In the volume holographic storage, improving the holographic diffraction performance from the perspective of optimizing the preparation process of holographic grating is simpler and more efficient than introducing new components to improve the storage material, and has certain applicability. Polymethyl methacrylate (PQ/PMMA) photopolymer doped with phenanthioquinone was prepared by thermoinduced polymerization. The diffraction properties and volume shrinkage of PQ/PMMA in off-axis holographic storage system were studied under different material thickness, light intensity and interference angle. The experimental results show that the thickness of the material is linearly related to the diffraction properties, and the best light intensity increases with the thickness. The maximum spatial frequency that PQ/PMMA is about 1285 lp/mm. The volume shrinkage law of holographic grating calculated by Bragg curve migration shows that the thickness and light intensity are negatively correlated with the shrinkage, but positively correlated with the spatial frequency. This study is of great significance for the application of PQ/PMMA in off-axis holographic data storage.

Based on the silicon on insulator platform, a silicon-based cross hybrid used for optical interference computation is designed and produced. Utilizing the structure parameter of the multimode interference coupling and the entire device of the finite-difference time-domain method, the simulation results indicated the ports of the output have a good transmission rate. After preparing the chip using the lithography process and packaging, the performance of the hybrid was characterized by an external voltage. The test results showed that at the working wavelength of1551.8 nm, after the voltage was applied, the output light power and voltage were in a sinusoidal style, verifying the phenomenon of constructive interference and destructive interference. The voltage that caused the π phase change of the two output ports was 2 V, and the voltage regulation π phase deviation accuracy was 0.991π and 1.007π respectively. The calculated phase deviation was 0.79°. The device size is 435 μm×80 μm. This device has a simple structure, low cost, and stable performance, which has broad application prospects in the field of interference imaging.

The symptoms of brain fatigue are reflected in a decline in cognitive function, which is mainly regulated by the prefrontal cortex (PFC). Functional near-infrared spectroscopy(fNIRS) can measure the changes in cerebral blood oxygen concentration over a period of time, thereby indirectly reflecting the degree of activation of the cerebral cortex. Therefore, a wearable fNIRS headband with 10 channels that can cover the prefrontal area is designed, and the headband is used to detect the subject's brain to observe whether the subject enters the fatigue state.The headband uses 780 nm and 850 nm laser diodes and silicon photodiodes as light source and photodetector. The light source uses frequency division multiplexing modulation method to distinguish two different wavelengths and to shield the interference of ambient light, and also time division multiplexing to drive the light source to obtain higher detection efficiency. After the fNIRS headband was made, it was applied to the interval cognitive test. The results showed that there were interval changes in the concentration of oxygenated hemoglobin （HbO）and hemoglobin （Hb）, which confirmed the feasibility of the fNIRS headband.Subjects were then recruited to participate in a simulated driving experiment, and cognitive ability was measured before and after the simulation. The results of fNIRS imaging showed a decrease in the concentration of HbO in the dorolateral prefrontal cortex (DLPFC) in the late stage of the experiment.Cognitive tasks showed a decline in cognitive ability, indicating that the subjects' brain began to fatigue in the late stage of the experiment, thus verifying the feasibility of fNIRS headband in detecting fatigue.

Lead halide perovskite nanocrystals have been gradually applied in the field of photovoltaic and light-emitting devices. However, the thermal quenching effect hinders the conversion process of materials to light-emitting devices such as LEDs. In this paper, a method for synthesizing CsPbBr3 nanocrystals using in-situ passivation of organic fluoride at room temperature is proposed, which effectively passivates surface defects and enhances the thermal stability of luminescence. Photoluminescence tests showed that the room temperature fluorescence emission intensity of in situ passivated CsPbBr3 nanocrystals was approximately doubled compared to pristine samples; When the ambient temperature rises to 100 °C, the passivated sample can still maintain more than 70% of the photoluminescence intensity. After restoring normal temperature, the passivated sample still maintains a stable photoluminescence peak wavelength and intensity for a long time. The test results show that the preparation method proposed in this paper can effectively suppress the thermal quenching of CsPbBr3 nanocrystals, which is conducive to its application in electroluminescence and down conversion LEDs.

In order to improve the brightness of the white LED light source and reduce the impact of the sudden drop in LED efficiency, the blue ray LD can be used to excite pc-WLED. Then, we studied the relationship between fluorescent ceramic sheets and reflective substrates, and the performance of different-doping fluorescent ceramic sheets. The fluorescent ceramic sheets were packaged. The performance was compared. Finally, different doping fluorescent ceramic sheets were assembled into the RC laser module for comparison. The results show that GaN blue LED chip is a very ideal reflection substrate, and the most suitable fluorescent ceramic for lighting is 4xAl2O3+(Ce0.01Y0.93Gd0.06)3Al5O12, because of its high alumina content and good thermal conductivity. The fluorescent ceramic can not only further improve the brightness of white LED light source, but also reduce the impact of LED efficiency drop.

In this paper, the optical rotation control of pyrolytic graphite disk suspend above a rectangular permanent magnet array is investigated. Using MATLAB to simulate the magnetic field distribution of the permanent magnet array at a levitation height of 1 mm, and the variation of torque of pyrolytic graphite disk with rotation angle of laser irradiation point, different distances along the radius and laser power. Using a laser with a wavelength of 808 nm to irradiate pyrolytic graphite disk, it was observed that when the laser was irradiated on the boundaries of x = 0, y = 0, y = x, and y= -x, the pyrolytic graphite disk was stationary. The pyrolytic graphite disk rotated clockwise or counterclockwise when the laser irradiated the regions Ⅰ, Ⅲ, Ⅴ, Ⅶ or Ⅱ, Ⅳ, Ⅵ, Ⅷ. As the laser irradiation point moved outward along the radius, the rotational speed of the pyrolytic graphite disk increased first, and then decreased. The rotational speed of pyrolytic graphite disk increased with the laser power. The experimental results and the calculated torque are consistent. The light driving law of a circular pyrolytic graphite sheet suspended above a rectangular permanent magnet array is obtained.

With the rapid development of information technology, the production capacity and yield of high-end chips are continuously expanded, to meet the growing demands for electronics in the present and future. During the extreme ultraviolet (EUV) lithography processes to produce these high-end chips, nanoscale particles falling on the EUV mask will lead to imaging defects during exposure, reducing the production yield and eventually increasing the costs of chip manufacturing significantly. Therefore, the EUV pellicle, a physical barrier effectively blocking particles of any size entering the focal plane of imaging, can be installed on the EUV mask, to greatly improve the yield of chip manufacturing. A detailed introduction of EUV pellicles is provided in this review, including material selection, structural design, preparation processes, and film characterizations. This review provides insightful references for the scholars and engineers engaged in the domestic research on advanced lithography and self-supporting thin-film devices.

The detection of ion concentration is of great significance in the fields of human health and environmental science. Compared with other ion detection methods, surface plasmon resonance (SPR) technology has the advantages of label-free detection, high sensitivity, and low detection limits, which brings new possibilities to the field of heavy metal ion monitoring. This article reviews the application and technical advances of SPR sensing technology in heavy metal ion detection. Firstly, this paper introduces the technical principles of SPR sensing. Then the paper focuses on the selection of sensing materials and surface modification, it emphasizes improvements in indicators such as sensitivity, linear dynamic range, specially for harmful heavy metal ions such as Pb2+ and Hg2+. Finally, the significant progress in terms of detection speed, sensitivity, etc. is introduced, and the development prospects of SPR technology is discussed.

In response to the challenges of eliminating the system noises from different viewing directions in a scanning ocular wavefront measurement system, this paper proposes a method to accurately locate the centroids of the spot array of Shack-Hartmann wavefront sensor and reconstruct the wavefront under high noise conditions. At first, the spot array images were globally processed using median filtering and mathematical morphology methods. Secondly, an improved maximum inter-class variance method was employed to determine the threshold for each sub-aperture. The Suzuki contour tracing algorithm was then utilized to identify the spot windows within which the centroids were computed. Finally, the proposed method combining the median area method precisely determined the centroid of the spots. A comparative analysis revealed that traditional methods failed to discriminate real spots under such high-noise conditions, whereas the proposed method could correctly identify them. The wavefront reconstruction errors, evaluated with PV and RMS values were less than 0.015λ and 0.001λ respectively, indicating that the accuracy and stability of the proposed method significantly outperformed traditional approaches.

As the fundamental units of matter distribution in three-dimensional space, particles hold significant research value in the fields of medicine, environmental monitoring, combustion analysis, and aerospace research. However, detecting particles in scattering media often faces challenges such as low resolution and difficulties in localization. This study introduces a novel detection method based on autofocus compressed holography, which integrates compressed sensing and autofocus techniques to significantly enhance the axial resolution of reconstruction and the accuracy of particle detection. Through simulation and experimental validation, this method had demonstrated an axial resolution error of less than 3 μm, ensuring excellent detection precision. Experimental results further confirmed that, compared to traditional angular spectrum methods, this technology offered distinct advantages in observing the three-dimensional distribution of particles in scattering media and in assessing particle diameters. The research outcomes provide an innovative technical approach for scientific research and practical applications in the related fields.