In a laser transmission system that uses an adaptive optical system, the polarization effect of optical thin films will cause the polarization chromatic aberration, decreasing the correction ability of the system. In this study, the polarization chromatic aberration analysis of the Cassegrain system is performed. First, we employ the Jones Matrix to describe the impact of the polarization aberration caused by optical thin films on the amplitude and phase. Then, the scalar wavefront is extracted from the Jones pupil using the singular value decomposition method, and is used to the wavefront detector and aberration analysis of a Hartmann wavefront detector. The wavefront fitting is performed using Zernike polynomials. Finally, we analyze the reduction of the correction ability of the adaptive optical system.

In order to suppress the nonlinear and nonstationary noise of a gyroscope, this paper proposes an improved de-noising method called EEMD-M based on ensemble empirical mode decomposition (EEMD). First, the information and noise dominated intrinsic mode function (IMF) components are obtained by EEMD threshold filtering. Then, EEMD is applied to the discarded IMF components in the first threshold filtering to extract the signal detail. The scaling index of each IMF component is defined by the detrended fluctuation analysis (DFA) method, and the useful components in the secondary decomposition are further extracted. Finally, the useful IMF components obtained after the two decompositions are reconstructed to obtain a de-noised signal. In order to verify the effectiveness of the proposed EEMD-M, the noise reduction experiments for the measured data are carried out. The results show that the proposed algorithm is superior to the empirical mode decomposition (EMD) de-noising method, DFA-EMD de-noising method, EEMD de-noising method, and wavelet analysis method. The mean square error of the measured data decreases by 82.9%, and the random drift is significantly suppressed, which verifies the feasibility and superiority of the proposed EEMD-M and improves the stability and reliability of the micro electromechanical system gyroscope in optical image processing.

In order to investigate the effect of signal light splitting ratio on the performance of coherent homodyne receiver, the effect of signal light splitting ratio of 90° spatial optical hybrid on the phase-locked performance of the receiver and the communication performance is modeled and analyzed. From our numerical simulation results, we know that the communication performance and detection sensitivity are improved with the signal light splitting ratio of Q branch kk=0.5. In the case of k>0.5, we can obtain an optimal value of k to minimize the residual phase error. Based on the above analysis, we design an adaptive adjustment system with signal light splitting ratio based on a half-wave plate using softare simulations, and its communication and phase-locked performances are analyzed at different splitting ratios. Those results show that under conditions of 1550 nm laser wavelength, 5 kHz linewidth and 10 Gbit/s communication rate, the phase-locked performance and detection sensitivity can be adjusted when k varies in the range of 0.1-0.6 by rotating half-wave plate. The detection sensitivity is improved by 2.56 dB with k=0.1, and for k=0.5, the frequency deviation lock range of the phase-locked branch is 133 MHz. What's more, the residual phase error is the smallest when k=0.6. Those results illustrate the system is feasible and also provide a reference for the application adjustment of the 90° hybrid with adaptive splitting ratio.

The error vector magnitude (EVM) and bit error rate (BER) performance of visible light communication (VLC) system will be deteriorated by the nonlinear characteristic of light emitting diode (LED). In this paper, the principle of optical orthogonal frequency division multiplexing (O-OFDM) VLC system based on nonlinear LED is introduced, and the BER expression of the system is derived. It is proposed to divide the LED nonlinear distortion into nonlinear distortion in the working area and clipping distortion outside the working area. For the clipping distortion, the subcarrier attenuation factor of the load information is calculated according to Bussgang theory, and then the clipping noise variance superimposed on the subcarrier is obtained. The nonlinear distortion in the working area is the equivalent to the driving signal plus the nonlinear distortion noise, and use the total average power of the nonlinear LED output deviates from the ideal linear signal minus direct current power as the noise variance. The influence of nonlinear distortion on constellation, EVM, and BER is analyzed by Monte Carlo simulation.

Mode division multiplexing technology can achieve the co-fiber-transmission technology of quantum signals and classical optical signals. A quantum key generation rate model with simultaneous nonlinear effects and mode coupling is constructed for a quantum mode division multiplexing simultaneous-transmission system. The relationship between the quantum key generation rate and the communication distance is studied by simulation calculations. Simulation results show that the maximum safe communication distance of the system is too short, and there is a big gap compared with the performance of traditional quantum key distribution systems. Accordingly, a quantum mode division multiplexing simultaneous-transmission scheme based on double decoy states is proposed to increase the maximum safe communication distance of multiplexing simultaneous transmissions. Moreover, to make full use of fiber channel resources, multiplex quantum signal multiplexing transmission is performed on an idle mode channel, which improved the communication performance of the quantum mode division multiplexing simultaneous-transmission system and narrowed the gap with the traditional quantum key distribution systems.

The limiting distance for illumination from a collimating illumination system with an extended source is determined by the divergence of the outgoing beam. Herein, the analytical expression for the surface of the plano-convex collimating lens based on Fermat's principle was obtained. The formula for calculating the divergence angle of the outgoing beam in such a system was derived according to the theory of imaging optics. Simulations and experimental validation were also conducted. Results reveal that the divergence angle of the outgoing beam from the collimating illumination system with an extended source is proportional to the source size, inversely proportional to the focal length of the collimating lens, and independent of the lens aperture. This conclusion provides a theoretical basis for compressing the divergence angle of the outgoing beam and extending the limiting distance for illumination from a collimating illumination system with an extended source. It has guiding significance for the selection of the light source and the design of the collimating lens in the development of searchlights.

Photoelectric scanning-based distributed metrology system is a large-size three-dimensional coordinate measuring system that is widely used in industrial manufacturing and assembly environments. However, the huge measurement network system and the complexity of the measurement environments increase the difficulty of networking orientation and changes in any node will require re-networking. The existing networking orientation method shows excessive dependence on manual operation and subjective estimation. Therefore, an automatic networking orientation method and calibration point planning strategy based on active mapping, global positioning, and automatic navigation are proposed. Experimental results show that the proposed method has improved the efficiency and automation level of networking and can realize the automatic maintenance of the measurement system and industrial automation.

Dual-frequency laser interferometers are widely used in the field of nanometer measurement. Particular usage context, reducing the errors in a measurement system and improving the measurement accuracy of the system becomes increasingly important. Accordingly, a method is proposed herein to use the vibration modal nodes in the measurement environment to reduce environmental vibrations and improve the measurement accuracy of a dual-frequency laser interferometer. First, the feasibility of the scheme is analyzed from a theoretical perspective, and the experimental measurement system is built based on this theory. Then, the node position in the measurement system is found by using an acceleration sensor. Finally, the measurement repeatability of the dual-frequency laser interferometer in the modal node position and other non-modal node positions are tested. Experimental results show that when there is an external vibration source, the measurement repeatability of the proposed method in the non-modal node position is ±9 nm, and that of the modal node position is ±4 nm. Thus, the measurement accuracy of the dual-frequency laser interferometer in the node position is 125% higher than that in the non-modal node position, which confirms the effectiveness of this method.

Sinusoidally structured light fields are widely used in three-dimensional (3D) measurements of precision optics, and their sinusoidality directly or indirectly affects the accuracy of the 3D measurement. Using geometric features such as the periodicity and symmetry of sinusoidal fringes, this study proposes the use of a single cycle of the standard sinusoidal computer-generated fringe as the coding object, coupled with a binary coding method of an S-path error diffusion. The entire sinusoidal light mask is obtained by periodically copying the coding unit, and it is then processed on the surface of the chrome-plated glass substrate using high-resolution photolithography technology. After the mask modulates the illumination form a light source, the high-frequency information that characterizes the binary coding feature is directly filtered by the optical projection system, whereas the low-frequency information that characterizes the sinusoidal fringe information is retained, thereby realizing a sinusoidally structured light field. Finally, the optical-transfer characteristics model of the optical system is established to explain its inherent low-pass filtering mechanism. Using computer simulation and experiments, results show that the proposed sinusoidally structured light field coding method and the manufacturing process are feasible.

We carry out a laser melting experiment of magnesium alloy by using a Nd∶YAG solid-state laser with rated power of 3 kW. The microstructure, phase, hardness and corrosion resistance of the sample are characterized by metallographic microscope, scanning electron microscopy, energy spectrometer, Vickers microhardness tester, and electrochemical workstation. The results show that when the laser power is 2 kW and the laser scanning speed of 40 mm/s, the surface of the sample has no cracks and severe depression. The surface structure is the melted zone is equiaxed crystals, and the internal structure is radioactive dendrites. With the increase of the laser scanning speed, the equiaxed crystal size of the surface layer decreases, and the radioactive dendrites in the melted zone gradually become non-radioactive dendrites. After laser melting, the heat-affected zone is organized into the grain boundary of the matrix, and the boundary between the heat-affected zone and the substrate is irregular. The energy spectrometer and line scanning results show that the surface elements in the melted zone are burnt, resulting in the peak hardness of the melted zone appearing in the near-surface. With the increase of the scanning speed, the peak hardness shows a downward trend, after laser melting, the corrosion resistance of the melting zone increases.

Aiming at the problem that the amplification of spontaneous emission (ASE) of high-power and large-diameter Nd∶YAG slab amplifiers a simplified three-dimensional ASE calculation model is proposed based on geometric optical ray tracing method, which corrects the diffuse reflection of the fluorescence side and the calculation error introduced by the temperature effect of the stimulated emission cross section. Through numerical simulation, the contribution weight of fluorescence reflection of each surface of large-diameter slab (size 150.2 mm×40.0 mm×2.5 mm) to the ASE effect is determined, and the gain of small signal under different pump powers are calculated. The effect of the ASE on the slab amplification performance is analyzed through the slab amplification. Experimental results and numerical calculations are compared, and the validity of the calculation model is verified.

Using the ABCD transmission matrix and Collins diffraction integral formula and by converting the relation between the beam and cavity coordinates, we derive an analytical expression for the cross-section distribution of a light field at different angles of incidence in the cavity of a fusion device after a flat-top Gaussian beam passes through a lens. This analysis focuses on the effect of angle of incidence of the beam on the light-intensity distribution at the focal point in the cavity. Simulation results show that as the angle of incidence of the beam increased, the light intensity of the spot at the focal point is affected in the X-axis direction, and the light spot diffused along the X-axis direction, but the light-intensity distribution in the Y-axis direction barely changed. As the transmission distance along the optical axis increased, the spot diameter in the cross section of the target cavity became larger, uniformity became worse, and spot position deviated to the right. Conclusively, the angle of incidence and distance of the beam transmission must be appropriately selected to obtain a light spot with good uniformity in the cavity.

In this study, the microstructure and mechanical properties of the laser cladding alloy coating on the surface of vermicular graphite cast iron are studied to overcome the technical bottleneck associated with the new dynamic vermicular graphite cast iron body materials that do not exhibit wear resistance. Laser cladding of nickel-based superalloy containing tungsten carbide (WC) reinforced phase on the surface of RuT300. Further, the microstructure and composition of the sample coating and the bonding zone are analyzed, the sample coating and substrate are subjected to the hardness test. The WC particles are unevenly distributed in the sample coating, and the uncompletely melted WC particles are considered to be non-uniform crystal nuclei. In addition, petal-like dendrites grow along the boundary of WC particles. The average hardness of the Ni-based WC composite coating is 4.52 times greater than that of the compacted graphite iron matrix. The distribution and solubility of the WC particles in this coating are non-uniform because the density of the WC particles is greater than that of the Ni-based powders and the heat dissipation in the molten pool is unbalanced. The presence of WC particles increases the hardness of the coating. In addition, the petal-like dendrites crystal provides a growth nucleus, which helps the particle phase in the coating to strongly combine with the Ni-based alloy solvent. Furthermore, the hardness and wear resistance of the coating are observed to improve.

In this work, supersonic plasma spraying technology and the laser remelting process are used to prepare the zirconia thermal insulating coating. The macroscopic morphology of the zirconia coating is characterized by optical microscope, scanning microscope, energy spectrometer, X-ray diffractometer, and hardness tester. The results show that the coating phase prepared by laser and plasma composite consists of metastable tetragonal crystal phase and cubic crystal phase. The cross-section of the coating is bowl-shaped, and the upper edge is uneven. The composite preparation process eliminates the layered structure, pores, and micro-cracks in the original supersonic plasma spray coating, improves the density of the coating, and the connection between the coating and the substrate becomes metallurgical after remelting. The matrix structure obtained after remelting gradually changes from strip-shaped crystal and needle-shaped crystal to fine needle-shaped crystal and perlite from top to bottom, and the structure of the heat-affected zone is equiaxed crystal. The average hardness of the remelted coating is about three times of the hardness of the original plasma coating.

The cylindrical rough structure was etched on the surface of 6061 aluminum alloy by microsecond laser with different power densities, and the etched rough aluminum alloy sheet was kept in a drying oven at 110 ℃ for 12 hours. The surface rough structures, and the changes of the wettability, surface element, group, and crystal structure before and after heat treatment were characterized by droplet shape analyzer, scanning electron microscope, optical profiler, and X-ray photoelectron spectroscopy. Experimental results show that the rough aluminum alloy surface etched by microsecond laser has a micro/nano composite structure, and the amount of hydroxyl (—OH) on the surface is reduced after heat treatment. The non-polar component (C—C(H)) is the main component of organics adsorbed on the aluminum alloy surface, and the heat treatment accelerates the adsorption process, which changes the wettability of the rough aluminum alloy surface from the superhydrophilic surface to the superhydrophobic surface.

In order to study the microstructure and mechanical properties of laser welded joint of 300M low alloy ultra-high strength steel, fiber laser is used to perform the self-fusion welding butt test of 300M steel. The weld morphology, microstructure change, and mechanical properties of welded joints are studied by means of tensile test and other analytical methods. The rapid solidification process of weld metal is discussed. The results show that the weld cross-section of the laser welded joint of the 300M low alloy ultra-high strength steel has a typical "Y" shape. The weld is mainly composed of columnar dendrites, and the weld structure is mainly composed of martensite and retained austenite. The heat effect near the weld is divided into a hardened zone and a softened zone. The hardness of the hardened zone is about 734 HV, the hardness of the softened zone is about 456 HV, the fracture location of the joint is the softened zone, and the tensile strength of the joint is 1269 MPa, which is about the 65% of the strength of host material.

Graphene membranes were prepared by laser ablation of polyimide membranes, and the graphene membrane with more oxygen-containing functional groups on surface was prepared by assisted oxygen plasma treatment. A scanning electron microscope was used to analyze the surface morphology of the membrane, and the prepared graphene had porous microstructures. The surface element content of graphene was analyzed by X-ray photoelectron spectroscopy. After oxygen plasma treatment, the oxygen content (atomic fraction) of graphene reached 15.6%. The contact angle measurement was used to characterize the underwater oleophobicity of graphene membranes. The contact angle of trichloromethane underwater was about 150°. This technology provides a feasible strategy for large-scale preparation of graphene membranes with the characteristic of underwater oleophobicity.

Increasing the volume of data poses huge challenges to information storage. Deoxyribonucleic acid (DNA) has the natural advantages of long life, good stability, low maintenance rate, and high storage capacity. Further, it is recognized as a potential natural information storage medium. Therefore, a new DNA information storage plan is proposed, where Raptor codes are used to convert the binary files into DNA base sequences and the structural characteristics of DNA are considered to introduce quaternary RS (Reed-Solomon) error correction code for ensuring the reliability of channel transmission. In addition, based on the guanine and cytosine base content, homopolymer screening schemes have been proposed to reduce the difficulty associated with DNA synthesis and sequencing as well as the error rate. Finally, files of different formats, such as text, images, and videos, are encoded into the DNA base sequences after they are passed through the storage framework, and biological experiments are conducted to synthesize DNA for achieving information storage. The experimental results show that the average coding efficiency of each basic of the DNA storage framework based on Raptor codes is 1.49 bit, and the DNA synthesized by biological experiments can recover files without errors and has a good information storage performance.

Through a theoretical analysis of fiber coupling conditions, an optical system of an beam-expanded optical fiber connector is designed and simulated in the hybrid mode of ZEMAX software. Quantitative analysis of the changes in beam quality and coupling efficiency caused by alignment errors of the collimator lens and focusing lens are performed. Simulation results show that the collimator lens and the focusing lens have eccentricity or tilt errors that are within the allowable range. The positions of the two lenses can be adjusted to compensate for aberrations and optical axis shifts to ensure that the beam quality and coupling efficiency meet standards. The simulation results are experimentally verified. Then, the allowable range of the alignment error of the optical fiber connector at different diameters is simulated and an alignment error compensation formula is derived. During the design and adjustment of the beam-expanded fiber optic connector, and derive the alignment error compensation formula. The alignment error causes by the misalignment of the collimator lens can be compensated by the focusing lens, which increases the design accuracy and simplifies the adjustment process. Finally, according to the results of the alignment error analysis, we design and manufacture a 12 kW@600 μm beam-expanded optical fiber connector.

Digital slit-lamp microscope is mainly used in the examination of ophthalmic diseases. The front objective lens is one of the important parts of the digital slit-lamp microscope, which affects the imaging quality of the entire system. Based on the parallel optical path principle of the stereo microscope, a high-performance front objective for a digital slit-lamp microscope is designed and optimized by using the Zemax software. Experimental results show that the maximum root mean squared radius of a spot diagram under low and high magnifications are 2.3 and 5.1 μm, respectively. At a spatial frequency of 115 lp/mm, the modulation transfer function (MTF) value of the full field of view under low magnification reaches 0.30, which is close to the diffraction limit and has a high resolution. Under high magnification, the MTF value is above 0.15, which meets the requirements of ophthalmology. Finally, further analysis the effect of eccentricity on the coma and astigmatism introduced by the system, providing a theoretical basis for machining and adjustment.

Based on electromagnetic theory and related research, a fitting formula for calculating the resonant frequency of the evanescent mode of a T-cavity terahertz parallel-plate waveguide is proposed. The resonant frequency of the evanescent mode under different parameters is studied using the fitting formula and COMSOL software. Experimental results show that the results obtained by the two methods are in good agreement, and the relative deviation does not exceed 0.3%. The fitting formula provides a fast and simple calculation method that can accurately obtain the resonance frequency of the evanescent mode.

An octagonal structure lithium niobate electro-optic deflector with quadrupole electrodes is designed in this paper. The electric field distribution characteristics of the octagonal structural deflector with quadrupole electrodes and ideal electrode structure are simulated and analyzed. The influences of structural parameters on the electric field distribution, field intensity gradient, and effective aperture ratio of the deflector are discussed. The selection method of structural parameters of the quadrupole electrodes octagonal deflector is proposed. Simulation results show that, under the same crystal and applied voltage, the electric field distribution of the octagonal structural deflector with quadrupole electrodes and ideal electrode structure are consistent in the paraxial region, and the field intensity error is less than 10%. According to the analysis results, an octagonal lithium niobate crystal electro-optic deflector is designed and developed. Experimental results show that the deflection sensitivity of the deflector is 0.312 μrad/V, which is consistent with the theoretical value of 0.340 μrad/V.

The holographic waveguide coupling element is a key optical component of the holographic waveguide imaging system. The beam is perpendicularly incident into the holographic waveguide plate and changes the beam propagation direction through the in-coupling element. A waveguide phenomenon is formed in the waveguide plate and transmitted to the out-coupling element. The direction of transmission is changed again from the holographic waveguide plate to the human eye through the coupling element. When both the in-coupling element and the out-coupling element are transmissive or reflective coupling elements, the angle values of changing the beam propagation direction twice are equal. Based on the imaging principle of holographic waveguide, combined with k-vector circle theory and holographic optical recording principle, a symmetric periodic structure of the holographic waveguide in-coupling element and the holographic waveguide out-coupling element is designed. The interference light intensity model of the holographic waveguide coupling element is simulated by MATLAB software. The change of the beam propagation angle caused by the coupling element of the holographic waveguide is simulated by using COMSOL software. The experimental results are consistent with the theoretical change of the beam propagation direction. It is proved that the two holographic waveguide coupling elements are arranged symmetrically in the holographic waveguide optical system, which can meet the requirements of the holographic waveguide optical system for the beam propagation direction.

A series of organic light-emitting diodes (OLEDs) were designed and fabricated to further enhance electroluminescence (EL) performances of the green phosphorescent emitter bis(2',6'-bis(trifluoromethyl)-2,3'-bipyridine) tetraphenylimidodiphosphinate. 4,4',4″-Tri(9-carbazoyl) triphenylamine (TcTa) and 9,9'-(2,6-pyridinediyldi-3,1-phenylene)bis-9H-Carbazole (26DczPPy) were selected as host materials of light-emitting layers (EMLs) 1 and 2, respectively, because of their well-matched energy levels and high carrier mobility. In addition, the design of double-EMLs device structure helps to broaden the recombination of holes and electrons by the analysis of devices performance. Finally, the green OLEDs with turn-on voltage of 3.1 V, maximum brightness of 12600 cd/m 2, current efficiency of 37.15 cd/A, maximum external quantum efficiency of 10.34%, and maximum power efficiency of 28.23 lm/W was obtained.

In InGaN/GaN multiple quantum well (MQW), the quantum-confined Stark effect (QCSE) induced by a strong piezoelectric polarization field decreases the electron-hole radiative recombination rate. We design and grow the MQW structure with an InGaN strained-layer to reduce the polarization field, and carry out the photoluminescence spectrum experiment with variable temperature and variable excitation intensity, the results indicate that the MQW internal quantum efficiency is increased by inserting an InGaN strained-layer.The analysis of the peak energy blue-shift shows that the strain-layer effectively weakens the QCSE and obviously increases the peak intensity of the corresponding electroluminescence spectrum. This verifies that the InGaN strained insertion layer has the effect of which is beneficial to improve the luminous efficiency of MQW and the performance of the device.

The optical parameters of anisotropic crystal, with optical axis parallel to surface is measured by employing a single-wavelength reflective ellipsometer and method of rotating the sample many times. The principle of measuring the optical parameters of anisotropic crystal by single-wavelength ellipsometer is analyzed, the simulated annealing simplex joint inversion algorithm is improved, the influence of the light incident angle, sample optical axis direction, rotation angle, and positioning error on the measurement results are numerically simulated and analyzed. Experimental results show that the measurement accuracy of the main refractive index, absorption coefficient, and optical axis azimuth angle of the crystal are 0.0001-0.0003, 0.000001-0.000400, 0.02°-0.40°, respectively, which indicates the method has high self-consistency and accuracy.

The current research investigates the characteristics of Airy beams generated with deformable mirrors (DM). After the Zernike polynomial was used to decompose their phases, a phase-tuning model consisting of linear combinations of multiple Zernike polynomials was established, and a coefficient was introduced for each polynomial in the combination. Then, the effects of different Zernike polynomial coefficients on the Airy beam structure and quality were simulated. The Airy beam generation experiment was conducted using a 69-unit deformable mirror, and the beam intensity distribution under different coefficient combinations was tested and analyzed. The beam characteristics of Airy beam can be controlled by the adjustment of Zernike polynomial coefficients.

In the sixth generation mobile communication network (6G), in order to solve the problem of smooth handover of quantum mobile terminals in overlapping regions of different cells, this paper proposes a soft handover strategy based on optimal entanglement degree. By establishing a calculation model of the optimal entanglement degree between the mobile terminal Alice and the current cell A, and the target cell B, the change trend of entanglement between Alice and different cells is in the process of motion is analyzed, and the cell corresponding to optimal entanglement degree is obtained. Through simulation, the characteristics of hard handover and soft handover are compared. The results show that as the distance between Alice and A-cell increases, the degree of entanglement between them decreases gradually. As Alice gradually approaches B-cell, the entanglement degree between Alice and cell B increases. If the B-cell is the optimal entangled cell, there will be a short link interruption during hard handover, and soft handover can achieve smooth handover between cells. It can be seen that in the 6G networking, the optimal entanglement soft handover strategy can effectively improve the communication connection rate during the handover process.

We propose a method of the combination of splicing and fusion based on the complex surface triangular mesh of karst caves. First, the two boundaries of the mesh to be spliced are found by traversing the spatial geometric relationship of the triangular mesh. Second, the constrained Delaunay triangular mesh method is used to connect different meshes and the B-spline interpolation is used to make the connection transition natural. Finally, the Laplacian principle is used for smoothing and eliminating the peaks to smoothen the edges. Experimental results show that the proposed method can achieve high-efficiency automation in the splicing and fusion of the triangular mesh of karst cave and can reduce human interventions. After the completion of splicing and fusion, the triangular mesh can be exported for the subsequent engineering design, which could be used as a reference for the development of engineering applications.

Photodynamic therapy (PDT) is a minimally invasive therapeutic modality that can selectively treat malignant and benign diseases by using a combination of photosensitizers, light, and oxygen molecules. The light source is one of the three key elements of PDT, and its emission wavelength, irradiation method, and dose directly determine the efficiency of PDT. According to the required performances of light sources for clinical treatment, the technical advantages of light-emitting diode (LED) as light source in PDT applications are discussed. The LED array light source, and the development of wearable and implantable novel PDT light sources based on the organic LED, quantum dot LED, and wireless powered LED are introduced in depth. The application status of LED in isolated cells, live animals, and clinical PDT is summarized comprehensively. The development of LEDs with tunable emission wavelengths and the real-time adjustment of the illumination area and dose are the future development trends of intelligent and personalized PDT light sources.

The research progress on graphene/graphene oxide (GO) based fiber sensors is briefly reviewed. Detection object, sensing mechanism, structural design, and sensitivity of various graphene/GO based fiber sensors are discussed. The graphene-based micro/nano fiber sensors, graphene-based photonic crystal fiber sensors, graphene-based fiber grating sensors, and GO based fiber sensors are briefly reviewed. The preparation process of graphene/GO-fiber composite waveguide is briefly described. The existing problems of graphene/GO based fiber sensors are summarized.

In this study, 96 surface soil samples are obtained from the typical oasis of the Ugan-Kuqa River in the Xinjiang Uyghur Autonomous Region and their spectral reflectance and soil organic carbon (SOC) content are evaluated. Using fractional order differential technique (with an order value range of 0-2 and a step size of 0.2) is combined with five machine learning algorithms, including the extreme learning machine, random forest, multiple adaptive regression spline function, elastic network regression, and gradient lifting regression tree (GBRT) algorithms, and high-precision estimation of SOC content. The experimental results show that the pretreatment effect obtained using a fractional order differential is better than that obtained using an integer order differential. The correlation at a specific band is significantly improved, and the maximum correlation is enhanced by approximately 0.220. In case of the GBRT, the verification concentration determination coefficient is 0.878 and the relative analysis error is 3.142, indicating that this type of integrated learning is superior to other models of different orders. GBRT based on a 1.6-order spectral reflectance should be used to estimate the SOC content of the oasis in arid areas. Thus, a new scheme based on the combination of visible light-near infrared(VIS-NIR)with the fractional order differential technology and machine learning algorithms is proposed in this study to improve the accuracy of the model used for estimating the SOC content of the oasis in arid areas.

Laser-induced breakdown spectroscopy (LIBS) technology and genetic algorithm optimization based error back propagation (GA-BP) neural network are used to classify and recognize 9 common plastics in this paper. Plasma spectra are generated by laser-induced breakdown of the plastic surfaces, and 100 sets of spectral data are collected for each plastic with a spectrometer. The national institute of standards and technology (NIST) atomic spectrum database is used as a reference to accurately calibrate the main element characteristic lines. In the experiment, 15 characteristic spectral lines are selected for analysis, and the dimension of spectral data is reduced by principle component analysis (PAC) method, and GA-BP neural network model is established. Experimental results show that the GA-BP neural network recognition efficiency is greatly improved after dimensionality reduction by PCA method, and the average recognition accuracy is 99.72%, which can identify a variety of plastics quickly and accurately.

Dense phase pulverized coal concentration is a key performance indicator for the operation of pulverized coal boiler. In this paper, terahertz time-domain spectroscopy is applied to the quantitative analysis of pulverized coal concentration. To improve the stability and accuracy of terahertz spectrum quantitative analysis of pulverized coal mixture with complex chemical components, genetic algorithm (GA) and partial least squares regression (PLS-R) are introduced into terahertz time-domain spectrum quantitative analysis of dense phase pulverized coal-high density polyethylene mixture. The optimal set of spectral variables is constructed by GA, and the quantitative analysis model of pulverized coal concentration is established by partial least squares. Experimental results show that the correlation coefficient and root mean square error of sample prediction set obtained by GA and PLS-R are 0.9568 and 1.0345, respectively. Compared with the quantitative analysis model established by traditional interval partial least squares methods (iPLS-R and biPLS-R), the model has higher accuracy and stability, which provides the basis for the application of terahertz time-domain spectrum in the quantitative analysis of dense phase pulverized coal concentration.

Aiming at the problem that it is difficult for micro-spectrometer to take into account both spectral resolution and spectral range, a design method of cascade Fabry-Perot interferometer and micro curved grating spectrometer is proposed in this paper. The matching conditions of the two spectrometers and the spectral characteristics of the cascade optical systems are analyzed, and a spectral data reconstruction algorithm is proposed. A laser Raman spectrometer is designed with ZEMAX software. The spectrometer has a size of 25 mm×6 mm×6 mm, a numerical aperture of 0.22, a Raman spectrum range of 150-3200 cm -1, and a spectral resolution of about 6 cm -1. The scanning process of the standard Raman spectrum signal is simulated, and the spectral signal is sampled with a 2.4 mm long linear array detector. The resolution of the reconstructed Raman spectrum is about 6.4 cm -1, and the deviation from the standard Raman spectrum is 0.4 cm -1. The feasibility of the design method and reconstruction algorithm are verified. At the same time, the spectrometer can be miniaturized and the cost can be reduced based on micro-electro-mechanical system technology, which can meet the application requirements of hand-held, portable spectral detection and industrial on-line spectral detection, and has high practical application value.

In order to achieve accurate classification of watercolor pen ink, 60 samples of watercolor pen ink from 15 series of 3 brands are tested by infrared spectroscopy in this work. First, after preprocessing such as smoothing and correction, root mean squared error is used to determine the optimal wavelet transform compression times, and the purpose of reducing the complexity of the operation is achieved after compression. Then, H?lder exponent is used to extract 30 characteristic waves of 3 brand samples, which are imported into the input layer of artificial neural network as input variables. The training set, validation set, and test set are assigned to train the model, and the final classification accuracy of the model is 83.3%. Finally, receiver operating characteristic (ROC) curve is drawn, and it is found that the classification accuracy of the second kind of samples is higher than that of the other two types of samples, which realize the pattern recognition of watercolor pen ink types.

Diabetes is increasingly threatening human health. However, noninvasive blood glucose detection methods for clinical use have not yet been developed. To solve this crucial problem, we study the spectral characteristics of light source through different mass concentrations of glucose in a solution. The wavelength range is 600-1300 nm, and the absorption spectral characteristics of glucose solutions with different mass concentrations and the reflection spectral characteristics of 2% Intralipid tissue phantoms with different glucose mass concentrations are studied. The spectral characteristics are evaluated based on their monotonicity, linearity and sensitivity. Experimental results show that light waves are absorbed in the range of 1140-1210 and 1130-1200 nm and those reflected in the range of 1010-1130 and 1150-1300 nm exhibited monotonicity, excellent linearity, and high sensitivity. Thus, light waves with these characteristics are expected to realize noninvasive blood glucose detection and also to improve accuracy and sensitivity, thereby promoting the application of optical noninvasive methods in clinical blood glucose detection.

To improve the anti-friction and anti-scratch ability of the mobile phone display screen and reduce the risk of display screen breakage, a hard antireflection film in visible light band has been prepared in this paper. By gradually increasing the proportion of the thickness of the SixNy film in the total thickness, the deposition process is optimized and the film hardness is improved. According to the design theory of antireflection coating, reasonable film grouping mode and reverse inversion analysis method, the film system design is completed, and the reflectivity of the film is reduced. Testing results show that the average reflectivity of the film is 0.58% and the hardness is 15.99 GPa.

A visual comfort evaluation method of video display terminal (VDT) based on pupil diameter was proposed. An eye movement experiment was conducted in three kinds of lighting and five kinds of video display terminal luminance, in which the pupil diameter data of the subjects were collected, and the subjective ratings were also given for visual comfort under each condition. Statistical analysis was used to systematically study the corresponding relationship between pupil diameter change and visual comfort from three aspects, including gender, eyes habit, and whether glasses-worn or not. Experimental results showed that, compared with the pupil diameter under the condition of visual comfort, the relative variation of pupil diameter is from 17.61% to 24.55% when the visual discomfort is caused by the dark light environment, the relative variation of pupil diameter is from -6.12% to -12.45% when the visual discomfort was caused by the bright light environment. But the relative variation of pupil diameter is from -2.14% to 2.14% when the subjects were in a state of visual comfort. This work is of great significance for the establishment of VDT visual health assessment standards and the design of healthy light environment.

For the Cellular Yule-Nielsen Spectral Neugebauer (CYNSN) model, the inverse nonlinear Gauss-Seidel iterative algorithm is studied. It is proposed to use the XYZ method of multi-illuminant dimensionality reduction to achieve the accelerated inverse CYNSN model, and use 3-ink and 4-ink printer data to test. It was found that for the 3-ink combination, the XYZ dimension reduction using one light source (D50), and the 4-ink combination, the reverse CYNSN model of XYZ dimension reduction under two light sources (D50, A), not only in accuracy (more chromatic aberration under the light source), and have advantages in calculation speed.