Ultrashort Laser Pulse Phenomena, 2nd Edition

580 Selected Applications

“Range gating” is another method to obtain depth information, by measuring

the transit time of the radiation from the source to the object and thereafter to

the detector. If—as is often the case—the source and detector are colocated, the

distance z from source to object is simply c× (roundtrip time)/2. This technique

has been used since World War II for localizing and tracking moving objects.

The resolution has shifted from meter (radar) to centimeter (lidar). Femtosecond

pulses offer the possibility of a depth resolution of a few microns. Another func-

tion of ultrashort range gating is to discriminate against scattering, ...