title: Autofocus technique for three-dimensional imaging, direct-detection laser radar using Geiger-mode avalanche photodiode focal-plane array.
abstract: 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.
authors.affiliation: Department of Physics, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, South Korea.
authors.forename: Min Seok
authors.initials: MS
authors.lastname: Oh
authors.forename: Hong Jin
authors.initials: HJ
authors.lastname: Kong
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Kim
authors.forename: Sung Eun
authors.initials: SE
authors.lastname: Jo