Research

24 pages, 12558 KiB

Open AccessArticle

Transmission of 3D Holographic Information via Conventional Communication Channels and the Possibility of Multiplexing in the Implementation of 3D Hyperspectral Images

by Sergey A. Shoydin and Artem L. Pazoev

Photonics 2021, 8(10), 448; https://doi.org/10.3390/photonics8100448 - 15 Oct 2021

Cited by 4 | Viewed by 2289

Abstract

This paper shows the possibility of transmitting 3D holographic information in real time with a TV frame rate over conventional radio channels by transmitting two two-dimensional signals in two image modes: depth map and surface texture of the object (mask + texture). The [...] Read more.

This paper shows the possibility of transmitting 3D holographic information in real time with a TV frame rate over conventional radio channels by transmitting two two-dimensional signals in two image modes: depth map and surface texture of the object (mask + texture). The authors point out that it is similar to compression through eliminating the carrier and it is inherently similar to SSB (single-sideband modulation) but has higher resolution ability in reconstructing 3D images. It is also shown that such technology for transmitting 3D holographic information is in good agreement with the tasks of both aggregating and multiplexing 3D images when they are transferred from one part of the electromagnetic spectrum of radiation to another and the creation of hyperspectral 3D images. Full article

(This article belongs to the Special Issue Holography)

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10 pages, 2128 KiB

Open AccessArticle

Deformation Measurements of Neuronal Excitability Using Incoherent Holography Lattice Light-Sheet Microscopy (IHLLS)

by Mariana Potcoava, Jonathan Art, Simon Alford and Christopher Mann

Photonics 2021, 8(9), 383; https://doi.org/10.3390/photonics8090383 - 09 Sep 2021

Cited by 5 | Viewed by 1905

Abstract

Stimuli to excitable cells and various cellular processes can cause cell surface deformations; for example, when excitable cell membrane potentials are altered during action potentials. However, these cellular changes may be at or below the diffraction limit (in dendrites the structures measured are [...] Read more.

Stimuli to excitable cells and various cellular processes can cause cell surface deformations; for example, when excitable cell membrane potentials are altered during action potentials. However, these cellular changes may be at or below the diffraction limit (in dendrites the structures measured are as small as 1 µm), and imaging by traditional methods is challenging. Using dual lenses incoherent holography lattice light-sheet (IHLLS-2L) detection with holographic phase imaging of selective fluorescent markers, we can extract the full-field cellular morphology or structural changes of the object’s phase in response to external stimulus. This approach will open many new possibilities in imaging neuronal activity and, overall, in light sheet imaging. In this paper, we present IHLLS-2L as a well-suited technique for quantifying cell membrane deformation in neurons without the actuation of a sample stage or detection microscope objective. Full article

(This article belongs to the Special Issue Holography)

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14 pages, 10078 KiB

Open AccessArticle

Multi-View 3D Integral Imaging Systems Using Projectors and Mobile Devices

by Nikolai Petrov, Maksim Khromov and Yuri Sokolov

Photonics 2021, 8(8), 331; https://doi.org/10.3390/photonics8080331 - 13 Aug 2021

Cited by 2 | Viewed by 3012

Abstract

Glassless 3D displays using projectors and mobile phones based on integral imaging technology have been developed. Three-dimensional image files are created from the 2D images captured by a conventional camera. Large size 3D images using four HD and Ultra HD 4K projectors are [...] Read more.

Glassless 3D displays using projectors and mobile phones based on integral imaging technology have been developed. Three-dimensional image files are created from the 2D images captured by a conventional camera. Large size 3D images using four HD and Ultra HD 4K projectors are created with a viewing angle of 35 degrees and a large depth. Three-dimensional images are demonstrated using optimized lenticular lenses and mobile smartphones, such as LG and Samsung with resolution 2560 × 1440, and 4K Sony with resolution 3840 × 2160. Full article

(This article belongs to the Special Issue Holography)

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15 pages, 4084 KiB

Open AccessFeature PaperArticle

Water Resistant Cellulose Acetate Based Photopolymer for Recording of Volume Phase Holograms

by Sabad-e- Gul, John Cassidy and Izabela Naydenova

Photonics 2021, 8(8), 329; https://doi.org/10.3390/photonics8080329 - 12 Aug 2021

Cited by 5 | Viewed by 2533

Abstract

The development of environmentally robust photosensitive materials for holographic recording is crucial for applications such as outdoor LED light redirection, holographic displays and holographic sensors. Despite the progress in holographic recording materials development, their sensitivity to humidity remains a challenge and protection from [...] Read more.

The development of environmentally robust photosensitive materials for holographic recording is crucial for applications such as outdoor LED light redirection, holographic displays and holographic sensors. Despite the progress in holographic recording materials development, their sensitivity to humidity remains a challenge and protection from the environment is required. One approach to solving this challenge is to select substrate such as cellulose acetate, which is water resistant. This work reports the development of a cellulose-based photopolymer with sensitivity of 3.5 cm²/mJ and refractive index modulation of 2.5 × 10⁻³ achieved in the transmission mode of recording. The suitability for holographic recording was demonstrated by recording gratings with the spatial frequency of 800 linepairs/mm. The intensity dependence of the diffraction efficiency of gratings recorded in 70 μm thick layers was studied and it was observed that the optimum recording intensity was 10 mW/cm². The robustness of the structures was studied after immersing the layer in water for one hour. It was observed that the diffraction efficiency and the surface characteristics measured before and after exposure to water remain unchanged. Finally, the surface hardness was characterized and was shown to be comparable to that of glass and significantly higher than the one of PVA-based acrylamide photopolymer. Full article

(This article belongs to the Special Issue Holography)

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10 pages, 3702 KiB

Open AccessArticle

Uncertainty in the Phase Flicker Measurement for the Liquid Crystal on Silicon Devices

by Zhiyuan Yang, Shiyu Wu, Jiewen Nie and Haining Yang

Photonics 2021, 8(8), 307; https://doi.org/10.3390/photonics8080307 - 01 Aug 2021

Cited by 3 | Viewed by 1815

Abstract

Phase flicker has become an important performance parameter for the liquid crystal on silicon (LCOS) devices. Since the phase response of the LCOS device cannot be measured directly, it is usually derived from the intensity response of the modulated light beam when the [...] Read more.

Phase flicker has become an important performance parameter for the liquid crystal on silicon (LCOS) devices. Since the phase response of the LCOS device cannot be measured directly, it is usually derived from the intensity response of the modulated light beam when the LCOS device was placed between a pair of crossed polarisers. However, the relationship between the intensity of the beam and the phase response of the LCOS device is periodic. This would lead to uncertainty in the phase flicker measurement. This paper analyses this measurement uncertainty through both simulation and experiments. It also proposed a strategy to minimise the uncertainty. Full article

(This article belongs to the Special Issue Holography)

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16 pages, 3762 KiB

Open AccessArticle

Occlusion Culling for Wide-Angle Computer-Generated Holograms Using Phase Added Stereogram Technique

by Juan Martinez-Carranza, Tomasz Kozacki, Rafał Kukołowicz, Maksymilian Chlipala and Moncy Sajeev Idicula

Photonics 2021, 8(8), 298; https://doi.org/10.3390/photonics8080298 - 27 Jul 2021

Cited by 8 | Viewed by 2122

Abstract

A computer-generated hologram (CGH) allows synthetizing view of 3D scene of real or virtual objects. Additionally, CGH with wide-angle view offers the possibility of having a 3D experience for large objects. An important feature to consider in the calculation of CGHs is occlusion [...] Read more.

A computer-generated hologram (CGH) allows synthetizing view of 3D scene of real or virtual objects. Additionally, CGH with wide-angle view offers the possibility of having a 3D experience for large objects. An important feature to consider in the calculation of CGHs is occlusion between surfaces because it provides correct perception of encoded 3D scenes. Although there is a vast family of occlusion culling algorithms, none of these, at the best of our knowledge, consider occlusion when calculating CGHs with wide-angle view. For that reason, in this work we propose an occlusion culling algorithm for wide-angle CGHs that uses the Fourier-type phase added stereogram (PAS). It is shown that segmentation properties of the PAS can be used for setting efficient conditions for occlusion culling of hidden areas. The method is efficient because it enables processing of dense cloud of points. The investigated case has 24 million of point sources. Moreover, quality of the occluded wide-angle CGHs is tested by two propagation methods. The first propagation technique quantifies quality of point reproduction of calculated CGH, while the second method enables the quality assessment of the occlusion culling operation over an object of complex shape. Finally, the applicability of proposed occlusion PAS algorithm is tested by synthetizing wide-angle CGHs that are numerically and optically reconstructed. Full article

(This article belongs to the Special Issue Holography)

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12 pages, 3427 KiB

Open AccessArticle

Three-Dimensional (3D) Printing Implemented by Computer-Generated Holograms for Generation of 3D Layered Images in Optical Near Field

by Chung-Fei Lee, Wei-Feng Hsu, Tzu-Hsuan Yang and Ren-Jei Chung

Photonics 2021, 8(7), 286; https://doi.org/10.3390/photonics8070286 - 19 Jul 2021

Cited by 2 | Viewed by 2506

Abstract

Photocurable three-dimensional (3D) printing is a stepwise layer-by-layer fabrication process widely used in the manufacture of highly specialized objects. Current 3D printing techniques are easily implemented; however, the build rate is slow and the surface quality is less than ideal. Holographic 3D display [...] Read more.

Photocurable three-dimensional (3D) printing is a stepwise layer-by-layer fabrication process widely used in the manufacture of highly specialized objects. Current 3D printing techniques are easily implemented; however, the build rate is slow and the surface quality is less than ideal. Holographic 3D display (3DHD) technology makes it possible to reform planar wavefronts into a 3D intensity distribution, which appears as a 3D image in space. This paper examined the application of holographic imaging technology to 3D printing based on photocurable polymers. The proposed system uses a 3DHD diffractive optics system based on a liquid-crystal-on-silicon spatial light modulator (LCoS-SLM), wherein a 3D layered image is created in the optical near field, based on a computer-generated hologram (CGH) optimized using the iterative angular spectrum algorithm (IASA) and a circular IASA. From a single CGH, multiple 2D sliced images are created in space to form a 3D optical image used to initiate the photopolymerization of photocurable resin to form 3D objects. In experiments, the proposed 3D printing system was used to create five polymer objects with a maximum axial length of 25 mm and minimum feature width of 149 μm. The phase-only CGH reformed the incident light into a distribution of optical intensity with high diffraction efficiency suitable for photocuring. Despite limitations pertaining to fabrication area and axial complexity in this initial study, the proposed method demonstrated high light efficiency, high resolution in the lateral direction, rapid fabrication, and good object continuity. Full article

(This article belongs to the Special Issue Holography)

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19 pages, 7082 KiB

Open AccessArticle

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

by Huadong Zheng, Jianbin Hu, Chaojun Zhou and Xiaoxi Wang

Photonics 2021, 8(7), 280; https://doi.org/10.3390/photonics8070280 - 15 Jul 2021

Cited by 8 | Viewed by 2992

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Holography)

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12 pages, 4027 KiB

Open AccessArticle

An Inexpensive Portable Self-Reference Module for Digital Holographic Microscopy

by Xin Fan, Zhengyuan Tang, Kevin O’Dwyer and Bryan M. Hennelly

Photonics 2021, 8(7), 277; https://doi.org/10.3390/photonics8070277 - 14 Jul 2021

Cited by 6 | Viewed by 2290

Abstract

This paper describes a novel optical system that can be integrated to the image port of an existing brightfield microscope in order to enhance the microscope with the features of digital holographic microscopy. The proposed system is modular and portable. It is relatively [...] Read more.

This paper describes a novel optical system that can be integrated to the image port of an existing brightfield microscope in order to enhance the microscope with the features of digital holographic microscopy. The proposed system is modular and portable. It is relatively inexpensive and robust to vibrations due to its compact design. An additional benefit is that the system does not need to undergo path-length realignment if the sample is changed, unlike several other architectures. The module is based on a square in-line Mach–Zender architecture but achieves the off-axis condition using two sets of wedge prism pairs. This design offers a significant advantage over competing Mach–Zender nearly common-path modules in terms of path length matching of object and reference wavefields for the case of low-temporal coherence sources, which are preferable for low noise phase imaging. An additional advantage that the proposed system has when compared with similar modules is the facility to continuously vary the tilt angles of the object and reference wavefields that are incident on the sensor, which enables the module to be readily adapted to any given microscope and camera. We provide a detailed overview of the module design and construction. Experimental results are demonstrated on a micro-lens array as well as buccal epithelial cells. We also provide a detailed discussion on the relationship between the proposed self-reference module and related common-path and nearly common-path holographic modules that have previously been proposed in the literature. Full article

(This article belongs to the Special Issue Holography)

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Graphical abstract

12 pages, 4045 KiB

Open AccessArticle

Dynamic Speckle Illumination Digital Holographic Microscopy by Doubly Scattered System

by Yun Liu, Peihua Bu, Mingxing Jiao, Junhong Xing, Ke Kou, Tianhong Lian, Xian Wang and Yumeng Liu

Photonics 2021, 8(7), 276; https://doi.org/10.3390/photonics8070276 - 14 Jul 2021

Cited by 5 | Viewed by 1798

Abstract

The coherent noise always exists in digital holographic microscopy due to the laser source, degrading the image quality. A method of speckle suppression using the dynamic speckle illumination, produced by double-moving diffusers, is presented in digital holographic microscopy. The space–time correlation functions are [...] Read more.

The coherent noise always exists in digital holographic microscopy due to the laser source, degrading the image quality. A method of speckle suppression using the dynamic speckle illumination, produced by double-moving diffusers, is presented in digital holographic microscopy. The space–time correlation functions are theoretically analyzed from the statistics distribution in the doubly and singly scattered system, respectively. The configuration of double-moving diffusers is demonstrated to have better performance in speckle suppression compared with the single diffuser and moving-static double diffusers cases. The experiment results verify the feasibility of the approach. The presented approach only requires a single shot interferogram to realize the speckle reduction, accordingly it has the potential application in real-time measurement. Full article

(This article belongs to the Special Issue Holography)

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16 pages, 3290 KiB

Open AccessArticle

Adaptation of the Standard Off-Axis Digital Holographic Microscope to Achieve Variable Magnification

by Xin Fan, John J. Healy, Kevin O’Dwyer, Julianna Winnik and Bryan M. Hennelly

Photonics 2021, 8(7), 264; https://doi.org/10.3390/photonics8070264 - 07 Jul 2021

Cited by 3 | Viewed by 2868

Abstract

Traditional microscopy provides only for a small set of magnifications using a finite set of microscope objectives. Here, a novel architecture is proposed for quantitative phase microscopy that requires only a simple adaptation of the traditional off-axis digital holographic microscope. The architecture has [...] Read more.

Traditional microscopy provides only for a small set of magnifications using a finite set of microscope objectives. Here, a novel architecture is proposed for quantitative phase microscopy that requires only a simple adaptation of the traditional off-axis digital holographic microscope. The architecture has the key advantage of continuously variable magnification, resolution, and Field-of-View, by simply moving the sample. The method is based on combining the principles of traditional off-axis digital holographic microscopy and Gabor microscopy, which uses a diverging spherical wavefield for magnification. We present a proof-of-concept implementation and ray-tracing is used to model the magnification, Numerical Aperture, and Field-of-View as a function of sample position. Experimental results are presented using a micro-lens array and shortcomings of the method are highlighted for future work; in particular, the problem of aberration is highlighted, which results from imaging far from the focal plane of the infinity corrected microscope objective. Full article

(This article belongs to the Special Issue Holography)

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13 pages, 53766 KiB

Open AccessArticle

Towards Reduced CNNs for De-Noising Phase Images Corrupted with Speckle Noise

by Marie Tahon, Silvio Montresor and Pascal Picart

Photonics 2021, 8(7), 255; https://doi.org/10.3390/photonics8070255 - 03 Jul 2021

Cited by 16 | Viewed by 2363

Abstract

Digital holography is a very efficient technique for 3D imaging and the characterization of changes at the surfaces of objects. However, during the process of holographic interferometry, the reconstructed phase images suffer from speckle noise. In this paper, de-noising is addressed with phase [...] Read more.

Digital holography is a very efficient technique for 3D imaging and the characterization of changes at the surfaces of objects. However, during the process of holographic interferometry, the reconstructed phase images suffer from speckle noise. In this paper, de-noising is addressed with phase images corrupted with speckle noise. To do so, DnCNN residual networks with different depths were built and trained with various holographic noisy phase data. The possibility of using a network pre-trained on natural images with Gaussian noise is also investigated. All models are evaluated in terms of phase error with HOLODEEP benchmark data and with three unseen images corresponding to different experimental conditions. The best results are obtained using a network with only four convolutional blocks and trained with a wide range of noisy phase patterns. Full article

(This article belongs to the Special Issue Holography)

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9 pages, 12121 KiB

Open AccessArticle

Multicolor Holographic Display of 3D Scenes Using Referenceless Phase Holography (RELPH)

by André F. Müller, Ilja Rukin, Claas Falldorf and Ralf B. Bergmann

Photonics 2021, 8(7), 247; https://doi.org/10.3390/photonics8070247 - 30 Jun 2021

Cited by 2 | Viewed by 1772

Abstract

In this paper, we present a multicolor display via referenceless phase holography (RELPH). RELPH permits the display of full optical wave fields (amplitude and phase) using two liquid crystal phase-only spatial light modulators in a Michelson-interferometer-based arrangement. Complex wave fields corresponding to arbitrary [...] Read more.

In this paper, we present a multicolor display via referenceless phase holography (RELPH). RELPH permits the display of full optical wave fields (amplitude and phase) using two liquid crystal phase-only spatial light modulators in a Michelson-interferometer-based arrangement. Complex wave fields corresponding to arbitrary real or artificial 3D scenes are decomposed into two mutually coherent wave fields of constant amplitude whose phase distributions are modulated onto the wave fields reflected by the respective light modulators. Here, we present the realization of that concept in two different ways: firstly, via temporal multiplexing using a single setup, switching between wavelengths for temporal integration of the respective wavefields; secondly, using spatial multiplexing of different wavelengths with multiple Michelson-based setups; and finally, we present an approach to magnify the 3D scenes displayed by light modulators with limited space–bandwidth product for a comfortable viewing experience. Full article

(This article belongs to the Special Issue Holography)

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10 pages, 6432 KiB

Open AccessArticle

Color Digital Holography Based on Generalized Phase-Shifting Algorithm with Monitoring Phase-Shift

by Minwoo Jung, Hosung Jeon, Sungjin Lim and Joonku Hahn

Photonics 2021, 8(7), 241; https://doi.org/10.3390/photonics8070241 - 28 Jun 2021

Cited by 2 | Viewed by 2140

Abstract

Color digital holography (DH) has been researched in various fields such as the holographic camera and holographic microscope because it acquires a realistic color object wave by measuring both amplitude and phase. Among the methods for color DH, the phase-shifting DH has an [...] Read more.

Color digital holography (DH) has been researched in various fields such as the holographic camera and holographic microscope because it acquires a realistic color object wave by measuring both amplitude and phase. Among the methods for color DH, the phase-shifting DH has an advantage of obtaining a signal wave of objects without the autocorrelation and conjugate noises. However, this method usually requires many interferograms to obtain signals for all wavelengths. In addition, the phase-shift algorithm is sensitive to the phase-shift error caused by the instability or hysteresis of the phase shifter. In this paper, we propose a new method of color phase-shifting digital holography with monitoring the phase-shift. The color interferograms are recorded by using a focal plane array (FPA) with a Bayer color filter. In order to obtain the color signal wave from the interferograms with unexpected phase-shift values, we devise a generalized phase-shifting DH algorithm. The proposed method enables the robust measurement in the interferograms. Experimentally, we demonstrate the proposed algorithm to reconstruct the object image with negligibly small conjugate noises. Full article

(This article belongs to the Special Issue Holography)

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Graphical abstract

12 pages, 6055 KiB

Open AccessArticle

Selective Couplers Based on Multiplexed Volume Holographic Gratings for Waveguide Displays

by Maria Shishova, Alexander Zherdev, Sergey Odinokov, Vladimir Venediktov, Dmitrii Lushnikov and Yohan Kim

Photonics 2021, 8(7), 232; https://doi.org/10.3390/photonics8070232 - 22 Jun 2021

Cited by 11 | Viewed by 2968

Abstract

Diffraction waveguides are widely used in augmented reality devices as information display systems for the introduction of data into the human visual field in order to supplement information about the world around us. This paper formulates the principles of radiation conversion in diffraction [...] Read more.

Diffraction waveguides are widely used in augmented reality devices as information display systems for the introduction of data into the human visual field in order to supplement information about the world around us. This paper formulates the principles of radiation conversion in diffraction waveguides made of photo-thermo-refractive glass on the basis of multiplexed volume holographic gratings, and the advantages and disadvantages of high spectral-angular selectivity are analyzed. In the optical scheme, each of the superimposed volume holographic gratings in the diffraction waveguide forms a corresponding part of the composite angular field of view of the augmented reality device. A proposed mathematical model based on angular multiplexing made it possible to synthesize the diffraction optical element for a new type of diffraction waveguide made from photo-thermo-refractive glass and to create a prototype with an angular resolution of at least 3.0 ± 0.5′, with a brightness change in the image of less than 20% and with a composite angular field of view of 32°. Full article

(This article belongs to the Special Issue Holography)

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11 pages, 7167 KiB

Open AccessArticle

Edge and Contrast Enhancement Using Spatially Incoherent Correlation Holography Techniques

by Vijayakumar Anand, Joseph Rosen, Soon Hock Ng, Tomas Katkus, Denver P Linklater, Elena P Ivanova and Saulius Juodkazis

Photonics 2021, 8(6), 224; https://doi.org/10.3390/photonics8060224 - 16 Jun 2021

Cited by 13 | Viewed by 2553

Abstract

Image enhancement techniques (such as edge and contrast enhancement) are essential for many imaging applications. In incoherent holography techniques such as Fresnel incoherent correlation holography (FINCH), the light from an object is split into two, each of which is modulated differently from one [...] Read more.

Image enhancement techniques (such as edge and contrast enhancement) are essential for many imaging applications. In incoherent holography techniques such as Fresnel incoherent correlation holography (FINCH), the light from an object is split into two, each of which is modulated differently from one another by two different quadratic phase functions and coherently interfered to generate the hologram. The hologram can be reconstructed via a numerical backpropagation. The edge enhancement procedure in FINCH requires the modulation of one of the beams by a spiral phase element and, upon reconstruction, edge-enhanced images are obtained. An optical technique for edge enhancement in coded aperture imaging (CAI) techniques that does not involve two-beam interference has not been established yet. In this study, we propose and demonstrate an iterative algorithm that can yield from the experimentally recorded point spread function (PSF), a synthetic PSF that can generate edge-enhanced reconstructions when processed with the object hologram. The edge-enhanced reconstructions are subtracted from the original reconstructions to obtain contrast enhancement. The technique has been demonstrated on FINCH and CAI methods with different spectral conditions. Full article

(This article belongs to the Special Issue Holography)

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10 pages, 2917 KiB

Open AccessCommunication

Holography and the Luxury Industry

by V. Michael Bove, Jr. and Nicole A. Reader

Photonics 2021, 8(6), 219; https://doi.org/10.3390/photonics8060219 - 13 Jun 2021

Cited by 2 | Viewed by 3975

Abstract

The luxury goods industry and holography have a lengthy history together. In this article, we review the applications of holography to the industry and the relevant technical requirements, in particular when the hologram itself is the luxury item, when the hologram is used [...] Read more.

The luxury goods industry and holography have a lengthy history together. In this article, we review the applications of holography to the industry and the relevant technical requirements, in particular when the hologram itself is the luxury item, when the hologram is used to promote luxury items, and when the hologram is used for authentication of luxury items. We then explore some possible scenarios for the evolution of this relationship. Full article

(This article belongs to the Special Issue Holography)

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12 pages, 4395 KiB

Open AccessArticle

Holographic Display System to Suppress Speckle Noise Based on Beam Shaping

by Di Wang, Yi-Wei Zheng, Nan-Nan Li and Qiong-Hua Wang

Photonics 2021, 8(6), 204; https://doi.org/10.3390/photonics8060204 - 06 Jun 2021

Cited by 4 | Viewed by 2498

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Holography)

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18 pages, 10650 KiB

Open AccessArticle

Digital Holographic Interferometry for the Measurement of Symmetrical Temperature Fields in Liquids

by Gramoz Cubreli, Pavel Psota, Petra Dančová, Vít Lédl and Tomáš Vít

Photonics 2021, 8(6), 200; https://doi.org/10.3390/photonics8060200 - 04 Jun 2021

Cited by 8 | Viewed by 2641

Abstract

In this paper, we present a method of quantitatively measuring in real-time the dynamic temperature field change and visualization of volumetric temperature fields generated by a 2D axial-symmetric heated fluid from a pulsatile jet in a water tank through off-axis digital holographic interferometry. [...] Read more.

In this paper, we present a method of quantitatively measuring in real-time the dynamic temperature field change and visualization of volumetric temperature fields generated by a 2D axial-symmetric heated fluid from a pulsatile jet in a water tank through off-axis digital holographic interferometry. A Mach-Zehnder interferometer on portable platform was built for the experimental investigation. The pulsatile jet was submerged in a water tank and fed with water with higher temperature. Tomographic approach was used to reconstruct the temperature fields through the Abel Transform and the filtered back-projection. Averaged results, tomographic view, standard deviation and errors are presented. The presented results reveal digital holographic interferometry as a powerful technique to visualize temperature fields in flowing liquids and gases. Full article

(This article belongs to the Special Issue Holography)

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10 pages, 1640 KiB

Open AccessArticle

Wavefront Modulation and Beam Shaping into Arbitrary Three-Dimensional Intensity Distributions

by Tatiana Latychevskaia

Photonics 2021, 8(6), 179; https://doi.org/10.3390/photonics8060179 - 23 May 2021

Viewed by 2355

Abstract

In this study the methods of three-dimensional (3D) wavefront intensity modulation by employing contrast-inverted holography, previously introduced as Gabor inverted holography, are further investigated. The present study provides the recipes for creating 3D wavefront intensity modulations using phase-only and amplitude-only modulators and compares [...] Read more.

In this study the methods of three-dimensional (3D) wavefront intensity modulation by employing contrast-inverted holography, previously introduced as Gabor inverted holography, are further investigated. The present study provides the recipes for creating 3D wavefront intensity modulations using phase-only and amplitude-only modulators and compares the results. The 3D wavefront modulation using spherical waves is also demonstrated, and the miniaturization of 3D intensity beams is discussed; it is shown that both the resolution and the size of the created 3D structures are ultimately given by the wavelength of the employed radiation. The manuscript also addresses the quality of the formed 3D intensity curves and determines the parameters that provide the best smooth appearance of the 3D curves. The presented methods of 3D intensity wavefront modulation can be realized for all kinds of waves: light, X-ray, electron, etc, provided the modulator can be manufactured for the corresponding wavelength. The methods of 3D intensity wavefront modulation can be applied in various techniques: lithography, micro-robotics, particle trapping, etc. Full article

(This article belongs to the Special Issue Holography)

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9 pages, 3194 KiB

Open AccessCommunication

Fourier Convolution Operation on Metasurface-Based Hologram in Microwave Region

by Shuai Yang, Chunsheng Guan, Xumin Ding, Kuang Zhang, Shah Nawaz Burokur and Qun Wu

Photonics 2021, 8(6), 174; https://doi.org/10.3390/photonics8060174 - 21 May 2021

Cited by 5 | Viewed by 2127

Abstract

In this paper, a 0.1λ₀-thick 1-bit coding metasurface is proposed to achieve a polarization-insensitive hologram under oblique incidence, utilizing compact ground-backed patch unit cells. Fourier convolution theory in a digital signal processing system is added to the hologram calculation of the [...] Read more.

In this paper, a 0.1λ₀-thick 1-bit coding metasurface is proposed to achieve a polarization-insensitive hologram under oblique incidence, utilizing compact ground-backed patch unit cells. Fourier convolution theory in a digital signal processing system is added to the hologram calculation of the improved weighted Gerchberg–Saxton (GSW) algorithm to achieve control of the scattered pattern in the microwave region. As a proof of concept, a prototype operating at 15 GHz is designed to verify the validity of our proposed approach. The measured performances show good imaging quality under different incident polarizations, providing potential applications in imaging processing and information storage. Full article

(This article belongs to the Special Issue Holography)

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9 pages, 1550 KiB

Open AccessCommunication

Diffraction Efficiency Characteristics for MEMS-Based Phase-Only Spatial Light Modulator with Nonlinear Phase Distribution

by Remington S. Ketchum and Pierre-Alexandre Blanche

Photonics 2021, 8(3), 62; https://doi.org/10.3390/photonics8030062 - 24 Feb 2021

Cited by 16 | Viewed by 2767

Abstract

Micro-electro mechanical systems (MEMS)-based phase-only spatial light modulators (PLMs) have the potential to overcome the limited speed of liquid crystal on silicon (LCoS) spatial light modulators (SLMs) and operate at speeds faster than 10 kHz. This expands the practicality of PLMs to several [...] Read more.

Micro-electro mechanical systems (MEMS)-based phase-only spatial light modulators (PLMs) have the potential to overcome the limited speed of liquid crystal on silicon (LCoS) spatial light modulators (SLMs) and operate at speeds faster than 10 kHz. This expands the practicality of PLMs to several applications, including communications, sensing, and high-speed displays. The complex structure and fabrication requirements for large, 2D MEMS arrays with vertical actuation have kept MEMS-based PLMs out of the market in favor of LCoS SLMs. Recently, Texas Instruments has adapted its existing DMD technology for fabricating MEMS-based PLMs. Here, we characterize the diffraction efficiency for one of these PLMs and examine the effect of a nonlinear distribution of addressable phase states across a range of wavelengths and illumination angles. Full article

(This article belongs to the Special Issue Holography)

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10 pages, 4001 KiB

Open AccessArticle

Design and Fabrication of a Holographic Radial Polarization Converter

by Jing-Heng Chen, Hung-Lung Tseng, Fan-Hsi Hsu, Chien-Yuan Han, Kun-Huang Chen, Chien-Hung Yeh and Ken-Yuh Hsu

Photonics 2020, 7(4), 85; https://doi.org/10.3390/photonics7040085 - 01 Oct 2020

Cited by 3 | Viewed by 2515

Abstract

Radial polarization converters can convert an incident light into a radially polarized light, which is beneficial in a variety of applications. In this paper, a new design of holographic radial polarization converter is proposed which consists of eight space-variant polarization-selective volume hologram gratings. [...] Read more.

Radial polarization converters can convert an incident light into a radially polarized light, which is beneficial in a variety of applications. In this paper, a new design of holographic radial polarization converter is proposed which consists of eight space-variant polarization-selective volume hologram gratings. According to the coupled wave theory, a feasible design of the polarization-selective volume hologram gratings was described. The prism-hologram-prism sandwiched recording method was adopted for the recording. The s- and p-polarization diffraction efficiencies of the fabricated polarization-selective volume hologram gratings at 443.29 nm are 90.83% and 22.09%, respectively. The operation bandwidth is about 4.42 nm. A prototype of holographic radial polarization converter was successfully assembled and tested. Due to the introduction of volume hologram gratings, this design should have the advantages of high diffraction efficiency, narrow band, compactness, and planar configuration, meaning it is especially suitable for low-cost mass production and has high application potential in related fields. Full article

(This article belongs to the Special Issue Holography)

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Review

Jump to: Research, Other

22 pages, 31169 KiB

Open AccessReview

Status of Leaky Mode Holography

by Daniel E. Smalley, Sundeep Jolly, Gregg E. Favalora and Michael G. Moebius

Photonics 2021, 8(8), 292; https://doi.org/10.3390/photonics8080292 - 21 Jul 2021

Cited by 3 | Viewed by 3569

Abstract

It will soon be a decade since leaky mode waveguide devices were presented as a solution for holographic video displays. This paper seeks to provide a brief, topical review of advances made during that time. Specifically, we review the new methods and architectures [...] Read more.

It will soon be a decade since leaky mode waveguide devices were presented as a solution for holographic video displays. This paper seeks to provide a brief, topical review of advances made during that time. Specifically, we review the new methods and architectures that have been developed over this period. This work draws primarily from papers seeking to present dynamic holographic patterns using mode coupling from indiffused waveguides on lithium niobate. The primary participants during this time period have been groups from the Massachusetts Institute of Technology, Brigham Young University, and Draper. We also describe the challenges that remain. The body of work reviewed speaks to the need for further development, but it also reaffirms that leaky mode waveguides continue to hold a unique place within spatial light modulation for holographic video displays. Full article

(This article belongs to the Special Issue Holography)

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13 pages, 5635 KiB

Open AccessReview

Magnetic Holography and Its Application to Data Storage

by Yuichi Nakamura

Photonics 2021, 8(6), 187; https://doi.org/10.3390/photonics8060187 - 25 May 2021

Cited by 3 | Viewed by 2868

Abstract

The principle of magnetic holograms and its application to holographic memory are reviewed. A magnetic hologram was recorded through a thermomagnetic recording as a difference in magnetization direction and reconstructed with the magneto-optical effect. To achieve a bright reconstruction image, it is important [...] Read more.

The principle of magnetic holograms and its application to holographic memory are reviewed. A magnetic hologram was recorded through a thermomagnetic recording as a difference in magnetization direction and reconstructed with the magneto-optical effect. To achieve a bright reconstruction image, it is important to record deep magnetic fringes on the materials with large Faraday rotation coefficients. This technique was applied to the holographic memory using transparent magnetic garnets as a recording material. The first reconstruction image was dark and noisy, but improvements in the recording conditions resulted in error-free recording and reconstruction of the magnetic hologram. To form deep magnetic fringes, insertion of heat dissipation (HD) layers into recording layer was proposed. It was found that this HD multilayer medium showed diffraction efficiency higher than that of a single layer medium, and error-free recording and reconstruction were also achieved, using magnetic assisted recording. These results suggest that HD multilayer media have potential applications in recording media of magnetic holographic data storage. In future, a high recording density technique, such as multiple recording, should be developed. Full article

(This article belongs to the Special Issue Holography)

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18 pages, 53862 KiB

Open AccessEditor’s ChoiceReview

Metasurface Holography in the Microwave Regime

by Guanyu Shang, Zhuochao Wang, Haoyu Li, Kuang Zhang, Qun Wu, Shah Nawaz Burokur and Xumin Ding

Photonics 2021, 8(5), 135; https://doi.org/10.3390/photonics8050135 - 22 Apr 2021

Cited by 24 | Viewed by 8796

Abstract

Hologram technology has attracted a great deal of interest in a wide range of optical fields owing to its potential use in future optical applications, such as holographic imaging and optical data storage. Although there have been considerable efforts to develop holographic technologies [...] Read more.

Hologram technology has attracted a great deal of interest in a wide range of optical fields owing to its potential use in future optical applications, such as holographic imaging and optical data storage. Although there have been considerable efforts to develop holographic technologies using conventional optics, critical issues still hinder their future development. A metasurface, as an emerging multifunctional device, can manipulate the phase, magnitude, polarization and resonance properties of electromagnetic fields within a sub-wavelength scale, opening up an alternative for a compact holographic structure and high imaging quality. In this review paper, we first introduce the development history of holographic imaging and metasurfaces, and demonstrate some applications of metasurface holography in the field of optics. We then summarize the latest developments in holographic imaging in the microwave regime. These functionalities include phase- and amplitude-based design, polarization multiplexing, wavelength multiplexing, spatial asymmetric propagation, and a reconfigurable mechanism. Finally, we conclude briefly on this rapidly developing research field and present some outlooks for the near future. Full article

(This article belongs to the Special Issue Holography)

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Other

Jump to: Research, Review

12 pages, 4718 KiB

Open AccessTutorial

Invasive and Non-Invasive Observation of Occluded Fast Transient Events: Computational Tools

by Soon Hock Ng, Vijayakumar Anand, Tomas Katkus and Saulius Juodkazis

Photonics 2021, 8(7), 253; https://doi.org/10.3390/photonics8070253 - 01 Jul 2021

Cited by 8 | Viewed by 2197

Abstract

Industrial processes involving thermal plasma such as cutting, welding, laser machining with ultra-short laser pulses (nonequilibrium conditions), high temperature melting using electrical discharge or ion-beams, etc., generate non-repeatable fast transient events which can reveal valuable information about the processes. In such industrial environments [...] Read more.

Industrial processes involving thermal plasma such as cutting, welding, laser machining with ultra-short laser pulses (nonequilibrium conditions), high temperature melting using electrical discharge or ion-beams, etc., generate non-repeatable fast transient events which can reveal valuable information about the processes. In such industrial environments containing high temperature and radiation, it is often difficult to install conventional lens-based imaging windows and components to observe such events. In this study, we compare imaging requirements and performances with invasive and non-invasive modes when a fast transient event is occluded by a metal window consisting of numerous holes punched through it. Simulation studies were carried out for metal windows with different types of patterns, reconstructed for both invasive and non-invasive modes and compared. Sparks were generated by rapid electrical discharge behind a metal window consisting of thousands of punched through-holes and the time sequence was recorded using a high-speed camera. The time sequence was reconstructed with and without the spatio-spectral point spread functions and compared. Commented MATLAB codes are provided for both invasive and non-invasive modes of reconstruction. Full article

(This article belongs to the Special Issue Holography)

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