Optical-mechanical system design, installation and performance test of lidar with small-field and high-repetition frequency

In order to provide data correction and simulation for later development of space-borne lidar with high-repetition frequency, the lidar verification system with small-field of view and high-repetition frequency was designed and developed. Its opto-mechanical system was designed in detail, and the light path diagram of the transmitting, receiving and aft optical units was simulated by Zemax. The divergence angle of the outgoing beam was accurately calculated to be 0.106 mrad, and the new beam steering structure was designed to ensure the normal incidence into the beam expander. The field of view of receiving unit was 0.25 mrad with the iris diameter of 0.4 mm, the eccentricity of the diaphragm on the focal plane of the system should not exceed 29 μm, so the high-precision three-dimensional steering structure was selected to accurately position the iris. The design of the whole machine structure adopted the modular design concept, the different unit modules were installed in the different positions of the square frame. The structure was highly integrated, and the overall size was 390 mm×390 mm ×550 mm.The system transmitting unit was installed and calibrated, its divergence angle was detected to be 0.11 mrad. Compared with the simulation calculation, the relative error was 4.1%. The receiving and aft optic units were installed and calibrated, and the parallel light emitted by the collimator tube was used to enter the receiving telescope to obtain the precise position of the focal point of the system to complete the high-precision installation and calibration. Through the calibration experiment of the gain ratio of the system, the gain ration is 1.15. The detection experiments on the system show that the system can achieve aerosol detection distance of up to 22 km, and the depolarization ratio can reach 10 km at night. In the daytime, the detection distance can reach 10 km and the depolarization ratio can reach 6 km. Compared with the solar photometer, the relative error of optical thickness is 7.1%. The performance of the whole machine meets the design requirements, which lays a good foundation for the later experiments on the boat-borne.