Liquid Crystal on Silicon Non-Mechanical Steering of a Laser Vibrometer System

摘要

This research examined the possibility of using a non-mechanical beam steering device to steer the beam of a coherent laser radar system. Non- mechanical beam steering devices offer many advantages in size, weight, power requirements, and steering speeds. Additionally, non-mechanical beam steering devices present the capabilities of splitting a single beam into multiple beams as well as beam forming and expanding. The coherent laser radar system used was a Laser Vibrometer System. The beam of the laser vibrometer was steered from 0 mrad to 3 mrad at 1 mrad increments using the liquid crystal on silicon (LCOS) device. The laser vibrometer was able to accurately measure a 2500 Hz vibration target on the steered vibrometry beam at all steered angles. A small LCOS noise signal was detected. The LCOS noise spectrum was determined to be consistent and predictable located at 60 Hz harmonics and was successfully subtracted from the signal. The LCOS device was used to split the vibrometry beam into 2 separate beams. The vibrometer was able to accurately measure two simultaneous independent target signals over the split beam.