Lidar frequency modulation vibrometry in the presence of speckle.
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.
Hill
Christopher A
CA
Department of Optronics, QinetiQ, St. Andrews Road, Malvern WR14 3PS, UK. chill@qinetiq.com
Harris
Michael
M
Ridley
Kevin D
KD
Jakeman
Eric
E
Lutzmann
Peter
P