In order to solve the problem that the video depth and stereoscopic sense of the video obtained by the short baseline binocular endoscopic imaging system are weak in the naked eye 3D display device, by analyzing the parameters of the binocular endoscope and the parallax of the image pair in the stereoscopic video, a stereo video correction and parallax adjustment method based on the short baseline binocular endoscopic imaging system is proposed. Firstly, the camera of the binocular endoscope system is calibrated to obtain the camera parameters and the position parameters between cameras; Secondly, the camera video is corrected by using the obtained parameters, and then the image parallax is adjusted according to the parameter requirements of the naked eye 3D display device for the video source, so as to finally obtain the real-time display stereoscopic video of the binocular endoscope system which meets the requirements of the naked eye 3D stereoscopic display device and is suitable for human eyes. The feasibility of the method is verified by experiments. A short baseline binocular endoscope imaging system with a baseline distance of 8mm is actually built. The original parallax range is (0,64) pixels, which can reach (-30,30) after parallax adjustment. The two-way parallel video processing is 25 frames/s for real-time display. Matching with the naked eye 3D stereoscopic display system designed in the laboratory, real-time naked eye 3D imaging of medical endoscope with obvious stereoscopic feeling can be realized.

Fluorescent carbon quantum dots (CQDs) are a new type of photoluminescent nanomaterials. Due to their stable luminescent properties, abundant surface functional groups, safety, non-toxicity, good biocompatibility and low cost, they have great application prospects in the field of latent fingerprint detection and recognition. Latent fingerprints refer to the traces of human finger secretions left on the solid contact surfaces that are difficult to distinguish with the naked eyes, which require effective physical or chemical methods to effectively display and extract. So far, there are few reports on the development of latent fingerprints using CQDs and their precise identification in combination with computer technology. In this paper, red CQDs were successfully synthesized by one-step solvothermal method using o-phenylenediamine as the precursor and zinc oxalate as the modifier. The prepared red CQDs were mixed with polyvinylpyrrolidone, dried and ground to prepare red solid luminescent CQDs with uniform dispersion and quantum yield up to 27%, which were successfully applied to enhance the detection of latent fingerprints on various substrates. In order to accurately evaluate the similarity between the developed latent fingerprint and the target reference fingerprint, the structural similarity algorithm was used for similarity analysis. The matching degree of the latent fingerprint on the tin foil was as high as 90.5%, indicating that the combination of red solid fluorescent CQDs with digital processing programs can effectively develop and accurately identify latent fingerprints, which has great application prospect in the field of criminal investigation.

Nitrogen ions emit narrowband coherent emission under the pump of intense femtosecond laser pulses of different wavelengths (mid-infrared, near-infrared, or ultraviolet). The 428 and 423 nm radiation of the nitrogen ions obtained by excitation with 400 nm femtosecond laser pulses has received less attention and their properties are unknown. In this study, the polarization of the 428 nm emission and its dependence on the nitrogen gas pressure and the pump laser energy are systematically measured. It is found that the polarization of the 428 nm emission is the same as the linearly polarized pump pulses. Moreover, the radiation signal presents nonlinear dependence on the gas pressure and the pump pulse energy. Based on the modeling of the strong-field ionization and the coupling of different energy levels of nitrogen ions in presence of the laser field, the population distribution of the nitrogen ions is simulated numerically. It is revealed that population inversion between the relevant energy levels of the upper level state $ {\mathrm{B}}^{2}{\mathrm{\Sigma }}_{\mathrm{u}}^{+} $and the lower $ {\mathrm{X}}^{2}{\mathrm{\Sigma }}_{\mathrm{g}}^{+} $level can be robustly established for a relatively large range of pump laser intensity, which agrees with the experimental observation.

In order to meet the requirements of micro-electro-mechanical system (MEMS) two-dimensional laser scanning system for microscope objective with small entrance pupil diameter, large incident angle and large field of view, a near-infrared infinite conjugate microscope objective with an entrance pupil diameter of 1.1 mm and a large scanning angle of ± 18 ° is designed by using optical design software Zemax. The total length of the objective lens is less than 23 mm. The numerical aperture reaches 0.4 and the resolution is 1.26 μm. The working distance is 900 μm. The aberration correction is good.The designed microscope objective can meet the needs of use. The results show that the microscope objective can meet the requirements of MEMS two-dimensional galvanometer laser scanning system for portable skin detection instruments.

In order to analyze the mechanism of chiral signal enhancement of spherical particles, the Mie scattering characteristics of spherical particles are studied based on the T-matrix method, and the mechanism of chiral signal enhancement is analyzed based on the regulation of incident beam with orbital angular momentum (OAM) and particle’s characteristic parameters. The wave front of tightly focused linearly polarized light is regulated, the dichroism of OAM is measured by regulating the sign of OAM carried by the beam, and the relationship between the order of OAM and the intensity of the chiral signal is studied. When the order of the OAM carried by the beam is matched with the size of the sphere, the scattering circular dichroism signal can be enhanced by 22.8 times compared to that of circularly polarized light. The influence of particle size and chiral parameters on OAM dichroism signal is also analyzed.

An electromagnetic wave absorber is a device that can absorb and annihilate electromagnetic waves, which is widely used in various fields of military, science and technology, and people’s livelihood. Absorbers based on metamaterials have received considerable attention due to their potent ability to absorb electromagnetic waves, ultra-thin characteristics, and design flexibility. In this paper, we design a broadband metamaterial absorber based on metal-dielectric-metal (MDM) structure, and analyze the absorption principle and physical mechanism, and simulate the parameters of the structure. The results show that the metamaterial absorber has an absorption rate higher than 80% for incident light from 490-1790 nm, with an average absorption rate of up to 90% and an optimal operating angle of 30°. In addition, the polarization-dependent tuning can be performed by modifying the symmetry of the cell structure. The proposed broadband metamaterial absorber is well suited for solar photovoltaic, optical communication, filtering and sensing applications.

The XUV optical system composed of mirrors and gratings has the property of plane- symmetry. Combining the wave aberration theory of the Lu plane symmetric grating system and the root mean aquare aberration evaluation function, the multi-parameter objective function for optimizing the XUV optical system is obtained. In order to solve the objective function with multiple independent variables and a large value interval, a real-coded genetic algorithm based on decimal is developed in this paper, and it is used for the optimization of two XUV optical systems. The optimized value obtained is traced with the optical simulation software Shadow, and compared with the reference. The results show that the optical system optimized in this paper has a significant improvement in imaging quality, indicating that the wave aberration theory and the real-coded genetic algorithm in this paper are effective in optimizing the XUV optical system, which provides a new idea for the optimal design of such systems.

In order to further optimize the traditional reflective cup for uniform light, anti-glare and other aspects of the problem, a new reflective cup based on Zemax is designed. The simulation results for using the squamous reflective cup show that the maximum light intensity at the front 25 m of the reflective cup is 234 lx, and the light intensity at the center HV point is greater than 0.80 Emax. All indicators meet the requirements of the national standard GB 25991—2010 automotive headlamps with LED sources. The squamous reflective cup can also combine with the micro-lens array. While meeting national standards, the spot energy is more uniform. The central area of light intensity has been further reduced, and the spot edge transition is more smooth. The effect of preventing glare from high beam is better. The system can be widely used in automobile headlamp.

The relationship between the topological phase of matter and interactions of the system was confirmed for the Kekulé lattice. The impact of non-Hermitian effect on topological insulator was investigated. Two types of gain and loss configurations were designed to illustrate their effects on bulk energy spectra and edge energy spectra. It is found that the bandgap decreases with the increase of the gain and loss, and is eventually closed and forms a non-Hermiticity-induced Dirac point. Finally, the Dirac point splits into a pair of singular points. Distinguishing from traditional Kekulé lattice, intercellular coupling is differentiated into horizontal and vertical dimensions for independent control based on the same intracellular coupling. This approach verifies that the gapless edge mode is not only related to geometric boundary, but also regulated by the intercellular coupling of the system.

Surface-enhanced Raman scattering (SERS) has great application prospects in the fields of medical diagnosis, food safety, and environmental monitoring because of its sensitivity as high as single-molecule detection. Preparation of SERS substrates with high-density "hot spots" is the key to the practical applications. Nanoporous metals with bicontinuous structures have excellent SERS enhancement properties due to the coupling effect between neighboring nanostructures. Ag-Zn alloy precursors were prepared by sputtering method, and silver substrates with nanoporous structure were prepared by free dealloying process and electrochemical dealloying process. Through the modulation of dealloying parameters, SERS substrates with high enhancement factor were obtained. The detection limit of crystal violet reached 10-12mol/L, which could be used for ultrasensitive detection.

Fundus vascular images are commonly used in clinical practice for the diagnosis and monitoring of eye diseases. The morphology and structure of blood vessels could reflect the essential features of the disease. Therefore, the segmentation of fundus vascular images is of great medical significance for the diagnosis and prevention of eye diseases. Current mainstream artificial intelligence algorithms, due to convolution and pooling operation, often neglect the extracted features of the spatial information in the images, making it difficult to segment fine blood vessels and other details. This study conducted research based on the U-net model, combining a spatial attention module to refine the spatial features. It also proposed a low compensation structure to reduce the feature loss during the feature extraction process of network, thereby improving the segmentation accuracy. Experiments were conducted on the DRIVE open dataset, and the algorithm achieved a segmentation accuracy of 96.97% and an F1 value of 74.36%. The results demonstrate that the proposed network structure exhibits better segmentation performance and more accurate identification of fine blood vessels structures.

In order to reduce the nonlinear error of the heterodyne interferometer, a polarization-maintaining retroreflector is used in a plane mirror heterodyne interferometer instead of a corner prism due to its defects. According to the basic optical path diagram of the plane mirror heterodyne interferometer, based on the basic optical characteristics of the polarization beam splitter and the corner cube, the effects of the yaw angle, the pitch angle and the rolling angle of the three polarization beam splitters in the plane mirror heterodyne interferometer, and the spacing and angle between the two polarization beam splitters in the polarization-maintaining retroreflector, and the yaw angle and pitch angle of the corner prism on the interferometer were analyzed. The maximum installation error of each optical component in the heterodyne interferometer is deduced, and its machining precision is specified to ensure the performance of the heterodyne interferometer.