title: Chirp-pulse-compression three-dimensional lidar imager with fiber optics.
abstract: A coherent three-dimensional (angle-angle-range) lidar imager using a master-oscillator-power-amplifier concept and operating at a wavelength of 1.5 microm with chirp-pulse compression is described. A fiber-optic delay line in the local oscillator path enables a single continuous-wave semiconductor laser source with a modulated drive waveform to generate both the constant-frequency local oscillator and the frequency chirp. A portion of this chirp is gated out and amplified by a two-stage fiber amplifier. The digitized return signal was compressed by cross correlating it with a sample of the outgoing pulse. In this way a 350-ns, 10-microJ pulse with a 250-MHz frequency sweep is compressed to a width of approximately 8 ns. With a 25-mm output aperture, the lidar has been used to produce three-dimensional images of hard targets out to a range of approximately 2 km with near-diffraction-limited angular resolution and submeter range resolution.
authors.affiliation: QinetiQ, St. Andrews Road, Malvern WR14 3PS, United Kingdom. gnpearson@qinetiq.com
authors.forename: Guy N
authors.initials: GN
authors.lastname: Pearson
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Ridley
authors.forename: David V
authors.initials: DV
authors.lastname: Willetts