Sony is leveraging its "3R Technology" - Reality, Real-time, and Remote - to inspire Kando (emotion) value creation. Immersive, large-screen displays give us a sense of reality as if we are traveling around the world while we're at home. Sensors for automotive provide real-time feedback to the drivers to provide safety and comfort. AR/MR/VR technology connects people who are separated remotely and enriches their communication. Photonics is one of the core technologies of Sony and is the foundation of the core devices which create the values of Reality, Realtime and Remote. In this talk, Sony's unique photonic device technologies are introduced, including micro-display, AR/MR/VR, light field displays and laser devices. The prospects for the evolution of these technologies will also be presented.

Waveguide technology is widely believed to constitute the most promising approach to realize affordable and fully immersive Augmented Reality (AR) / Mixed Reality (MR) devices. For all major technology platforms (diffractive, reflective, or holographic), specialty grade high index optical glass is the central component to achieve some of the key features of AR devices, such as field of view, MTF, or weight. We will provide insights into SCHOTT’s roadmap for dedicated glass development for the AR sector and discuss the latest achievement with high relevance for the industry. It is a game of trade-offs between the desired properties to produce an optical glass which enables the entry of AR devices into the consumer market.

The classical treatment option of amblyopia is occlusions of non-amblyopic eye. The newest methods involve specialized computer and phone games, applications that involve both eyes in visual processing during treatment as well as stimulate binocularity. The aim of the work was to assess the efficiency of specialized phone application ‘Duovision’ in the treatment of amblyopia in preschool-age children. There were 30 participants (5-8 years old): 16 participants had occlusion therapy; 14 participants played the specialized phone application Duovision®. The visual acuity of amblyopic eye, as well as stereopsis was evaluated at near and far distances before the treatment, 2 and 4 months after the beginning of treatment. The results show statistically significant improvement in visual acuity and stereovision in both treatment groups after four months of therapy. The extent of improvement is similar in both groups. Specialized phone applications for amblyopia treatment may be recommended to patients from an age 3 when they are able to use a mobile phone, who want to improve their visual acuity in the amblyopic eye and are not willing to use occlusions. The only requirement for using specialized applications – patients need to have binocular single vision. In conclusion, the use of specialized phone applications is an alternative type of amblyopia treatment compared to occlusion therapy.

The COVID-19 pandemic has unexpectedly transformed the access and the organization of repair services for industrial equipment. Operation or maintenance and a breakdown of industrial equipment require interaction with the specialists of the equipment manufacturer. The personal presence of a specialist repairman at an industrial facility leads to high financial costs, which consist of losses from prolonged downtime of equipment and production in general and transportation costs. A way out in such situations can be remote work of enterprise engineers and an expert of an equipment supplier, organized using a remote assistant's hardware and software complex. The article compares AR systems by numerous parameters in the following groups: software functionality, technical features for software operation, data security, compatibility requirements. This analysis will allow potential users of such systems to determine the optimal implementation approach in production based on the required parameters. The correct choice of such systems will ensure that employees can work safely and efficiently in production, reduce the risk of incorrect work and reduce production downtime.

The paper describes the implementation of practical laboratory settings in a virtual environment. With the entry of VR glasses into the mass market, there is a chance to establish educational and training applications for displaying some teaching materials and practical works. Therefore our project focuses on the realization of virtual experiments and environments, which gives users a deep insight into selected subfields of Optics and Photonics. Our goal is not to substitute the hand on experiments rather to extend them. By means of VR glasses, the user is offered the possibility to view the experiment from several angles and to make changes through interactive control functions. During the VR application, additional context-related information is displayed. By using object recognition, the specific graphics and texts for the respective object are loaded and supplemented at the appropriate place. Thus, complex facts are supported in an informative way. The prototype is developed using the Unity Engine and can thus be exported to different platforms and end devices. Another major advantage of virtual simulations to the real situation is the high degree of controllability as well as the easy repeatability. With slight modifications, entire experiments can be reused. Our research aims to acquire new knowledge in the field of e-learning in association with VR technology. Here we try to answer a core question of the compatibility of the individual media components.

Imprint materials for optical applications can have a multitude of different properties, dictated by the function they must fulfill. Apart from optical properties such as refractive index, wavelength-dependent transmission or scattering behavior, a frequently neglected parameter is the thermo-mechanical behavior. We will discuss the importance to balance all these properties to achieve the best performance in different application and production scenarios, based on simulations and experimental tests.

Obtaining a varying refractive index distribution has always been attracting a high interest in the optics community to produce gradient-index (GRIN) optics. The conventional way to store and process data by GRIN media is through volume holograms, where the recording is done by optical means, which prevents independently accessing each point in the volume. Additive manufacturing, specifically 2-photon polymerization, inherits this ability. Considering the scalability advantage of the 3D implementation of computation architectures and the power-speed advantage of optics, there lie many opportunities for additively manufactured GRIN optics performing complex tasks. Independent access to each voxel in fabrication volume opens the way for digital optimization techniques to design GRIN optics since each calculated voxel can be translated into fabrication. In this work, Learning Tomography (LT), which is a nonlinear optimization algorithm originally developed for optical diffraction tomography, is used as the optimization framework to calculate necessary refractive index distribution to perform computation tasks such as matrix multiplication. Here, instead of imaging an object in optical diffraction tomography, we calculate the 3D GRIN element that performs the desired task as defined by its input-output relation. This input-output relation can be chosen such that a computational functionality is satisfied. We report functional robust GRIN elements where the refractive index dynamic range (<0.005) is comparable to the dynamic range of conventional holography materials. We present the digital optimization methodology with details on the beam propagation method as the forward model and the corresponding error reduction scheme for the desired input-output mapping along with the experimental verification of the approach along with the details of the fabrication process by additive manufacturing.

Bayfol® HX photopolymer films prove themselves as easy-to-process recording materials for volume holographic optical elements (vHOEs) and are available in customized grades at industrial scale. Their full-color (RGB) recording and replay capabilities are two of their major advantages. Moreover, the adjustable diffraction efficiency, tunable angular and spectral selectivity of vHOEs recorded into Bayfol® HX as well as their unmatched optical clarity enables superior invisible “off Bragg” optical functionality. As a film product, the replication of vHOEs in Bayfol® HX can be carried out in a highly cost-efficient and purely photonic roll-to-roll (R2R) process. Utilizing thermoplastic substrates, Bayfol® HX was demonstrated to be compatible to state-of-the-art plastic processing techniques like thermoforming, film insert molding and casting, all enabled using a variety of industry-proven integration technologies for vHOEs. Therefore, Bayfol® HX made its way in applications in the field of augmented reality such as Head-up-Displays (HUD) and Headmounted- Displays (HMD), in free-space combiners, in plastic optical waveguides, and in transparent screens. Also, vHOEs made from Bayfol® HX are utilized in highly sophisticated spectrometers in astronomy as well as in narrow band notch filters for eyeglasses against laser strikes. Based on a well-established toolbox, Bayfol® HX can be adopted for a variety of applications. To further offer access to more applications in sensing and continuously improve the performance in existing applications, we recently extended our chemical toolbox to address both the sensitization beyond RGB into the Near Infrared Region (NIR) and increase the achievable index modulation Δn₁ beyond 0.06. In this paper, we will report on our latest developments in these fields.

Augmented and mixed reality applications have recently gained large interest. In order to fabricate lightweight near eye displays surface relief gratings are used for coupling the light from the source into the light guide and out of the light guide towards the eye. To suppress higher diffraction orders and thus maximize the light yield those gratings are slanted. In order to achieve high field of view variation of the slant angle is desirable yet rather difficult to achieve. Ion beam trimming (IBT) is a method well established in MEMS and sensor manufacturing to locally modify the thickness of a layer or substrate in order to achieve a desired target topography. This method has been adapted towards fabrication of surface relief gratings with both varying slant angle and varying trench depth. The optically transparent substrate (e.g. SiO2) had been covered with a hard mask providing the basic grating geometry such as period and duty cycle. Localized ion beam etching was then applied to etch the trenches. Varying the ion irradiation dose (by means of dwell time variation) sets the trench depth on a local level. The angle of incidence of the ion beam directly transfers into the substrate as the slant angle and can be varied independently of the dwell time providing the unique possibility to achieve a continuous variation of the slant angle across one die. To avoid redeposition of the sputtered trench material to the grating side walls the etching was carried out in the reactive ion beam etching (RIBE) regime. Furthermore the choice of the process parameters (process gas composition, ion energy) allows for tuning the selectivity between hard mask and target material such that high aspect ratio trenches are possible while keeping the hard mask thin avoiding shadowing of neighboring structural features.

The integration of gaze gesture sensors in next-generation smart glasses will improve usability and enable new interaction concepts. However, consumer smart glasses place additional requirements to gaze gesture sensors, such as a low power consumption, high integration capability and robustness to ambient illumination. We propose a novel gaze gesture sensor based on laser feedback interferometry (LFI), which is capable to measure the rotational velocity of the eye as well as the sensors distance towards the eye. This sensor delivers a unique and novel set of features with an outstanding sample rate allowing to not only predict a gaze gesture but also to anticipate it. To take full advantage of the unique sensor features and the high sampling rate, we propose additionally a novel gaze gesture classification algorithm based on single sample. At a mean F1-score of 93.44 performance at a negative latency between gaze gesture input and command execution.

This paper discusses a 3D depth-sensing system for mobile application consisting of a structured-light illuminator based on a Vertical-Cavity Surface-Emitting Laser (VCSEL) array and an embedded imaging system equipped with a high-speed CMOS-sensor and a Field Programmable Gate Array (FPGA) device. For structured-light projection, an elliptical array pattern generated with two-photon polymerized micro-optics on top of the VCSEL is employed. To solve the correspondence problem and estimate objects’ distance, we proposed light-weight and robust algorithms in favor of hardware implementation. We demonstrate the validation of the proposed approach with initial experimental results.

Using an optical transmission electroabsorption modulator (T-EAM) in combination with a common image sensor and a high-power illumination source allows to build a three-dimensional (3D) imaging system based on the indirect time-of-ight (iTOF) principle. In contrast to most available iTOF systems that use specialized image sensors, in this case the EAM is doing the required demodulation at the receiver in the optical domain. A first 3D imaging setup was built and investigations on the performance of the system are reported. A high-power laser source was characterized in order to design and fabricate matched large-area T-EAMs. The fabricated modulators show extinction ratios of about 6 dB and bandwidths of up to 37MHz at 1mm² size. 3D images taken with the prototype camera consisting of the T-EAM, the laser source, and a Raspberry Pi camera show promising results with a depth inaccuracy below 5 cm at a distance of 1 m.

Currently, there are four major medical imaging technologies in the clinic: X-ray computer tomography (X-CT), ultrasound scan imaging (US), positron emission tomography (PET), and magnetic resonance imaging (MRI). They have developed rapidly, but they all have their own disadvantages. Compared with the above four imaging methods, the photoacoustic imaging (PAI) technology based on the photoacoustic effect has been extensively researched. PAI combines the high-contrast advantages of pure optical imaging and the high resolution of pure ultrasound imaging, which can achieve deeper imaging of biological tissues, and is currently widely used in biological imaging. The research in this paper is the expansion of the depth of field of the PAI system. The basic principle of PAI is to irradiate the target tissue with a short pulse laser, to excite ultrasound. The light absorption distribution reflecting the internal structure of the target tissue is reconstructed from the sampled sound waves. Since it needs to focus the laser strongly, this will result in a small imaging depth of field. Many biological tissues (such as brain, abdomen, etc.) have curved surfaces. Due to the limited depth of field of the optical imaging system, the blood vessels in the imaging field of view may not be on the same focal plane. It is arduous to get all accurately focused blood vessel images. It is not conducive to the observation of changes in the structure and composition of blood vessels, which brings great inconvenience to related researchers. In order to solve this problem, this paper proposes a large depth of field and high-resolution three-dimensional photoacoustic information fusion technology suitable for PAI systems. In this paper, the virtual blood vessel data sets are used to simulate the three-dimensional data sets of blood vessels at different focal positions collected by the PAI system. Based on the visualization software Amira, the two sets of three-dimensional data are reconstructed and fused. The results demonstrate that the fused virtual blood vessel imaging structure shows a complete high-resolution structure in the entire field of view. The validity and reliability of the method are verified.

As a new imaging modality, photoacoustic imaging combines the advantages of optical imaging and ultrasonic imaging, which can provide deeper imaging depth and higher spatial resolution. At the same time, the high optical contrast between different tissues in photoacoustic images provides an important means for the study of biological tissue morphology, physiological and pathological characteristics. It has a very broad application prospect in the whole tissue structure and functional imaging. Therefore, it has been closely concerned in the field of biomedicine and has been developed rapidly in recent years. In the field of nuclear magnetic resonance (NMR), how to restore the original signal to be known with less measured values is an important research topic. In this paper, based on photoacoustic imaging technology and compression sensing reconstruction algorithm, a virtual simulation platform for compression sensing photoacoustic tomography is constructed by using k-wave simulation toolbox. Through this platform, a simulation model of photoacoustic propagation was established, we analyzed the photoacoustic signal generated by the simulation model. Finally, the basis pursuit denoising algorithm in the compressed sensing reconstruction algorithm is used to reconstruct the image of the vascular network. The results show that the virtual simulation platform successfully realizes the compressed sensing photoacoustic tomography with small amount of data but high reconstruction quality, which has practical significance and theoretical value for the research of the application of compress sensing in photoacoustic imaging.

A volumetric display forms three-dimensional (3D) graphics in real space by generating light emission or scattering points as volume pixels (voxels). In order to realize this display, we have proposed several types of system using femtosecond-laser-excited voxel and holographic beam control with computer-generated hologram. In our systems, a gas-state type which employs air as a screen shows touch interaction applications between user and graphics, and also demonstrated augmented reality in real 3D space. However, this system still has a challenge to display color graphics because the color of the aerial voxel is monochromatic bluish white. In this research, we try to form the graphics with multi-color by selectively re-imaging light from voxels with only arbitrary colors using two parabolic mirrors including variable color filters.

Traditional compressed sensing matrices like the Gaussian random matrices and Bernoulli matrices are signal structure agnostic due to their adherence to the Restricted Isometry Property (RIP). However, practical measurement operators like the Walsh measurement matrix do not posses RIP and their reconstruction quality can be improved when the measurements are adapted to the signal structure. Sparsity in natural images decay in an asymptotic manner with dense low spatial frequency subbands and sparser higher frequency subbands. Existing methods use decaying power laws to generate a probability map that mimics this sparsity behaviour. Specifying the subbands to sample and the number of measurements to sample in each subband is difficult in such methods. Also generating frequency selective maps is difficult. We propose a sampling pattern design procedure that adheres to the asymptotic sparsity principle but allows selection of the spatial frequency subbands. Bounds are provided such that maximum measurements are allocated to low spatial frequencies. Through experiments on airborne imagery we show that the proposed method works at-par with existing methods for regular imaging requirements. In an unknown environment the proposed method ensures acquisition of spatial frequencies as- sociated with maximum energy and allows easy and flexible design of sampling patterns for frequency selective imaging in specialized scenarios.

High Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H part2 is the state of art video encoder standard developed by the Joint Collaborative Team on Video Coding (JCT-VC). It achieves up to 50% better data compression at the same level of video quality than its predecessor (H.264-AVC). One of the main challenges of the HEVC coding is its overall performance as the improved quality and bit rate of the standard coding comes with significant performance overhead. This motivates significant research to reduce the overall complexity. In this paper, we explore the effect of applying down sampling and up sampling of coded video on the performance of the HEVC. The down sampling is applied to all video frames before the encoder process begins and the up sampling is applied to all the video frames after the decoding process is completed. We use an average filter in down sampling, and machine learning based network (SRCNN) for the up sampling. In contrast to other methods, the down sampling and up sampling are applied on frame level outside the encoding/decoding processes and not in block level. Our experiments show the down sampling and up sampling can improve the HEVC encoding/decoding performance by up to 50% in some sequences with limited impact on the output encoded bit rate and decoded video quality. The performance comparison is done using different quantization values.

Head-mounted display (HMD) technologies are improving in resolution and brightness, but are not generally solving three key issues of prescription, accommodation and presbyopia. Eyeglasses worn within head-mounted devices reduce their optical quality, eyetracking efficacy, and comfort, they add stray light/reflections and increase bulk. Fixed inserts are more compact, but require many stock keeping units (SKU's), are incompatible with shareability, and have achieved a low market share. Adjustable lenses present a low SKU, integrated, on-demand solution to these issues, but with some remaining technology challenges. We show how the spherical optics adjustable non-round fluid-filled lens may be extended to general ophthalmic prescriptions by the inclusion of astigmatism correction on an arbitrary axis. We also describe methods to produce the long lifetime fluid-filled lens with an anti-reflective surface. Finally, we define the rules for building a minimal thickness and weight liquid lens.

Progress in LED technology has enabled a variety of new application scenarios also in automotive exterior lighting. A characteristic feature of this field is the dynamic behavior of the lighting scenario. Whereas in the past, mechanical adjustments or several disjoint light sources were necessary, the newest μLED technology enables a high-resolution source array based on a monolithic block of IC-chip, opto chip, and converter layer. Still, an optical system is required to project the μLED array onto the road. The optics discussed has to serve multiple functions as it provides imaging quality, bright illumination, as well as stray light control.

There are currently various near-infrared (NIR) light sources for sensing applications. To expand the application of NIR sensing, we are advancing research and development a self-emissive NIR-OLED microdisplay featuring a compact form factor and active drive as a new sensing light source. In general, in the NIR region having a narrow energy gap, an exciton of organic emitters readily decays non-radiatively to the ground state. Therefore, it is challenging to obtain high-efficiency light emission. To overcome this problem, a TADF (thermally-activated delayed fluorescence) material having a rigid electron-accepting unit exhibiting strong electron-withdrawing properties is used as an assisting dopant for a molecule exhibiting fluorescence in the 900nm band. It thereby realized a near-infrared light-emitting characteristic with a longer wavelength, higher efficiency, and higher durability than a conventional device. 　 Furthermore, in order to actively drive this highly efficient NIR-OLED material on a silicon substrate, a top emission structure is required. To cope with this issue, the optical design was optimized for NIR band emission by the micro-cavity effect. The optimum structure for high-efficiency NIR emission was adopted by examining the structure around the emission layer and the encapsulation process. By integrating this high-efficiency NIR-OLED device with a CMOS-based high-definition backplane formed on a silicon substrate, it’ll have the potential to be realized a high-efficiency NIR-OLED microdisplay with a pixel pitch of 7.8 μm and a maximum external quantum efficiency of approximately 1% and an emission wavelength of over 900 nm. Through this study, it was confirmed that the NIR light emission was possible with high efficiency with fine pixel in principle. It’s expected to contribute to power saving and miniaturization as a new sensing light source to be applicable to new value creation.

We demonstrate a miniaturized, full-color RGB light source module for near-to-eye display systems, incorporating three semiconductor laser diodes (LDs) that are integrated on a free-space, micro-optical bench together with collimation optics and wavelength filters. The ultra-compact package has a footprint of 4.4 mm x 4.15 mm with a height of 2.9 mm (0.053 cm³) and an optical output window for the collimated and collinearly aligned RGB beams. The light source module delivers up to 10 mW per color at low power dissipation values of 640 mW and provides low-divergent output beams having a high circularity and a diameter of 250-650 μm at a reference distance of 50 mm.

Light field visualization is an emerging 3D technology that does not rely on viewing devices, such as special glasses. Without the need for such additional devices, multiple users may simultaneously enjoy the glasses-free 3D experience from a virtually infinite number of viewing positions, as the motion parallax is continuous and smooth. Although this immensely valuable property of light field displays does enable a great deal of viewing freedom, the proper perception of the visualized content still depends on the position of the observer. Position in this context determines the distance and the angle of the observer, with respect to the screen of the display. The validity of the latter is relatively straightforward to assess: if the observer is viewing the screen from inside the angle set by the field of view of the display, then the content shall be seen from its perceptually correct angle. However, the fundamental issue with the underinvestigated topic of viewing distance is that light field visualization may lose its 3D nature if viewed from a far-away position. This is due to the fact that in such a case, a single point of the screen may emit identical rays of light towards the two pupils of the observer. Therefore, the deficiency of disparity, the lack of distinct rays may lead to a 2D visual experience, nullifying the core scientific contribution of this technology. Of course, moving sideways in front of a horizontal-only-parallax display may, in fact, induce a 3D experience via the natural sense of parallax, but it should be applicable regardless of movement. Needless to say, in a multitude of professional environments, the users of such displays are not expected to be highly mobile during the work-related utilization of the technology. However, at the time of this paper, merely a few publications of the scientific literature address the topic of viewing distance, and standardization efforts are still in a rather early phase. Summa summarum, light field displays need clear guidelines with regard to viewing distance, which may benefit both the manufacturers and the users. Such guiding principles may make development and production more cost-efficient and user-oriented, and may contribute to the increased efficiency of usage-focused display design. In this paper, we provide a series of recommendations on the viewing distance of light field displays. The displays are separately analyzed within the context of their own use cases, taking into account the key performance indicators of both the apparatus and the visualized content, the various environmental conditions, as well as the relevant use-case-scenario-specific necessities and the professional requirements. The investigated use cases include medical imaging, telepresence, resource exploration, prototype review, training and education, gaming, digital signage, cinematography, cultural heritage exhibition, air traffic control and driver assistance systems.

LED technologies expectedly will dominate future displays by outperforming current mainstream technologies, while LED walls have already become the key solution in large-scale displaying. LED walls are not just display walls anymore; they offer a creative modular platform for displaying in any size, aspect, shape, and on any surface. At the time of this paper, there is no real 3D solution for such an attractive technology. In the recent years, rapid miniaturization of LEDs, including microLEDs, and LED control ICs has paved the way for novel LED wall displays with extremely high LED density. In this line, Holografika has developed a unique glasses-free 3D LED wall technology and this article describes the implementation of the 3D LED display prototype, focusing on the challenges in designing the optical elements, and also describes the software components that drive it. To match the high expectations for image quality, the optical system was designed with great care, balancing the conflicting 2D- and 3D-related parameters, like pitch size, angular resolution, FOV, considering practical use cases with typical viewing distances, covering specific LED layouts, up to the theoretical limits with regard to the chip sizes; novel optics for wide angle and high angular resolution beyond what usual lenticular systems can provide; preparing for volume production through designing plastic injection molded optics and tools; custom designed record high-density LED backplane, including PCB, seamlessly tileable LED panels where known slanted structures were not acceptable. The software system was designed to be run on GPUs and to be flexible enough to handle various configurations of display geometry and electronics. Not only are arbitrary layouts supported for the arrangement of the pixels and color channels of the 3D pixel under the sheet array, but also the geometries of the individual cabinets of the LED wall are separately addressable. The software calculates the correct ray field for the light field geometry and the color channel and pixel position shuffling table for the individual cabinets. The rendering consists of two distinct phases. The first phase is rendering the 3D scene for all camera rays. The system can render using various algorithms, such as real-time ray tracing; rasterization with orthogonal projection in the horizontal and perspective projection in the vertical axis, with individual images corresponding to directions selected by the lens array; rasterization of an array of horizontally asymmetric perspective cameras coupled with a ray-selection GPU render pass. The second phase enables shuffling the pixels and color channels to the correct byte order for the LED controller ICs. This allows the system to address individual cabinets. It also allows the usage of different ICs in subsequent generations of the display, without the need to deploy costly FPGAs with large area and power consumption requirements to handle the correct shuffling. Furthermore, the system enables the rendering hardware to scale across multiple PCs and GPUs. This is necessary to allow the system to render the high amount of pixels required to drive the LEDs.

Comprehensive overview of design requirements and issues in the development of phase-only spatial light modulator (SLM) based liquid crystal on silicon (LCOS) technologies is presented. Phase-only SLMs enable many applications such as holographic three-dimensional (3D) displays, head-up displays for automobiles, laser processing, 3D printers, optical communication, and optical computing. Our LCOS panel can achieve high image quality represented by world-class high contrast ratio. In addition, our LCOS has high reflectivity, high-definition pixels, and high durability against high-power light. In phase-only SLM, high reflectivity means high light use efficiency, high-definition pixels achieve wide-diffraction angle, and high durability against light enables use of high-power laser. In this presentation, we will report a development of phase-only SLM based on LCOS technologies and promising candidates of applications using our phase-only SLM.

Volumetric display implementations come in different forms. One of the most robust ways is an entirely solid-state volumetric architecture based on cholesteric liquid crystal optical diffuser elements. Stacking these elements enables formation of a volumetric screen – a projection volume, which is scanned time-sequentially. In this way two crucial components are working in conjunction – an image projector and an electronically switchable diffuser-element stack. LightSpace Technologies have been researching this concept of solid-state volumetric display technology since 2014. Improvements to the key enabling component – optical diffuser element – have been achieved over this period and include improved responsiveness, as well as enhanced optical characteristics – haze and transparency over visible spectrum. This work overviews and discusses key aspects of diffuser elements as well as a large-scale volumetric screen as a whole. Key characteristics of diffuser elements have been discussed and studied in regards to application in high refreshrate 3D display systems. Methods of improving optical performance of diffuser stacks have been analyzed and supported by experimental results. The base of a volumetric screen element within this work was a polymer-free chiral nematic liquid crystal filled in a homeotropic cell. A typical switching time of a full image cycle was around 1.5 ms. Influence of cell gap and driving voltage on the switching characteristics have been analyzed. In terms of volumetric screen improvements, viability and gains of lamination approach has been investigated. It has been found that even a non-ideal refractive index matching improves an overall light transmittance through a stack of diffuser elements significantly.

This presentation was recoded for the 2021 SPIE Digital Optical Technologies conference

Photoacoustic imaging is a new non-destructive medical imaging method in recent years. It combines the advantages of high resolution and rich contrast of optical imaging with the advantages of high penetration depth of acoustic imaging. It can provide safe, high resolution and high contrast tissue imaging. As an important branch of the field of photoacoustic imaging, photoacoustic microscopy can achieve higher-resolution imaging. Therefore, this technology has been widely applied in the field of medicine. However, the limited depth of field limits the speed of volumetric imaging. Therefore, improving the depth of field of photoacoustic microscopy is of great significance. The acoustic lens used to collect the photoacoustic signal is a very important part of the photoacoustic microscopy. The acoustic lens commonly used are spherically focused, where the ultrasonic signal is focused at a single point. This results in a limited and uneven detection range of photoacoustic signals, which reduces the volume imaging speed. Here we design a multi-focus acoustic lens to expand the detection range of photoacoustic signals, and then achieve large depth of field photoacoustic detection. We used COMSOL to simulate the transmission of ultrasonic field of the designed multi-focus acoustic lens, and compare it with the single-focus acoustic lens. The results show that the depth of field of the multi-focus acoustic lens is about 3.4 times that of the conventional single-focus acoustic lens. And the depth of field of the multi-focus acoustic lens can be further adjusted by adjusting the number of focus of the multi-focus acoustic lens.

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