spatially specific loss of the intra-cavity high reflectivity mirror allows loss to be controlled on certain transverse cavity modes. The regions of spatially specific loss are defined through the removal of Bragg layers from the surface of the cavity high reflectivity mirror in the form of crosshair patterns with undamaged central regions, which are created using a laser ablation system incorporating a digital micromirror device (DMD). By aligning the laser cavity mode with the geometric centre of the loss patterns, the laser simultaneously operated on two Hermite-Gaussian spatial modes: the fundamental HG00 and the higher order HG11 mode. We demonstrate bi-frequency operation over a range of pump powers and sizes of spatial loss features, with a wavelength separation of approximately 5 nm centred at 1005 nm. [ABSTRACT FROM AUTHOR]

Metalenses are emerging as an alternative to digital micromirror devices (DMDs), with the advantages of compactness and flexibility. The exploration of metalenses has ignited enthusiasm among optical engineers, positioning them as the forthcoming frontier in technology. In this paper, we advocate for the implementation of the phase-change material, Sb 2 Se 3 , capable of providing swift, reversible, non-volatile focusing and defocusing within the 1550 nm telecom spectrum. The lens, equipped with a robust ITO microheater, offers unparalleled functionality and constitutes a significant step toward dynamic metalenses that can be integrated with beamforming applications. After a meticulously conducted microfabrication process, we showcase a device capable of rapid tuning (0.1 MHz level) for metalens focusing and defocusing at C band communication, achieved by alternating the PCM state between the amorphous and crystalline states. The findings from the experiment show that the device has a high contrast ratio for switching of 28.7 dB. [ABSTRACT FROM AUTHOR]

Vat photopolymerization (VPP) is an effective additive manufacturing (AM) process known for its high dimensional accuracy and excellent surface finish. It employs vector scanning and mask projection techniques to cure photopolymer resin at a specific wavelength. Among the mask projection methods, digital light processing (DLP) and liquid crystal display (LCD) VPP have gained significant popularity in various industries. To upgrade DLP and LCC VPP into a high-speed process, increasing both the printing speed and projection area in terms of the volumetric print rate is crucial. However, challenges arise, such as the high separation force between the cured part and the interface and a longer resin refilling time. Additionally, the divergence of the light-emitting diode (LED) makes controlling the irradiance homogeneity of large-sized LCD panels difficult, while low transmission rates of near ultraviolet (NUV) impact the processing time of LCD VPP. Furthermore, limitations in light intensity and fixed pixel ratios of digital micromirror devices (DMDs) constrain the increase in the projection area of DLP VPP. This paper identifies these critical issues and provides detailed reviews of available solutions, aiming to guide future research towards developing a more productive and cost-effective high-speed VPP in terms of the high volumetric print rate. [ABSTRACT FROM AUTHOR]

Self‐propelling active particles are an exciting and interdisciplinary emerging area of research with projected biomedical and environmental applications. Due to their autonomous motion, control over these active particles that are free to travel along individual trajectories, is challenging. This work uses optically patterned electrodes on a photoconductive substrate using a digital micromirror device (DMD) to dynamically control the region of movement of self‐propelling particles (i.e., metallo‐dielectric Janus particles (JPs)). This extends previous studies where only a passive micromotor is optoelectronically manipulated with a translocating optical pattern that illuminates the particle. In contrast, the current system uses the optically patterned electrode merely to define the region within which the JPs moved autonomously. Interestingly, the JPs avoid crossing the optical region's edge, which enables constraint of the area of motion and to dynamically shape the JP trajectory. Using the DMD system to simultaneously manipulate several JPs enables to self‐assemble the JPs into stable active structures (JPs ring) with precise control over the number of participating JPs and passive particles. Since the optoelectronic system is amenable to closed‐loop operation using real‐time image analysis, it enables exploitation of these active particles as active microrobots that can be operated in a programmable and parallelized manner. [ABSTRACT FROM AUTHOR]

Diffractive optical elements (DOEs) with rotationally symmetric phase distribution are mainly produced by laser direct writing technique in a polar coordinate system, which has slow processing speed and limited fabrication area. In this paper, we propose a digital micro-mirror device maskless digital lithography technique based on stepwise rotary stitching. DOEs with rotationally symmetric phase distribution are fabricated by exposure of stitching units and rotation of rotary tables. Then, different stitching units are designed to compensate for the errors caused by the accuracy of the rotary table. Finally, the high quality DOEs are produced by the double-exposure method. When increasing the fabrication area, significantly improves the saw-tooth of the lithography pattern edge while reducing misalignment and overlap of stitching caused by residual errors. The diameter of the fabricated Fresnel zone plate was increased from 5.25 mm to 11.40 mm, and the fabrication area was 4.72 times larger than conventional lithography. The stitching error of 18.95 μ m has been eliminated after optimization, and the pixelization has been smoothed. The diffraction results show that the method not only can produce large area and high-quality diffraction elements but also greatly reduce the processing cost. [ABSTRACT FROM AUTHOR]

A single multimode fiber (MMF) provides almost an ideal optical channel to constitute a hair-thin endoscope for minimally invasive biomedical imaging at depths in tissue, especially if the imaging operation can be performed with one single shot in reflection mode, which, however, remains challenging to date. In this work, we present single-shot wide-field reflectance imaging by using a single MMF as the illumination unit and imaging probe simultaneously. To achieve single-shot image capture, a reflection matrix of the fiber was built by a learning-assisted approach for the universal inverse conversion from the output amplitudes to the input amplitudes. The performance was tested by imaging more than 30 000 natural scenes projected by a digital micromirror device, and an averaged Pearson correlation coefficient over 0.84 with respect to the ground truth was achieved in the experiment. Furthermore, the ability to image dynamic scenes at a high frame rate of up to 180 frames per second was demonstrated together with real-time observation of a freely moving microneedle located at the distal end of the MMF. The proposed reflection-mode single-fiber imaging scheme paves the way for practical video-rate microendoscopy at depths in tissue in a minimally invasive manner. [ABSTRACT FROM AUTHOR]

In this contribution, we demonstrate a wide-field hyperspectral mid-infrared (MIR) microscope based on multidimensional single-pixel imaging (SPI). The microscope employs a high brightness MIR supercontinuum source for broadband (1.55 μ m –4.5 μ m ) sample illumination. Hyperspectral imaging capability is achieved by a single micro-opto-electro-mechanical digital micromirror device (DMD), which provides both spatial and spectral differentiation. For that purpose the operational spectral bandwidth of the DMD was significantly extended into the MIR spectral region. In the presented design, the DMD fulfills two essential tasks. On the one hand, as standard for the SPI approach, the DMD sequentially masks captured scenes enabling diffraction-limited imaging in the tens of millisecond time-regime. On the other hand, the diffraction at the micromirrors leads to dispersion of the projected field and thus allows for wavelength selection without the application of additional dispersive optical elements, such as gratings or prisms. In the experimental part, first of all, the imaging and spectral capabilities of the hyperspectral microscope are characterized. The spatial and spectral resolution is assessed by means of test targets and linear variable filters, respectively. At a wavelength of 4.15 μ m a spatial resolution of 4.92 μ m is achieved with a native spectral resolution better than 118.1 nm. Further, a post-processing method for drastic enhancement of the spectral resolution is proposed and discussed. The performance of the MIR hyperspectral microsopce is demonstrated for label-free chemical imaging and examination of polymer compounds and red blood cells. The acquisition and reconstruction of Hadamard sampled 64 × 64 images is achieved in 450 ms and 162 ms, respectively. Thus, combined with an unprecedented intrinsic flexibiliy gained by a tunable field of view and adjustable spatial resolution, the demonstrated design drastically improves the sample throughput in MIR chemical and biomedical imaging. [ABSTRACT FROM AUTHOR]

The division of focal plane (DoFP) polarization imaging sensors, which can simultaneously acquire the target's two-dimensional spatial information and polarization information, improves the detection resolution and recognition capability by capturing the difference in polarization characteristics between the target and the background. In this paper, we propose a novel polarization imaging method based on deep compressed sensing (DCS) by adding digital micromirror devices (DMD) to an optical system and simulating the polarization transmission model of the optical system to reconstruct high-resolution images under low sampling rate conditions. By building a simulated dataset, training a polarization super-resolution imaging network, and showing excellent reconstructions on real shooting scenes, compared to current algorithms, our model has a higher peak signal-to-noise ratio (PSNR), which validates the feasibility of our approach. [ABSTRACT FROM AUTHOR]

Convolutional neural networks are paramount in image and signal processing, and are responsible for the majority of image recognition power consumption today, concentrated mainly in convolution computations. With convolution operations being computationally intensive, next‐generation hardware accelerators need to offer parallelization and high efficiency. Diffractive optics offers the promise of low‐latency, highly parallel convolution operations. However, thus far parallelism is only partially harvested, thereby significantly underdelivering in comparison to its throughput potential. Here, a parallelized operation high‐throughput Fourier optic convolutional accelerator is demonstrated. For the first time, simultaneous processing of multiple kernels in Fourier domain enabled by optical diffraction orders is achieved alongside input parallelism. The proposed approach can offer ≈100× speedup over the previous generation optical diffraction‐based processor and 10× speedup over other state‐of‐the‐art optical Fourier classifiers. [ABSTRACT FROM AUTHOR]

We present the novel use of a digital micromirror device (DMD) as a digitally adjustable and programmable aperture for lens-free digital in-line holographic microscopy (LFDIHMY). The proposed micro-electro-mechanical system (MEMS) based DMD aperture can be used as a compact and inexpensive replacement for existing mechanical based aperture control methods required for many resolution enhancement methods. Simulation of the DMD aperture in an in-line holography setup is presented using a general DMD model from literature. A hardware prototype was successfully implemented and demonstrated. The resolution of both simulated and experimental holograms recorded with a conventional pinhole aperture and the proposed DMD aperture are compared using a 1951 USAF resolution test target. We show that a resolution of 2.46 $\mathrm { \mu {\textbf {m}}}$ , close to the sensor pixel limit, can be obtained with each aperture. This demonstrates that a DMD can be used as a programmable replacement for a pinhole aperture. [ABSTRACT FROM AUTHOR]

A portable Raman spectrometer cannot complete homogeneity analysis of mixtures due to its low accuracy which limits the applications. Here a Raman sensing system based on a digital micromirror device (DMD) is presented. Combined with a digital micromirror, the fixed-focus measurement has been changed with high-frequency mobile measurements which expands the applications. Using fast scanning detection by the digital micromirror, the usual fixed focus (generally 50 μm diameter) is upgraded to high-speed surface scanning. The side length of the scanning rectangle may set according to the application or sample size. The point-by-point scanning function further improves the analysis of mixtures through multi-point measurement of samples in a specific area. [ABSTRACT FROM AUTHOR]

When combined with computational approaches, fluorescence imaging becomes one of the most powerful tools in biomedical research. It is possible to achieve resolution figures beyond the diffraction limit, and improve the performance and flexibility of high-resolution imaging systems with techniques such as structured illumination microscopy (SIM) reconstruction. In this study, the hardware and software implementation of an LED-based super-resolution imaging system using SIM employing GPU accelerated parallel image reconstruction is presented. The sample is illuminated with two-dimensional sinusoidal patterns with various orientations and lateral phase shifts generated using a digital micromirror device (DMD). SIM reconstruction is carried out in frequency space using parallel CUDA kernel functions. Furthermore, a general purpose toolbox for the parallel image reconstruction algorithm and an infrastructure that allows all users to perform parallel operations on images without developing any CUDA kernel code is presented. The developed image reconstruction algorithm was run separately on a CPU and a GPU. Two different SIM reconstruction algorithms have been developed for the CPU as mono-thread CPU algorithm and multi-thread OpenMP CPU algorithm. SIM reconstruction of 1024 × 1024 px images was achieved in 1.49 s using GPU computation, indicating an enhancement by ∼28 and ∼20 in computation time when compared with mono-thread CPU computation and multi-thread OpenMP CPU computation, respectively. [ABSTRACT FROM AUTHOR]

Cultured neuronal networks (CNNs) are powerful tools for studying how neuronal representation and adaptation emerge in networks of controlled populations of neurons. To ensure the interaction of a CNN and an artificial setting, reliable operation in both open and closed loops should be provided. In this study, we integrated optogenetic stimulation with microelectrode array (MEA) recordings using a digital micromirror device and developed an improved research tool with a 64-channel interface for neuronal network control and data acquisition. We determined the ideal stimulation parameters including light intensity, frequency, and duty cycle for our configuration. This resulted in robust and reproducible neuronal responses. We also demonstrated both open and closed loop configurations in the new platform involving multiple bidirectional channels. Unlike previous approaches that combined optogenetic stimulation and MEA recordings, we did not use binary grid patterns, but assigned an adjustable-size, non-binary optical spot to each electrode. This approach allowed simultaneous use of multiple input–output channels and facilitated adaptation of the stimulation parameters. Hence, we advanced a 64-channel interface in that each channel can be controlled individually in both directions simultaneously without any interference or interrupts. The presented setup meets the requirements of research in neuronal plasticity, network encoding and representation, closed-loop control of firing rate and synchronization. Researchers who develop closed-loop control techniques and adaptive stimulation strategies for network activity will benefit much from this novel setup. [ABSTRACT FROM AUTHOR]

Due to advantages such as the high efficiency of light utilization, small volume, and vibration resistance, digital micro-mirror device (DMD)-based spectrometers are widely used in ocean investigations, mountain surveys, and other field science research. In order to eliminate the stray light caused by DMDs, the stray light in DMD-based spectrometers was first measured and analyzed. Then, the stray light was classified into wavelength-related components and wavelength-unrelated components. Moreover, the noise caused by the stray light was analyzed from the perspective of encoding equation, and the de-noising decoding equation was deduced. The results showed that the accuracy range of absorbance was enhanced from [0, 1.9] to [0, 3.1] in single-stripe mode and the accuracy range of absorbance was enhanced from [0, 3.8] to [0, 6.3] in Hadamard transform (HT) multiple-stripe mode. A conclusion can be drawn that the de-noising strategy is feasible and effective for enhancing the SNR in DMD-based spectrometers. [ABSTRACT FROM AUTHOR]

The quantum matter synthesizer (QMS) is a new quantum simulation platform in which individual particles in a lattice can be resolved and re-arranged into arbitrary patterns. The ability to spatially manipulate ultracold atoms and control their tunneling and interactions at the single-particle level allows full control of a many-body quantum system. We present the design and characterization of the QMS, which integrates into a single ultra-stable apparatus a two-dimensional optical lattice, a moving optical tweezer array formed by a digital micromirror device, and site-resolved atomic imaging. We demonstrate excellent mechanical stability between the lattice and tweezer array with relative fluctuations below 10 nm, diffraction-limited imaging at a resolution of 655 nm, and high-speed real-time control of the tweezer array at a 2.52 kHz refresh rate, which will be adopted to realize fast rearrangement of atoms. The QMS also features new technologies and schemes, such as nanotextured anti-reflective windows and all-optical long-distance transport of atoms. [ABSTRACT FROM AUTHOR]

Scattering interference (SI) is the possible scattering of intense radiation from the source, which is superimposed directly onto the resonance fluorescence signal of interest. It will lead to sham high results when using a non-dispersive optical system for As detection. To solve the SI of As, in this paper, a real-time suppression method named the non-fluorescent line ratios (NFLR) method was proposed after detailed analysis using dispersive atomic fluorescence spectrometry based on an ultraviolet digital micromirror device spectrometer (UV-DMD-AFS). Specifically, according to the characteristic of fast wavelength selection of UV-DMD-AFS, the source of SI and the effect of external factors on SI were analyzed, the non-fluorescent lines of As and the ratios of non-fluorescent lines to fluorescent lines (simplified as "Ratios") were determined, and the stability of the Ratios was studied under different parameters. The NFLR method suppressed the SI of As effectively, whose suppression proportion was 98.50–102.43%. Compared with the non-dispersive AFS, the NFLR method had a higher long-term accuracy (>99.20%) validated with certified reference materials (CRMs) of water quality samples. [ABSTRACT FROM AUTHOR]

• The application of DMD in two techniques of phase and amplitude modulation were summarized. • Three wavefront shaping techniques were summarized. • Four typical methods for improving the signal-to-noise ratio in PAWS were summarized. • Four methods that push the boundaries of the acoustical limit in PAWS were summarized. In recent years, wavefront shaping technology has made it possible to refocus scattered photons through turbid media. The utilization of photoacoustic signal as feedback for wavefront shaping offers non-invasive and deep-penetrating advantages, making it increasingly attractive in the field of biomedical research. However, due to the short decorrelation time of scattered light in living biological tissues, demonstrating the technique in vivo remains challenging. Digital Micromirror Devices (DMD) with their various modulation modes and high refresh rates hold great potential in addressing this challenge and have been widely employed in Photoacoustic Guided Wavefront Shaping (PAWS) applications. This paper presents the fundamental principles of using photoacoustic signal as feedback to guide wavefront shaping and highlights the advantages of PAWS in biological tissue imaging. Furthermore, a comparative analysis of three commonly used spatial light modulators in PAWS is provided, along with an overview of the three main techniques employed in wavefront shaping. Additionally, methods for improving the signal-to-noise ratio and imaging resolution in PAWS are summarized, followed by a discussion on potential future directions for this field. [ABSTRACT FROM AUTHOR]

• An innovative quaternary hybrid light modulation (QHLM) based projection display is proposed. • A quaternary spatial light modulator is constructed by illuminating two parallel digital micro-mirror devices (DMDs) with different light intensities. • The quaternary digit-plane decomposition and the pixel-level alignment of two DMDs are realized. • The prototype is designed and implemented to verify that the QHLM can achieve 16-bit projection at 220 fps. Conventional spatial light modulators (SLM) can only be used for projecting 8-bit or 10-bit images at normal frame rate. Therefore, commercial high dynamic range (HDR) displays typically focus on boosting the contrast while neglecting to raise the bit-depth. Existing methods for high bit-depth display generally rely on stacking two SLMs to modulate the outgoing beam twice, namely multiplicative modulation, resulting in many troubles such as low optical efficiency, difficulty in pixel-level alignment, and complex image rendering algorithm. In this paper, an innovative quaternary hybrid light modulation (QHLM) based projection display is proposed and realized. By illuminating two parallel digital micro-mirror devices (DMDs) with different light intensities, the quaternary digit-planes (QDs) with four gray levels are able to be modulated rapidly. Aiming at this ability, the quaternary pulse width modulation (QPWM) is incorporated with the quaternary light-intensity modulation (QLM) to fundamentally improve the modulation efficiency compared to the binary light modulation mode. Furthermore, the quaternary digit-plane decomposition (QDD) based image splitting algorithm is adopted to split a high bit-depth image into two images that drive two DMDs respectively. The prototype is designed and built to verify the feasibility of the QHLM based projection display. The experimental results demonstrate that the prototype can project 16-bit images at 220 fps. Through additive modulation of two DMDs in parallel, the QHLM entirely avoids the drawbacks of multiplicative modulation. As a completely different technology, the QHLM has a great potential for HDR projection applications. [ABSTRACT FROM AUTHOR]

This paper provides an in-depth exploration of holographic methodologies, focusing particularly on digital holography facilitated by Digital Micromirror Devices (DMD). We thoroughly examine the theoretical foundations of holographic capture and reconstruction, emphasizing the role of DMDs in these processes. The study covers the principles of diffraction that govern the interaction between light waves and DMDs, alongside a detailed look at the structure, operating principles, and holography-relevant properties of DMDs. We discuss various approaches to creating holographic displays, addressing the inherent challenges and proposing potential solutions. The paper further explores computational strategies for crafting holograms for 3D displays using DMDs and examines multiple advanced techniques for holographic image reconstruction. Our findings highlight the distinctive advantages of DMDs in holography, such as their fast switching speeds, increased angular separation between reconstructed and incident beams, and finer mirror pitch, all contributing to superior hologram quality. We conclude that DMD-based systems hold significant promise for advancing the field of holographic displays. • Examines digital holography with Digital Micromirror Devices (DMD) and explores theoretical foundations. • Explores diffraction principles in light-DMD interaction. • Explores computational strategies for 3D hologram crafting with DMDs. • Explores advanced holographic techniques with DMDs. [ABSTRACT FROM AUTHOR]

In our earlier paper [Adamov, E. V., Aksenov, V. P., Dudorov, V. V., Kolosov, V. V., & Levitskii, M. E. (2022). Controlling the spatial structure of vector beams synthesized by a fiber laser array. Optics & Laser Technology , 154 , 108,351], we presented the method to control the spatial intensity distribution of a beam synthesized as a result of coherent combining of subbeams from an array of phase-controlled fiber radiation sources, each subbeam characterized by its own direction of linear polarization. In this paper, we consider theoretically and experimentally the feasibility of controlling the polarization structure of such synthesized beams by changing the phase relations between individual subbeams. It is shown that for fixed polarization directions of the subbeams, the nonuniform polarization distribution of the synthesized beam, whose character depends on the phase relations and polarization directions of the subbeams, can be controlled via a change of only subbeam phases. • In our earlier paper [Adamov, E. V., Aksenov, V. P., Dudorov, V. V., Kolosov, V. V., & Levitskii, M. E. (2022). Controlling the spatial structure of vector beams synthesized by a fiber laser array. Optics & Laser Technology , 154 , 108,351], we presented the method to control the spatial intensity distribution of a beam synthesized as a result of coherent combining of subbeams from an array of phase-controlled fiber radiation sources, each subbeam characterized by its own direction of linear polarization. In this paper, we consider theoretically and experimentally the feasibility of controlling the polarization structure of such synthesized beams by changing the phase relations between individual subbeams. It is shown that for fixed polarization directions of the subbeams, the nonuniform polarization distribution of the synthesized beam, whose character depends on the phase relations and polarization directions of the subbeams, can be controlled via a change of only subbeam phases.. [ABSTRACT FROM AUTHOR]

• A structured light generation scheme using the anti-blaze condition (ABC) of a digital micromirror device (DMD) is proposed. • Since the ABC does not produce a DC component, various structured lights can be generated using a single iris diaphragm. • A series of DMD patterns with various orientation angles are introduced and experimentally verified for the ABC. • The ABC of a DMD can be used in many structured light-based applications. Generating high-frequency sinusoidal intensity patterns with different orientations, periods, and phases is crucial in many optical measurement systems. As the required measurement resolution of an optical metrology system is increased, interference-based structured light generation with a coherent light source is preferred over a projection-based method with an incoherent light source. We propose a powerful high-frequency intensity pattern generation scheme using the anti-blaze condition (ABC) of a digital micromirror device (DMD). Unlike conventional methods using the blaze condition of a DMD, our proposed method is intrinsically free from a DC component, which can circumvent the requirements of matched spatial filters and sophisticated alignments. We have experimentally verified the feasibility of our proposed method by proposing a series of DMD patterns that can generate various high-frequency two-beam interference patterns. [ABSTRACT FROM AUTHOR]

Spatial light modulators (SLMs) are versatile devices used for optical studies. These instruments have a wide area of application in photonics. Additionally, SLMs have potential utility in different applications, such as biomedical applications, laser based surgery for precise cutting and as optical tweezers to separate cells in a petri container. However, the high cost of SLM devices prevents their widespread use in many areas, including industrial areas and scientific research laboratories. This paper demonstrates how to design a digital light processor (DLP) based low-cost SLM and describes how to obtain structured electromagnetic waves with the designed SLM. Therefore, this research was undertaken to design and produce a low-cost SLM device for optical applications. For this purpose, two prerequisites had to be fulfilled, the first was to use suitable components of a projection device with DLP-based digital micro-mirror device (DMD), and the second was to eliminate unnecessary SLM components from the system. Finally, holographic images reflected on the SLM screen were created by using Mathematica software program to change the amplitude and phase of the electromagnetic waves in order to obtain the structured electromagnetic waves. [ABSTRACT FROM AUTHOR]

Complex vector modes of light, non-separable in their spatial and polarisation degrees of freedom, are revolutionising a wide variety of research fields. It is therefore not surprising that the generation techniques have evolved quite dramatically since their inception. At present it is common to use computer-controlled devices, among which digital micromirror devices have become popular. Some of the reason for this are their low-cost, their polarisation-insensitive and their high-refresh rates. As such, in this manuscript we put forward a novel technique characterised by its high stability, which is achieved through a common-path interferometer. We demonstrate the capabilities of this technique experimentally, first by generating arbitrary vector modes on a higher-order Poincaré sphere, secondly, by generating vector modes in different coordinates systems and finally, by generating various vector modes simultaneously. Our technique will find applications in fields such as optical manipulations, optical communications, optical metrology, among others. [ABSTRACT FROM AUTHOR]

A complex wavefield imaging using single-pixel compressive sensing of an off-axis digital Fresnel hologram is proposed. A digital micromirror device (DMD) sampling prior to the single-pixel detection does the sparse representation of the hologram. The digital hologram is computationally recovered using a compressive sensing (CS) algorithm, and then the complex object wavefield is reconstructed using a complex wave retrieval method. The impact of the use of two measurement operators namely random and Walsh–Hadamard measurement matrices on the reconstruction quality of the hologram and complex object wavefield is compared. The cases of CS algorithm using different sparsification criteria i.e. Haar wavelet, Fresnelet sparsification and without sparsification of the digital hologram are analysed. The computer simulation results of the proposed CS method reveals that the Walsh–Hadamard sampling with Fresnelet sparsification achieves good quality reconstructions of both intensity and phase of the object wavefield. [ABSTRACT FROM AUTHOR]

Lattice light sheet microscopy is uniquely positioned in biomedical imaging modalities due to its superior performance in temporal-spatial resolution and low phototoxicity. However, the imaging system is commonly complicated because producing lattice light sheets involves mechanical scanning and precise alignment. In this Letter, we present an experimental scheme for motionless synthesis and scanning of lattice light sheets using a single digital micromirror device. By fully exploiting its ability of complex amplitude modulation and fast switching, single-shot construction of a uniform lattice light sheet can be achieved by digital dithering. In particular, fast scanning of the lattice light sheet in the depth direction is also realized without any mechanical motion. As a proof of concept, various lattice light sheets are generated and characterized in the experiments. Our work is expected to benefit the development of a compact and low-price lattice light-sheet microscope for biomedical imaging. [ABSTRACT FROM AUTHOR]

Single-pixel imaging (SPI) has attracted widespread attention because it generally uses a non-pixelated photodetector and a digital micromirror device (DMD) to acquire the object image. Since the modulated patterns seen from two reflection directions of the DMD are naturally complementary, one can apply complementary balanced measurements to greatly improve the measurement signal-to-noise ratio and reconstruction quality. However, the balance between two reflection arms significantly determines the quality of differential measurements. In this work, we propose and demonstrate a simple secondary complementary balancing mechanism to minimize the impact of the imbalance on the imaging system. In our SPI setup, we used a silicon free-space balanced amplified photodetector with 5 mm active diameter which could directly output the difference between two optical input signals in two reflection arms. Both simulation and experimental results have demonstrated that the use of secondary complementary balancing can result in a better cancellation of direct current components of measurements, and can acquire an image quality slightly better than that of single-arm single-pixel complementary measurement scheme (which is free from the trouble of optical imbalance) and over 20 times better than that of double-arm dual-pixel complementary measurement scheme under optical imbalance conditions. [ABSTRACT FROM AUTHOR]

Single-pixel imaging (SPI) is a new type of imaging technology that uses a non-scanning single-pixel detector to image objects and has important application prospects and value in many fields. Most of the modulators currently used in SPI systems are digital micromirror device (DMD) modulators, which use a higher frequency for binary modulation than other alternatives. When modulating grayscale information, the modulation frequency is significantly reduced. This paper conducts research on multiple discrete objects in a scene and proposes using binary patterns to locate and image these objects. Compared with the existing methods of using gray patterns to locate and image multiple objects, the method proposed in this paper is more suitable for DMD-type SPI systems and has wider applicability and greater prospects. The principle of the proposed method is introduced, and the effectiveness of the method is experimentally verified. The experimental results show that, compared to traditional SPI methods, the number of patterns required by the proposed method is reduced by more than 85%. [ABSTRACT FROM AUTHOR]

Superresolution (SR) imaging technology based on compression coding has always been considered as the key to break through the geometric resolution of the detector. In addition to factors such as the reconstruction algorithm and mounting platform vibrations, the impact of inherent errors in the optical system itself on the reconstruction results of SR imaging is also obvious. To address this issue, a study on the design of the SR optical system and the influence of optical alignment errors on SR imaging was conducted. The design of the SR optical system based on digital micro-mirror device (DMD) for long-wave infrared wavelength was completed, and an athermal analysis of the system was carried out. The design results showed that the SR optical system has good imaging quality in the operating temperature range. The imaging model of the DMD SR imaging optical system is established according to the designed SR optical system. We investigated the influence of various alignment errors, including decenter, tilt, lens interval error and defocus, on the imaging properties of the SR optical system. Various random combinations of alignment errors were introduced into the optical system, respectively, and the SR reconstructed image quality of the imaging system was analyzed using the inverse sensitivity method to obtain the tolerance limits when the system was assembled. Finally, the effectiveness of the method to obtain the alignment tolerance limit of the compression coding SR imaging optical system was verified through a desktop demonstration experiment. [ABSTRACT FROM AUTHOR]

Microscale surface structures are commonly found on macroscale bodies of natural creatures for their unique functions. However, it is difficult to fabricate such multi-scale geometry with conventional stereolithography processes that rely on either laser or digital micromirror device (DMD). More specifically, the DMD-based mask projection method displays the image of a cross section of the part on the resin to fabricate the entire layer efficiently; however, its display resolution is limited by the building area. In comparison, the laser-based vector scanning method builds smooth features using a focused laser beam with desired beam-width resolution; however, it has less throughput for its sequential nature. In this paper, we studied the hybrid-light-source stereolithography process that integrates both optical light sources to facilitate the fabrication of macro-objects with microscale surface structures (called micro-textures in the paper). The hardware system uses a novel calibration approach that ensures pixel-level dimensional accuracy across the two light sources. The software system enables designing the distribution and density of specific microscale textures on a macro-object by generating projection images and laser toolpaths for the two integrated light sources. Several test cases were fabricated to demonstrate the capability of the developed process. A large fabrication area (76.8-80.0 mm) with 50 μm micro-features can be achieved with a high throughput. [ABSTRACT FROM AUTHOR]

Digital light processing (DLP) is one of the most important additive manufacture technologies to fabricate ceramic parts with complex geometries. Compared with pure photosensitive resin, the cure performance of ceramic suspensions is obviously different due to the optical property change after the addition of ceramic powders. In this paper, a unique oxidation process was used to modify the optical properties of nitride powders including AlN and Si 3 N 4. The properties of oxidized ceramics were investigated and the cure performance of ceramic suspensions was then characterized. The effect of oxidation time on cure performance was evaluated. The results showed that for AlN, oxidation process leads to the smaller cure depth and smaller excess cure width as compared with non-oxidized AlN and for Si 3 N 4 , oxidation process leads to the larger cure depth and larger excess cure width as compared with non-oxidized Si 3 N 4 , indicating that both refractive index and light absorbance of ceramic powders have obvious effects on cure behaviors. Additionally, the cure behavior of oxidized ceramic suspension in this study shows that the relationship of cure depth vs. incident energy agrees well with Beer- Lambert model, but the excess cure width vs. incident energy is not consistent with quasi Beer-Lambert model due to the nature of digital micromirror device (DMD). [ABSTRACT FROM AUTHOR]

• A large field lensless holographic dynamic projection system was developed. • Pure amplitude holograms are loaded in a digital micromirror device. • Creating color-accurate white projection using a single hologram. • A lightweight network is used for hologram generation. Diffraction-based lensless projection system offers the advantages of a compact size with high flexibility. However, existing iterative methods of computation for computer-generated holograms (CGHs) in projection systems are not mature enough. Furthermore, slow CGH generation process is not suitable in dynamic display pattern. Here, a lensless projection system with large field of white light without chromatic aberration is proposed, enabling rapid hologram generation and white light display utilizing a single hologram under trichromatic illumination. The core innovation lies in leveraging differences in reconstructed images from holograms acquired under different wavelength conditions to constrain network training. Additionally, a lightweight hologram generation network is designed for hologram synthesis. This network is trained in a weakly supervised manner, utilizing the Gerchber-Saxton (GS) iterative algorithm based on the scaled angular spectrum method (SASM–GS) to generate reference holograms. The utilization of a weakly supervised approach enhances the efficiency of network training and overcomes the limitations imposed by label-based training. Simulation results demonstrate that the proposed method can rapidly generate holograms with low chromatic aberration, achieving a hologram generation speed of 40 frames per second while maintaining a peak signal-to-noise ratio of 35 dB for reconstructed images. A lensless projection system based on digital micromirror device (DMD) is constructed, and optical experiments confirm that the proposed method enables color-consistent white light display using a single hologram, making it applicable to low-cost, small-scale projection systems and other domains. [ABSTRACT FROM AUTHOR]

• The modulation of amplitude, phase, and polarization to generate complex vector light fields with spatially variant polarization distribution has become a hot research topic in recent years. As an amplitude-only modulation device, a digital micromirror device (DMD) has advantages compared with SLM. It is insensitive to the polarization distribution of the incident beam, which simplifies the experimental design, so it has been widely used in vector beam generation. In this work, we attempt to generate high radial node vector beams and vector vortex beams at arbitrary position on high-order Poincaré spheres(HOPS) and hybrid-order Poincaré spheres(HyPS). We derive the correspondence between half plate angle θ HWP and Poincaré sphere latitude 2 θ based on Jones vector, and we can control arbitrary longitude by changing the phase difference η between phase pattern Φ 1 and Φ 2 which is loaded on DMD. Based on this, we correct the experimental defects of DMD and propose a binary multiplexed hologram, which significantly improves the quality of vortex beam generation by adjusting the ellipticity of vortex beam amplitude and phase distribution. Then we build an experimental interference setup with a Wollaston prism, HWP, and DMD. We generate the vector beam with l = 4 , m = - 4 , p = 4 and reconstruct the State of Polarization distribution of the light field. Furthermore, the high radial node vector vortex beam of p = 10 and the multi-radial node vector vortex beam of polarization order up to 25 are generated. Finally, the vector quality factors of the vector beam l = 4 , m = - 4 , p = 4 on the HOPS while 2 σ = 0 , 2 θ ∈ [ - π / 2 , π / 2 ] and 2 θ = 0 , 2 σ ∈ [ 0 , 2 π) are analyzed. The VQF at the (0 , 0) position of the HOPS can reach 96 %. The experimental results are in good agreement with the theoretical analysis, and good beam quality results are obtained. Our results set a new benchmark for the generation of vector beams and vector vortex beams based on DMD. The modulation of amplitude, phase, and polarization to generate complex vector light fields with spatially variant polarization distribution has become a hot research topic in recent years. We propose a new method for generating high radial node vector vortex beams (VVB) based on a digital micromirror device (DMD). Firstly, we propose a multiplexed binary hologram with varying ellipticity, which can significantly optimize the vortex beam generated by DMD while the mode purity of the scalar vortex beam after optimization can reach 97.23 %. Secondly, a novel interference experimental setup is proposed based on the Wollaston prism, which can realize arbitrary control of VVBs. Based on this, the high radial node VVBs with p = 10 and high polarization order VVBs with polarization order up to 25 are generated experimentally. Finally, we reconstruct the State of Polarization (SoP) of the vector beam l = 4 , m = - 4 , p = 4 based on the Stokes parameter S 1 , S 2 , S 3 , and the variation of vector quality factor (VQF) on the high-order Poincaré sphere (HOPS) is analyzed. Our technology provides a high-quality vector beam generation scheme with important applications in laser detection, optical communication, and optical micro-manipulation. [ABSTRACT FROM AUTHOR]

Although many hybrid convolutional neural networks using optical convolution processors have been demonstrated for high energy efficiency and fast image processing speed, the need for accurate modeling of the optical convolution hardware and large Fourier kernel sizes result in a long and energy-intensive training process. Here, we demonstrate a hybrid convolutional neural network based on an optimized optical convolution processor—the system uses kernels trained in the spatial domain and compensates the optical path mismatch that arises from the reflection of digital micromirror devices for convolution computation. The spatial-domain convolution kernels are Fourier transformed and then binarized before being programmed into a digital micromirror device in the optical convolution processor. This method minimizes overhead from the optical convolution process in the training of the hybrid convolutional neural network, and it can improve the energy efficiency and reduce the training time of the hybrid optical convolutional neural network. For convolution computation using digital micromirror devices with grayscale images, bit-plane-wise convolution is also presented. We tested the hybrid neural network on MNIST, Fashion-MNIST, and CIFAR-10 color datasets and obtained classification accuracies of 98.7%, 85.8%, and 57.8%, respectively. [ABSTRACT FROM AUTHOR]

Keywords: CsPbBr3; pattern; perovskite quantum dots; photocuring; photopolymerizationPatterning Perovskite Quantum DotsIn article number 2302574, Hideyuki Nakanishi and co‐workers discuss the mechanism of perovskite quantum dot patterning based on the inhomogeneous photopolymerization, where appropriate polymerization conditions for obtaining distinct patterns are presented. The comprehension of the patterning mechanism enables extensive application of the method as a general technique for patterning nanocrystals..By Hayato Tanaka; István Lagzi and Hideyuki NakanishiReported by Author; Author; Author [Extracted from the article]

Plane waves generated and alternated using a Digital Micromirror Device (DMD) were evaluated for modulating the spatial coherence of a laser beam. The spatial coherence and its modulation can be represented as a sampling problem in the temporal domain. In this way, the integration time in the detector, the frame rate of the DMD, and the laser coherence time were properly adjusted or chosen to achieve the effect of a beam with a particular state of spatial coherence. Two methods were applied to superpose the plane waves and produce controlled visibility variations in the interferogram of a Young's experiment. The visibility measurements show the variation of the modulus of the complex degree of spatial coherence, controlled by simple phase modulation, and between a pair of points on the wavefront. This procedure, which uses no mobile parts, could be applied in digital holography denoising, beam shaping, optical communications and optical metrology and imaging. [ABSTRACT FROM AUTHOR]

Many biomedical applications require measurements of Raman spectra of tissue under ambient lighting conditions. However, the background light often swamps the weaker Raman signal. The use of time-gated (TG) Raman spectroscopy based on a single photon avalanche diode (SPAD) operating in time-correlated single photon counting and near-infrared laser excitation was investigated for acquisition of Raman spectra and spectral images of biological tissue. The results obtained using animal tissue samples (adipose tissue and muscle) show that the time gating modality enables measurement of Raman spectra under background light conditions of similar quality as conventional continuous wave Raman spectroscopy in the absence of background light. Optimal suppression of the background light was observed for time gate widths of 300â€"1000 ps. The results also showed that TG Raman spectroscopy was able to detect subtle spectral differences required for medical diagnostics, such as differences in Raman spectra of cancer and normal tissue. While the current instrument required scanning of the grating in order to obtain full Raman spectra, leading to impractical times for multi-wavenumber Raman mapping, imaging time could be drastically reduced by spectral multiplexing (compressed detection) using digital micromirror devices or by using SPAD arrays. [ABSTRACT FROM AUTHOR]

Stimulated emission depletion (STED) microscopy has been widely applied in single-cell and single-molecular studies benefiting from its ability of super-resolution imaging. However, it is challenging to perform STED imaging in highly scattering media, such as biological tissues, due to high scattering, which destroys the structured illumination beams. Here, we present a technique to produce the desired illumination beams beyond high scattering for STED microscopy. A dual-wavelength transmission matrix method is employed for shaping the excitation beam and the STED beam simultaneously, achieving the temporal and spatial overlap of the two beams behind a scattering medium. Experimentally, the overlapped foci were constructed by using a digital micromirror device (DMD). The extinction ratio of the STED focus reaches −23.8 dB, which compares favorably to the oft-quoted desirable value for STED applications. In particular, raster scanning of overlapped foci and the switching of the STED focus were demonstrated by adopting the fast switching ability of the DMD. Construction of the illumination beams beyond scattering will benefit STED microscopy in deep tissues. [ABSTRACT FROM AUTHOR]

A dispersive atomic fluorescence spectrometer based on a UV digital micromirror device (UV-DMD-AFS) has been proposed by our team for attenuating spectral and scattering interferences. Software is nontrivial for the automation of component control and sample analysis in the new instrument. In this work, the software was developed using the C# programming language together with multi-threading and combined with the SQLite database, which consists of component control and data acquisition, database, wavelength initialization, and real-time interference reduction module. To realize the accurate analysis of the trace heavy metal concentration, the spectral interference was avoided by measuring the non-interference wavelength, and the scattering interference was eliminated by the real-time proportional coefficient method. The microsecond rotation speed of the DMD is the key to achieving real-time reduction. The concentration of arsenic in Water Quality (GSB 07-3171-2014) was detected to validate the practicability of the software with the concentration deviation of 0.02 ng/mL. [ABSTRACT FROM AUTHOR]

Magnetic field source localization and imaging happen at different scales. The sensing baseline ranges from meter scale, such as magnetic anomaly detection, to centimeter scale, such as brain field imaging, to nanometer scale, such as the imaging of a magnetic skyrmion and single cell. Here, we show how an atomic vapor cell can be used to realize a baseline of 109.6 μm with a magnetic sensitivity of 10 pT/Hz1/2 @0.6–100 Hz and a dynamic range of 2062–4124 nT. We used a free induction decay (FID) scheme to suppress low-frequency noise and avoid scale factor variation for different domains due to light non-uniformity. The measurement domains are scanned by a digital micromirror device. The currents of 22, 30, 38, and 44 mA are applied in the coils to generate different fields along the pumping axis, which are measured respectively by fitting the FID signals of the probe light. The residual fields of every domain are obtained from the intercept of linearly fitting of the measurement data corresponding to these four currents. The coil-generated fields are calculated by deducting the residual fields from the total fields. The results demonstrate that the hole of shield affects both the residual and the coil-generated field distribution. The potential impact of field distribution measurement with outstanding comprehensive properties of spatial resolution, sensitivity, and dynamic range is far-reaching. It could lead to capability of 3D magnetography for small things and/or organs in millimeter or even smaller scale. [ABSTRACT FROM AUTHOR]

Digital micro-mirror devices (DMDs) have been deployed in many optical applications. As compared to spatial light modulators (SLMs), they are characterized by their much faster refresh rates (full-frame refresh rates up to 32 kHz for binary patterns) compared to 120 Hz for most liquid crystal SLMs. DMDs however can only display binary, unipolar patterns and utilize temporal modulation to represent with excellent accuracy multiple gray-levels in display applications. We used the built-in time domain dynamic range representation of the DMD to project 8-bit complex-fields. With this method, we demonstrated 8-bit complex field modulation with a frame time of 38.4 ms (around 0.15 s for the entire complex-field). We performed phase conjugation by compensating the distortions incurred due to propagation through free-space and a scattering medium. For faster modulation speed, an electro-optic modulator was used in synchronization with the DMD in an amplitude modulation mode to create grayscale patterns with frame rate ~ 833 Hz with display time of only 1.2 ms instead of 38.4 ms for time multiplexing gaining a speed up by a factor of 32. [ABSTRACT FROM AUTHOR]