The conventional holography is based on recording of intensity of holographic fringes. An alternative polarization stage recording approach is proposed to increasing storage capacity of holographic memory.

We report on recording technology of practical holographic drive (HD). We aimed for practical holographic data storage system for archival or ultra-high-definition data storage purpose. We are developing angular-multiplexing holographic drive (AM-HD) using photopolymer as the recording medium. There is a trade-off relationship between improvement of recording density and reproduction signal quality in HD. In this research, we modeled this relationship with signal to noise ratio (SNR) and developed a recording condition optimization technique that can maximize the potential of the recording medium. First, we classified the noise factors of the system into four main components: “optical system noise”, “intrinsic scattering noise”, “crosstalk noise” and “medium damage noise”. And we constructed a model of SNR. Using this model, we have established a method to optimize the recording conditions such as “multiple recording number”, “recording energy” and “signal/reference power ratio” to maximize the potential of the recording medium. In addition, we performed recording and playback experiments using the prototype of the holographic drive under development and demonstrated the usefulness of the developed method. We are convinced that we have achieved a major step towards realizing a practical holographic data storage system.

When an image shown on an 8K display is projected onto the entire hemisphere, the size of a single pixel is almost equal to 1’, which is same as human visual acuity. This indicates that the resolution of an 8K display is beyond the visual ability of humans, in most cases. A display can show not only an image, but also coded information on its screen. When this ultra-high-definition display is used as a light-field display that consists of a high-definition display and lens array plate, its redundancy of resolution is used for depth information of 3D objects, and a volume 3D image can be reconstructed near the screen. We fabricate a 3D light-field display using a 4K cellular phone and obtain a good image quality. An 8K display is more suitable for a light-field display that generates 3D images of higher resolutions, although the reproduced depth is limited. Herein, I report our light-field display utilizing an ultra-high-definition flat display.

8K, also known as Super Hi-Vision, is a next-generation ultra-high-resolution television system created by NHK. Its video format comprises 7,680 × 4,320 pixels (16 times the total number of pixels of an HDTV). 8K features four times the number of pixels as 4K, but that does not mean to say that 8K specifications are decided based on a competition in pixel count. They are determined, rather, on human science research that aims to determine the conditions under which video can provide “high presence” that makes the viewer feel as if he or she is actually present in the scene shown. Medical Imaging Consortium (MIC) has studied endoscopic surgeries using 8K imaging technologies since 2013. It was confirmed that an 8K endoscope clearly depicts details that are difficult to see using conventional HDTV endoscopes, including thin blood vessels, nerves and the borders of body organs. Based on the fundamental research at MIC, we have developed the world’s first 8K endoscope commercial camera system.

We have started clinical application of 8K ultra-high definition (UHD; 7680 x 4320 pixels) technology to a rigid endoscopic system for advanced minimal invasive surgery. Our 8K UHD endoscopic system consists of an 8K UHD camera head with a lens adapter, rigid endoscope, xenon light source, 8K UHD monitor, and 8K UHD recorder. The first model of an 8K UHD camera head was developed based on a broadcasting camera in 2014, and the weight was 2.2 kg. The second model of an 8K UHD camera head was our original achievement in 2016, and the weight was 450 g. In 2017, we finally succeeded in developing the world’s smallest 8K UHD camera head of 370 g weight for mass production. We were able to achieve clinical success using the first model in two cases of cholecystectomy in 2014. Furthermore, after downsizing and weight saving of the 8K UHD camera head, we performed four cholecystectomies with higher maneuverability in the abdominal cavity using the second model in 2017. These experimental and clinical studies revealed the engineering and clinical feasibility of the 8K UHD endoscope. The 8K UHD endoscope promises new possibilities for intricate procedures including anastomoses of thin blood vessels and identification of thin nerves, as well as more confident surgical resections of various types of cancer tissues. We believe that our 8K UHD endoscopic imaging is very likely to lead to major changes in the future of medical practice, not only in typical endoscopic surgery but also in new heads-up surgery.

Several kinds of optical polymer films in liquid crystal displays (LCDs) greatly contribute to image quality. However, contrast ratio of LCDs degrades with an increase in birefringence of polymer films used in the LCDs. The major types of birefringence are orientational birefringence and photoelastic birefringence. Furthermore, it was recently found that the birefringence caused by specified conformation and degree of orientation of polymer chains strongly depends on the temperature. We designed and synthesized a temperature-independent zero-birefringence polymer (TIZBP): poly(methyl methacrylate/benzyl methacrylate/phenyl methacrylate = 45/22/33(wt.%)) that has zero intrinsic birefringence over a wide temperature range in the random copolymerization method. However, the glass transition temperature Tg of this TIZBP is 95°C, and heat-drawn films of this TIZBP shrank at lower temperature than Tg, for example, at about 60°C. Upper limit of operating temperature of LCDs in automobile is higher than 60°C. Therefore, this TIZBP is not proper for practical use in automobile. In this research, after analysis of heat shrinkage of heat-drawn films, heat-resistant TIZBP (HRTIZBP) that exhibits sufficiently low heat shrinkage at 60°C, zero intrinsic birefringence and zero temperature coefficient of intrinsic birefringence was designed and synthesized. First of all, heat shrinkage ratio of heat-drawn films of poly(methyl methacrylate)，poly(methyl methacrylate/benzyl methacrylate) and TIZBP was investigated. The heat shrinkage of polymer films began at Tg-55°C. Based on the results, because targeting Tg for HRTIZBP was determined to 125°C, higher than 115°C with a sufficient margin, poly(methyl methacrylate/phenyl methacrylate/N-ethyl maleimide = 39/45/16 (wt.%)) was synthesized. This polymer exhibits lower heat shrinkage than the existing polymers, especially the heat shrinkage at 60°C is 0.0%. Therefore, this polymer was confirmed to be HRTIZBP.

The continuing need of improvements governed by the development of all optically controlled devices providing wide broadband sensitivity, high spatial resolution and low energy consumption rapidly increase. In this paper, we review varieties of organic-inorganic hybrid structures that can be used as all optically driven high resolution spatial light modulators. In the proposed structures all optical processes are controlled by the surface activated photorefractive phenomena, typical for highly photoconductive substrates. The performed two-beam coupling measurements at Bragg match regime show prospective amplification values and sub-micron spatial resolution. The structures are easy to fabricate and their operation simple to control.

As ultrahigh definition (UHD) video moves moves to ever-higher resolution and ever-higher data rates, optical transmission solutions become attractive at increasingly short distances. In recent years, active optical cables (AOCs) have been developed with plastic optical fibers (POF) to meet these needs. In this talk, I will discuss new approaches to POF AOCs, aimed at minimizing the cost of AOCs for UHD video.

Along with the increase of the demand for Ultra-High-Definition (UHD) such as 8K, a tremendously large bit-rate data transmission will be required inside home and among consumer devices. For 8K video, a required transmission speeds will be up to 240 Gb/s. Conventional metal cables such as serial digital interfaces are not suitable for UHD application, because of increases in electric consumption and electro-magnetic interference. Therefore, the key is to implement optical fibers into every corner of homes and consumer devices. It means a paradigm-shift from electrical wire to optical fiber. Recently, we have a discovery that the novel graded-index plastic optical fiber (GI POF) with specified micro-heterogeneities in core of fiber dramatically reduces the modal noise, resulting in the stable data transmission without optical isolator and precise alignment. This novel GI POF is being paid a lot of attention to as one of the strongest candidates for supporting UHD displays and tablets especially in consumer photonics. We have successfully proposed and developed both the new zero-birefringence polymer films and ultra-high birefringence polymer films towards real-color high-definition displays ahead of the world. The new zero-birefringence polymer exhibits always “zero-birefringence” for deformation of polymer chains, adding stress to polymer, and changing temperature. The ultra-high birefringence polymer films have been already commercially used in LCD TV, and have been developed for new type displays including both LED and OLED. These polymers eliminate the long-standing issue of birefringence which causes color irregularities, and realizes the extremely real color for ultra-high definition display.

The growing demand for high-speed data transmission in consumer applications such as 4K/8K television motivates the development of multilevel modulation. Multilevel modulation can increase bit rate over 2-level modulation for same symbol rate, but is subject to noise and modulation instability in optical link. Recently, we experimentally demonstrated that a graded-index plastic optical fiber (GI POF) significantly improved the transmission signal quality compared with a silica GI multimode fiber (MMF) in the consumer-friendly MMF link without an optical isolator, where laser and optical fiber easily coupled. This high-quality transmission is related to reflection noise reduction because of a strong mode coupling in the GI POF. However, the signal quality also depends on the modulation response of the vertical-cavity surface-emitting laser (VCSEL) coupled with optical fibers. Here, we investigate the influence of the strong mode coupling in the low-noise GI POF on the modulation response of the VCSEL in the consumer-friendly MMF link. We show that the low-noise GI POF can significantly decrease the distortion of the modulation response compared with the silica GI MMF which easily coupled with the VCSEL. This low-distortion performance is related to the strong mode coupling in the low-noise GI POF, which stabilizes the VCSEL owing to the self-coupling reduction of the optical feedback into the VCSEL cavity. This suggests that the novel GI POF allows for highly-stabilized multilevel transmission for consumer-friendly 8K interface. In the conference, we will also discuss the mechanism for the stabilization effects of the low-noise GI POF using theoretical analyses.

We presented the digital holography (DH) system with enhanced image quality. While conventional DH uses highcoherence laser for illuminations, the speckle noise included in the image degrades the quality of the reconstructed data. To reduce the noise regards to the light source, lower-coherence light source could be applied in DH system. In this paper, the quantum dot (QD) based wavelength converter is utilized as the light source. Compared with light-emitting diode (LED), QD-based light source could be applied to versatile system, including dual-wavelength DH. Due to the low coherence both temporally and spatially, spatial filtering and collimation is presented. Also, numerical processes including noise reduction and aberration compensation is described to enhance the quality of the image. By experimental verifications, the proposed DH system shows better quality compared with conventional system, which is enough to utilize the quantitative measurement.

Data amount circulated in the world is increasing year by year. Most of data are not desirable to erase even though the access frequency is not so high. To store the data, a data storage with long lifetime is required. TV program archives are the one of them and the data amount are increased with increasing the pixel number of display devices. Therefore, holographic data storage with large data capacity and long lifetime is expected for UHD TV. In holographic data storage, coded images called data pages are recorded on a recording medium by volume holography. However, the image quality is reduced by low-pass spatial frequency filtering, optical system error, and characteristics of recording medium. When the properties of optical system including recording medium are precisely known, the change of data page pattern can be expressed by an analytical function. In reconstruction, a deteriorated data page pattern from a volume hologram is captured by an image sensor. Then, an image sensor pixel detects signals from multiple data page pixels because a pixel pattern is spread. The weight coefficients from all data page pixels to an image sensor pixel can be calculated by using the analytical function. When the weight coefficients are calculated at all image sensor pixels, simultaneous equations are obtained. Original data page patterns can be reconstructed by solving the simultaneous equations. In this paper, the expression method of a deteriorated data page pattern with an analytical function is discussed.

Holographic data storage is expected to realize capacity of terabytes as well as fast data-transfer rate of Gbits/sec on a disk format. This kind of performance will be a potential solution for next-generation storage of big data in diversities of applications such as cloud servers and ultra-high definition systems. In this work, we analyze and optimize the axial response of the holographic data storage, aiming at maximizing storage density while suppressing the inter-page crosstalk on the reconstructed data pages. The optical model of the three dimensional hologram recorded in the medium is presented. Based on the reconstructed data page model, inter-layer crosstalk is also analyzed by use of orthogonal reference patterns. The signal to noise ratio and bit error rate of the reconstructed data page are improved. Experiments are conducted to obtain the axial shift selectivity curves and verify the predicted storage density and capacity of a holographic optical disk.

Polarization-Controlled dual images recording with linear polarization holography Jinliang Zang*, Fenglan Fan, Ying Liu, Yifan Hong, Long Shao, Xiaodi Tan （School of Optoelectronics, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081, China 100081） *Corresponding author: jlzang@bit.edu.cn Abstract: Polarization holography is a promising technique for its unique capacity of recording intensity, phase as well as polarization of light wave field simultaneously. In recent years, dual-channel images recording by polarization holography has been proposed. However, in conventional dual-channel images recording, an unchanged polarized reference wave is employed while signal waves have orthogonal polarization, which makes two holographic images can only be read out simultaneously. In this paper, we report polarization-controlled dual images recording within polarization holography written by orthogonal linear polarization waves. In this method, two polarization multiplexed holographic images could be sequentially readout by shifting the polarization state of reference wave based on null reconstruction effect(NRE) of linear polarization holography. NRE is an unique phenomena in polarization holography which means the diffraction efficiency goes down to zero when the hologram is reconstructed by orthogonal polarized reading wave. In this paper, we study polarization holography recorded by orthogonal linear waves and find that the NRE of orthogonal linear polarization holography can be achieved at large cross-angle of inside the polarization-sensitive media. The NRE of linear polarization holography is experimentally demonstrated by recording orthogonal linear polarization hologram in fabricated cubic material PQ/PMMA whose size is 10 mm ×10 mm ×15 mm. Based on the NRE of orthogonal linear polarization holography, polarization-controlled dual images recording is carried out. Two images encoded by orthogonal linear polarization waves are sequentially recorded in same position of cubic PQ/PMMA by orthogonal linear polarization holography. In reconstruction stage, The two holographic images are sequentially readout by shifting the polarization state of reference wave with negligible inter-channel crosstalk. The experimental results agree well with theoretical predictions. And this polarization-controlled dual images recording method has promising applications in optical storage, vector light field modulation and multi-functional optical devices. Keywords: Polarization holography, Holographic data storage, Polarization-multiplex, Image processing

In this paper, we introduce hologram printing technology. This technology includes the following technologies, computer-generated hologram, hologram printer, duplication, and application-depended technologies. When this technology is applied to static hologram, the media can present static 3D objects more clearly than traditional 3D technologies such as lenticular lens and integral photography(IP) because it is based on holography. When this technology is applied to holographic optical elements(HOE), the HOE will be useful for many purposes especially for large optical elements. For example, when it is used as screen, the visual system which consists of the screen and projector can present dynamic 2D or 3D objects. Since this technology digitally designs hologram/HOE and manufactures them by wavefront printer, it is good at generating small lot of production. As a result, it is effective for the research stage of both 2D and 3D display. In addition, it is also effective for commercial stage due to simple duplication method.

To make full use of the spatial bandwidth product of imaging systems, grating based single-shot digital lens-free holography with spatial spectrum multiplexing is proposed. Multiple object waves are generated by a one-dimensional grating which is placed in near contact with the object to avoid the crosstalk among different diffraction orders during reconstruction. A multiplexed off-axis hologram is created by interference between the object waves and reference wave and captured by an image sensor in one shot. Multiple imaging areas corresponding to the captured object waves can be simultaneously retrieved during reconstruction, which is equivalent to increase the imaging area. A formula which guarantees accurate full FOV imaging without crosstalk or information loss is presented. The imaging experiments of a USAF resolution target are presented to demonstrate the feasibility of this method.

In the context of measurement technology, optical methods have a number of unique features. These features include in particular the non-contact and high speed interaction with the object under test, the largely free scalability of the dimension of the probing tool, the high resolution of the data, the diversity of information channels in the light field, and the flexible adaptability of the comparative standard – the wavelength. On the other hand the user is confronted with a number of serious challenges. Two of the biggest challenges that currently attract high attention in both the technical as well as life sciences, relate to exceeding the physical limits of resolution and to improve the precision of the measurement. Therefore optical measurement methods are subject to constant improvement. The characteristics that give rise to improve the performance of the systems are obviously dependent on the purpose of the measurement and the object under test. But there are also general features that can be used to assess the performance of a measurement system. Here we refer to the spatial and temporal resolution, the area related resolution, the precision and trueness of the results, the robustness, the degree of automation, the process capability and the ability to work as close as possible to the process. In this contribution we describe the current challenges for measurement systems. Based on this we discuss general and application dependent features for the assessment of modern optical measurement systems. Afterwards, we describe measures to assess and to improve their performance. Finally, we show an advanced optical measurement system where several of these features were considered with regard to ensuring a high performance.

We have developed three types of prototype cameras based on multi-purpose and DSLR models equipped with full-frame (35 mm) CMOS sensors, i.e. modified versions of the Canon ME20F-SH, EOS-1D X, and EOS 5DS. We have also made a prototype interchangeable lens that is highly transmissive in the visible and near infrared (NIR) region, based on a Canon EF 100-400 mm lens. High signal-to-noise (S/N) ratio spectral images up to 1,100 nm were observed using the following tools: the modified ME20F-SH, which features a monochromatic sensor with a 19 μm pixel pitch; the modified EF 100-400 mm lens; NIR optical bandpass filters ranging from 1,000 to 1,200 nm with 25 nm bandwidth; and a short wavelength cut-off filter that blocks light below 840 nm. This camera and lens, with a liquid crystal tunable filter (LCTF) attached, was able to clearly observe absorption bands attributed to hydroxyl groups near 960 nm in aqueous sucrose solutions. This experimental set was also applied to discrimination between dairy cream and whipped topping in combination with multivariate analysis; multi spectral data set obtained by this experimental set was processed by principal component analysis followed by a modified algorithm of independent component analysis. The Canon EOS-1D X’s 18.1 million pixel sensor was modified by introducing NIR pixels in addition to its RGB pixels. The modified EOS-1D X and the lens were able to acquire both high-image-quality photography and high-resolution NDVI (Normalized Difference Vegetation Index) in the observation of a lawn with a single press of the shutter button. This camera and lens set was also applied to observe hair in dried seaweed, producing a high-resolution NIR image in which each hair was visualized. Furthermore, a sharper image of the hair was obtained using the modified EOS 5DS and the LCTF.

An 8K4K-LCD with the diagonal size of 55 inch has been developed. The backplane is based on an amorphous silicon (a-Si) technology and can operate at 120Hz, which is achieved by developing a technology to compensate the charging voltage of pixels. The realization of a high resolution of 8K4K and a high frame frequency of 120Hz is the world first for LCDs with a-Si backplanes. Moreover, a backlight system with laser light sources expands the color gamut. The newly developed LCD covers 99% of color space defined in BT.2020.

Additionally, we have established three dimensional 8K4K technology. A 3D polarization filter is attached on the 55-in. 8K4K LCD. The vertical viewing angle of 8K-3D LCD prototype is 8.6 degrees at its optimal viewing position set to 1.2m.

High performance silicon-based optical circuits and modules will be required for the future high bandwidth optical data transmission system applications. We are now engaging in fabrication of integrated optical waveguides and modules using hybrid structure of high performance functional photonic polymers and silicon photonics. We present recent progress of photonic polymers and waveguide-type device technologies for next generation integrated optical circuits. High performance photonic polymer is a potential candidate for functional optical waveguide material by combining silicon waveguide platform. Using electrooptic (EO) polymer limit of bandwidth and/or driving voltage of a silicon modulator can be overcome. Light-induced self-written (LISW) waveguide technology enables optical interconnection between optical components using photocurable resin. Athermal silicon optical waveguide can be achieved by using organic-Inorganic hybrid material with large negative thermooptic (TO) coefficient as a cladding material of silicon waveguide. By combining high performance functional photonic polymer and silicon waveguide, we attempt to realize integrated optical devices for next-generation optical interconnection application. Moreover, we present data transmission system demonstration using the hybrid modules.

A graded-index plastic optical fiber (GI POF) with a high bandwidth and flexibility is expected to be a transmission medium for short-reach communication in home networks. However, the pluggable interconnects for consumers have not been emerged. Recently, we have developed ballpoint-pen interconnects where ball lens can be precisely mounted on GI POF end face using ballpoint-pen production technology, enabling easy connection, low-cost production, and fiber end face protection of GI POFs. Here, data transmission quality through coupled GI POFs with the ballpoint-pen connector is investigated. For evaluating data transmission quality, we measured bit error rate versus received optical power (BER curve) for a connector separation of 1.5 mm in the ballpoint-pen interconnect. The result shows error-free transmission (BER<10-12) was achieved by using the ballpoint-pen interconnect whereas transmission quality was significantly deteriorated by using the butt-coupling which is generally physically-contacted without fiber separations. This achievement with the ballpoint-pen interconnect may result from little dependence of the coupling loss on the connector separation because of the collimated output beam from GI POF with the ballpoint-pen connector. Furthermore, even for same received optical powers in the BER curve, the butt-coupling has worse transmission quality than the ballpoint-pen interconnect. This may result from some noises such as modal noise which occurs in multimode fiber connection as fluctuations of the coupling power. These results suggest that the ballpoint-pen interconnect is suitable for a consumer applications where the pluggable interconnects are essential. In the conference, the connector separation dependence of transmission quality through ballpoint-pen interconnect will be discussed.

Recently, ultra-high definition (UHD) displays have been rapidly developed for video formats with 4K (3840x2160) and 8K (7680x4320) resolutions. In Japan, 4K/8K broadcastings are scheduled to be started, accelerating research and development of 4K/8K distribution technologies. Current UHD displays require uncompressed video transmission with a bit rate well above 100 Gb/s, suggesting that extremely high bit-rates are required even at home in the upcoming 4K/8K era. Therefore, consumer-friendly pluggable optical interface has been highly demanded. A graded-index plastic optical fiber (GI POF) has been has been a promising optical interface cable for the consumer applications because of its flexibility, safety, and high bandwidth, which allows for transmission speeds up to ~ 40 Gb/s through a 100-m GI POF. Recently, we demonstrated that GI POFs have noise reduction effects which are closely related to microscopic heterogeneities of the core material. Here, we propose a low-noise GI POF for uncompressed 8K video transmission based on noise-sensitive multilevel pulse amplitude modulation (PAM). We evaluated worst-case bit-error-rate curve of for the low-noise GI POF and a silica GI MMF in the extremely-short optical link, where we used PAM-2 with the corresponding modulation voltage to minimum symbol-level difference in PAM-4. The results showed that the transmission quality is dominantly determined by not loss and bandwidth but noise and stability. Using the low-noise GI POF, we could significantly stabilized data transmission without precise alignment, angled fiber-facets, and optical isolators. The novel GI POF allows for consumer-friendly optical interface for the 8K video multilevel transmission. This research is based on results obtained from a project commissioned by the NEDO.

High space-bandwidth product (SBP) imaging platform is an indispensable technique in diverse research fields, particularly in medical imaging and diagnosis. Because of the scale-dependent geometric aberrations of optical elements and the limited number of pixels of image sensor, high resolution and large field of view are hard to be realized simultaneously in traditional imaging systems. Compared with off-axis holography, in-line lens-less holography could maintain high SBP without an imaging lens. Compressive holography (CH), which combines compressive sensing and in-line lens-less holography, is considered as a promising solution for high SBP three-dimensional imaging. We developed a high SBP three-dimensional imaging algorithm using CH based on total-variation sparsity constraint. An efficient block-wise CH algorithm is proposed to reduce the reconstruction time. The block-wise model could locate accurate reconstruction searching spaces, resulting in high convergence speed and high image contrast.