Energy-Efficient Adaptive 3D Sensing

Author(s):

Tilmon, Brevin; Sun, Zhanghao; Koppal, Sanjeev; Wu, Yicheng; Evangelidis, Georgios; Zahreddine, Ramzi; Krishnan, Guru; Ma, Sizhuo & Wang, Jian

Abstract:

“Active depth sensing achieves robust depth estimation but is usually limited by the sensing range. Naively increasing the optical power can improve sensing range but induces eye-safety concerns for many applications, including autonomous robots and augmented reality. In this paper, we propose an adaptive active depth sensor that jointly optimizes range, power consumption, and eye-safety. The main observation is that we need not project light patterns to the entire scene but only to small regions of interest where depth is necessary for the application and passive stereo depth estimation fails. We theoretically compare this adaptive sensing scheme with other sensing strategies, such as full-frame projection, line scanning, and point scanning. We show that, to achieve the same maximum sensing distance, the proposed method consumes the least power while having the shortest (best) eye-safety distance. We implement this adaptive sensing scheme with two hardware prototypes, one with a phase-only spatial light modulator (SLM) and the other with a micro-electro-mechanical (MEMS) mirror and diffractive optical elements (DOE). Experimental results validate the advantage of our method and demonstrate its capability of acquiring higher quality geometry adaptively.”

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Publication: Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR)
Issue/Year: 2023
Link: https://btilmon.github.io/e3d.html

Extending the Imaging Depth of Field through Scattering Media by Wavefront Shaping of Non-Diffraction Beams

Author(s):

Han, Tongyu; Peng, Tong; Li, Runze; Wang, Kaige; Sun, Dan & Yao, Baoli

Abstract:

“Increasing the depth of field (DOF) is a crucial issue for imaging through scattering media. In this paper, an improved genetic algorithm is used to modulate the wavefront of light through scattering media, by which high-quality refocusing and imaging through scattering media are achieved. Then, the DOF of the imaging system is effectively extended by further modulating the refocused beam into a non-diffraction beam. Two kinds of non-diffraction beams, i.e., a Bessel beam and Airy beam, were produced as a demonstration. The experimental results show that compared to the Gaussian beam, the DOF of the imaging system by combining the wavefront shaping and non-diffraction Bessel beam or Airy beam can be improved by a factor of 1.1 or 1.5, respectively. The proposed method is helpful for the technical development of high-quality imaging through scattering media with a large DOF.”

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Publication: Photonics
Issue/Year: Photonics, Volume 10; Number 5; Pages 497; 2023
DOI: 10.3390/photonics10050497

Computational holographic ghost diffraction

Author(s):

Ye, Zhiyuan; Hou, Wanting; Zhao, Jilun; Wang, Hai-Bo & Xiong, Jun

Abstract:

“Since the paradigm shift in 2009 from pseudo-thermal ghost imaging (GI) to computational GI using a spatial light modulator, computational GI has enabled image formation via a single-pixel detector and thus has a cost-effective advantage in some unconventional wave bands. In this Letter, we propose an analogical paradigm known as computational holographic ghost diffraction (CH-GD) to shift ghost diffraction (GD) from classical to computational by using self-interferometer-assisted measurement of field correlation functions rather than intensity correlation functions. More than simply “seeing” the diffraction pattern of an unknown complex volume object with single-point detectors, CH-GD can retrieve the diffracted light field’s complex amplitude and can thus digitally refocus to any depth in the optical link. Moreover, CH-GD has the potential to obtain the multimodal information including intensity, phase, depth, polarization, and/or color in a more compact and lensless manner.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Volume 48; Number 7; Pages 1618; 2023
DOI: 10.1364/ol.484537

Extended Depth-of-Field Lensless Imaging using an Optimized Radial Mask

Author(s):

Neto, Jose Reinaldo da Cunha Santos Aroso Vieira da Silva; Nakamura, Tomoya; Makihara, Yasushi & Yagi, Yasushi

Abstract:

“The freedom of design of coded masks used by mask-based lensless cameras is an advantage these systems have when compared to lens-based ones. We leverage this freedom of design to propose a shape-preserving optimization scheme for a radial-type amplitude coded mask, used for extending the depth of field (DOF) of a lensless camera. Our goal is to identify the best parameters for the coded mask, while retaining its radial characteristics and therefore extended-DOF capabilities. We show that our optimized radial mask achieved better overall frequency response when compared to a naive implementation of a radial mask. We also quantitatively and qualitatively demonstrated the extended DOF imaging achieved by our optimized radial mask in simulations by comparing it to different non-radial coded masks. Finally, we built a prototype camera to validate the extended DOF capabilities of our coded mask in real scenarios.”

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Publication: arXiv
Issue/Year: arXiv, 2023
DOI: 10.48550/ARXIV.2303.11554

Wavefront Sensing by a Common-Path Interferometer for Wavefront Correction in Phase and Amplitude by a Liquid Crystal Spatial Light Modulator Aiming the Exoplanet Direct Imaging

Author(s):

Yudaev, Andrey; Kiselev, Alexander; Shashkova, Inna; Tavrov, Alexander; Lipatov, Alexander & Korablev, Oleg

Abstract:

“We implemented the common-path achromatic interfero-coronagraph both for the wavefront sensing and the on-axis image component suppression, aiming for the stellar coronagraphy. A common-path achromatic interfero-coronagraph has its optical scheme based on a nulling rotational-shear interferometer. The angle of rotational shear can be chosen at a small angular extent of about 10 deg. Such a small angular shear maintains the coronagraphic contrast degradation known as the stellar leakage effect, caused by a finite stellar size. We study the phase and amplitude wavefront control by a liquid crystal spatial light modulator of reflection type which is used as the pixilated active adaptive optics unit. Therefore, adaptive optics perform a wavefront-correcting input toward a stellar interfero-coronagraph aiming at the direct exoplanet imaging. Presented here are both the numeric evaluations and the lab experiment stand to prove the declared functionality output.”

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Publication: Photonics
Issue/Year: Photonics, Volume 10; Number 3; Pages 320; 2023
DOI: 10.3390/photonics10030320

Generalized Talbot Self-Healing of Periodic Images

Author(s):

Rowe, Connor M. L.; Cortes, Luis Romero; de Chatellus, Hugues Guillet; Seghilani, Mohamed & Azana, Jose

Abstract:

“Spatially periodic images are useful in a broad range of scientific fields, but are often corrupted by spatial jitter, noise, or missing repetitions. We review recent work on the use of diffraction-induced Talbot self-imaging to recover corrupted periodic images through a passive amplification process.”

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Publication: IEEE Photonics Society Summer Topicals Meeting Series (SUM)
Issue/Year: IEEE Photonics Society Summer Topicals Meeting Series (SUM), Cabo San Lucas, Mexico, 2022
DOI: 10.1109/sum53465.2022.9858325

Varifocal diffractive lenses for multi-depth microscope imaging

Author(s):

Reda, Francesco; Salvatore, Marcella; Borbone, Fabio; Maddalena, Pasqualino; Ambrosio, Antonio & Oscurato, Stefano Luigi

Abstract:

“Flat optical elements enable the realization of ultra-thin devices able to either reproduce or overcome the functionalities of standard bulky components. The fabrication of these elements involves the structuration of material surfaces on the light wavelength scale, whose geometry has to be carefully designed to achieve the desired optical functionality. In addition to the limits imposed by lithographic design-performance compromises, their optical behavior cannot be accurately tuned afterward, making them difficult to integrate in dynamic optical systems. Here we show the realization of fully reconfigurable flat varifocal diffractive lens, which can be in-place realized, erased and reshaped directly on the surface of an azopolymer film by an all-optical holographic process. Integrating the lens in the same optical system used as standard refractive microscope, results in a hybrid microscope capable of multi-depth object imaging. Our approach demonstrates that reshapable flat optics can be a valid choice to integrate, or even substitute, modern optical systems for advanced functionalities.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 30; Number 8; Pages 12695; 2022
DOI: 10.1364/oe.455520

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

Lensless Optical Encryption of Multilevel Digital Data Containers Using Spatially Incoherent Illumination

Author(s):

Cheremkhin, Pavel; Evtikhiev, Nikolay; Krasnov, Vitaly; Ryabcev, Ilya; Shifrina, Anna & Starikov, Rostislav

Abstract:

“The necessity of the correction of errors emerging during the optical encryption process ledto the extensive use of data containers such as QR codes. However, due to specifics of optical encryp-tion, QR codes are not very well suited for the task, which results in low error correction capabilitiesin optical experiments mainly due to easily breakable QR code’s service elements and byte datastructure. In this paper, we present optical implementation of information optical encryption systemutilizing new multilevel customizable digital data containers with high data density. The results ofoptical experiments demonstrate efficient error correction capabilities of the new data container.”

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Publication: Applied Sciences
Issue/Year: Applied Sciences, Volume 12; Number 1; Pages 406; 2021
DOI: 10.3390/app12010406

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
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