An autofocus technique is proposed for a three-dimensional imaging, direct-detection laser radar system that uses a Geiger-mode avalanche photodiode focal plane array (GmAPD-FPA). This technique is implemented by pointing laser pulses on a target of interest and observing its scattered photon distribution on a GmAPD-FPA. Measuring the standard deviation of the photon distribution on a GmAPD-FPA enables the best focus condition to be found. The feasibility of this technique is demonstrated experimentally by employing a 1×8 pixel GmAPD-FPA. It is shown that the spatial resolution improves when the GmAPD-FPA is located in the best focus position found by the autofocus technique.
© 2010 Optical Society of America
(110.6880) Imaging systems : Three-dimensional image acquisition
Original Manuscript: July 28, 2010
Revised Manuscript: November 11, 2010
Manuscript Accepted: November 13, 2010
Published: December 15, 2010
Min Seok Oh, Hong Jin Kong, Tae Hoon Kim, and Sung Eun Jo, "Autofocus technique for three-dimensional imaging, direct-detection laser radar using Geiger-mode avalanche photodiode focal-plane array," Opt. Lett. 35, 4214-4216 (2010)