Open AccessCamera-based speckle noise reduction for 3-D absolute shape measurements
Author(s) -
Hao Zhang,
Robert Kuschmierz,
Jürgen Czarske,
Andreas Fischer
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.012130
Subject(s) - speckle pattern , optics , physics , doppler effect , speckle noise , position (finance) , superposition principle , speckle imaging , detector , metrology , measurement uncertainty , laser doppler velocimetry , noise (video) , computer science , artificial intelligence , finance , quantum mechanics , astronomy , economics , image (mathematics) , medicine , blood flow
Simultaneous position and velocity measurements enable absolute 3-D shape measurements of fast rotating objects for instance for monitoring the cutting process in a lathe. Laser Doppler distance sensors enable simultaneous position and velocity measurements with a single sensor head by evaluating the scattered light signals. The superposition of several speckles with equal Doppler frequency but random phase on the photo detector results in an increased velocity and shape uncertainty, however. In this paper, we present a novel image evaluation method that overcomes the uncertainty limitations due to the speckle effect. For this purpose, the scattered light is detected with a camera instead of single photo detectors. Thus, the Doppler frequency from each speckle can be evaluated separately and the velocity uncertainty decreases with the square root of the number of camera lines. A reduction of the velocity uncertainty by the order of one magnitude is verified by the numerical simulations and experimental results, respectively. As a result, the measurement uncertainty of the absolute shape is not limited by the speckle effect anymore.