Telescope design for 2 μm spacebased coherent wind lidar system

The telescope is a key optical component which largely affects the signal intensity in coherent Doppler Lidar. In the paper the normalized signal to noise ratio(SNR) as a function of range z and diameter D of the telescope is investigated for pulsed coherent wind lidar, then the telescope aperture requirement for 300 km orbit is calculated and presented. After that the initial structure parameters for space-based (40×) off-axis telescope are obtained with the PW method, furthermore, the initial structure has been optimized by the Zemax software. The telescope's RMS wavefront error is optimized to be less than 1/10λ (2 μm), and the tolerance requirement is discussed. The designed structure of the telescope is simple and compact, can be easily applied to other similar fields due to its high portability.