Alexei A. KAMSHILIN, Serguei V. MIRIDONOV¹, Igor S. SIDOROV, Dmitry V. SEMENOV, and Ervin NIPPOLAINEN

Department of Physics, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland
¹Optics Department, Centro de Investigación Cientifica y de Educación Superior de Ensenada, C.P. 22860, A.P. 360, Ensenada, B.C. Mexico

(Received July 15, 2008; Accepted December 3, 2008)

We present an analysis of statistical properties of dynamic speckles to estimate the limiting accuracy of measurements achievable in a distance sensor using spatially filtered dynamic speckles. The main reason for inaccurate measurements using dynamic speckles is their stochastic nature. It is shown that the average lifetime of dynamic speckles is the key factor defining the measurement accuracy. Main conclusions of the theoretical analysis were confirmed in an experiment carried out with a fast moving rough surface. Special attention is paid to a recently proposed range sensor using dynamic speckles generated by a fast-deflecting laser beam. It is shown that this sensor possesses the best combination of accuracy and response time.

Key words: dynamic speckles, accuracy of measurements, distance measurements, optical sensing, spatial filtering