Optical fiber Fabry-Perot(F-P) sensor is an important branch of optical fiber sensor, which has the advantages of high detection accuracy, large measurement dynamic range, intrinsic explosion-proof and so on. It has been widely studied and applied in the industrial field. For the high temperature and harsh environment over 1 000 ℃, ordinary electrical sensors can’t meet the application requirements. In recent years, many experts and scholars have devoted themselves to the development of high temperature optical fiber F-P sensors. Many high temperature sensors with novel structure and excellent performance have been obtained by continuously optimizing and improving the structure and preparation process of the sensors, and selecting new high temperature resistant materials. Based on the interference principle of F-P cavity, the sensing mechanism of fiber F-P sensor is introduced. The research progress of fiber F-P temperature sensor, pressure sensor, strain sensor, vibration sensor and composite sensor is summarized respectively. The problems and challenges of current research are analyzed. Finally, the development process of optical fiber F-P sensor is summarized, and its future development trend is prospected.

In the optical manufacture process, the material removal in the rough grinding and fine grinding stage is the largest, while it is rather small in the polishing stage. Therefore, if the rough and fine grinding surface is measured in the whole field, the machining process will be greatly shortened. Among the existing measurement methods, CMM (the coordinate measuring machine) and infrared interferometer are expensive or inefficient. In this paper, a binocular structured light 3D measurement is used in the optical manufacture process to realize a non-contact, full field, fast and high-precision measurement of dynomizing optical elements. The experimental results prove its feasibility and the measurement error is less than 10 um. There is a great significant application value for the rapid and accurate measurement of cutting amount in the optical manufacture process.

Micro spectrophotometers are widely used in water quality online analysis instruments, and thestray light is one of the key parameters to evaluat the performance of spectrophotometers.It can effect the datafrom the measurement results.The source of stray light and its effect on the measurement results of the spectrophotometer are analyzed in this paper. The stray light of two spectrophotometers is detected, and the two spectrophotometers are used in the hexavalent chromium water quality analyzer to measure different concentrations of standard solutions. The results show that the larger measurement errorsare introduced due to the stray light, and as the concentration of the solution increased, its impact would become more serious. The suppression and control of stray light should be emphasized in order to improving the measurement accuracy, ensuring the safety of agricultural water, and reducing the various risks caused by water pollution.

In the phase measuring deflectometry, the calibration accuracy of the system has a decisive influence on the accuracy of the profile measurement. When the calibration target with markers is used for calibration, the error will be introduced because the surface of calibration target is not an ideal plane, which leads to the inaccuracy of solving the pose of the virtual screen image, thus affecting the calibration accuracy. In order to reduce the error, a high precision standard plane mirror is used as a reflector. Starting from the initial system parameters, the system geometric parameters are calibrated using the method of alternating direction optimization, which improves the calibration accuracy and avoids the matrix ill-condition caused by too many variables. In this paper, the binocular phase measurement deflection system with the proposed method is calibrated, and then the standard plane mirror with diameter of 100 mm is measured. The results show that the proposed method improves the accuracy and stability of the calibration compared with the traditional method with a calibration target with markers.

The coded circular fringe has zero-phase in the center of fringe image, which can be used as a reference for the subsequent calculation of absolute phase and unwrapping. However, the carrier frequency phase provided by circular fringes is nonlinear. When it is used to measure three-dimensional surface shape, the method for obtaining object height information is different from that of projecting single frequency straight fringes. The calculation method of object height information in phase-shifting profilometry are studied based on circular fringe projection. The calculation method of coordinate displacement is discussed caused by height in detail. The corresponding error analysis is completed. Computer simulation and experimental verification show that the method can directly obtain the absolute phase of out of plane object, which can be used to reconstruct the three-dimensional shape of the object.

With the development of integrated circuit manufacturing technology, the package size has become more compact, and the problem of interconnection short-circuit caused by solder deformation has become more prominent. The need for coplanarity defect detection for chip bumps, the measurement of bump height, is more urgent. To achieve this goal, A simulation model of chip bump height measurement is established based on white light triangulation. The system is divided into a light source shaping module, a precision slit, a microscopic projection system, and a microscopic imaging system. The analysis of the change of the reflected light spot on the top of the bump is focused during the movement of the sample. The influence of the convergent light and traditional parallel light of the system is compared on the imaging light spot on the top of the bump. Based on the above analysis, a method suitable for the detection of the height of the bump is proposed and the simulation results are used.

Combined with typical anti-telephoto lens design method and PWC method, initial structure was built from theoretical model and assisted by ZEMAX. The operating wavelengths bands of system are 436 nm, 486 nm, 546 nm, 587 nm and 656 nm. F# is 1.5. Full field of view is 160°. This optical length of 18.5 mm is applied to the lens of car rear view system. The lens has significant improvement in existing product indicators in the market: the stability in operating temperature and its reasonable tolerance range. The result shows that the lens has more excellent effects, lower prices and stronger expressive than that who has not combined with the ideal anti-telephoto model, PWC method and practical requirements. It can provide useful reference for lens design in related fields.

In this paper, a stepped-frequency continuous wave synthetic aperture radar imaging system based on millimeter wave is studied. Based on the algorithm, the imaging hardware and software system are built to realize the signal scanning and the acquisition and processing of echo signal. The processed signal is calculated by the imaging algorithm, and the 3D image data of the target is obtained. The results show that the resolution in x direction is 8~9 mm, the resolution in y direction is 12 mm, and the resolution in z direction is about 40 mm. The optimal imaging distance of the system is studied, and the results show that when the target is within the range of 5~16 cm from the transceiver, the target can be clearly imaged with only a small background noise. In the application of human security inspection, the penetration effect of five common fabrics is tested. The results show that the system can effectively penetrate the fabric and clearly image the hidden objects under normal clothing thickness.

In order to resist the load at full load, the car body base will retain a certain upward flexural deformation when the rail vehicle is manufactured. It requires the surface profile of the base to be measured before laying aluminum honeycomb panels and floor glue. A method for measuring the surface shape of the car body base based on the principle of point target image measurement is proposed. This method uses a CMOS camera to measure the 4 LED on the car body base, in which 4 LED form a correlation Multi-target points. the LED target image gathered by CMOS camera is preprocessed by means of mean filtering, dynamic threshold binarization and contour extraction, and then the gray-centroid method is used to extract the positions of multiple light spots. By judging the position and size of each light spot, possible false target points or obstructions are eliminated, and different reference points are used for comparison according to the number of extracted light spots. When any LED target is obstructed, the center position of the LED target can still be solved effectively.It is shown by the experimental results that the maximum deviation of the center extraction of the LED target is less than 0.06 mm, which can fully meet the needs of vehicle body base surface measurement.

Visual object tracking based on deep learning has become one of the mainstream algorithms in the target tracking field due to its performance. The main idea of algorithms is to learn the similarity of the previous and next frames to complete the matching of the template frame and the search frame. Among them, similarity learning is a key step that affects the performance of tracking algorithms. This paper takes the similarity learning of siamese network as an entry point, improves the similarity learning method of deep-wise cross correlation (DW-XCorr), and proposes a target tracking algorithm for multi-scale similarity learning.Under the basic network framework of SiamRPN, this algorithm applies a multi-scale cross correlation (MS-XCorr) module, which improves the crosscorrelation operation in multi-scale, thereby increasing the diversity of learning feature scales and improving the similarity of the tracking network The efficiency of similarity learning ultimately further improves the tracking performance of the algorithm.In the experimental part, the improved algorithm is compared with its baseline: the algorithm has improved success rate, precision and norm precision, and the success rate has increased. 4.3%, the accuracy increased by 4.4%, and the average accuracy increased by 4.0%. Experiments show that the multi-scale cross correlation module has stronger similarity learning ability than the deep-wise cross correlation module.The proposed multi-scale similarity learning target tracking algorithm has better tracking performance in complex situations such as target illumination, morphological changes, occlusion and interference.

Image hiding technology plays an important role in the era of big data, especially in the fields of copyright protection and confidential communication. An image hiding method based on computational ghost imaging is proposed in this paper. The target image is encrypted by the computational ghost imaging system, random speckle is used as the system key, and the result of the binary ciphertext is embedded into the host image using the least significant bit algorithm. The corresponding watermark extraction rules and the second-order correlation algorithm are used to restore the target image. The simulation results show that the method has good concealment. The peak signal-to-noise ratio of the embedded watermark image can reach 50 dB. The authorized user can use the key to obtain the target image. At the same time, the proposed scheme has a certain fault tolerance. Image cropping is robust.

In order to fuse infrared and low light image effectively, under the premise of obtaining good fusion visual effect and achieving entropy increase, while minimizing the complexity of the algorithm, an adaptive weight fusion method is proposed based on detail enhancement. According to the characteristics of infrared and low light image, the adaptive weight matrix is calculated, and the fusion is performed for the first time, and then combined with the detail image for the second fusion. After using three conventional algorithms and the algorithm of this paper to simulate and analyze five types of typical scenes in MATLAB, and combining with subjective and objective evaluation mechanism, the algorithm in this paper has a better standard deviation and entropy increase, and the subjective fusion effect is also relatively better. Finally, it is verified in the embedded FPGA platform to realize the real-time fusion output of 50 Hz images.

The algorithm based on infrared target detection plays an important role in military and civil fields. However, under the condition of low signal-to-noise ratio, it is difficult to detect infrared spotted targets such as aircraft and ships, with high false detection rate and false alarm rate.?To solve this problem, an algorithm based on machine learning to detect infrared speckled targets with pixel areas ranging from 3×3 to 100×100 is proposed.?In the algorithm part, morphological method is used to pre-extract the target, and HOG feature extraction and SVM machine learning are used to classify the real target.?The proposed algorithm achieves 94.01%, 92.86% and 92.19% detection accuracy in large, medium and small scale target detection respectively.?In addition, the algorithm on SoC platform is implemented, and the algorithm has high real-time performance on the basis of low resource utilization.

In view of the complex structure of distributed photovoltaic power station, the traditional distributed photovoltaic power station monitoring system can not achieve the effectiveness and accuracy of distributed photovoltaic power station monitoring. In order to solve this problem, the application research of ZigBee in distributed photovoltaic power station monitoring system is proposed. Based on the overall architecture of distributed photovoltaic power station monitoring system, through the design of distributed photovoltaic power station monitoring module and distributed photovoltaic power station monitoring system induction module, the system hardware design is completed. Through the processing of distributed photovoltaic power station monitoring data and the design of distributed photovoltaic power station monitoring process, the system software design is completed, and the ZigBee technology in distributed photovoltaic power station is realized. The test results show that the distributed photovoltaic power station monitoring system based on ZigBee technology can not only improve the effectiveness of distributed photovoltaic power station monitoring system, but also improve the accuracy of distributed photovoltaic power station monitoring system.

In the cold atom interferometer, the fluctuation of the number of trapped atoms will be transformed into the equivalent phase fluctuation of the interference signal, which will directly affect the measurement results. To solve this problem, the active stabilization technology for the number of trapped atoms in the cold atom interferometer is proposed in this paper. By measuring the number of atoms in the final state of interference and feedback controlling the loading time of 3D-MOT, the active stabilization of the number of trapped atoms has been realized. By applying this technology, when the loading time is about 40 ms, the short-term fluctuation of the number of atoms trapped in 3D-MOT is reduced from 27.1%@0.5 h to 7.4%@0.5 h, and the long-term drift is reduced from 39.9%@10 h to 10.4%@10 h, which significantly improves the stability of atom trapping. This technology can solve the problem of large fluctuation of the number of trapped atoms caused by the attitude change of the cold atom interferometer under dynamic conditions.

As an ion beam emitting device, ion source is often used in the preparation of optical films. However, the ion beam contains ions with various energy, which seriously affects the microstructure and properties of optical films. In view of the disadvantage that the output energy spectrum of ion sources at home and abroad is too wide, based on the electromagnetic field theory, the ion motion trajectories of each energy level are simulated and analyzed, and an ion energy filter is designed. The results show that the filter can effectively remove the ions with too high and too low energy, and the screening rate deviates from the central ion energy by negative 100eV, It has reached 82.24%, and has a good application prospect in the field of optical film preparation.

Waveguide bandpass filter is an important component of high-power microwave filtering, which provides the possibility of high-power microwave transmission for 5G communication base stations. Based on the frequency band gap characteristics of photonic crystals, a two-dimensional cylindrical photonic crystal is introduced into the rectangular waveguide, and a two-dimensional cylindrical photonic crystal waveguide bandpass filter for 5G communication is designed. The filtering characteristics of the filter is simulated and studied. Furthermore, the characteristics and performance changes of the filter are also presented when point defects and line defects are introduced. The two-dimensional photonic crystal structure exhibits bandpass characteristics between 3 GHz and 7 GHz in the rectangular waveguide. The simulation results show that the filter can be applied to the n77, n78, and n79 frequency bands of 5G communication.

The thermal characteristics and thermal design of optical machine in infrared thermal imager are completed via multi-physics coupling simulation analysis technology of computational fluid dynamics, heat transfer, solid elasticity and optics.The optical mechanical temperature, stress distribution and the deformationdisplacement of the optical cell are obtained via finite element method and computational fluid dynamics.The rigid body displacement of optical cell is successfully removed by the least square method, the rigid body displacement and standard Zernike coefficient are introduced into the optical system. By comparing the spot diagram and MTF curve under different conditions of natural heat dissipation and strong convection heat dissipation, the optical mechanical thermal integration and coupling simulation analysis of infrared thermal imager are realized. The simulation results of optical mechanical thermal integration have important reference significance for the design and assembly of optical system.

The existing domestic vanadium oxide uncooled infrared detectors mostly use baffle correction for nonuniformity correction, which leads to complex structure and image interruption, thus affecting the normal use of the detector. A new non-uniformity correction method without baffle is proposed, which combines the non-uniformity correction method based on calibration correction and scene correction to realize the non baffle correction of uncooled infrared detector. Experimental results show that this method can achieve nonuniformity correction quickly after the start of correction, and the correction effect is good, and there is no “ghost” problem existing in traditional scene correction methods. This method avoids the image interruption of the infrared imaging system, and helps to reduce the volume and power consumption of the infrared imaging system.

Aiming at the problem of detecting and identifyingto ground target for 3~5 μm airborne medium wave infrared system in complex meteorological conditions, based on the theoretical research, by the use of PcModWin atmospheric simulation software, the simulating experiments are carried out for the meteorological conditions of clearness atmosphere, fog, cloud and rainy. The distribution curves of this wave band infrared radiation transmittance and the variation law of peak parameters in thedifferent distance range under different conditions are analyzed. Combined with the theory of atmospheric molecules, the detection angle, atmospheric visibility, fog type, cloud type, rainfall (snowfall) intensity, etc., are proved the important factors that affect the effect of detecting and identifying toground target for this wave band airborne infrared system. The strategy methods is put forward which should be taken in engineering application. The researched conclusion not only has an important guiding role in following engineering tests and application practices, but also has an important signification in rising the application effect to thiswave band airborne infrared system.