The optical 3D measuring method based on fringe projection is widely used in various industries such as medical diagnosis and industrial testing. Computer-generated Moiré profilometry plays an important role in fringe projection profilometry due to its high accuracy, real-time measurement ability, and insensitivity to object surface reflectivity and so on. In recent years, many derivative methods based on computer-generated Moiré profilometry have been proposed, which not only achieve further improvements in both measuring accuracy and measuring speed, but also enhance the adaptability of measuring different types of objects. In this paper, the basic theory and derived methods of computer-generated Moiré profilometry are summarized, and their characteristics are analyzed. The development trends of computer generated Moiré profilometry have been clarified.

Ocean temperature monitoring is of great value for the study and protection of marine ecological environment and of great practical significance in preventing the occurrence of marine natural disasters. Traditional electric sensors are difficult to supply power at a long distance, and it is difficult to meet the multiplexing requirements of large-scale sensor networks. Based on the interferometric sensing system platform of weak fiber Bragg grating array, this paper presents an interferometric high precision temperature sensing method which uses phase generated carrier (PGC) algorithm to demodulate temperature signals. In the range of 26.00~30.00 ℃, the temperature phase sensitivity is 1 132.6 rad/℃ and Pearson square correlation coefficient is 0.999 3. Theoretically, the temperature sensitivity can reach 0.000 1 ℃. The results show that the method of demodulation of dynamic signals can achieve high sensitivity detection by applying it to the demodulation of quasi-static signals such as temperature, which has a good application potential in the application of ocean temperature monitoring.

Aiming at low energy efficiency and high complexity of high-level modulation in DCO-OFDM(DC-biased optical OFDM) system, subcarrier index power modulated (Subcarrier Index-Power Modulated, SIPM) layered asymmetric clipped optical OFDM(LACO-OFDM) is proposed. The proposed transmission technology adopts low order constellation mapping formats 8-PSK and QPSK for high and low power subcarriers respectively, and combines LACO technology, which effectively avoids the reductions of energy efficiency of OFDM system caused by DC bias and increases the signal transmission bit rate. The simulation results show that SIPM-LACO-OFDM improves the energy efficiency without reducing the spectral efficiency, and has better BER performance and nonlinear tolerance performance. Compared with the traditional SIPM-OOFDM system, the received optical power penalties in SIPM-LACO-OFDM is ~1.8 dB over 25 km IMDD SSMF PON system.

OPGW anomaly monitoring based on fiber Bragg grating has been widely studied, but anomaly detection data is difficult to classify and identify whether it is a normal signal or a false signal. Aiming at the above problems, this paper studies random forest classification based on improved grid search method. Firstly, a classification and recognition model is built theoretically. The optimal classification solution is found iteratively by particle swarm optimization algorithm. Then, the monitoring data is divided into multi-frame training set, test set and verification set to realize classification and recognition of abnormal vibration by traditional random forest algorithm, grid search random forest algorithm and improved grid search random forest algorithm. Finally, the accuracy and precision of identifying abnormal signals are used to quantify the comparison results of the three algorithms. It is proved that the improved grid search random forest algorithm studied in this paper can achieve 98.56% accuracy of abnormal signal recognition in test set and 99.56% accuracy of abnormal signal recognition in verification set, which proves the effectiveness of the method and has practical significance for classification and recognition of OPGW optical cable abnormal vibration.

Smart grid applications need timely and reliable data communication systems, but the traditional fiber optic wireless sensor network (Fi WSN) system may not meet its short delay requirements. Therefore, a digital intelligent communication mechanism (XWMOC) for passive optical network (PON) based on the quality of service (QoS) mechanism is proposed in this paper. Firstly, cooperate with optical network units (ONUs) through wireless communication networks to reduce latency while avoiding interference from external devices. Secondly, the cross layer interaction between the application layer and the medium access control layer (MAC) can reduce packet delay in wireless sensor networks. Finally, by introducing service differentiation into the optical encoding ONU through two priority queues, the ultimate communication rate and reliability improvement can be achieved. Based on the above method and combined with user data from relevant regions of State Grid Chongqing, the research experiment on remote protection and synchronizer was conducted using the IEEE 802.15.4 standard. The experimental results show that the mechanism proposed in this paper can realize digital intelligent communication of power grid, reduce the end-to-end delay in Fi WSN system and long-distance passive optical network (LR PON), and provide a more efficient and reliable data communication system for smart grid applications.

In order to study the influence of optical devices on the temperature stability of fiber optical current transformer (FOCT), the polarization crosstalk’s influence of 3 types of optical devices： polarizer, LiNbO3 phase modulator and PM(Polarization Maintaining) fiber delay line, on FOCT’s accuracy is analyzed. With each of above optical device’s ambient temperature over a range from -40 ℃ to +70 ℃, the extinction ratio variation of the polarized light from polarizer, the polarization crosstalk variations of LiNbO3 phase modulator and PM fiber delay line, and the error variations of FOCT are tested. The results show that the polarization crosstalk variations with the temperature of the LiNbO3 phase modulator and the PM fiber delay line cause FOCT’s error variation, and LiNbO3 phase modulator is the key component that can affect FOCT’s temperature stability.

Grating-coupled external cavity diode lasers play an important role in cold atoms physics research and other fields. In this paper, combined with the application requirements in the interference process of 87Rb atom interferometer, the tuning and frequence-locking characteristics of a self-made compact 100 kHz external cavity diode laser seed coupled with volume Bragg grating(VBG) are chiefly studied with the optical phase locked loop. The measured coefficients of frequency-current and frequency-temperature are 400 MHz/mA and 16 GHz/℃, respectively. Laser frequency locking of the 100 kHz diode seed is demonstrated, and the frequency fluctuation of the locked seed is less than 500 kHz(peak to peak) within a 10 s measurement, and the power fluctuation of 12 hours is better than 0.1%(rms), which can meet the application requirements of all physical processes of the cold atoms interferometer, especially in the interference process.

The accurate positioning of laser spot center plays an important role in confocal microscopy system. In order to improve the accuracy of spot center location, a high-precision spot center location detection method based on OpenCV is designed. First, the denoise and filter the collected spot image, and then filter the connected domain to eliminate gross errors through clustering analysis. Then, perform morphological processing on the edge of the connected domain of the object, and finally fit the edge data into an ellipse to locate the spot center. The simulation and experimental results show that the method in this paper has a sub-pixel level positioning accuracy of less than 0.1 pixel and more stable detection results than other traditional spot center location methods, and is a high-precision spot center location method.

In order to meet the test and analysis requirements of axis rotation error for the axis that cannot rotate complete circle, a new method is researched on the basis of the mathematical modeling track analysis. At first, the measurement error model caused by the pose errors of plane mirror and collimator for axis rotation error test is derived by using the quaternion method. The pose errors of plane mirror and collimator will cause an ellipse track on the collimator screen, while the ellipse will degenerate into a standard circle when the errors are small. Then, the fitting method of track parameters, including the center and radius, is established based on the least square principle to remove the influences of the pose errors on the test results. Finally, the effectiveness of the method proposed in this paper is verified by simulations and experiments. The experimental results indicate that the track parameters method has obvious advantages in the axis rotation error test for the axes that cannot rotate a complete circle and it can be used as a powerful supplement to the traditional Fourier series method. Besides the method needs not to fine adjust the plane mirror and collimator in the test, increasing the test and analysis efficiency.

Aiming at the analysis of the principle of corneal pressure detection, a method for calibrating intraocular pressure during corneal pressure measurement with non-contact tonometer is presented, an experimental system has been set up and a prototype of the principle has been developed. By recording the data of photosensitive sensor and air pressure sensor, the optimum algorithm of corneal barometric center of gravity based on optimal envelope factor was used to extract the values of pressure sensor at barometric moment, and the optimal polynomial interpolation fitting method based on least squares was used to calibrate intraocular pressure. Simulated eye experiments showed that when the optimal envelope factor is 0.7, the instantaneous variance was the smallest (0.068); 5-order polynomial interpolation fit between in-cylinder pressure and intraocular pressure has the largest correction (0.997 1) and the smallest root mean square error (0.525 3). Conclusion： Experiments were carried out to verify the IOP measurement in human eyes. Compared with gold standard measurements, the measurement deviation is within ±1 mmHg. It shows that this calibration of IOP measurement is effective and feasible, and can help to diagnose eye diseases accurately.

A novel approach for achieving high-resolution, three-dimensional temperature measurement is proposed by utilizing optical coherence tomography. A mathematical model is developed based on the scattering properties of gas-phase flames for coherent measurement of the flame temperature field. Numerical simulations are conducted to generate three-dimensional temperature fields for Sandia Flame D at two different Reynolds numbers (Re=10 000, Re=20 000), and the feasibility of measuring the three-dimensional temperature field using optical coherence tomography is demonstrated under these simulation conditions. Specifically, the coherence length of optical coherence tomography is found to be shorter than the minimum scale of the flame for low turbulent flow rate flames, indicating that the proposed approach can successfully measure the three-dimensional temperature field distribution. These findings provide a theoretical foundation for utilizing optical coherence tomography to measure three-dimensional temperature fields.

The instrument that can continuously measure catenary ware, catenary guide height, and pull-out value is designed by analyzing current status of pantograph and catenary system in urban rail transit and discussing current problems of catenary detection techniques and methods. The “∏” structure characteristic of the rigid busbar is used, and continuous movement function on the surface of the rigid busbar in the form of wheel symmetry and connecting rod is realized, in the meantime, continuous synchronous measures of contact line wear, lead value and pull-out value are realized with the method of laser triangulation and contour matching. Finally, the instrument function and measurement accuracy are verified by means of the laboratory testing and the field manual comparison test. The experiment result shows that the precision of the measuring instrument is 0.01mm, the average error of the contact net abrasion is 0.128 mm, the average errors of the lead height and the pull value are 2.297 mm and 3.119 mm. The research achieves the goal of improving catenary detection method and efficiency.

Underwater electro-optical imaging technology can obtain high-resolution information of underwater targets, which has important applications in civil and military fields such as underwater resource exploration or underwater threat target detection and warning. The research on underwater electro-optical imaging model aims to clarify the degradation mechanism of underwater images and obtain high-quality underwater electro-optical images. Based on underwater steady light field distribution, the underwater image is obtained through the path radiance integral in the direction of line of sight, so as to establish the relationship between the underwater image and the underwater light source distribution, target layout, water optical parameters and view point position, at last the underwater electro-optical imaging model is obtained and the effectiveness is preliminarily verified by taking the actual underwater image as an example. The imaging model theoretically explains the formation principle of underwater image under natural light and artificial illumination, and has guiding significance for designing excellent underwater electro-optical imaging system and underwater image restoration algorithm.

The traditional commercial white LED has low color rendering index due to the lack of red light component. In order to improve the color rendering performance of white LED, Sm3+ can be added to the fluorescent powder to enhance the emission ability of orange and red light. Double perovskite oxide Ca2YNbO6：Sm3+ phosphors with red luminescence are prepared by traditional high temperature solid phase method. The crystal structure, elemental composition, emission spectrum, photoluminescence spectrum, thermal stability and fluorescence lifetime of the fluorescent powder are studied in detail. Results show that the phosphor is a pure compound with particle size about 5 μm, Sm3+ has a strong red emission at 650 nm when excited at 408 nm. According to data fitting, it is shown that the luminescence of phosphor belongs to Sm3+ electric dipole-dipole interaction process. High temperature testing shows that the oxide fluorescent powder has high thermal stability. By mixing commercial blue and green powder with Ca2Y0.96NbO6：0.04Sm3+ powder and excited by 365 nm-InGaN chip, a warm white LED with color coordinate of (0.344, 0.350), color temperature of 4 989 K and a color rendering index of 81 is realized.

The phased array DVL adopts phased array technology to transmit and receive acoustic signals, without the need to compensate for sound speed, and has high precision. For the inherent scale factor error and the complex underwater environment problem, the stability of the speed measurement accuracy is poor, and the navigation accuracy of the inertial navigation combination is seriously affected. Firstly, the error characteristics of Doppler log are introduced. Then the characteristics of laser inertial navigation with high short-term precision are analyzed. The high-order Kalman filtering model for scale factor and installation error is established, and the integrated navigation and positioning technology algorithm is obtained. Finally, the combined navigation algorithm is carried out with the laser inertial navigation to measure the lake condition. The voyage of individual voyages is within 10 km, the maximum positioning error is less than 10 meters, and the general voyage is within 20 km. The maximum positioning error is less than 0.2%D. The test results show that the integrated navigation technology has obvious technical advantages, and provide an important theoretical reference for integrated navigation products.