A modulation transfer function test system that can test miniature lenses quickly is designed, compared with the traditional pattern contrast test method. In this paper, the design of an auxiliary imaging lens applied to a modulation transfer function test system is proposed. The optical system has a long entrance pupil distance and perfect image quality to reduce the impact on test results. We built a test platform and developed modulation transfer function calculation algorithms by using image processing technology to calculate the modulation transfer function in the tangential and sagittal direction of the lens effectively and quickly.
The time-of-flight (TOF) camera has recently received significant attention due to its small size, low cost, and low-power consumption, which can be widely used in fields such as automatic navigation and machine vision. The TOF camera can calculate 3D information of targets with dozens of frames per second. However, poor accuracy still exists in the presence of various inevitable disturbances. In particular, the imaging distance and object reflectivity are remarkable factors. In this study, the depth imaging conditions, including ambient light, detection distance, and object reflectivity, are theoretically analyzed using differential entropy. Because many coupled factors disturb the imaging accuracy simultaneously, we propose a type of supervised learning machine, entropy-based k-nearest neighbor, based on differential entropy. Experiments show that this method can significantly improve the accuracy of depth data obtained by a TOF camera.
A kind of new all-fiber coherent Dopple lidar made with a 1.55μm laser, a beam expander, circulator, and a signal sampling and signal processing system based on a SOPC chip. First , no the acousto-optic modulator was proposed to lock the frequence of the local oscillator light .The system obtains the fundamental frequency signal and the echo signal with larger mount of frequency shift by linearly modulating the driving current provided by the laser driving device to the photonic crystal laser,and obtain the difference frequency signal by mixing the fundamental frequency signal and the echo signal Then,the simulation results indicate that the more noise is added to the signal,the more errors will be obtained from the calculation.then, the lidar system was utilized to measure the velocity of atmosphere produced by a fixed fan.The results conform very closely to the reference ,whose absolute errors are less than 0.15m/s. The experient results validate the accuracy of the lidar system.
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