Research on multi-axis and MTF testing methods for laser rangefinder system in vacuum environment

There are significant differences between the environment of the laser rangefinder system during in orbit operation and ground installation. The system is easily affected by temperature, vibration, and air pressure during in orbit operation, which in turn affects the suability and imaging quality of the remote sensor. It is necessary to place the laser rangefinder system in vacuum environment and test its stability. The key indicators of laser rangefinder system are multi-axis consistency and modulation transfer function(MTF). Multi-axis consistency refers to whether the optical axes of the laser transmitter, laser reciving system, and camera are parallel. MTF characterizes the imaging quality of the camera. Testing multi-axis consistency and MTF simultaneously in a vacuum environment is a huge challenge, and there is mutual interference between systems. Only multi-axis consistency or camera MTF can be tested separately, and the testing coverage is incomplete, requiring repeated entry and exit of the vacuum tank for testing. A new method of conjugate optical path is proposed to address thin challenge. The target surface of MTF is conjugated with the focal plane of the multi-axis consistency through high-precision calibration, and placed on the focal plane of the parallel light tube. A reflector is set in the conjugated optical path, and the mirror is moved in and out through the method of structural reference positioning, which can achieve simultaneous measurement of multi-axis and MTF under different working conditions. Greatly improving the testing efficiency of laser rangefinder system in vacuum environment.