Quad-directional coaxial telescope for non-scanning common-path wind LiDAR

Wind LiDAR systems employ the optical Doppler effect to measure radial wind velocities by detecting frequency shifts between transmitted laser pulses and backscattered echoes from atmospheric aerosols. The optical system in wind LiDAR determines measurement performance while governing system dimensions and cost. For non-scanning configurations, achieving optimal performance-cost-size trade-offs remains the primary engineering challenge. To address the challenge, we designed and fabricated a quad-directional coaxial telescope prototype for non-scanning common-path wind LiDAR. The quad-lens configuration achieves an F/3.9, a 15° field of view, and a 7.802 µm spot diameter, balancing manufacturing feasibility and optical performance. Thermal-mechanical stability and fabrication tolerances were addressed during optimization. Wavefront distortion was experimentally quantified below λ/14 across all four channels using phase-shifting Fizeau interferometry, confirming compliance with coaxial alignment standards. Field experiments demonstrated 3-D wind vector measurement at ranges exceeding 400 m without scanning. These results validate the proposed quad-directional coaxial telescope as a high-performance, compact, and cost-effective optical transceiver solution for non-scanning common-path wind LiDAR implementations.