A coherent three-dimensional (angle–angle–range) lidar imager using a master-oscillator-power-amplifier concept and operating at a wavelength of 1.5 μm 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-μJ 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.
© 2005 Optical Society of America
Revised Manuscript: September 9, 2004
Manuscript Accepted: September 9, 2004
Published: January 10, 2005
Guy N. Pearson, Kevin D. Ridley, and David V. Willetts, "Chirp-pulse-compression three-dimensional lidar imager with fiber optics," Appl. Opt. 44, 257-265 (2005)