Optimal design of the telescope in coherent lidar and detection performance analysis

A fiber laser with pulse energy of 110 mJ, pulse repetition frequency of 20 kHz and pulse width of 300 ns is employed to develop the coherent lidar for wind sensing at 1.55 mm. The specifications of the main components employed to assemble the lidar are listed. By taking the advantage of the principle of backpropagated local oscillator (BPLO), the optimal truncation ratio of the telescope is calculated. The result shows that the optimal antenna efficiency of 0.422 is obtained when the truncation ratio arrives at 0.823. The effect of the aperture of the telescope on the carrier-to-noise ratio (CNR) of the coherent lidar is analyzed on the condition of the optimal truncation ratio. The design parameters of the telescope are optimized. The performance of the lidar is theoretically calculated and listed as follows: detection range is longer than 3 km; wind velocity range is ± 62 m/s; range resolution is 84 m; wind velocity accuracy is better than 0.1 m/s; time resolution is 0.5 s. ©, 2015, Chinese Optical Society. All right reserved.