Laser radar using a 1.55-μm passively Q-switched microchip laser

Abstract

We investigate a laser range finder for obstacle detection in automotive field. This device is based on the use of an eye-safe pulsed microchip laser, emitting near 1.55 micrometer. The technology of solid-state microchip lasers is a good way to obtain a compact, reliable and low cost laser source. Passively Q-switched microchip lasers are of great interest for time of flight range finding: short pulse duration and high peak power have been obtained. A short pulse duration gives good precision and high peak power gives a long range of detection. The distance measurement is obtained with an ASIC chronometer which implements the time-of- flight technique. We also developed reception circuit for start and stop signals and data input/output. The ASIC chronometer is based on two complementary techniques: a clock counter for coarse measurement and multiple slopes generator for fine measurement.