FPGA is widely used in optoelectronic systems. In complex optoelectronic systems, multiple FPGA signal processing systems may be integrated, and the FPGA of each subsystem generally does not have the conditions for online JTAG update programs in the overall state. This article proposes an Aurora optical fiber FPGA remote update method, which divides data into packets for FPGA burning files. A handshake and resend mechanism is added to the optical fiber transmission, and the data packets are sent to the FPGA through the optical fiber interface. The FPGA verifies that each packet of data is correct and caches it in the DDR. After the DDR receives the complete packet data, the SOC system uses the Microblaze soft core to write the data in the DDR to the corresponding FLASH address, achieving remote update of the FPGA program. The experimental results show that the bandwidth of the optical fiber module can work stably at 10 Gbps, and the remote update time for 8.52 MB FPGA burning files is 117 s. This method solves the problem of FPGA remote update for long-distance and complex systems, effectively improving the efficiency of remote update and reducing data transmission error rate.

Space target monitoring and detection is an important guarantee for maintaining the safety of the space environment, and space-based observation is one of the important observation methods. In space-based observation images, the shape and size of stars and small spatial targets are similar, which affects the detection of small spatial targets. Moreover, the spatial environment is complex, and the noise in the image can also interfere with the detection of small spatial targets. A method for detecting small spatial targets in orbit based on trajectory prediction is proposed to address the above issues. Firstly, the image is preprocessed, including image filtering, which is used to remove bad pixels and reduce background influence, and threshold segmentation. Distortion error correction on the camera is performed, then coordinate system conversion is performed as well, and the star catalog is matched to remove most stars. Then the method collects multiple frames of images, performs trajectory correlation and prediction on candidate targets, and determines the search range. Finally, the detection of small spatial targets is achieved. This detection method has the following advantages: Achieving high detection accuracy and low false alarm rate under low signal-to-noise ratio; Reducing search scope and improving real-time detection capability in orbit; Having the ability to detect discontinuous occurrences of targets on continuous frame images, adapting to the needs of target detection in more complex spatial environments. The detection ability of this detection method has been verified on a hardware system. The experimental results show that the algorithm has a high detection rate and a low false alarm rate when detecting low signal-to-noise ratio targets, which provides a reference for small target detection in orbit space.

Due to the limitations of materials and manufacturing processes, stripe non-uniformity is commonly present in infrared images, which seriously affects the imaging effect of the image and subsequently interferes with subsequent target recognition, detection, and other work. The classic least mean square error (LMS) algorithm can suppress stripe non-uniformity to a certain extent, but its scene adaptability is poor, and there are trailing and “ghost” phenomena. This article proposes an improved least mean square error (LMS) adaptive filtering algorithm for image processing, which utilizes bilateral filtering and steepest descent method to quickly obtain accurate correction parameters. The correction results calculated from the previous frame are used as the initial input values for the following frame, improving the accuracy of the algorithm. At the same time, the algorithm also adds an edge detection module to preserve image details. The article uses real infrared images of non cooled detectors in different scenarios, and compares the algorithm proposed in this paper with the classic LMS algorithm from both subjective and objective aspects. The results show that the algorithm proposed in this paper can effectively protect image details and has good scene adaptability.

There are huge challenges in how to comprehensively utilize multi-modal data from ship monitoring in complex sea area scenarios for efficient feature extraction and feature fusion to comprehensively improve ship identification accuracy. Aiming at the problem of ship identification accuracy from a single data source in the maritime environment, an effective ship identification algorithm for multi-modal data feature extraction and feature fusion is proposed, and then feature fusion is performed based on a deep residual network model to improve the accuracy of ship identification rate. Through comparison of experimental results, compared with other algorithms, the average accuracy of the ship identification algorithm based on multi-modal data is increased by about 18%, which effectively improves the accuracy of ship identification and has reference significance for research and development in related ship fields.

The normal field of the scene can be obtained by various methods such as shadow shape, deflection measurement and photometric stereo. The height field function obtained from the normal field plays an important role in 3D reconstruction methods such as shadow shape and photometric stereo, so the depth information of the scene reconstructed from the normal field is worth studying. A method to recover height field function from discrete normal vector is proposed in this paper. Firstly, based on the principle of discrete geometry, the row height value of the scene is estimated line by line. Then, a small number of column heights are calculated. Finally, according to the column height value, the average height of each row is adjusted row by row to obtain the height distribution of the whole scene. The least square method is used in the process of estimating the row height value and column height value. This method reduces the amount of optimization data. It does not need large matrix operations and operation memory, and has a good effect on the surface of the object, which is continuous and smooth. Experimental results show that the depth recovery of the scene with few continuous surface mutations is better, but for the scene with many mutations, the recovered height will have horizontal stripes.

The precision of tracking and targeting, the divergence angle of the laser beam emitted by the laser ranging sensor, the detection field of the laser echo receiving system, particularly for small targets also related to the range and detection probability of laser ranging are all factors that influence the requirement of parallelism of the optical axis of the optoelectronic tracker. This paper examines the properties of energy distribution of illuminated beam, takes into account temperature, vibration, and other environmental factors, as well as the optical axis stability error caused by variable focusing, and proposes the calculation method of optical axis parallelism requirements of optoelectric tracker based on the principle and index requirements of laser ranging of optoelectronic tracker. Moreover, the optical axis parallelism error distribution model is established, and the general control requirements and estimation methods of each random error term and each calibration residual error term are discussed. This information serves as a guide for the design and analysis, manufacturing process, and maintainability improvement of the optoelectric sensors while taking into account their maintainability for in-place replacement and field calibration.

City gas has great safety hazards in the pipeline transportation process, and once the danger occurs, the consequences are unimaginable, so the monitoring and localization of gas pipeline leakage is of great significance. To solve the problems that most of the current pipeline leakage detection and localization methods are susceptible to environmental interference, low accuracy, narrow scope of application, and high computational difficulty, this paper proposes a weak fiber Bragg grating (wFBG) array pipeline leakage detection and localization technology based on time delay estimation, which collects vibration signals through wFBG technology. Based on the characteristis of the collected leakage viberation signals in the time and frequency domain, the method first detects whether the pipeline is leaking by the method based on short-time energy analysis, then performs polynomial fitting between the peaks for the signal fragments that meet the requirements to obtain the arrival time of the leakage information, and finally locates the leakage point according to the time difference. The experimental results show that the method can effectively detect leakage, and the localization error is about 1 m at a measurement distance of 40 m.

The photoelectric equipment servo system will generate feedback energy due to deceleration braking and generate pump lift voltage, which will cause power supply overvoltage protection. Traditional energy dissipation methods are difficult to effectively solve. This paper studies and analyzes the pump lift voltage problem caused by feedback energy from two aspects: the software and hardware of the servo system. The mechanism of feedback energy action of the servo system is discussed, and several effective methods to deal with the feedback energy are put forward. The pump lift voltage problem from the aspects of servo power supply, servo drive circuit, control parameters are solved. A new zero feeding control method is proposed, with a pump lift voltage suppression rate of 74.7%. Based on a full-bridge drive circuit, the rapid braking of the motor is realized by using the feedback energy, and the pump lift voltage is eliminated at the same time. The debugging and test of the photoelectric equipment servo system has practical engineering guiding significance.

The evolution of surface morphology after nanosecond laser polishing of inclined surfaces and the influence of surface inclination on polishing results are investigated, which may provide a reference for laser polishing of free form surfaces in additive manufacturing. A nanosecond laser is used to laser polish rough surfaces that are not perpendicular to the optical axis, and the surface morphology after laser polishing is measured and analyzed using a laser confocal microscope. The results show that when the surface is tilted at 30°, there is an abnormal increase in surface profile fluctuations on the polished surface near 4 mm from the starting point, and the surface roughness value increases to 15.80 μm. When the inclination angle increases to 45°, the position where the surface profile fluctuation abnormally increases changes to around 2 mm. When the inclination angle is 60°, there is no abnormal increase in surface profile fluctuations. The abnormal increase in surface profile fluctuations reflects the transition process of laser polishing from over melt polishing to shallow melt polishing. The laser polishing process for free-form surfaces requires selecting appropriate laser power density and defocus amount based on the inclination and surface roughness of the polishing area, in order to achieve good laser polishing quality.

Aiming at the requirements of the quality, control speed and control accuracy of the synthetic beam in the linear array fiber laser coherent synthesis system, the design of the linear array fiber laser coherent synthesis controller is completed. The controller uses DSP2812 and CPLD as the core processor, receives the voltage signal of the photodetector through AD976A analog-to-digital converter, and outputs analog voltage from AD8544 digital to analog converter to control the piezoelectric ceramic phase controller, and then controls the phase change of the light. In order to realize the communication between the controller and the target image detection board and the upper computer, two serial communication interfaces are designed, and related test procedures have been written. Finally, the coherent synthesis, scanning and tracking experiments of four 1 064 nm lasers are completed in the linear array fiber laser coherent synthesis system. The experimental results show that the controller is equipped with SPGD algorithm, and can realize fiber laser phase locked with the cooperation of photodetectors. After phase locked, the energy change of the main lobe is better than ± 5%, and the scanned range of the main lobe is ± λ. The scanned frequency is about 25 Hz. At the same time, the target tracked experiment is completed in combination with the target image detection board to realize the target tracked of laser coherent synthetic stripes.

With consideration of the fact that bias voltage for Si-APD changes in different ambient temperature and the corresponding electric network requires low ripple voltage, a kind of bias circuit is built based on Royer oscillator and MCU. The circuit is made up of four key parts (including their peripheral networks): synchronous Buck-converter controller BL8032, supplying input power source for Royer oscillator; DAC MS5221M, serving as the direct adjustment of the input power source for Royer oscillator; ADC AD7890, with the OPA AD8606 as an buffer, used for sampling output voltage of Royer oscillator; and an MCU STM32F103TBU6, working as the main computing and timing sequence controller. This bias circuit not only provides low ripple, low noise and low power consumption, but also meets requirement of wide input voltage of 9~36 VDC and safety electric isolation. It works well at ambient temperature from -40 ℃ to 70 ℃.

As a new type of laser detection radar, Brillouin lidar can be used for monitoring seawater parameters. In view of the disadvantage of the existing Brillouin lidar inversion models that have smaller inversion accuracy and parameter range, the new inversion model for temperature and salinity is proposed by using the least squares method with frequency shift and linewidth as independent variables. This model improves the inversion accuracy and inversion range of temperature and salinity, and the inversion model is analyzed in terms of sensitivity, error and uncertainty. The results show that the Brillouin frequency shift and linewidth can be used to achieve simultaneous monitoring of ocean temperature and salinity. In the temperature inversion model, the effect of Brillouin linewidth on temperature is greater than that of frequency shift, and the temperature inversion range of the new model is extended from 15 ℃≤T≤30 ℃ to 10 ℃≤T≤30 ℃ with a maximum error of 0.17 ℃, an average error of 0.07 ℃ and an average relative error is 0.27%, which is 63.16% better than the accuracy of the existing model. In the salinity inversion model, the effect of Brillouin frequency shift on salinity is greater than that of linewidth, and the inversion range of the model is expanded from 30‰≤S≤35‰ to 15‰≤S≤35‰, with a maximum error of 0.20‰, an average error of 0.09‰ and an average relative error is 0.29%, which is 77.50% better than the accuracy of the existing model. The research results in this paper have guiding significance for Brillouin lidar to detect seawater temperature and salinity.

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. In order to expand the usage direction and field of infrared detectors, a new non-uniformity correction method without baffle is proposed in this paper, which combines the non-uniformity correction method based on calibration correction and scene correction to realize the non baffle correction of uncooled infrared detector. The image non-uniformity of a domestic uncooled infrared imaging system using this method is 0.5% after one hour of operation. 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, and helps for the application of domestic uncooled infrared detectors in various fields such as aerospace, aviation, and weapon equipment.

Global Navigation Satellite System(GNSS) time transfer techniques with low cost, high precision and wide coverage, are widely used in high precision time-frequency. Traditional satellite common-view (CV) technology uses Common GNSS Generic Time Transfer Standard(CGGTTS) file to realize post high-precision time transfer, and it is difficult to realize real-time time transfer. To meet the needs of digital converter station, power internet of things, mobile communication and etc. This paper studies real-time common-view time transfer based on the pseudo-range observations of the Beidou-3 global navigation and positioning system (BDS-3). Short baseline and Xi’an-Sanya long-baseline real-time CV time transfer experiments are carried out to evaluate the performance of real-time CV method. The results show that the precision of real-time CV time transfer based on BDS-3 is better than 1ns, and it can provide nanosecond time synchronization and nanosecond timing services for time-frequency system, digital converter station and some other applications.

The optomechanical cavity accelerometer based on photonic crystal microcavity combines the mechanical resonator with the high-quality factor photonic crystal cavity, and the mechanical vibrator is sensitive to weak force/displacement in the mechanical vibration mode, which can achieve extremely low noise level and theoretically reach the standard quantum noise limit, which is an important direction for the development of high-precision accelerometer. This paper analyzes the principle and structural characteristics of the zipper type photonic crystal cavity optical-mechanical accelerometer, and designs a silicon-based zipper type photonic crystal cavity and mechanical vibrator structure for accelerometer. The influence of the structural parameters of the zipper cavity on the optical Q factor is analyzed in detail. The resonant frequency of the optical cavity is controlled around 195 THz by adjusting the structural parameters, and the mechanical resonance characteristics of the mechanical vibrator and the optical cavity are analyzed. The effective mass of the optical cavity is 30 pg, plus the effective mass of the mechanical vibrator is 3.1 ng, and the opto-mechanical coupling rate reaches the order of GHz/nm, which provides guidance for the manufacture and characterization of the silicon-based zipper cavity accelerometer.

In various cold atomic interferometry systems, MOT, compensation and bias magnetic control are indispensable techniques. The precise manipulation of atomic groups is directly affected by table and fast magnetic field control in the process of atomic cooling, trapping and interference. A set of high-performance precision magnetic field control system is designed in this paper. In circuit topology, the low-noise constant current source based on precision amplifier is used to reduce the noise level of magnetic field driven current. In control mode, analog PID plus disturbance suppression control strategy is adopted to improve the switching speed of magnetic field driven current. The experimental tests are implemented in the laboratory environment. In case of 1 A magnetic field driven current, the opening time is shorter than 300 μs, while the shutdown time is less than 50 μs. Meanwhile, overall current noises are superior to -80 dB at the frequency ranges of DC(0 Hz)~250 kHz. Finally, through experimental tests in cold atom absolute gravimeter/gravity gradiometer and gyroscope, the designed magnetic field control system could meet control requirements of cold atomic interferometry systems and achieve the expected affect. Moreover, its independent development could solve the dependence on commercial magnetic-field control modules, and promote the equipment of quantum measurement devices.