Learning-based compensation of spatially varyingaberrations for holographic display (invited paper)

In this article, we propose a reference light wave multiplexing scheme to increase the information capacity of computer-generated holograms. The holograms were generated by different reference light waves and superimposed together as a multiplexed hologram. A modified Gerchberg–Saxton algorithm was used to improve image quality, and different images could be reconstructed when the multiplexed hologram was illuminated by corresponding reference light waves. We performed both numerical simulations and optical experiments to demonstrate the feasibility of the proposed scheme. Numerical simulations showed that the proposed method could reconstruct multiple images successfully by a single multiplexed hologram and optical experiments are consistently good with numerical simulations. It is expected that the proposed method has great potential to be widely applied in holographic displays in the future.

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A real-space interactive holographic display based on a large-aperture HOE

10.1117/12.2021633 ◽

2013 ◽

Cited By ~ 6

Author(s):

Javid Khan ◽

Chi Can ◽

Alan Greenaway ◽

Ian Underwood

Keyword(s):

Real Space ◽

Holographic Display ◽

Large Aperture

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Holographic Display System to Suppress Speckle Noise Based on Beam Shaping

Photonics ◽

10.3390/photonics8060204 ◽

2021 ◽

Vol 8 (6) ◽

pp. 204

Author(s):

Di Wang ◽

Yi-Wei Zheng ◽

Nan-Nan Li ◽

Qiong-Hua Wang

Keyword(s):

Optical Element ◽

Speckle Noise ◽

Beam Shaping ◽

Diffractive Optical Element ◽

The Other ◽

Spatial Light Modulators ◽

Viewing Angle ◽

Display System ◽

Holographic Display ◽

Light Modulators

In this paper, a holographic system to suppress the speckle noise is proposed. Two spatial light modulators (SLMs) are used in the system, one of which is used for beam shaping, and the other is used for reproducing the image. By calculating the effective viewing angle of the reconstructed image, the effective hologram and the effective region of the SLM are calculated accordingly. Then, the size of the diffractive optical element (DOE) is calculated accordingly. The dynamic DOEs and effective hologram are loaded on the effective regions of the two SLMs, respectively, while the wasted areas of the two SLMs are performed with zero-padded operations. When the laser passes through the first SLM, the light can be modulated by the effective DOEs. When the modulated beam illuminates the second SLM which is loaded with the effective hologram, the image is reconstructed with better quality and lower speckle noise. Moreover, the calculation time of the hologram is reduced. Experiments indicate the validity of the proposed system.

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Computing 3D Phase-Type Holograms Based on Deep Learning Method

Photonics ◽

10.3390/photonics8070280 ◽

2021 ◽

Vol 8 (7) ◽

pp. 280

Author(s):

Huadong Zheng ◽

Jianbin Hu ◽

Chaojun Zhou ◽

Xiaoxi Wang

Keyword(s):

Deep Learning ◽

Signal To Noise Ratio ◽

Contrast Ratio ◽

Angular Spectrum ◽

Structural Similarity ◽

Computational Time ◽

Experimental Investigations ◽

Training Strategy ◽

Holographic Display ◽

Phase Type

Computer holography is a technology that use a mathematical model of optical holography to generate digital holograms. It has wide and promising applications in various areas, especially holographic display. However, traditional computational algorithms for generation of phase-type holograms based on iterative optimization have a built-in tradeoff between the calculating speed and accuracy, which severely limits the performance of computational holograms in advanced applications. Recently, several deep learning based computational methods for generating holograms have gained more and more attention. In this paper, a convolutional neural network for generation of multi-plane holograms and its training strategy is proposed using a multi-plane iterative angular spectrum algorithm (ASM). The well-trained network indicates an excellent ability to generate phase-only holograms for multi-plane input images and to reconstruct correct images in the corresponding depth plane. Numerical simulations and optical reconstructions show that the accuracy of this method is almost the same with traditional iterative methods but the computational time decreases dramatically. The result images show a high quality through analysis of the image performance indicators, e.g., peak signal-to-noise ratio (PSNR), structural similarity (SSIM) and contrast ratio. Finally, the effectiveness of the proposed method is verified through experimental investigations.

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Investigation on dynamic holographic display in liquid crystal film doped with carbon dots

Materials Express ◽

10.1166/mex.2020.1743 ◽

2020 ◽

Vol 10 (6) ◽

pp. 780-787

Author(s):

Hongyue Gao ◽

Suna Li ◽

Jicheng Liu ◽

Wen Zhou ◽

Fan Xu ◽

...

Keyword(s):

Liquid Crystal ◽

Electric Field ◽

Real Time ◽

Diffraction Efficiency ◽

Carbon Dots ◽

Applied Electric Field ◽

Light Polarization ◽

Forming Process ◽

Time Dynamic ◽

Holographic Display

In this paper, we studied the holographic properties of liquid crystal (LC) thin film doped with carbon dots (CDs) which can be used as real-time holographic display screen. The maximum value of diffraction efficiency can reach up to 30% by using a low applied electric field 0.2 V/μm. Holograms in the LC film can be dynamically formed and self-erased. The hologram build-up time and the hologram self-erasure time in the material is fast enough to realize video refresh rate. In addition, the forming process of hologram was studied. The holographic diffraction efficiency was measured depending on the intensity of recording light, applied electric field, the intensity of readout light, and readout light polarization direction. Triple enhancement of the diffraction efficiency value by the modulation of voltage under the condition of low recording energy is presented. Therefore, we develop an easy way to obtain real-time dynamic holographic red, green and blue displays with high diffraction efficiency, which allow the LC film doped with CDs to be used as a holographic 3D display screen.

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Phase-only transmissive spatial light modulator based on tunable dielectric metasurface

Science ◽

10.1126/science.aaw6747 ◽

2019 ◽

Vol 364 (6445) ◽

pp. 1087-1090 ◽

Cited By ~ 64

Author(s):

Shi-Qiang Li ◽

Xuewu Xu ◽

Rasna Maruthiyodan Veetil ◽

Vytautas Valuckas ◽

Ramón Paniagua-Domínguez ◽

...

Keyword(s):

High Resolution ◽

Spatial Light Modulator ◽

Deflection Angle ◽

Beam Steering ◽

Beam Deflection ◽

Spatial Light Modulators ◽

Light Modulator ◽

Steering Angle ◽

Holographic Display ◽

Light Modulators

Rapidly developing augmented reality, solid-state light detection and ranging (LIDAR), and holographic display technologies require spatial light modulators (SLMs) with high resolution and viewing angle to satisfy increasing customer demands. Performance of currently available SLMs is limited by their large pixel sizes on the order of several micrometers. Here, we propose a concept of tunable dielectric metasurfaces modulated by liquid crystal, which can provide abrupt phase change, thus enabling pixel-size miniaturization. We present a metasurface-based transmissive SLM, configured to generate active beam steering with >35% efficiency and a large beam deflection angle of 11°. The high resolution and steering angle obtained provide opportunities to develop the next generation of LIDAR and display technologies.

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