Lab demonstration of the hybrid Doppler wind lidar (HDWL) transceiver

The recommended design approach for the 3D Tropospheric Winds mission is a hybrid Doppler lidar which combines the best elements of both a coherent aerosol Doppler lidar operating at 2 μm and a direct detection molecular Doppler lidar operating at 0.355 μm. In support of the mission, we built a novel, compact, light-weighted multi-field of view transceiver where multiple telescopes are used to cover the required four fields of view. A small mechanism sequentially selects both the “transmit” and “receive” fields of view. The four fields are combined to stimulate both the 0.355 μm receiver and the 2 μm receiver. This version is scaled (0.2 m diameter aperture) from the space-based version but still demonstrates the feasibility of the hybrid approach. The primary mirrors were conventionally light-weighted and coated with dielectric, high reflectivity coatings with high laser damage thresholds at both 2 μm and 0.355 μm. The mechanical structure and mounts were fabricated from composites to achieve dimensional stability while significantly reducing the mass. In the laboratory, we demonstrated the system level functionality at 0.355 μm and at 2 μm, raising the Technology Readiness Level (TRL) from 2 to 4.