Three error estimation criteria for solving nonlinear transmission equation of multimode fiber— max, sum and ave criterion are proposed. The multimode error vector is converted to the error scalar, and the adaptive step size uniform change of multi-mode is realized based on the local error method of symmetric split-step Fourier. By simulating the transmission of Gaussian pulse in the graded-index multimode fiber, the performance of local error and global error of the fixed-step and variable-step method in different criteria are verified. The experimental results show that all the variable step size algorithms of the three criteria are convergent, besides, using the sum criterion calculate local error to control step size change can obtain higher numerical precision under the same calculation amount, and in the case of the same global error, the calculation amount is relatively less. The study is of significance for further improving the computational efficiency of multimode nonlinear transmission equations.

In order to address the wavelength demodulation of the overlapped spectra for the fiber Bragg grating sensor networks with limited source bandwidth, a wavelength demodulation method based on peak match estimation of distribution algorithm is proposed. The proposed method transforms the wavelength demodulation problem into a function optimization problem, where the optimization model is constructed through minimizing the difference between the theoretical spectra and the overlapped spectra. The peak match estimation of distribution algorithm is applied to solve the optimization model and obtain the sensing data for each fiber Bragg grating. Estimation of distribution algorithmutilizes the Gaussian mixture model to build probability distribution of the solution space for fiber Bragg grating sensor network, and the probability model can generate new individuals in the evolution of estimation of distribution algorithm. The peak match operator is introduced into the estimation of distribution algorithm to avoid the mismatch of the peak values of fiber Bragg gratings and obtain the final optimal solution. The experiments are conducted under different numbers of fiber Bragg grating sensor network using the proposed method. The experimental results demonstrate that the proposed method yields the mean errors within 10 pm for the large scale fiber Bragg grating sensor network even when the spectra of fiber Bragg gratings are completely overlapped. Compared with other demodulation methods, accuracy of the proposed method is higher, and it can well solve the wavelength demodulation problem when the spectra of fiber Bragg gratings within the network are partially or completely overlapped. The proposed method provides a new way to improve the multiplexing capability of fiber Bragg grating sensor networks.

A random sampling mean-shift clustering algorithm based on frame difference light flow was proposed. Firstly, the moving target region was extracted by frame difference method, and the moving region was calculated by optical flow, and the moving target was accurately extracted by adaptive optical flow threshold segmentation method. Then, the connected region labeling algorithm was used to preliminarily divide the moving region, and several connected domain subset eigenvector sample points were obtained. The sampling times of sample points in the subset space were determined by the random sampling strategy proposed. At last, mean shift algorithm was used to carry out several sampling calculations of sample points in each subset, and analyzed whether the clustering convergence results were the same. This strategy improves the detection speed and accuracy of the target by reducing the sampling times of all sample points of the marked results. Experimental results in different infrared test scenarios show that, compared with the traditional infrared multi-target detection algorithm, the method in this paper has good local anti-blocking, accuracy and real-time performance, and the detection rate can reach 95.27%, and the processing time per frame reaches 39.12 ms, which meets the real-time processing needs.

In the phase retrieval process of partially coherent illumination for the transport of intensity equation method, since the CCD acquisition frequency is not synchronized with the LED emission frequency, which case the black and white stripes appearing in the phase retrieval result, as well as the phase result error caused by the acquisition angle deviation due to the mechanical movement and other issues, a registration progressive compensation algorithm is proposed. Firstly, the corner detection and cross-correlation matching are performed on the three intensity images with a certain angular deviation, and the error point pairs are removed to get the transformation matrix in order to correct the original deviation. At the same time, since the slow dynamic change of the illumination light wave is related to its low frequency component, initial compensation is performed in the new registration image to improve the illumination stroboscopic effect. Then, the initial phase of the sample is solved by using Transport of Intensity Equation. In order to resolve the halo that occurs at the initial phase edge, the phase is compensated for the highlighting of the vital sample information again. The real optical path system is built for experimental verification in this paper, and the results show that the proposed method improves the stroboscopic effect while correcting the angle deviation. In the experiment of microlens array, the relative error between the restored result and the actual result is 1.7%, which fully proves the correctness and effectiveness of the proposed algorithm.

Aiming at the fusion problem of long-exposure image and short-exposure image under low-light condition, a patchmatch-based method is proposed to fuse low-light image pair into a better one. Firstly, a bi-directional ghost detection scheme based on pyramid multi-scale algorithm is proposed, which reduces the influence of noise and under-exposure on ghost detection, and is used to accurately detect the inconsistent region caused by the motion of the object between the image pairs.Then, the patchmatch algorithm is used to reconstruct the ghost region. And finally the Poisson fusion algorithm of improved edge characteristics is used to extract the information from the two exposures. Experimental results show that the proposed method effectively preserves sharp outlines of the short-exposed image, and maintains the color, brightness and details of the long-exposed image.

Aiming at the high data bandwidth problem in the virtual reality applications, this paper presents a data transmission method for the OLED-on-silicon microdisplay with the human eye visual perception characteristic. With the study on the human visual system, the foveation filtering algorithm of the texture pyramid is used to simulate the dynamic gaze effect of the human eye. The multi-resolution image fusions with the multi-level texture pyramids for the output image are realized. The hardware modules are designed using Verilog HDL language under the FPGA platform, including the video signal decoding and the 1 600×1 600 color OLED-on-silicon microdisplay driving. The experimental results show the multi-resolution image fusion compression algorithm based on the visual perception of human eye has a good data compression ratio. It can effectively decrease the transmission bandwidth for the OLED-on-silicon microdisplay. The proposed method meets the visual perception of the human eye. It has good rendering quality, which meets the real-time rendering requirements of the OLED-on-silicon microdisplay in the virtual reality embedded environment.

The scanning exposure patterns by Digital Micro-mirror Device(DMD) array in some directions have a saw-tooth edge of one pixel, to solve this problem a free surface optical lens is designed and installed at 1 mm distance of DMD window glass. The imaging of the microscopy array has a linear dislocation which caused by free surface optical lens. When the original line width and photolithography efficiency are invariable, the edges of the exposure pattern are smoothed. The linear dislocation form is analyzed theoretically. Based on the mapping principle, the initial data of the free surface is calculated by Matlab. The model of the ideal lens shape is constructed and optimized by Zemax. And the exposure effect with and without the lens is simulated. The results show that within the tolerance range of 2 μm, the dash saw-tooth edge of the exposure pattern is reduced from 0.14 pixel to 0~0.01 pixel, the slash edge of the saw-tooth is reduced from 0.338 to 0.110~0.125 pixel, and the change of the line length and width range respectively from －0.153 to 0.05 pixel, and from －0.058 to 0.153 pixel, when the energy decreases to 0.9 times of the original after installing the lens. The deformation range of the pixels and scribe line meets the manufacture precision of PCB which is about 10~30 μm. The proposed method has the advantage of reducing exposure energy demand and light source cost.

The method for suppressing OH fluorescence images background must be researched to improve the accuracy of image processing and velocity calculation in the complex combustion Hydroxyl Tagging Velocimetry(HTV) measurement. Firstly, the background interference in the complex combustion is analyzed and identified, and the noised signal simulation model is constructed. Secondly, an adaptive difference method combined with adaptive spatial filtering is proposed for background suppression image preprocessing, based on the characteristic of residual background and OH tagging line signal. Interference in the intensive combustion reaction area is eliminated through the adaptive difference method which is utilized by inducing spatial transformation. The background interference elimination results background is optimized through adaptive spatial filtering difference method by exploiting the spatial distribution difference between the signal and the residual background. Finally, simulation and experiments are carried out to test the effectiveness of this method. Results show that, with this image preprocessing method, the signal to noise ratio is raised by 11.83 dB, the peak signal to noise ratio is elevated by 8.66 dB, while the velocimetry calculation error is improved to 1.2% demonstrating that this method meets the accuracy requirements of HTV measurements and is ready for practical application.

In order to solve the calibration problem in augmented reality system, a novel optical transmission head up display system calibration method was proposed. First, the different coordinate systems are defined by analyzing the relationship among the components in system. Because of the distortion of camera and optical display system, virtual image distortion will be brought to some error. Therefore, the distortion of the camera and the optical display part is taken into account and corrected simultaneously when building the model. Finally, the non-linear regression estimation method is used to solve the model and calculate the calibration parameters. This calibration method, which combines optical display image distortion and camera imaging distortion correction, improves the calibration accuracy of optical transmission head up display system. The experimental results show that the average relative error of the calibration algorithm is less than 0.42% which basically satisfied the requirements of the system for calibration accuracy.

The problem of optical distortion caused by the contamination of the toothed gear profile surface was studied which affects the accuracy of measurement on the toothed gear profile deviation and the pitch deviation. Iterative Approximation-Proximity Discrimination algorithm(IAPD) using visual measurement is proposed to determine the image edge distortion of the toothed gear profile. The algorithm constructs the mapping relationship between the normal pixel offset in the edge transition zone of the involute profile image and the polar diameter of the pixel. This mapping converts the complex two-dimensional image edge signal into a one-dimensional signal, which is easier to process. The wavelet denoising algorithm was used to process the signal to extract the distortion features of the toothed gear profile edge, and the variable threshold iterative fitting algorithm was used to separate the toothed gear profile tilt deviation. According to the reasonable range of the normal toothed gear profile error, K-proximity classification method is adopted. The starting and ending position of the edge distortion of the toothed gear profile image is determined, and the positioning basis is provided for correcting the edge distortion of the toothed gear profile image during the measurement of the pitch and the toothed gear profile deviation. In order to verify the reliability of the IAPD algorithm, according to the similarity of the real edges of adjacent ipsilateral tooth profiles, the sub-pixel edges are extracted from the distortion tooth profile and the distortion-free tooth profile image, and similarity comparison is performed to realize the profile edge similarity comparison algorithm of distortion region recognition. The algorithm is used to verify the distortion region discrimination accuracy of the IAPD algorithm. The experimental results show that the toothed gear profile image edge distortion detecting algorithm can identify the image distortion region with good accuracy. The accuracy of radial range of the distortion region can reach 2.5 pixels(50 μm), which can meet the requirement of the image edge distortion correction. In addition, the algorithm is easy to understand and highly effective, which is easy to deploy and can meet the requirements of real-time calculation during gear measurement.

In order to accurately and quickly detect and predict the concentration of methane gas, a methane concentration detection system based on infrared differential absorption method was designed. The detection system adopted a double-chamber structure to reduce the influence of system component instability, and the input and output interfaces of the gas chamber were connected to the transmission fiber through a graded-index lens to reduce the loss of light intensity. The average error of the detection system is 0.007 5. An error back propagation neural network algorithm based on particle swarm optimization was used to construct a prediction model with methane gas in the range of 0.2%~2.0%. In the process of sample training, the accuracy of the prediction model reaches 10－4, the correlation coefficient between the actual output value and the expected linear regression is 0.998 8, and the maximum relative standard deviation is 0.248%. The experimental results show that the prediction performance of particle swarm optimization error back propagation neural network is better than that of error back propagation neural network prediction model in methane concentration prediction.

Due to the gamma nonlinear effects of the projectors and cameras, the Direct Current(DC) component of the deformed fringe pattern and the intensity distribution of background image are not equal, so measurement errors are introduced. This paper introduces a background image correction method in the traditional 2+1 phase-shifting algorithm. The intensity distribution of the captured background image is used as a template, and the DC component of the deformed fringe pattern is approximated by the least squares principle, which can effectively improve the measurement accuracy. And the phase shift of the 2 phase-shifting sinusoidal gratings is no longer fixed to be π/2 in the new 2+1 phase-shifting algorithm, the algorithm is more flexible. The experimental results verify the effectiveness and practicability of the algorithm.

N and S co-doped carbon dots with bright blue emission have been synthesized by a facile one-pot hydrothermal treatment. A specific compound, guanidine thiocyanate via a hydrogen bond to form the molecule unit, was chosen as the dopant. In the structure characterization, N and S elements could be sufficiently doped by means of the heteroatom or the functional groups bonded on the surface of carbon dots. The results of the photoluminescence spectra indicated a change of emission process from excitation-independent to excitation-dependent with the optimal excitation wavelength at 395 nm, suggesting that some small fluorophore molecules exist in citric acid-derived carbon dots solution and bond on the surface of the carbon dots after carbonization in view of the triexponential feature of fluorescence lifetimes of carbon dots. Now that so many fluorophores attach on the carbon dots surface, the as-prepared carbon dots were used as a sensing probe for the detection of silver ion. As expected, the changes of fluorescence intensities were linearly proportional to the different concentration ranges of silver ion. The －S－C≡N group could accelerate the quenching of carbon dots towards silver ion. The facile preparation method and high performace of as-prepared carbon dots provide a possible approach for efficient detection of silver ion for the application in industrial pollutants.

The effects of Fe3+ or Fe2+ ions on the interaction of CS-Fe3O4@ZnS∶Mn/ZnS Magnetic-Fluorescent Nanoparticles(MFNPs) with Bovine Serum Albumin(BSA) have been studied using UV-visible and fluorescence spectroscopy. It was found that both the fluorescence intensity of CS-Fe3O4@ZnS∶Mn/ZnS MFNPs and BSA became weakened when Fe3+ or Fe2+ concentrations reached their physiological levels. Meanwhile, the interaction of CS-Fe3O4@ZnS∶Mn/ZnS MFNPs with BSA in the presence of Fe3+ or Fe2+ enhanced. There is synergic effect of CS-Fe3O4@ZnS∶Mn/ZnS MFNPs and Fe3+ or Fe2+ on the damage of BSA. These results are important for understanding the influence of different biological environments on interaction between MFNPs and proteins.

Diamond Like Carbon(DLC) films were deposited on glass substrates by magnetron sputtering using graphite as the target. The morphology of the films under different nitrogen flow conditions was characterized by atomic force microscopy. Microstructure, valence state of elements and transmittance of the samples were analyzed by Raman spectrometer, X-ray photoelectron spectrometer and spectrophotometer. Results showed that all the deposited films were amorphous. The optical transmittance of the film greatly increased when 2 sccm nitrogen was put in, and the nitrogen content, sp3 bond percentage and ID/IG in DLC film was 5.88%, 64.65% and 1.81, respectively. The optical transmittance of N-doped DLC films in the visible range is about 95.69%. As the nitrogen gas flow rate increased, the optical transmittance of the films decreased. After annealing for 2 h, the optical transmittance of diamond like carbon films with no nitrogen content decreased slightly, while the optical transmittance of diamond like carbon films doped with nitrogen showed little change.

A silicon-based silica optical waveguide phased array chip was designed and fabricated. The chip consisted of three parts, including a beam splitting unit, a phase modulation unit and an output waveguide array. The splitting unit was cascaded by three 1×2 optical beam splitters. The phase modulation unit adopted the method of thermo-optic modulation, and the output part comprised 8 dense array waveguides. Light output from 8 waveguides formed interference in the far field, becoming scanning beam. Passing through the thermal photo-effect of the silica after power-on,when the refractive index changed by 0.027%(0.000 4), the scanning beam changed by 5.5°. The waveguide phased array adopted 2.0% ultra-high refractive index difference silicon-based silica waveguide as material, which was fabricated by material growth and annealing by plasma enhanced chemical vapor deposition and then etched by inductive coupled plasma dry etching technology, and finally cut and polished. The test results show that the static output of the eight output array waveguides forms a clear interference spot. When voltage is up to 130 V, the scanning beam angle changes by 5.5 °.

The finite-time difference method is used to simulate the influence of the concave and convex defects on the edge of the antenna on the response characteristics and electric field distribution of the strip antenna on the silicon substrate. The calculation results show that both types of defects change the electric field direction and electric field strength near the defect. The convex defect can enhance the electric field in the vicinity, while the concave defect is opposite, and the closer to the end of the antenna, the stronger the effect of defects. Defects of different positions and sizes have different effects on the area of the electric field enhancement. When the concave-defect is located at the end of the antenna, as the size increases, the area where the electric field strength is increased by 2 times monotonously decreases, and the area where the electric field is enhanced by 4 times monotonously increases. When the defect is 20 nm, the area where the electric field strength is increased by 2 times is reduced by about 3%, and the area where the electric field is enhanced by 4 times is increased by about 4%. Different from the concave defect, the convex defect has no simple monotonicity, and the defect position is different, and the influence is also different. However, controlling defects within 10 nm can significantly reduce the impact. This result provides a theoretical basis for the accuracy requirements of optical antenna processing.

A resonant method is proposed to measure the optical-pulse-propagation delay of the Fabry-Perot filter. The Fabry-Perot filter is placed in a resonant cavity, so its transmission delay is converted to the decrease of the resonant fundamental frequency, according to the relationship between the cavity length and the resonant frequency. The change in the fundamental frequency of the resonance is measured to be 0.167 MHz, which corresponds to a change in the length of the resonant cavity of 3.570 m. Subtracting the package length, the transmission delay is 1.542 m. No other parameters are needed in the scheme, such as the reflection coefficient of specular surface, the fineness and so on, it is easy to get noticeable propagation delay of high-finesse Fabry-Perot filters, even a minor-sized one. A transmission delay of 1.581 m is obtained by spectral analysis, which is a verification to the above experimental results.

A novel charge generation unit comprising of CsN3: Bphen/Al/HAT-CN was employed to fabricate an efficient tandem white organic light-emitting device. In normal direction, the maximum efficiencies are 45.4 cd/A and 28.5 lm/W, respectively. When the operating current density varies from 10 mA/cm2 to 30 mA/cm2, there are nearly no variations in color coordinates and the correlated color temperature slightly changes from 3 135 K to 3 147 K. The emissions are all within the defined warm white region, as is beneficial to the alleviation of blue-light hazards. As the viewing angles increases from 0 to 60° no obvious shift of the emission peaks was observed and the color coordinates and slight variation of(0.02, 0.03) in color coordinates was occurred. Moreover, the emission pattern was very closed to the desirable Lambertian distribution.

A novel method was investigated to achieve in-plane graphene surface plasmon anderson localization in mid-infrared region by transferring a graphene sheet on the one-dimensional random silicon gratings. By adjusting the Fermi level of graphene, the resonance wavelengths of anderson localizated graphene surface plasmon caused by its random nature can be easily tuned. The field intenstiy of localizated graphene surface plasmon is higher than the corresponding one in the periodic silicon gratings 70 times when the Fermi level is set to be 0.6 eV. The structure proposed can be appiled to the tunable integrated filters, broadband modulators and plasmonic sensors.

For the surface-plasma holographic display scheme of refractive index modulation, the relationship between the structural parameters of the variable-refractive-index thin-film sinusoidal grating and the diffraction efficiency is simulated by using the rigorous coupled-wave calculation method. The results show that when the silver is used as the surface plasmon excitation material, 0.2 μm is the optimum thickness of the grating. On this basis, the diffraction efficiency of the first-order light is proportional to the refractive index difference and the period. The refractive index range is expanded, confirming that when the refractive index modulation range is 1.34~1.8 and the period is 0.9 μm, the diffraction efficiency can reach more than 33%. This study has reference significance for the design of surface plasmon holographic display structures.

Based on Braczyk's theoretical work, the spectral function of interference filter is considered, and a more conventional formula of Hong-Ou-Mandel interference coincidence probability is derived, which improves the controllability of interference experiment. The HOM interference is studied experimentally by using interference filters with different bandwidths, and the experimental results are close to the theoretical prediction. The comparison of experimental data and theoretical simulation shows that the interference filter with different bandwidth can flexibly adjust the interference curve and obtain higher coincidence counting rate and interference visibility. The interference visibility measured in the experiment is higher than 97%, and the best case is 99.9%, which shows the reliability of the experimental scheme. The study could provide references for similar emperiments on quantum interferences.

A model of helical groove structure is proposed. The surface plasmons excited by the incident light with different spin angular momentum have different intensity distributions on the structure, attributed to the coupling of the helical groove structure and the optical spin angular momentum. So the spin angular momentum of incident light can be obtained by the intensity distribution of surface plasmons excited by the helical groove structure. The finite element method is used to calculate the extinction ratio of the surface plasmon excited by the left-handed polarized light and the right-handed polarized light at the center of the spiral groove. The maximum extinction ratio reaches 168, which can distinguish the photons with different spin angular momentum. In the numerical simulation, the intensity extinction ratio for different incident wavelengths is analyzed. The extinction ratio of the incident light wavelength in the range of 600~740 nm is above 50, with a best extinction ratio in the wavelength of 670 nm. In addition, the effect of the helical groove structure parameters on the extinction ratio is illustrated. And the maximum extinction ratio is obtained with the groove width of 200 nm, the groove depth of 70 nm, and the turn number of 2, at this time, the spiral groove structure has the best ability to detect the optical spin angular momentum. This work could provide a new approach to detect the optical spin angular momentum in integrated optics.

The automatic calibration system laid in Dunhuang radiometric calibration site was adopted to carry out the high-frequency automatic absolute radiometric calibration experiment from the visible to short-wave infrared of SNPP VIIRS remote sensor in allusion to the high-frequency, high-aging and high-precision calibration of remote sensing satellites. The principle automatic calibration was described in detail. In order to solve the mismatching problem between the channel reflectance and the reference reflectance spectral shape, a reference reflectance database was established for the change of the spectral shape of the surface spectral reflectance in a long-time span. A total of 13 effective automated calibrations of SNPP VIIRS were completed and compared with the apparent reflectance observed on SNPP VIIRS satellite from May to November, 2018. The results show that the relative deviation of the apparent reflectance obtained from the site automatic calibration and satellite is less than 5%, and the root mean square is less than 3.2%. This phenomenon indicates that the automatic calibration results of the site and the satellite have a high consistency and stability, which could be used for the high-frequency on-orbit radiometric calibration.

Using a 355 nm CW laser to pump BBO crystal, the measurement device was set up based on spontaneous parametric down conversion. The channel detection efficiency of system at 737 nm was calibrated at different photon rates, with time-to-digital conversion and time-to-amplitude conversion for performing coincidence counts. The influence of death time and afterpulse on the selection of coincidence gate width and accidental coincidence at high photon counting rate is analyzed. The measurement results of different photon counting rates are compared and the correction factors of coincidence measurement are analyzed. The experimental results show that the relative deviations of the two coincidence measurement methods are better than 0.25%. The afterpulse probability at different photon counting rates are measured by time interval analysis, which provides a basis for improving the accuracy of single photon detectors counting and entangled photons photon calibration.

The automatic multi-band solar radiometer was developed, which contains eight spectral channels, covering visible-near infrared bands. By two-dimensional rotary table and four-quadrant tracking module, the instrument can accomplish real-time automatic measurement of direct solar irradiance, sky radiance, aerosol optical thickness, moisture content of large gas column and ozone content, and can control and transmit data remotely. In order to reduce the influence of temperature change on detector response, temperature control was designed for the eight-channel main part of the optical machine head. Based on the actual situation of the field environment, the thermodynamic finite element analysis of the key parts of the eight-channel main body and the heat dissipation enclosure was carried out. The results show that the installation structure of the main optical components can meet the requirements of parts deformation caused by actual temperature changes. Increasing the heat dissipation area of the enclosure can effectively improve the temperature control efficiency of the eight-channel body and enhance the adaptability of the field environment. Instrument in dunhuang radiation correction field worked for a long time with weathered sand, rain, and temperature, the temperature control system of temperature remain at 25±0.2℃, showing good stability and reliability of the design of temperature control.