Numerical optimization of writing computer-generated holograms in threshold media

Recent developments in binary photo-magnetic materials showed efficient and ultra-fast rewriting of holograms where the intensity threshold allows for a dense, sub-diffraction limit packing of hologram points. This paper describes the numerical optimization of the process of writing and reconstructing of 2-D images in a binary-phase computer-generated holograms stored in the said threshold-like medium. Global optimization of the free parameters of the writing process is shown, including the intensity threshold level, propagation distance, hologram spot size and the shape of the boundary regions of the written spots. We present the optimal set of parameters for the best possible writing quality. Full Text: PDF ReferencesA. Stupakiewicz, K. Szerenos, D. Afanasiev et al., "Ultrafast nonthermal photo-magnetic recording in a transparent medium", Nature 542, 71 (2017). CrossRef J. Starobrat, A. Frej, J. Bolek, R. Trybus, A. Stupakiewicz, and M. Makowski, "Photo-magnetic recording of randomized holographic diffraction patterns in a transparent medium", Opt. Lett. 45, 5177 (2020). CrossRef V. Ostroverkhov, et al., "Micro-Holographic Storage and Threshold Holographic Recording Materials", Jap. J. App. Phys. 48.3S1, 03A035 (2009). CrossRef K. Matsushima, T. Shimobaba, "Band-Limited Angular Spectrum Method for Numerical Simulation of Free-Space Propagation in Far and Near Fields", Opt. Express 17, 19662 (2009). CrossRef F. Wyrowski, O. Bryngdahl, "Iterative Fourier-transform algorithm applied to computer holography", JOSA A 5.7, 1058 (1988). CrossRef I. Ducin, T. Shimobaba, M. Makowski, K. Kakarenko, A. Kowalczyk, Jaroslaw Suszek, M. Bieda, A. Kolodziejczyk, M. Sypek, "Holographic projection of images with step-less zoom and noise suppression by pixel separation", Opt. Comm. 340, 131 (2015). CrossRef M. Makowski, "Minimized speckle noise in lens-less holographic projection by pixel separation", Opt. Express 21, 29205 (2013). CrossRef

Download Full-text

Optical Encryption Based on Computer Generated Holograms in Photopolymer

Polymers ◽

10.3390/polym13091358 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1358

Author(s):

Taihui Wu ◽

Jianshe Ma ◽

Chengchen Wang ◽

Haibei Wang ◽

Liangcai Cao ◽

...

Keyword(s):

High Speed ◽

Three Dimensional ◽

Angular Spectrum ◽

Quick Response ◽

Response Code ◽

Optical Encryption ◽

Large Size ◽

Quick Response Code ◽

Computer Generated Holograms ◽

Encryption Method

An optical encryption method based on computer generated holograms printing of photopolymer is presented. Fraunhofer diffraction is performed based on the Gerchberg-Saxton algorithm, and a hologram of the Advanced Encryption Standard encrypted Quick Response code is generated to record the ciphertext. The holograms of the key and the three-dimensional image are generated by the angular spectrum diffraction algorithm. The experimental results show that large-size encrypted Quick Response (QR) code and miniature keys can be printed in photopolymers, which has good application prospects in optical encryption. This method has the advantages of high-density storage, high speed, large fault tolerance, and anti-peeping.

Download Full-text

A Facile Fabrication Route of Poly(Ethylene Glycol Phenyl Ether Acrylate) Photopolymers with Efficient Optical Response for Holographic Storage

Crystals ◽

10.3390/cryst10100935 ◽

2020 ◽

Vol 10 (10) ◽

pp. 935

Author(s):

Fang-Yong Lee ◽

Xin-Jin Wang ◽

Wei-Hung Su ◽

Tzu-Chien Hsu

Keyword(s):

Ethylene Glycol ◽

Response Time ◽

Diffraction Efficiency ◽

Optical Parameter ◽

Optical Response ◽

Holographic Recording ◽

Initiator Concentration ◽

Holographic Storage ◽

Poly Ethylene ◽

Exposure Energy

A series of photopolymers based on ethylene glycol phenyl ethyl arylate (EGPEA) monomers and poly(methyl methacrylate) (PMMA) matrix with varying initiator concentrations and sample thicknesses have been synthesized and their optical performance characterized in this study. The advantages of lowering the initiator concentration, including a rather short initiation time within a few seconds; a sharp rising optical response; and a stable saturated diffraction efficiency are demonstrated. The variation in the diffraction efficiency and response time with the exposure energy under various sample thickness and initiator concentrations is examined; a diffraction efficiency as high as 80% and a relatively short response time of 12–39 s are attainable. The dependence of the normalized optical parameter “sensitivity” on the exposure time is depicted, and the peak value of S ranges vastly from about 0.2 to 1.2 × 104 cm/J within a period of 15 s or so, with a maximum value of nearly 1.2 × 104. Favorable evidence of low initiator concentration can further be found when the dependence of the saturated diffraction efficiency with the exposure energy is examined. The data from this study using a low initiator concentration cover a range of exposure energy from 100 to 800 mJ/cm2 and a saturated diffraction efficiency from about 15% to 80%. The successful image reconstruction of 6-membered-ring metal nuts on a hologram based on this EGPEA/PMMA photopolymer system using a reflective holographic recording setup is demonstrated to verify its applicability to holographic storage.

Download Full-text

Polarization Holography in 3-Indoly-Benzylfulgimide/PMMA Film

Journal of Atomic Molecular and Optical Physics ◽

10.1155/2011/509507 ◽

2011 ◽

Vol 2011 ◽

pp. 1-20 ◽

Cited By ~ 2

Author(s):

Neimule Menke ◽

Baoli Yao ◽

Yingli Wang ◽

Yi Chen

Keyword(s):

Polarization State ◽

Polymeric Films ◽

Holographic Recording ◽

Orthogonal Polarization ◽

Pmma Film ◽

Holographic Storage ◽

Polarization Holography ◽

Photochromic Compounds ◽

Storage Media ◽

Properties Of Materials

The photochromic and photoanisotropic properties of materials can be used in ordinary and polarization holographic recording respectively. Fulgides are well known as thermally irreversible organic photochromic compounds. And it is found that there exists photoinduced anisotropy in fulgide-doped polymeric films. In this report, a 3-indoly-benzylfulgimide/PMMA film was studied as a holographic storage media. First, the spectra and dynamics of photochromic and photoanisotropic properties of the sample are measured or calculated. Second, the diffraction efficiency (DE) dynamics at 633 nm of four kinds of different polarization holograms recorded in this sample are measured. The maximum DE value about 1% was gotten. Third, the DE spectra and DE dynamics are theoretically calculated in detail, and a good correlation of theoretically derived DE dynamic curves and the measured experimental curves was found. From the DE spectra, it is known that at the wavelengths less than 450 nm or greater than 700 nm, the nondestructive reading can be realized. The DWPS obtained in the experiments are same with the theortically deduced ones, which shows that in the orthogonal polarization holography, the polarization state of the diffracted light is orthogonal to that of the reconstruction light, which is very important to increase the SNR of the holographic storage. And all these results are applied and proved to be correct in high-density holographic image storage experiment. The area density of 2×108 bits/cm2 was obtained, and the encoded data was retrieved without error.

Download Full-text

Band-limited double-step Fresnel diffraction and its application to computer-generated holograms

Optics Express ◽

10.1364/oe.21.009192 ◽

2013 ◽

Vol 21 (7) ◽

pp. 9192 ◽

Cited By ~ 52

Author(s):

Naohisa Okada ◽

Tomoyoshi Shimobaba ◽

Yasuyuki Ichihashi ◽

Ryutaro Oi ◽

Kenji Yamamoto ◽

...

Keyword(s):

Fresnel Diffraction ◽

Double Step ◽

Computer Generated Holograms ◽

Band Limited

Download Full-text

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

Applied Sciences ◽

10.3390/app12010293 ◽

2021 ◽

Vol 12 (1) ◽

pp. 293

Author(s):

Rafał Kukołowicz ◽

Maksymilian Chlipala ◽

Juan Martinez-Carranza ◽

Moncy Sajeev Idicula ◽

Tomasz Kozacki

Keyword(s):

Angular Spectrum ◽

Human Vision ◽

Wide Angle ◽

3D Display ◽

Display Devices ◽

Overlapping Data ◽

Viewpoint Change ◽

Computer Generated Holograms ◽

Small Change ◽

Holographic Displays

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.

Download Full-text

Improved playback uniformity of random-phase free holograms by pixel separation method

Photonics Letters of Poland ◽

10.4302/plp.v13i4.1120 ◽

2021 ◽

Vol 13 (4) ◽

pp. 82

Author(s):

Michal Makowski ◽

Tomoyoshi Shimobaba

Keyword(s):

Light Propagation ◽

Noise Suppression ◽

Random Phase ◽

Low Frequency ◽

Angular Spectrum ◽

Speckle Noise ◽

Numerical Approach ◽

Binary Images ◽

Spatial Frequencies ◽

Band Limited

Random-phase free computer-generated holograms offer excellent quality of virtually noise-free playback of low-frequency images, but have limited efficiency in the case of highly contrast binary images with dominant high spatial frequencies. Introduction of weak random phase allows the partial suppression of this problem, but causes strong noise in the outcome. Here we present the influence of pixel separation technique on the uniformity of far field reconstructions from such random-phase free holograms. We show the improved image quality with no additional speckle noise. Full Text: PDF ReferencesJ.W. Goodman, Roberts and Company (2005). DirectLink R.W. Gerchberg, W.O. Saxton, "A practical algorithm for the determination of phase from image and diffraction plane pictures", Optik 35, 237 (1972). DirectLink M. Makowski, "Minimized speckle noise in lens-less holographic projection by pixel separation", Opt. Express 21, 29205 (2013). CrossRef I. Ducin, T. Shimobaba, M. Makowski, K. Kakarenko, A. Kowalczyk, Jaroslaw Suszek, M. Bieda, A. Kolodziejczyk, M. Sypek, "Holographic projection of images with step-less zoom and noise suppression by pixel separation", Opt. Comm. 340, 131 (2015). CrossRef T. Shimobaba, T. Ito, "Random phase-free computer-generated hologram", Opt. Express 23, 9549 (2015). CrossRef T. Shimobaba, T. Kakue, Y. Endo, R. Hirayama, D. Hiyama, S. Hasegawa, Y. Nagahama, M. Sano, M. Oikawa, T. Sugie, T. Ito, "Random phase-free kinoform for large objects", Opt. Express 23, 17269 (2015). CrossRef M. Sypek, "Light propagation in the Fresnel region. New numerical approach", Opt. Comm. 116, 43 (1995). CrossRef K. Matsushima, T. Shimobaba, "Band-Limited Angular Spectrum Method for Numerical Simulation of Free-Space Propagation in Far and Near Fields", Opt. Express 17, 19662 (2009). CrossRef

Download Full-text