Objective Humans live in a four-dimensional space-time world, and it is a natural need to interact with visual information in a four-dimensional form. From stereoscopic films to virtual reality (VR), augmented reality (AR) and metaverse, these are attempts to present and interact with information through direct perception (vision, hearing, smell, touch, and taste, etc.). Real-time three-dimensional(3D) display is one of the key technologies. Holographic 3D display is considered the ultimate 3D display technology. It can truly provide a virtual window for observing the real 3D world containing all the characteristics of real-world objects. However, the application of large size, high-resolution dynamic holographie 3D display still faces challenges due to the massive data processing. transmission, and the space-bandwidth product of hologram bearing media. Currently, directly using a single panel spatial light modulator (SLM) cannot meet the spatial bandwidth product requirements for providing holographic 3D displays with suitable field angles and parallax angles. Utilizing existing SL.Ms to achieve holographic 3D displays with a large space-handwidth product is one of the research hotspots. Methods A method utilizing seamless splicing of reflective jiquid crystal SL.Ms is proposed to expand the space handwidth product of holographie display systems. The core of this method is the 3-SLM splicing module, which seamlessly splices three SLMs using two mirrors placed at 45 to form a larger SL.M. In this module, me SIM serves as a reference, with two other SLMs distributed un its left and right sides, perpendicular to it. The left and right reflecting mirrors respectively reflect the light from the corresponding SI.Ms. The reflected images of the SLMs are located on the same plane as the teference SLM. By adjusting the positions of the reflecting mirrors, seamless splicing of three SLMs is achievad. Multiple 3-SLM modules are spliced using the same method to form even larger SL.Ms. To obtain a reconstricted image of the hologram with appropriate size and parallax angle, a subsystem for enlarging the reconstructed image and expanding the viewing angle using a holographie functional screen was designed. The subsystem consists of two convex lenses and one holographic directional weak speckle screen. The convex lenses magnify the reconstructed image. The holographic screen is placed near the magnified reconstructed image, which slightly scatters the image while further imaging the SLMs, forming an observation window. Based of the characteristics of the spliced SL.M, a cylindrical beam expander for efficient illumination using cylindrical lenses was designed. The subsystem comprises a beam exponder, a spherical lens, and two cylindrical lenses. The focal lines of the two cylindrical lenses coincide, but their focal lengths differ. The light emitted by the laser is expanded and collimated into parallel light. The first cylindrigal lens transforms the parallel light into a cylindrical beam. The second cylindrical lens further expande the cylindrical beam into parkiel light. In this way, the beam is expanded and collimated into a long strip shape. In onfer to reduce the cost of the demonstration system, commercial projectors from Sony, which have three reflective liquid crystal display (LCD) panels with a resolution of 4096 pixels 2160 pixels and a pixel size of 4,06 pm, were modified to construct the spliced SLM. A signal deception circuit was designed to replace the original light source control circuit, allowing the projector to function normally after removing the light source Two mirrors were used to fold the illumination path. A beam To reduce the size of the system, a folding optical path was designed. litter was used to fold the observation path and realize the AR effect. Results and Discussion Using the proposed method. I SL.Ms were apliced to obtain a large SLM with a resolution of 32400 pixels 4096 pixels and an effective display size of 131 mm x 17 mm. A holographic functional screen was designed and produced. A holographic display system was built, with a viewing window width of 69 mm, a maximum reconstructed image size of 157 mm x 157 mm, and a refresh rate of 30 Hz. Using data catnined by 310 scanning, data synthesized from 3D scanning and manual creation, and scanned data of a dynamic 3D scene, computer-generated lensless Fourier-transform holograms were generated for experimentation. The holograms were sent to the display sytem for reconstruction. From the reconstructed images, it can be seen that the displayed disparity information is accurate and there is no blurring caused by stitching. From the reconstructed image of the dynamic 310 scene, it can be seen that the system can necurately display the dynamic 3D scene without ghost images. Conclusions To achieve real-time holographic 3D display with a large viewing angle, a seamless SLM splicing scheme, a holographic reconstructed image amplification system, and an efficient beam collimation system were proposed. An experimental setup was constructed for verification. The experimental results show that the proposed scheme can achieve dynamic holographic 3D display. The observation window covers the interpupillac distance of human eyes. The currently proposed solution realizes monochrome holographic display. By further adopting color synthesis light path or spatial multiplexing methods, the system con achieve color dynamic holographic 3D display.

Optical projection tomography (OPT) is a computational imaging technique to acquire the volumetric images of biological samples ranging from millimeters to centimeters. For in-vivo OPT, it is essential to minimize the inspection time to reduce the adverse impacts on organisms, including the anesthetic side effect and phototoxicity. It can be achieved by projecting the samples from equally spaced sparse angles, but this method will induce radial artifacts in the reconstructed tomographic images. This paper develops a high-quality reconstruction method for sparse-angle OPT by jointly exploiting the multi-layer sparsity prior and deep image prior (DIP) on the volumetric images. The DIP module works in an unsupervised manner without requirement on a training dataset. This method can also address the inter-layer correlation within the samples, and process multi-layer images in parallel to improve the reconstruction accuracy and efficiency. Simulations and experiments demonstrate the superiority of the proposed method over some widely used reconstruction algorithms for sparse-angle OPT.

数字全息层析(HT)显微术是一种先进的无标记三维显微成像方法,可以恢复细胞等生物样品的三维折射率分布,进而实现细胞体积、干质量等形态学和生理学参数的三维可视化.HT在数字全息显微记录和再现单幅数字全息图的基础原理上,通过旋转样品或旋转照明等方式获取多角度下全息图,然后通过投影层析或衍射层析等算法重建待测样品的三维折射率分布.综述HT中光路设计与重建算法的技术研究与生物学应用进展,为HT技术的国产化发展与应用研究提供借鉴.

High-resolution color Fresnel hologram is computation extensive. In this research, we propose a spatial sampling method to reduce the information redundancy of high-resolution Fresnel holograms. The color Fresnel hologram by combining of three monochromatic sampled holograms is achieved without barrier effect. Theoretical analysis of human visual perception of the color Fresnel hologram is conducted. A color holographic 3D display method using RGB LEDs as illumination sources is implemented for color holographic 3D display using color Fresnel holograms with the size of 30 mm × 30 mm at the resolution of 94,208 × 94,208 pixels. The proposed method is verified through experimental study illustrating the effectiveness of the proposed method.

A novel approach for the measurement of information content of light field on the image plane illuminated by an incoherent light source has been proposed according to Shannon's information theory. We put forward a hypothetical concept named "coherent wavelet source" on an incoherent light source which can form an independent coherent signal on the object surface based on the expression of mutual intensity on the object surface. As a result, the number of independent coherent signals on the object surface can be made out by dividing the whole illumination source on a coherent wavelet source size. Meanwhile, the maximum number of degree of freedom of light field which can reach the image plane is given based on the structure of imaging system. Concrete algorithm for the information content of the imaging light illuminated by a 1D linear light source and a 2D circular light source are presented.

为了实现数字全息图和计算全息图再现像的融合,将数字全息、计算全息与空间光调制器相结合,构建了一个数字化动态三色全息三维显示系统,用数字全息术记录实际物体的全息图,用计算全息术计算得到虚拟物体的全息图,然后将2种全息图输入到空间光调制器中.结果显示:通过空间光调制器的衍射,在空间中得到虚拟信息与实际信息融合的再现像.该方法实现了数字全息图和计算全息图再现像的融合,达到了增强真实物体的三维显示效果.

In this study, we propose a method for calculating a large scale high resolution synthetic color rainbow hologram using the frequency domain splicing technique. This method is motivated by the observation that if the plane wave is used as the reference light, the spectra of the three primary colors of the object light in the color rainbow hologram frequency domain are mutually separated frequency bands. According to this principle, the color views of different angles of a colored 3D object are separated and interpolated, and 2D Fourier transform is performed to form an object light spectrum distribution of the color rainbow hologram. Following the operation, efficient one-dimensional Fourier inverse transform in the row and column directions of the frequency is conducted. The proposed method is able to achieve a significant boost in terms of large scale high resolution hologram computational speed. We demonstrate that a synthetic color rainbow hologram with a size of 30 x 30 mm and a resolution of 94 340 x 94 340 is achieved through our holographic printing system with an unprecedented time of only 25 min. The method is also able to achieve a visually appealing computer generated white light color rainbow hologram, thus having great potential to be used for a practical holographic 3D display.

In this research, a color grating projection system is designed to effectively and flexibly display spatially sampled large size and high resolution color Fresnel hologram. The sampled color Fresnel hologram is placed in the image plane of projection system. The parameters of color grating are adjusted for 3D color display. Specifically, one effective scheme of spatially sampled color Fresnel hologram is used for reducing the data redundancy of computer generated Fresnel hologram while keeping a high resolution of reconstructed 3D image. A hologram with the size of 30mm×30mm at the resolution of 94208×94208 is calculated and optically reconstructed to verify the proposed display system.

以P123(聚环氧乙烷-聚环氧丙烷-聚环氧乙烷三嵌段共聚物)为模板剂,Ce(NO3)3,Pr(NO3)3为原料,采用水热反应制备前驱物,经萃取除去P123后既得表面羟基含量较高的Ce-Pr-O介孔材料.利用氨基硅烷与表面羟基间的缩合作用,合成了氨基功能化介孔Ce-Pr-O.利用XRD,N2吸脱附,Raman,FT-IR,XPS等技术对合成样品结构性能进行了表征.结果表明:以25％ Pr(NO3)3掺杂所获得的Ce-Pr-O结构性能较好;该样品氨基功能化后,除孔径、表面积及孔容变小外,其他性能基本保持不变.以酸性红14 (AR14)为探针分子,对合成材料的光催化性能进行评价.结果表明:由于Pr掺杂后形成氧缺位,提高了样品的可见光吸收强度;此外,通过嫁接氨基,提高AR14的吸附量.因此,所合成的氨基功能化介孔Ce-Pr-O在可见光作用下,能较彻底地催化降解溶液中的AR14.

It was analyzed the factors that affected the resolution of reconstructed images in the process of re-cording and reconstruction of digital holograms, a real-time optical 3D microscope system was constructed by combining spatial light modulator with digital holography. The quantitative relationship between the size of the object to be recorded and the resolution was deduced by the theory,and the optimum reference condition and the best recording distance were given. On this basis, four different regions of USAF 1951 discrimination board were used as recording objects. The results showed that the experiment agreed well with the theoretical analysis.

针对单路单室航空发动机喷油嘴的内锥角测量难题,采用基于锥光全息技术的Cono激光测头,设计了一台五轴坐标测量机作为测量平台,建立了该坐标测量机的测量数学模型.利用参数化建模的方法,给出了空间锥面的最小二乘参数化目标函数,借助L-M优化算法实现求解.实验结果表明,测量的重复误差为0.001 9°,标准差仅为0.0009°.故本文所提对喷油嘴内锥角的测量方法是可行的.

Novel single-phased phosphors SrY2O4: Bi3+, Eu3+ (SYO: Bi3+, Eu3+) with tunable emitting were successfully synthesized by the conventional solid-state method. X-ray diffraction, excitation and emission spectra, decay curves as well as temperature-dependent luminescence were applied to characterize the as-obtained phosphors. Under ultraviolet (UV) excitation, blue luminescence centered at 410 nm was found in SYO: Bi3+. By introducing Eu3+ into SYO: Bi3+, highly efficient energy transfer (ET) process with ET efficiency of 92.65% from Bi3+ to Eu3+ was obtained before concentration quenching. The possible ET mechanism from Bi3+ to Eu3+ were investigated systematically. By altering Eu3+ content, tunable emission from blue to red was realized. More importantly, investigation of the thermal stability showed that over 98% of the room-temperature emission intensity was still preserved at 155 degrees C, which is superior to that of most recently reported Bi3+, Eu3+ co-doped phosphors. These results indicate that this kind of easy fabrication, low-cost and highly stable SYO: Bi3+, Eu3+ are potential candidates for blue-red phosphors for application in UV chip based w-LEDs. (C) 2018 Elsevier B.V. All rights reserved.

In this study, we demonstrate a practical synthetic hologram with a size of 30 mm x 30 mm at resolution of 94340 x 94340. The high-definition large-scale computer-generated full-parallax synthetic hologram is achieved through frequency mosaic with different perspective images. The sparsity characteristics mosaic frequency of full parallax synthetic hologram is analyzed for reducing the complexity of computation. Following elimination of the sparsity, the hologram is calculated by normalization of 2D inverse Fourier transform of the mosaic frequency. The error and object point size are analyzed and we conclude that the error is sufficiently small for human visual perception given that parallax angle and object depth are within acceptable limits.

Because elliptical beams have many special properties and applications, an elliptical Airy beam with and without a vortex phase has been proposed. Based on the definition of the elliptical Airy beam, an experimental setup for the generation is given, and the formula for the evolution of the intensity is derived. Meanwhile, from the propagation of the Airy beam in vacuum, the abruptly autofocusing length is derived. Based on the formula of the abruptly autofocusing length, the intensity distributions at some special locations are analyzed and discussed, especially in the autofocusing point. Study shows that some interesting intensity profiles are reformed due to the asymmetry intensity distribution of the elliptical Airy beam and abrupt autofocusing of the circular Airy beam during propagation. The different eccentricity of the elliptical Airy beam has similar properties, such as the beam split with the propagation distance and the reformed beam shaped like a ”light knife” (very narrow beam) at some positions due to the convergence process out of synchronization along the x- and y-axis. When we impart a vortex on the elliptical Airy beam, the intensity distribution will rotate and split with the propagation distance.

According to the reversible principle of optical path, a computer generated half-circle view-able color rainbow holographic algorithm based on frequency domain synthesis is proposed. Firstly, the principle of half-circle view-able color rainbow hologram is analyzed, and the corresponding relationship between observation window and frequency domain is summarized. It is pointed out that the frequency spectrum of half-circle view-able color rainbow hologram object light is composed of the half-ring frequency spectrum of three primary colors. A plurality of projection images in a specific direction of a color three-dimensional object are used to separately perform color separation and interpolation, and perform a two-dimensional Fourier transform. The object light frequency spectrum of the half-circle view-able color rainbow hologram in the frequency domain is synthesized. And the synthesis object light frequency spectrum is transformed by two-dimensional inverse Fourier transform. Half-circle view-able color rainbow hologram is got by taking the real part and adding a bias component. Using this algorithm, a hologram with the area of 47 mm X 47 mm and a resolution of 84000 pixel X 84000 pixel is calculated and output by the holographic output system. Then it is followed by development, fixation and bleaching. Half-circle view-able color rainbow hologram with white light reconstruction is realized. The hologram shows vivid three-dimensional effect, brilliant colors, and can be watched by many people at the same time.

Using P123 as template and Ce(NO3)3 and Fe(NO3)3 as raw materials,mesoporous Ce-Fe-O materials with good structural properties were synthesized via hydrothermal reaction.Amino-functionalized mesoporous materials were successfully obtained by the condensation between amino silane and surface hydroxyl group.The synthesized materials were characterized by XRD,N2 adsorption-desorption,Raman,and FT-IR technologies.The results showed that the structural properties of mesoporous CeO2 doped with 15％ Fe(NO3)3 were preferable and that the structural properties of Ce-Fe-O remained constant except lower pore size,specific surface area and pore volume after animo-functionation.The photocatalytic performance of synthesized materials was evaluated by the degradation of acid red (AR14) from aqueous solution.The photocatalytic results presented that AR14 can be thoroughly degraded by the amino-functionalized mesoporous Ce-Fe-O under the irradiation of visible light due to the stronger higher adsorption of visible light and the higher adsorption of AR14 resulting from the formation of oxygen vocation and the introduction of amino group,and that the degradation efficiency of amino-functionalized mesoporous Ce-Fe-O was higher than that of the related photocatalysts.

The 3D scene is captured with a 3D scanner. Then the computer-generated hologram (CGH) of scene is calculated and displayed on a 4K SLM. The algorithms are implemented on a multi-core CPU in real-time.

With the development of invisibility technology, invisibility devices have now become more practical, with properties such as working at visible wavelengths, using natural materials, and hiding macroscopic objects. Recently, the cloaking of dynamic objects was experimentally realized using ray-optics. Here, based on a phase retrieval algorithm and phase conjugation technology, we design and fabricate a system to hide dynamic objects that changes at speeds faster than 8 seconds per frame. Different from shell cloaks and carpet-like cloaks, which conceal the entire region covered by the cloak, our system works when the object is at a distance and hides only the selected part of an object when the entire object is within the working area of the system. We experimentally demonstrate the concealment of a millimeter-scale object at different wavelengths. We believe that our work may provide a new approach to hiding objects in real life and may also be applicable in biological imaging and atmospheric imaging.

Fringe pattern can be projected fast by digital projector using DLP technology. The projection speed is higher when patterns with lower bit-depth are adopted. The phase error of sinusoidal fringe pattern with different bit-depth is studied with three-step phase-shifting algorithm. The uniform quantization algorithm (UQA) and quantization algorithm with error diffusion (EDA) are used for pattern quantization. The conclusions are as following. 1) With UQA, the maximum of phase error will less than 1% of 2 Pi when bit-depth is higher than 4 bits. If the projector is defocused, the error will be decreased. 2) With EDA, the maximum of phase error is larger than that with UQA. But the error will be decreased significantly when the projector is defocused. The phase error of pattern with EDA is smaller than that of pattern with UQA when the projector is nearly focused and the period of pattern is long (for example longer than 20 pixels). If the period of pattern is short, the performance of UQA is always better. 3) The error difference of UQA and EDA will be very small when the bit-depth is higher than 4 bits.