Holographic Glasses for Virtual Reality

Author(s):

JONGHYUN KIM, NVIDIA, USA and Stanford University, USA
MANU GOPAKUMAR, SUYEON CHOI, AND YIFAN PENG, Stanford University, USA
WARD LOPES, NVIDIA, USA
GORDON WETZSTEIN, Stanford University, USA

Abstract:

“We resent Holographic Glasses, a holographic near-eye display system with an eyeglasses-like form factor for virtual reality. Holographic Glasses are composed of a pupil-replicating waveguide,
a spatial light modulator, and a geometric phase lens to create holographic images in a lightweight
and thin form factor. The proposed design can deliver full-color 3D holographic images using an optical stack of 2.5 mm thickness. A novel pupil-high-order gradient descent algorithm is presented for the correct phase calculation with the user’s varying pupil size. We implement benchtop and wearable prototypes for testing. Our binocular wearable prototype supports 3D focus cues and provides a diagonal field of view of 22.8? with a 2.3 mm static eye box and additional capabilities of dynamic eye box with beam steering, while weighing only 60 g excluding the driving board.”

Link to Publications Page

Publication: Association for Computing Machinery
Issue/Year: Association for Computing Machinery, 2022

High-resolution surface plasmon resonance holographic microscopy based on symmetrical excitation

Author(s):

Dou, Jiazhen; Dong, Chen; Dai, Siqing; Mi, Jingyu; Luo, Xiangyuan; Di, Jianglei; Zhang, Jiwei & Zhao, Jianlin

Abstract:

“Surface plasmon resonance holographic microscopy (SPRHM) is able to simultaneously obtain the amplitude- and phase-contrast surface plasmon resonance (SPR) images, showing great potentials in imaging near-field targets with high sensitivity. However, suffered by the decaying length of surface plasmon wave which can be as long as tens of microns, the spatial resolution of SPRHM is lower than that of traditional holographic microscopy. In this work, we propose to enhance the spatial resolution in SPRHM by exciting surface plasmon resonance in two symmetrical directions and detecting the complex amplitudes of the reflected light symmetrically. Through the Fourier analysis of the recorded composite hologram, the reconstruction schemes for high-resolution amplitude- and phase-contrast SPR images are established, respectively. The feasibility and advantages of the proposed method is verified by numerical simulations and experimental demonstrations of small-size particles and micro-structures.”

Link to Publications Page

Publication: Optics and Lasers in Engineering
Issue/Year: Optics and Lasers in Engineering, Volume 153; Pages 107000; 2022
DOI: 10.1016/j.optlaseng.2022.107000

Large depth-of-field fluorescence microscopy based on deep learning supported by Fresnel incoherent correlation holography

Author(s):

Wu, Peng; Zhang, Dejie; Yuan, Jing; Zeng, Shaoqun; Gong, Hui; Luo, Qingming & Yang, Xiaoquan

Abstract:

“Fluorescence microscopy plays an irreplaceable role in biomedicine. However,

limited depth of field (DoF) of fluorescence microscopy is always an obstacle of image quality,

especially when the sample is with an uneven surface or distributed in different depths. In

this manuscript, we combine deep learning with Fresnel incoherent correlation holography to

describe a method to obtain significant large DoF fluorescence microscopy. Firstly, the hologram

is restored by the Auto-ASP method from out-of-focus to in-focus in double-spherical wave

Fresnel incoherent correlation holography. Then, we use a generative adversarial network to

eliminate the artifacts introduced by Auto-ASP and output the high-quality image as a result.

We use fluorescent beads, USAF target and mouse brain as samples to demonstrate the large

DoF of more than 400µm, which is 13 times better than that of traditional wide-field microscopy.

Moreover, our method is with a simple structure, which can be easily combined with many

existing fluorescence microscopic imaging technology”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 30; Number 4; Pages 5177; 2022
DOI: 10.1364/oe.451409

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”

Link to Publications Page

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

Coded aperture correlation holography (COACH) with a superior lateral resolution of FINCH and axial resolution of conventional direct imaging systems

Author(s):

Bulbul, Angika; Hai, Nathaniel & Rosen, Joseph

Abstract:

“Fresnel incoherent correlation holography (FINCH) is a self-interference incoherent digital holography technique. It possesses a higher lateral resolution than an equivalent incoherent imaging system. However, FINCH has lower axial resolution than the direct imaging systems with the same numerical aperture. A decade after the FINCH invention, a different incoherent holographic method named coded aperture correlation holography (COACH) was developed with improved axial resolution but with the same lateral resolution as direct imaging. In this study, we propose and demonstrate a variant of COACH called coded aperture with FINCH intensity responses (CAFIR) with an improved lateral resolution that is similar to the FINCH system while maintaining its high axial resolution similar to the direct imaging system. CAFIR is implemented with coded phase masks to generate an ensemble of quasi-randomly distributed FINCH-like responses. Point spread holograms and object holograms are recorded under identical conditions, and they are cross-correlated to obtain the image reconstruction. Imaging of a multiplane object is studied to compare the axial resolution of CAFIR with FINCH and direct imaging systems.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 25; Pages 42106; 2021
DOI: 10.1364/oe.446945

Speckle-free holography with partially coherent light sources and camera-in-the-loop calibration

Author(s):

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

Abstract:

“Computer-generated holography (CGH) holds transformative potential for a wide range of applications, including direct-view, virtual and augmented reality, and automotive display systems. While research on holographic displays has recently made impressive progress, image quality and eye safety of holographic displays are fundamentally limited by the speckle introduced by coherent light sources. Here, we develop an approach to CGH using partially coherent sources. For this purpose, we devise a wave propagation model for partially coherent light that is demonstrated in conjunction with a camera-in-the-loop calibration strategy. We evaluate this algorithm using light-emitting diodes (LEDs) and superluminescent LEDs (SLEDs) and demonstrate improved speckle characteristics of the resulting holograms compared with coherent lasers. SLEDs in particular are demonstrated to be promising light sources for holographic display applications, because of their potential to generate sharp and high-contrast two-dimensional (2D) and 3D images that are bright, eye safe, and almost free of speckle.”

Link to Publications Page

Publication: Science Advances
Issue/Year: Science Advances, Volume 7; Number 46; 2021
DOI: 10.1126/sciadv.abg5040

Comparison of state-of-the-art Computer Generated Holography algorithms and a machine learning approach

Author(s):

Madsen, Andreas Erik Gejl; Eriksen, René Lynge & Glückstad, Jesper

Abstract:

“This work studies the use of machine learning and, in particular, a Convolutional Neural Network (CNN) to generate digital holograms and how such a network compares to state-of-the-art iterative methods, both in terms of reconstruction quality and computation time. Since CNNs only require a single pass through the network by a target image to generate a result, and not tens or hundreds of expensive iterations as in the iterative methods, they may be able to accomplish real-time hologram generation; an ability that could open the technology to proper commercial use.

In this work, a CNN built on the UNet architecture, capable of hologram generation, is presented. The network is trained on 4096 images of varying spatial frequencies, both user-generated and from the DIV2K dataset. It is compared to the most common iterative method for hologram generation, namely the Gerchberg–Saxton(GS) algorithm and its modern and improved implementations. In reconstruction quality, the neural network outperforms the original implementation of GS when evaluating Mean Square Error (MSE), geometric error (GE), Structural Similarity Index Measurement (SSIM), and Peak Signal-Noise Ratio (PSNR) of 64 unseen test images. However, on the same test images, the network lacks behind the modern, optimized GS implementations in all error and accuracy measurements. The network does, however, achieve these results at a rate 70–280 times faster than the iterative methods, depending on the particular implementation of the GS algorithm, which corresponds to a possible generation rate of the network of 32 FPS on average.”

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Publication: Optics Communications
Issue/Year: Optics Communications, Pages 127590; 2021
DOI: 10.1016/j.optcom.2021.127590

Wide angle holographic video projection display

Author(s):

Chlipała, Maksymilian; a; Kozacki, Tomasz; Yeom, Han-Ju; Martinez-Carranza, Juan; Rafał; Kukołowicz; Kim, Jinwoong; Yang, Jong-Heon; Choi, Ji Hun; Pi, Jae-Eun & Hwang, Chi-Sun

Abstract:

“Holographic projection displays provide high diffraction efficiency. However, they have a limited projection angle. This work proposes a holographic projection display with a wide angle, which gives an image of size 306mm×161mm at 700 mm and reduced speckle noise. The solution uses single Fourier lens imaging with a frequency filter and hologram generation utilizing complex coding and nonparaxial diffraction. The experiment was performed with a 4K phase-only spatial light modulator (SLM) to prove the high efficiency of the developed numerical tools. Optical reconstruction shows high resolution and high image quality achieved from a single frame. Hence, displaying video at a full frame rate of the SLM is possible.”

Link to Publications Page

Publication: Optics Letters
Issue/Year: Optics Letters, Volume 46; Number 19; Pages 4956; 2021
DOI: 10.1364/ol.430275

All-optical image identification with programmable matrix transformation

Author(s):

Li, Shikang; Ni, Baohua; Feng, Xue; Cui, Kaiyu; Liu, Fang; Zhang, Wei & Huang, Yidong

Abstract:

“An optical neural network is proposed and demonstrated with programmable matrix transformation and nonlinear activation function of photodetection (square-law detection). Based on discrete phase-coherent spatial modes, the dimensionality of programmable optical matrix operations is 30∼37, which is implemented by spatial light modulators. With this architecture, all-optical classification tasks of handwritten digits, objects and depth images are performed. The accuracy values of 85.0% and 81.0% are experimentally evaluated for MNIST (Modified National Institute of Standards and Technology) digit and MNIST fashion tasks, respectively. Due to the parallel nature of matrix multiplication, the processing speed of our proposed architecture is potentially as high as 7.4∼74 T FLOPs per second (with 10∼100 GHz detector).”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 17; Pages 26474; 2021
DOI: 10.1364/oe.430281

Single-shot digital multiplexed holography for the measurement of deep shapes

Author(s):

Kozacki, Tomasz; Mikuła-Zdańkowska, Marta; Martinez-Carranza, Juan & Idicula, Moncy Sajeev

Abstract:

“This work develops a single-shot holographic profilometer that enables shape characterization of discontinuous deep surfaces. This is achieved by combining hologram frequency multiplexing and an illumination technique of complex amplitude in multi-incidence angle profilometer. Object illumination is carried out from seven directions simultaneously, where the radial angular coordinates of illumination plane waves obey the geometric series. It is shown that: (i) the illumination pattern provides the required frequency separation of all object wavefronts in transverse frequency space, which is necessary for hologram demultiplexing, and (ii) numerical generation of longitudinal scanning function (LSF) is possible, which has large measurement range, high axial resolution, and small side lobes. Low side lobes of LSF and the developed multiplexed field dependent aberration compensation method are essential to minimize the negative influence of speckle noise of single-shot capture on the measurement result. The utility of the proposed method is demonstrated with experimental measurement of heights of two step-like objects.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 14; Pages 21965; 2021
DOI: 10.1364/oe.428419
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