Scalability of all-optical neural networks based on spatial light modulators

Author(s):

Ying Zuo, Zhao Yujun, You-Chiuan Chen, Shengwang Du & Liu, Junwei

Abstract:

“Optical implementation of artificial neural networks has been attracting great attention due to its potential in parallel computation at speed of light. Although all-optical deep neural networks (AODNNs) with a few neurons have been experimentally demonstrated with acceptable errors re- cently, the feasibility of large scale AODNNs remains unknown because error might accumulate inevitably with increasing number of neurons and connections. Here, we demonstrate a scalable AODNN with programmable linear operations and tunable nonlinear activation functions. We ver- ify its scalability by measuring and analyzing errors propagating from a single neuron to the entire network. The feasibility of AODNNs is further confirmed by recognizing handwritten digits and fashions respectively.”

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Publication: Physical Review Applied
Issue/Year: Physical Review Applied, 2021
DOI: https://doi.org/10.1103/PhysRevApplied.15.054034

Precise position and angular control of optical trapping and manipulation via a single vortex-pair beam

Author(s):

Jisen Wen, Binjie Gao, Guiyuan Zhu, DadongLiu, Li-GangWang

Abstract:

“Optical trapping and manipulation using structured laser beams now attract increasing attention in many areas including biology, atomic science, and nanofabrication. Here we propose and demonstrate experimentally the use of a single vortex-pair beam in two-dimensional optical trapping and manipulation. Using the focal properties of such vortex-pair beams, we successfully manipulate two spherical microparticles simultaneously, and obtain the precise position-control on the microparticles by adjusting the off-axis parameter of the vortex-pair beam. Furthermore, we also realize the high-precision angular-controllable rotation of cylindrical microrods by rotating the initial phase structure of such vortex-pair beams, which is like an optical wrench due to two focused bright spots at the focal plane of objective lens. Our experimental result provides an alternative manipulation of microparticles and may have potential applications in biological area, and optically driven micromachines or motors.”

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Publication: Optics and Lasers in Engineering
Issue/Year: Optics and Lasers in Engineering, Volume 148, 106773 (2022)
DOI: 10.1016/j.optlaseng.2021.106773

Neural 3D holography

Author(s):

Choi, Suyeon; Gopakumar, Manu; Peng, Yifan; Kim, Jonghyun & Wetzstein, Gordon

Abstract:

“Holographic near-eye displays promise unprecedented capabilities for virtual and augmented reality (VR/AR) systems. The image quality achieved by current holographic displays, however, is limited by the wave propagation models used to simulate the physical optics. We propose a neural network-parameterized plane-to-multiplane wave propagation model that closes the gap between physics and simulation. Our model is automatically trained using camera feedback and it outperforms related techniques in 2D plane-to-plane settings by a large margin. Moreover, it is the first network-parameterized model to naturally extend to 3D settings, enabling high-quality 3D computer-generated holography using a novel phase regularization strategy of the complex-valued wave field. The efficacy of our approach is demonstrated through extensive experimental evaluation with both VR and optical see-through AR display prototypes.”

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Publication: ACM Transactions on Graphics
Issue/Year: ACM Transactions on Graphics, Volume 40; Number 6; Pages 1–12; 2021
DOI: 10.1145/3478513.3480542

Multi-Incidence Holographic Profilometry for Large Gradient Surfaces with Sub-Micron Focusing Accuracy

Author(s):

Idicula, Moncy Sajeev; Kozacki, Tomasz; Józwik, Michal; Mitura, Patryk; Martinez-Carranza, Juan & Choo, Hyon-Gon

Abstract:

“Surface reconstruction for micro-samples with large discontinuities using digital holog-

raphy is a challenge. To overcome this problem, multi-incidence digital holographic profilometry

(MIDHP) has been proposed. MIDHP relies on the numerical generation of the longitudinal scanning

function (LSF) for reconstructing the topography of the sample with large depth and high axial

resolution. Nevertheless, the method is unable to reconstruct surfaces with large gradients due to

the need of: (i) high precision focusing that manual adjustment cannot fulfill and (ii) preserving

the functionality of the LSF that requires capturing and processing many digital holograms. In this

work, we propose a novel MIDHP method to solve these limitations. First, an autofocusing algorithm

based on the comparison of shapes obtained by the LSF and the thin tilted element approximation is

proposed. It is proven that this autofocusing algorithm is capable to deliver in-focus plane localization

with submicron resolution. Second, we propose that wavefield summation for the generation of the

LSF is carried out in Fourier space. It is shown that this scheme enables a significant reduction of

arithmetic operations and can minimize the number of Fourier transforms needed. Hence, a fast

generation of the LSF is possible without compromising its accuracy. The functionality of MIDHP for

measuring surfaces with large gradients is supported by numerical and experimental results”

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Publication: Sensors
Issue/Year: Sensors, Volume 22; Number 1; Pages 214; 2021
DOI: 10.3390/s22010214

Fast 3D Content Update for Wide-Angle Holographic Near-Eye Display

Author(s):

Rafał Kukołowicz; Chlipala, Maksymilian; Martinez-Carranza, Juan; Idicula, Moncy Sajeev & Kozacki, Tomasz

Abstract:

“Near-eye holographic displays are the holy grail of wear-on 3D display devices because they are intended to project realistic wide-angle virtual scenes with parameters matching human vision. One of the key features of a realistic perspective is the ability to move freely around the virtual scene. This can be achieved by addressing the display with wide-angle computer-generated holograms (CGHs) that enable continuous viewpoint change. However, to the best of our knowledge there is no technique able to generate these types of content. Thus, in this work we propose an accurate and non-paraxial hologram update method for wide-angle CGHs that supports continuous viewpoint change around the scene. This method is based on the assumption that with a small change in perspective, two consecutive holograms share overlapping data. This enables reusing the corresponding part of the information from the previous view, eliminating the need to generate an entirely new hologram. Holographic information for the next viewpoint is calculated in two steps: first, a tool approximating the Angular Spectrum Propagation is proposed to generate the hologram data from previous viewpoint; and second, the efficient Phase Added Stereogram algorithm is utilized for generating the missing hologram content. This methodology offers fast and accurate calculations at the same time. Numerical and optical experiments are carried out to support the results of the proposed method.”

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Publication: Applied Sciences
Issue/Year: Applied Sciences, Volume 12; Number 1; Pages 293; 2021
DOI: 10.3390/app12010293

Reconstructing images of two adjacent objects passing through scattering medium via deep learning

Author(s):

Lai, Xuetian; Li, Qiongyao; Chen, Ziyang; Shao, Xiaopeng & Pu, Jixiong

Abstract:

“In this paper, to the best of our knowledge, we first present a deep learning based method for reconstructing the images of two adjacent objects passing through scattering media. We construct an imaging system for imaging of two adjacent objects located at different depths behind the scattering medium. In general, as the light field of two adjacent objects passes through the scattering medium, a speckle pattern is obtained. We employ the designed adversarial network, which is called as YGAN, for reconstructing the two images simultaneously from the speckle. It is shown that based on the trained YGAN, we can reconstruct images of the two adjacent objects with high quality. In addition, the influence of object image types, and the location depths of the two adjacent objects on the imaging fidelity will be studied. Results demonstrate the strong generalization ability and effectiveness of the YGAN. Even in the case where another scattering medium is inserted between the two objects, the YGAN can reconstruct the object images with high fidelity. The technique presented in this paper can be used for applications in areas of medical image analysis, such as medical image classification, segmentation, and studies of multi-object scattering imaging, three-dimensional imaging etc.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 26; Pages 43280; 2021
DOI: 10.1364/oe.446630

LC 2012 und ein reflektiver HE SLM vll 6001

Optically computed phase microscopy for quantitative dynamic imaging of label-free cells and nanoparticles

Author(s):

Liu, Xuan; Wan, Zhaoxiong; Zhang, Yuanwei & Liu, Yuwei

Abstract:

“Numerous drug delivery systems based on nanoparticles have been developed, such

as those used in BioNTech/Pfizer’s and Moderna’s Covid vaccines. Knowledge on mechanical

interactions between cells and nanoparticles is critical to advance the efficiency and safety

of these drug delivery systems. To quantitatively track the motion of cell (transparent) and

nanoparticles (nontransparent) with nanometer displacement sensitivity, we investigate a novel

imaging technology, optically computed phase microscopy (OCPM) that processes 3D spatial-

spectral data through optical computation. We demonstrate that OCPM has the capability to

image the motion of cells and magnetic nanoparticles that are mechanically excited by an external

magnetic field, quantitatively and in the en face plane.”

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Publication: Biomedical Optics Express
Issue/Year: Biomedical Optics Express, Volume 13; Number 1; Pages 514; 2021
DOI: 10.1364/boe.449034

Focal beam structuring by triple mixing of optical vortex lattices

Author(s):

Stoyanov, Lyubomir; Maleshkov, Georgi; Stefanov, Ivan; Paulus, Gerhard G. & Dreischuh, Alexander

Abstract:

“On-demand generation and reshaping of arrays of focused laser beams is highly desired in many areas of science and technology. In this work, we present a versatile approach for laser beam structuring in the focal plane of a lens by triple mixing of square and/or hexagonal optical vortex lattices (OVLs). In the artificial far field the input Gaussian beam is reshaped into ordered arrays of bright beams with flat phase profiles. This is remarkable, since the bright focal peaks are surrounded by hundreds of OVs with their dark cores and two-dimensional phase dislocations. Numerical simulations and experimental evidences for this are shown, including a broad discussion of some of the possible scenarios for such mixing: triple mixing of square-shaped OVLs, triple mixing of hexagonal OVLs, as well as the two combined cases of mixing square-hexagonal-hexagonal and square-square-hexagonal OVLs. The particular ordering of the input phase distributions of the OV lattices on the used spatial light modulators is found to affect the orientation of the structures ruled by the hexagonal OVL. Reliable control parameters for the creation of the desired focal beam structures are the respective lattice node spacings. The presented approach is flexible, easily realizable by using a single spatial light modulator, and thus accessible in many laboratories.”

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Publication: Optical and Quantum Electronics
Issue/Year: Optical and Quantum Electronics, Volume 54; Number 1; 2021
DOI: 10.1007/s11082-021-03399-5

Distortion correction for wide angle holographic projector

Author(s):

Jędrzej Szpygiel, Maksymilian Chlipała, Rafał Kukołowicz, Moncy Idicula, Tomasz Kozacki

Abstract:

“This letter presents a distortion correction method enabling a distortion minimized, large size image in a wide angle holographic projector. The technique applies numerical predistortion of an input image used for hologram generation. It is based on estimation of distortion coefficients by comparing optically a reconstructed point test chart with the original one. Obtained experimental results prove that the technique allows reconstruction of high-quality image.”

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Publication: Photonics Letters of Poland
Issue/Year: Photonics Letters of Poland, Volume 13; Number 4; Pages 79; 2021
DOI: 10.4302/plp.v13i4.1125

Improving Multiphoton Microscopy by Combining Spherical Aberration Patterns and Variable Axicons

Author(s):

Bueno, J.M.; Hernández, G.; Skorsetz, M.; Artal, P.

Abstract:

“Multiphoton (MP) microscopy is a well-established method for the non-invasive imaging of biological tissues. However, its optical sectioning capabilities are reduced due to specimen-induced aberrations. Both the manipulation of spherical aberration (SA) and the use of axicons have been reported to be useful techniques to bypass this limitation. We propose the combination of SA patterns and variable axicons to further improve the quality of MP microscopy images. This approach provides enhanced images at different depth locations whose quality is better than those corresponding to the use of SA or axicons separately. Thus, the procedure proposed herein facilitates the visualization of details and increases the depth observable at high resolution.”

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Publication: Photonics
Issue/Year: Photonics, Volume 8; Number 12; Pages 573; 2021
DOI: 10.3390/photonics8120573
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