title: Lidar frequency modulation vibrometry in the presence of speckle.
abstract: We report laboratory target vibration measurements that use an easily aligned and adjusted fiber-based 1.5-microm heterodyne lidar. The targets are simple spherically curved retroreflectors with well-controlled vibration frequencies and amplitudes. A rotating ground-glass screen creates Gaussian speckle. We wish to understand the modulated and fast-fading lidar returns seen from real target. We frequency demodulated the recorded laboratory data by phase differencing to provide estimates of dphi/dt, where phi is the phase of the received carrier-plus-noise phasor. Experimental results for signal strength and signal-to-noise ratio, for specific target modulation parameters, agree well with our recently developed dphi/dt correlation-function theory.
authors.affiliation: Department of Optronics, QinetiQ, St. Andrews Road, Malvern WR14 3PS, UK. chill@qinetiq.com
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Hill
authors.forename: Michael
authors.initials: M
authors.lastname: Harris
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Ridley
authors.forename: Eric
authors.initials: E
authors.lastname: Jakeman
authors.forename: Peter
authors.initials: P
authors.lastname: Lutzmann