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Proceedings Paper

Laser power modulation with wavelength stabilization in multiple exposure laser speckle contrast analysis
Author(s): Tomi Smausz; Dániel Zölei; Béla Hopp
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Paper Abstract

Switching mode intensity modulation had been applied to the illumination of a LASCA system using multiple exposure times to substitute a variable neutral filter, which allows the variation of the exposure time from frame to frame. In most cases the direct current (DC) control of the laser intensity can lead to changes in the wavelength of regular laser diodes. The use of pulsed mode operation can avoid the mode hopping of the laser light while it offers the tuning of the average intensity in a wide range. While operating the camera at a constant integration time, the length of the exposition was varied from 2 ms to 100 ms by changing the duration of the illuminating laser pulse train. The pulse train was built up of 10 pulses, each having the length of 40 μs with variable separation time. The mode stability of the light source was monitored with a spectrometer, meanwhile speckle images of a static scattering surface were recorded as well. This paper demonstrates the usefulness of this technique in a multi-exposure LASCA system for monitoring the changes in the skin perfusion.

Paper Details

Date Published: 11 September 2012
PDF: 6 pages
Proc. SPIE 8413, Speckle 2012: V International Conference on Speckle Metrology, 84131J (11 September 2012); doi: 10.1117/12.978230
Show Author Affiliations
Tomi Smausz, Univ. of Szeged (Hungary)
Dániel Zölei, Univ. of Szeged (Hungary)
Béla Hopp, Univ. of Szeged (Hungary)

Published in SPIE Proceedings Vol. 8413:
Speckle 2012: V International Conference on Speckle Metrology
Ángel Fernandez Doval; Cristina Trillo, Editor(s)

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