We demonstrate a simplified dual-comb lidar setup for precision absolute ranging that can achieve a ranging precision at a meter of 2 υm in 140 υs acquisition time. With averaging, the precision drops below 1 micron at 0.8 msec and below 200 nm at 20 ms. The system can measure the distance to multiple targets with negligible dead zones and a ranging ambiguity of 1 meter. The system is much simpler than a previous coherent dual-comb lidar because the two combs are replaced by free-running, saturable-absorber-based femtosecond Er fiber lasers, rather than tightly phase-locked combs, with the entire time base provided by a single 10-digit frequency counter. Despite the simpler design, the system provides a factor of three improved performance over the previous coherent dual comb lidar system.
Citation: Optics Express
Pub Type: Journals
distance measurement, frequency comb, LIDAR