Hologram generation via Hilbert transform

Author(s):

Tomoyoshi Shimobaba, Takashi Kakue, Yota Yamamoto, Ikuo Hoshi, Harutaka Shiomi, Takashi Nishitsuji, Naoki Takada, and Tomoyoshi Ito

Abstract:

“We propose an indirect method for generating a complex hologram and phase-only hologram from an amplitude hologram using the Hilbert transform. The Hilbert transform generates an imaginary part of complex amplitude from only an amplitude hologram, resulting in the reduction of the total computational complexity of complex and phase-only holograms. More importantly, the proposed method can reduce the hardware resources of dedicated hologram processors.”

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Publication: OSA Continuum
Issue/Year/DOI: Vol. 3, Issue 6, pp. 1498-1503 (2020)
DOI: 10.1364/OSAC.395003

Fabrication of oil–water separation copper filter by spatial light modulated femtosecond laser

Author(s):

Xiaoyan Sun, Zhuolin Dong, Kaifan Cheng, Dongkai Chu, Dejian Kong, Youwang Hu and Ji’an Duan

Abstract:

“Surface with oil–water separation performance has attracted more and more attention in the application of oil-containing wastewater purification. Much related work has been done by many researchers. However, there are still many difficulties in rapid manufacturing of filter membranes with special wettability. In this paper, an efficient, flexible method to fabricate microporous arrays by using a femtosecond (fs) laser combined with a spatial light modulator is proposed. The laser treated copper sheet surface shows hydrophobic and superoleophilic properties due to the microstructure. Meanwhile, the array of micro-through-holes on the surface can allow oil to penetrate through holes and prevent water from penetrating. The manufacturing process is not only extremely efficient, with a 10 × 10 focus array used in the ablation, but also it is without chemical method and the filter presents a long-term stable hydrophobic and superoleophilic performance.”

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Publication: Journal of Micromechanics and Microengineering

Issue/Year/DOI: Volume 30, Number 6
DOI: 10.1088/1361-6439/ab870d

Rapid tilted-plane Gerchberg-Saxton algorithm for holographic optical tweezers

Author(s):

Yanan Cai, Shaohui Yan, Zhaojun Wang, Runze Li, Yansheng Liang, Yuan Zhou, Xing Li, Xianghua Yu, Ming Lei and Baoli Yao

Abstract:

“Benefitting from the development of commercial spatial light modulator (SLM), holographic optical tweezers (HOT) have emerged as a powerful tool for life science, material science and particle physics. The calculation of computer-generated holograms (CGH) for generating multi-focus arrays plays a key role in HOT for trapping of a bunch of particles in parallel. To realize dynamic 3D manipulation, we propose a new tilted-plane GS algorithm for fast generation of multiple foci. The multi-focal spots with a uniformity of 99% can be generated in a tilted plane. The computation time for a CGH with 512512 pixels is less than 0.1 second.
We demonstrated the power of the algorithm by simultaneously trapping and rotating silica beads with a 77 spots array in three dimensions. The presented algorithm is expected as a powerful kernel of HOT.”

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Publication: Optics Express

Issue/Year/DOI: Vol. 28, Issue 9, pp. 12729-12739
DOI: 10.1364/OE.389897

Full parallax three-dimensional computer generated hologram with occlusion effect using ray casting technique

Author(s):

Hao Zhang, Qiaofeng Tan and Guofan Jin

Abstract:

“Holographic display is capable of reconstructing the whole optical wave field of a three-dimensional (3D) scene. It is the only one among all the 3D display techniques that can produce all the depth cues. With the development of computing technology and spatial light modulators, computer generated holograms (CGHs) can now be used to produce dynamic 3D images of synthetic objects. Computation holography becomes highly complicated and demanding when it is employed to produce real 3D images. Here we present a novel algorithm for generating a full parallax 3D CGH with occlusion effect, which is an important property of 3D perception, but has often been neglected in fully computed hologram synthesis. The ray casting technique, which is widely used in computer graphics, is introduced to handle the occlusion issue of CGH computation. Horizontally and vertically distributed rays are projected from each hologram sample to the 3D objects to obtain the complex amplitude distribution. The occlusion issue is handled by performing ray casting calculations to all the hologram samples. The proposed algorithm has no restriction on or approximation to the 3D objects, and hence it can produce reconstructed images with correct shading effect and no visible artifacts. Programmable graphics processing unit (GPU) is used to perform parallel calculation. This is made possible because each hologram sample belongs to an independent operation. To demonstrate the performance of our proposed algorithm, an optical experiment is performed to reconstruct the 3D scene by using a phase-only spatial light modulator. We can easily perceive the accommodation cue by focusing our eyes on different depths of the scene and the motion parallax cue with occlusion effect by moving our eyes around. The experiment result confirms that the CGHs produced by our algorithm can successfully reconstruct 3D images with all the depth cues.”

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Publication: Journal of Physics: Conference Series

Issue/Year/DOI: Volume: 415
DOI: 10.1088/1742-6596/415/1/012048

Color translucent head-up display based on a segmented Fourier hologram

Author(s):

Jaroslaw Suszek, Maciej Sypek, Andrzej Siemion, Agnieszka Fajst, Michal Makowski and Andrzej Kolodziejczyk

Abstract:

“The paper presents the numerical and experimental results of reconstructing images from a spatially segmented Fourier hologram with additional carrier frequencies, acting as a translucent head-up display (HUD). Successful reconstructions of colorful images visible at the infinity were achieved. The design procedure is described and some limitations of the method are discussed, like the appearance of ghost images. Exemplary results from numerical and real experiments are given. In order to obtain color images three beams of primary colors were successfully utilized to create a color mixture.”

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Publication: Photonics Letters of Poland

Issue/Year/DOI: Vol 1, No 3 (2009)
DOI: 10.4302/plp.2009.3.02