Scintillation-induced jitter of projected light with centroid trackers.
When light radiating from a distant object passes through extended turbulence, the light is scintillated. Such scintillated light may be received by an optical system and passed to a camera in the focal plane, and used to track an object. Such trackers often use centroid trackers. Then a laser or other light may be projected back toward the object, steered by the centroid measured on the tracker. The presence of scintillation on the tracker return will cause a jitter error in the pointing of projected light, if the projected light's intensity differs from that of the incoming scintillation pattern. This error is caused by a lack of full-field conjugation of the tilt component of the received return. This error is considered, for horizontal path conditions, as a difference between centroid tilt and gradient tilt. The estimated error is typically not large, and is estimated by both simulation and analytic means, and these are found to agree for conditions of interest. The possibility of means for correction of this error is discussed briefly.
Holmes
Richard B
RB
Nutronics, Inc., 3357 Chasen Drive, Cameron Park, California 95682, USA. rholmes@nutroninc.com