In a class of photoelectric tracking systems with only the target image sensor and MEMS accelerometer installed, an equivalent acceleration feedforward control method can improve the tracking ability of the system effectively. However, due to the low-frequency noise of accelerometers, the delay of the synthetic trajectory and the uncertainty of the movement model, the tracking accuracy will be limited. Therefore, in this paper, an equivalent acceleration feedforward method based on sensor optimization and robust prediction is proposed to further improve the tracking ability of the system. The frequency-domain fusion using the accelerometer measurement and the calculated acceleration can optimize the low-frequency performance of the accelerometer. Meanwhile, the robust prediction algorithm can reduce the impact of the delay of the synthetic trajectory and the uncertainty of the movement model and give more accurate feedforward acceleration. The experiment shows that this method can further improve the tracking ability of 0.1 Hz~ 4.5 Hz.

In this paper, the optothermal microactuation technology and optothermal microactuator (OTMA) suitable for water or other liquids are proposed and developed. The model of optothermal expansion and temperature rise distribution is established, and simulation on a 1080 μm long OTMA is conducted, revealing the feasibility of optothermal microactuation technology in water. The optothermal microactuation experiment of a symmetrical OTMA is carried out in water under the irradiation of a laser with a wavelength of 520 nm and adjustable power, revealing that the optothermal deflection increases with the increase of the laser power. Another experiment is carried out under the irradiation of a laser pulse with a wavelength of 520 nm, effective power of 4 mW, and an adjustable frequency, demonstrating that the symmetric OTMA has a good dynamic response under the laser irradiation. The amplitude of the actuating (deflection) amount varies between 2.6 μm and 3.7 μm when irradiated by the laser pulse with a frequency of 0.9 Hz~16.4 Hz, and it decreases with the increase of the frequency of the laser pulse. The theoretical research and experimental curve trend reveals that it is completely feasible to obtain greater deflection and higher frequency optothermal microactuation in water by appropriately increasing the laser power and laser pulse frequency. This research provides new methods and approaches for the application of micro-opto-electromechanical systems and micro-nano technology.

During the instance segmentation for contour convergence, it is a general problem that target occlusion increases the time for contour processing and reduces the accuracy of the detection box. This paper proposes an algorithm for real-time instance segmentation, adding fragment matching, target aggregation loss function and boundary coefficient modules to the processing contour. Firstly, fragment matching is performed on the initial contour formed by evenly spaced points, and local ground truth points are allocated in each fragment to achieve a more natural, faster, and smoother deformation path. Secondly, the target aggregation loss function and the boundary coefficient modules are used to predict the objects in the presence of object occlusion and give an accurate detection box. Finally, circular convolution and Snake model are used to converge the matched contours, and then the vertices are iteratively calculated to obtain segmentation results. The proposed method is evaluated on multiple data sets such as Cityscapes, Kins, COCO, et al, among which 30.7 mAP and 33.1 f/s results are obtained on the COCO dataset, achieving a compromise between accuracy and speed.

In this paper, a highly sensitive detection method - polarized cavity ring-down (P-CRD) technique - is employed to investigate the influence of deposition angle on the optical loss and stress-induced birefringence of single-layer SiO2 films prepared with specific deposition process parameters. The P-CRD technique is based on measuring the decay behavior of accumulated polarized light reflecting back and forth inside a resonant cavity. The decay time and oscillating frequency of resulted phase difference of the CRD signal are applied to measure simultaneously the absolute values of the optical loss and residual stress-induced birefringence at the same measurement point of single-layer SiO2 films. In the experiment, the optical losses and stress-induced birefringence of the single-layer SiO2 film samples prepared under different deposition angles of 60°, 70°, and 80° are measured and analyzed. The results revealed the effects of the changes of surface roughness and film compact density caused by the different deposition angles on the optical loss and stress-induced birefringence of the single-layer SiO2 films, respectively. These results are helpful to the preparation of high-performance SiO2 films with low optical loss and low residual stress.

In the three-dimensional (3D) measurement system by the light-source-stepping method using LED, due to the large divergence angle of LED, the large fringe projection area can be achieved in a short distance, resulting in a short working distance of the system. In addition, the large luminous size of high-power LED leads to low fringe contrast, and it is difficult to project fringes with high brightness and high contrast. To solve the above problems, it is proposed to use laser diode (LD) as the light source to realize high brightness and high contrast phase-shift fringe projection in the light-source-stepping projection device. A portable and high-speed three-dimensional measurement system is designed by using the projection device and binocular camera. Firstly, an improved Fourier transform profilometry is used to obtain the phase and modulation of deformed fringe. Secondly, using the randomness of laser speckle, the rough matching of the binocular image is realized in the modulation map. Then, the fringe phase is unwrapped on the basis of rough matching, and the phase is used to realize fine matching. Finally, the three-dimensional shape of the object to be measured is obtained. The experimental verification is carried out by using the designed system. The measurement volume of the system is 360 mm×290 mm×100 mm, and the maximum 3D point captured is 1280×1024 points. The 3D shape measurement speed of 100 f/s was achieved. The measurement standard deviation of the plane is 0.19 mm. Five planes with a distance of 1.00 mm were measured, and the average error of the measurement distance is 0.05 mm.

In order to obtain a super-resolution prior model with higher confidence and balance the reconstructed results between noise and details, this paper establishes a Gauss-Lorenz hybrid prior model based on the mixed sparse representation framework. This prior model's advantages and specific application schemes are studied. Firstly, according to the type of prior information, the advantages and problems of some traditional algorithms are introduced. Next, the statistical characteristics of different components of the image are modeled separately. Then, based on the analysis of the mixed sparse framework, the Gauss-Gibbs prior and the Lorenz prior, the super-resolution algorithm based on the Gauss-Lorenz hybrid prior under the group sparse framework is illustrated. Finally, the implementation and the final iteration scheme are introduced. The aim of noise suppression while maintaining details in the reconstruction process has been completed, which can be used for in more complex environments with super-resolution resconstruction.

Aiming at the problems of poor robustness of rotation change, high feature dimension, and long retrieval time of existing color image retrieval algorithms, this paper proposed an innovative image retrieval method by fusing color features and improved directional gradient features. It proposed an improved directional gradient algorithm based on the principal curvatures (P-FHOG) by combining the geometric curvature information of the image surface into the FHOG descriptor from multiple scales. At the same time, the color information of the image was further fused to obtain the multi-scale image retrieval method based on the color features and the improved directional gradient features (CP-FHOG). The experiment was compared with the advanced image retrieval methods on the Corel-1000 and Coil-100 data sets, and the average accuracy rates of 85.89% and 93.38% were achieved, respectively. The results show that the proposed algorithm is more accurate and robust (in rotation change) than other algorithms.