This PDF file contains the front matter associated with SPIE Proceedings Volume 12909, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

The old theory of polarization holography is based on Jones matrix formalism, where the angle between two lights to be interfered each other should be small, and the results are limited under the paraxial approximation. However, since the tensor theory of polarization holography was proposed, the research of polarized holography has become hot, and has made a lot of new progress. There are also many researching works of reconstruction characteristics have been reported. One of the examples is that multi-channel recording was applied to data storage high density recording. In this paper, the representative works are introduced.

Volume holograms exhibit unique optical characteristics based on selective diffraction dependent on the state of incident light. For example, they are applicable to holographic data storage for ultra-high-definition video, holographic optical elements utilizing selective diffraction, super-resolution imaging, and optical combiners for AR head mount display. Since optical combiner is realized by using a partially reflective mirror, the larger the area to be displayed, the larger volume the mirror occupies. By using a holographic optical element, the volume occupied by the optical combiner can be decreased. However, thin holographic optical element exhibits strong wavelength dependence, so that multiple holographic optical elements are used for full color display. On the other hand, optical expansion system is important to decrease the volume of display system. In this study, a cylindrical wave volume holographic optical element was investigated to use as an optical combiner.

Although polarization holography introduces polarization dimensions, it is well known that polarization has only two orthogonal dimensions, and the expansion of recording capabilities is limited. Therefore, we introduce the polarization encoding for theoretical analysis and calculation, the orthogonal polarization array of arbitrary dimensions is obtained. Assuming that the n-dimensional vectors Q1, Q2, …, and Qx are a group of non-zero vectors that are orthogonal to each other in the orthogonal polarization array. The Schmidt orthogonalization method is used to expand the column vector group of the n-dimensional orthogonal polarization array into a set of canonical orthogonal basis of the space Kn. During the experiment, when the signal S1 is recorded with Q1, it can be faithfully reconstructed with Q1, while it shows null reconstruction with Q2 or Qx. By analogy, multiple recording and independent reconstruction experiments are carried out successively.

Surface holograms, such as computer-generated holograms, as a recording medium enable optical data storage systems that combine high-speed readout, semi-permanent storage lifetime, and mass production. We proposed a unique system that enables simultaneous parallel readout of multi-channel time series signals by shift multiplexing hundreds of surface holograms. The degradation of readout signals caused by Raman-Nath diffracted light, which had been the greatest scientific challenge, was significantly improved by properly designing signal and reference light patterns. The storage density and data transfer rate of the proposed system with this method were quantitatively evaluated considering the signal-to-noise ratio. The recording density was estimated to be comparable to current optical disks, which are limited by the diffraction limit. On the other hand, it was estimated that the proposed system can be expected to simultaneously readout time series signals with approximately 500 times more channels than an optical disk.

Experiments have shown that deep learning can improve the data reading of holographic data storage. However, it requires a large amount of storage materials and time to obtain data to optimize the network model. In data encoding, each encoded data page consists of 51sub-pages with the same structure. This paper proposes a deep learning method for image segmentation based on encoding features in collinear holographic data storage. Using a deep learning method of image segmentation, the encoded data page is segmented into data sub-pages. It can reduce material loss and data collection time.

Holographic data storage has emerged as one of the promising technologies to satisfy the demands of high-density data storage and retrieval. Here we propose the usage of Azo functionalized copolymer as the storage material and structured light as data encoding technique to realize high-density data storage and retrieval. A hybrid polarization-angle-depth multiplexing technique us employed to further increase the data density without crosstalk. The material also exhibits long retention time and faster re-writability and thereby possesses the potential to satisfy the demands of next generation data storage technologies.

Liquid crystalline (LC) materials, particularly, polymers allow generating molecular orientation patterns with submicrometer resolution. By that, materials and fabrication technology have been developed to reach half-wave (HW) retardation for visible and even infrared wavelengths thus ensuring feasibility of geometrical phase optical components that are practically 100% efficient. Such LC polymer films allow rich architectures for designing spectrally selective optical components and polarization-independent systems. Thin LC films with customized optical functions make promising basis for high throughput and high definition display systems.

With the rapid development of flexible electronics and soft robotics, there is an emerging topic of preventing fracture in materials and devices integrated on largely bending film substrates of >100 µm thickness. The high demand for strategically reducing strain in bending materials requires a facile method that enables one to accurately and precisely analyze the surface bending strain in a wide variety of materials. This study proposes the surface-labeled grating method that is the fundamental and efficient technique for measuring surface bending strains merely by labeling a thin, soft grating onto various film substrates composed of flexible polymeric and rigid inorganic materials. The surface strain with a single-nanoscale (<1.0 nm) can be quantified in real time with no need of material information such as Poisson's ratio, Young's modulus, and film thickness. The fracture limit of a hard coating overlying flexible substrates is successfully determined by the accurate and precise quantification of surface bending strains.

Liquid-crystal and organic light-emitting diode displays emit linearly polarized light, which causes blackout and color change problems when the displays are viewed through polarized sunglasses. To address both the blackout and color change problems, we proposed a random depolarization film (RDF), a polymer film doped with birefringent microparticles. Owing to the birefringence of randomly dispersed particles, the RDF converts linearly polarized light to randomly polarized light. In this study, to realize real-color displays with the RDF, the dopant particles were investigated based on a retardation, which is defined as a product of a birefringence and thickness of the dopant particles.

We develop a novel graded-index plastic optical fiber (GI POF) that achieves ultra-low bit error rate of less than 10^-15 for four-level pulse-amplitude modulation (PAM4) at 53 Gb/s without error correction techniques in short-reach multimode fiber (MMF) links. The stability of data transmission is attributed to significant noise reduction in MMF links through strong mode coupling closely related to the microscopic heterogeneities in the novel GI POF core material. The novel GI POF can eliminate the need for error correction techniques in high-speed multilevel PAM transmission systems to reduce communication delay and power consumption, paving the way for optical interconnects in real time at a high speed and with low power consumption for data centers and UHD transmission systems.

Optical transmission is becoming common medium for high-speed transmission in the market of datacom, telecom and consumer electronics. There are several types of optical transmission such as embedded optics (On Board Optics, Co-packaged Optics, Near-packaged Optics), Pluggable optics and Active optical cables. They are mainly based on glass or silicon materials. However, based on polymer technologies, Nitto has been developing new and unique types of optical transmission products, Plastic Optical Fiber and Optical waveguide with Flexible printed circuit (OFPC). For existing and emerging market requirements, Nitto continues developing total solutions regarding optical transmission. In this presentation, several values for many markets by using our polymer-based transmission medium will be explained.

In order to achieve lightweigt and high-speed in-vehicle data transmission in the future, there is growing anticipation for the utilization of multimode optical fibers. Conventional physical contact of two fibers cause damage of the fiber end face due to vibration. As a way to solve such problems related to splicing between optical fibers, we are developing light-induced self-writing (LISW) optical waveguide technology using gel materials that retain adhesiveness and flexibility. Recently, we have realized a flexible LISW optical interconnect between graded index optical fibers (50GI-fiber) to solve the optical coupling problem under vibration. In this study, an all-solid flexible LISW optical interconnect between 50GI-fibers is presented.

We have developed a prototype of a needle-sized rigid endoscope using graded-index plastic optical fiber (GI-POF) technology. With highly accurate control of refractive index within a GI-POF, we can utilize it for an ultra-fine lens as a replacement for a relay lens in rigid endoscope. The rigid endoscope with GI-POF lens has a possibility to allow doctors to directly observe a patient's inner affected area before and after surgery in a minimally invasive procedure, enabling rapid and accurate assessment of the patient's condition and efficient post-operative follow-up.

Coherent fiber bundles (CFBs) can transmit light from one end to the other in identical order, which are the important components of fiber endoscopes. However, the tiny fiber tip limits the field of view, and the inherent honeycomb artifact degrades the image quality. Here, we proposed a high-resolution wide-field microendoscopic imaging method. Multi-frame CFB images with random displacement are continuously captured during the observation. Motion parameters can be automatically estimated by alternate optimization with high-resolution and wide-field image instead of image registration. The method can provide strong support for the diagnosis and treatment of major diseases such as cancer.

Aerial display, which forms a real image in mid-air by converging light from a wide aperture, enables us to realize non-contact touch interfaces and glass-free augmented reality. Optical performance of an aerial display depends on its real-image-forming optics. Typical optical systems for aerial display are optical systems by use of a dihedral corner reflector array, crossed slit mirror arrays, layered micro-lens arrays, and a retro-reflector. This paper reviews optical systems for aerial display and reports the line-based MTF measurement results.

This work presents an advanced imaging system designed for automating rock characterization in environmental and industrial applications. The system utilizes dual spectroscopy techniques: white-light direct absorption for color and texture analysis, and UV-induced fluorescence for hydrocarbon identification. To meet the requirements of both spectroscopy applications, we have developed a highly integrated optical system that achieves a wide field of view and ultra-high-resolution imaging. This optimization enhances image sharpness and color accuracy for white-light imaging, as well as high contrast and short exposure time for ultraviolet fluorescence imaging.

Modern quantitative optical imaging possesses a huge information capacity. We present an aberration-free high-bandwidth holographic microscopy which exploits high-throughput label-free quantitative phase image. The maximum space bandwidth efficiency in a single multiplexing hologram can be reached at 78.5%. By assisting with the off-axis optimized initial phase in the phase retrieval, high-resolution and full-field reconstruction by exploiting the full bandwidth are demonstrated for complex-amplitude reconstruction. Then, we import variable sparse splitting framework on quantitative phase aberration extraction in holographic microscopy. The aberration-free two-dimensional and three-dimensional imaging experiments are demonstrated.

This paper describes a snapshot full- Stokes imager by two RGB polarization cameras with linear micro-polarizer array which is aligned to 0, 45, 90 and 135° of azimuthal direction. We screeded to determine full Stokes parameter imager for with achromatic non-polarizing beam splitter, retarders and two polarization cameras with calibration method for error of retarder to increase an accuracy. We succeed to analyze a high-definition polarization image by Stokes analysis in the Fourier domain although a polarization camera requires 2x2 pixels in monochromatic and 4x 4 for color with linear micro-polarizer array and color filleters in the space for one polarization analysis. We demonstrate same applications of bio-imaging using a differential interferometric microscope and some industrial applications by high-speed polarization camera.

Afterglow emission allows for imaging that is independent of autofluorescence under ambient conditions. Although higher-resolution afterglow is required for increasing the quality of the autofluorescence-free emission imaging, increasing the excitation intensity to generate brighter afterglow emission decreases the resolution of afterglow images. Therefore, methods and materials that provide afterglow imaging with higher resolution remain to be developed. In this study, we performed photoinduced triplet depletion and demonstrated improved resolution of bright afterglow emission using the depletion. Triplet depletion is related to charge separation via photoionization from a triplet state caused by depletion and subsequent rapid singlet formation. Triplet excitons that accumulated in a solid material by excitation were depleted under irradiation using a depletion beam with a longer wavelength than the absorption wavelength of the material. A higher-resolution afterglow image with an improvement of 25% was obtained by simultaneously focusing a donut-shaped depletion beam and an excitation beam.

The persistent emission that remains after excitation light irradiation is stopped enables high-contrast imaging without relying on surrounding autofluorescence. However, the luminance of common persistent emitting materials hardly increases even when the excitation light intensity is increased. Therefore, they have not been utilized for emission imaging in the nano-sized regions. Here we introduce high-resolution afterglow imaging using long-lived room temperature phosphorescence (RTP), which remains strongly emitted after excitation light irradiation is stopped. While looking at the correlation between the estimated value based on a unique dynamic calculation and the experimental value regarding RTP performance, we designed and synthesized molecules that are expected to improve the quantum yield of long-lived RTP. The RTP yield of the designed molecules has been greatly improved, allowing afterglow detection from small objects independent of autofluorescence. We introduce examples of afterglow imaging, where the resolution and contrast change depending on the excitation light intensity.

A single optical system with features of both automatic calibration and multiple configurations has been developed for high-resolution wavefront measurements. With the configuration of fine measurements, the tester can scan a large area to obtain mapping data with detailed local wavefront information of the sample. The tester can also take a fast snapshot of wavefront measurement by using the configuration of coarse measurements.

This paper proposes a novel display technique that reconstructs an aerial image just around viewing eyes to realize ultrawide field-of-view that cover entire field of view with images. Although it is known that getting closer to the information screen usually makes images larger and covering the entire field of view with images, the closest distance is limited by our nose. However, aerial display overcome this hardware limitation and has a possibility to present information just around the viewing eyes, even behind eyes, because aerial display has no hardware around the aerial image. When observer stands between the display hardware and the aerial image, reconstructed aerial image is behind the observer. To clarify what can be seen in this situation, we have developed a prototype aerial display to form an image just around viewing eyes by using aerial imaging by retro-reflection (AIRR). The image size for observer and binocular disparity have been estimated using this prototype. Even when aerial image is reconstructed behind viewing eyes, inverted image to aerial image can be observed, , whose size and negative disparity become very large toward infinity. Furthermore, our proposed method can cover entire field of view with images. This method is promising for new possibilities for aerial displays, such as one providing an immersive sensation with ultra-wide field-of-view.

In recent years, the resolution of video technology has been improved. As a result, the required data capacity is increasing as year by year. Therefore, storage that be able to store a huge amount of data is required. It is desirable for the storage to be able to store images for a long time, and holographic data storage is expected as long lifetime, high-density, large-capacity data storage. However, holographic data storage has not been commercially used yet because the size of holographic recording system is large, and it is difficult to increase the recording density further by the inter-pixel crosstalk noise and inter-page crosstalk noise. To achieve higher density, crosstalk separation is required. In this study, interpixel-crosstalk separation using a volume holographic optical element (VHOE) is investigated.