Image distortions during the propagation of optical beam in the turbulent atmosphere are provoked. Exposure time has effect on the space distribution characteristics of light image in the focal-plane CCD or CMOS sensor. The effect of exposure time on the spot size and shape is analyzed both theoretically and experimentally. The expression of spot size variable with exposure time has been developed from the angle-of-arrival fluctuation by the longitudinal and transverse components. In an optical free-space laser transmission experiment over a three-month period, measurements of spot size at variable exposure times are shown. Theoretical and experimental results illuminate the important point that the effect of exposure time must be considered for the optical design. The results show that the spot size decreases with exposure time increasing. A rapid decrease is showed in the spot size for short exposure times up to about 20msec.

Date Published: 11 January 2007
PDF: 9 pages
Proc. SPIE 6279, 27th International Congress on High-Speed Photography and Photonics, 62792O (11 January 2007); doi: 10.1117/12.725350

Published in SPIE Proceedings Vol. 6279:
27th International Congress on High-Speed Photography and Photonics
Xun Hou; Wei Zhao; Baoli Yao, Editor(s)