Share Email Print

Proceedings Paper

Preamplifier impulse-response shape-driven shot-noise in direct-detection photon-counting laser radars
Author(s): Douglas G. Youmans
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

The number of photons returning form a target in a given time interval is well described by a negative-binomial distributed random variable. A photomultipler tube (PMT) photon-counting detector is optimal for direct detection, and the number of detected-photon 'electron pulses' produced is also negative-binomially distributed per time bin, with a reduced mean due to the device quantum efficiency. These time distributed electron pulses are amplified and filtered by the preamplifier electronics prior to digitization and signal processing. The voltage output pulse per individual photo-electron event is known as the 'impulse-response- function' of the detector and preamplifier. In this study we employ a typical analog preamplifier filter response, modeled as a Butterworth lowpass filter of order two, which filters a 200 ps wideband PMT input voltage pulse. The random summation of these lowpass voltage impulse-responses, as created by the negative-binomial photon arrival times and random photo-electron creation, is the classical electronic 'shot-noise' random process. We derive numerically the voltage probability density function of this negative- binomial/impulse-response driven shot-noise random process following the stochastic process literature. We also show a technique to include PMT variations in gain, known as the 'pulse height distribution,' and to incorporate Gaussian baseline-noise voltage. Agreement with AMOR experiments is shown to be excellent. In addition, a Monte Carlo realization is presented, using the same impulse-response temporal shape, which also gives excellent agreement with AMOR data and with the analytical/numerical calculations.

Paper Details

Date Published: 19 September 2001
PDF: 14 pages
Proc. SPIE 4377, Laser Radar Technology and Applications VI, (19 September 2001); doi: 10.1117/12.440112
Show Author Affiliations
Douglas G. Youmans, SPARTA, Inc. (United States)

Published in SPIE Proceedings Vol. 4377:
Laser Radar Technology and Applications VI
Gary W. Kamerman, Editor(s)

© SPIE. Terms of Use
Back to Top