Correction of the Doppler Velocity of the NOAA Mini-Doppler Lidar for Ship Motion Technical memo

摘要

The NOAA/ETL Mini-MOPA lidar has been deployed on research vessels. The lidar's measured Doppler velocity requires correction for the ship motion. The lidar consists of many optical elements fixed on an optical table; those elements are therefore constrained to move together as a rigid body. The lidar also has a periscope containing several mirrors, including a scanning mirror for directing the light beam into the atmosphere. That periscope is itself a rigid body that can rotate relative to the optical table. Rigid-body constraints are used to demonstrate that it is only the velocity of the final mirror in a sequence of mirrors that determines the Doppler shift relative to the light source. It is demonstrated that no matter how many internal mirrors there may be, for reflections entirely upon the optical table, the frequency measured by the detector equals that emitted by the source.