Borysow J, Golnabi H, Taylor RH, Keto JW. Techniques for measuring small changes in the intensity of a pulsed laser.
APPLIED OPTICS 1992;
31:2814-2819. [PMID:
20725215 DOI:
10.1364/ao.31.002814]
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Abstract
Several techniques are described that compensate for the pulse-to-pulse laser fluctuations that occur when small absorption or gain measurements are taken with pulsed lasers. The best approach tested used two matched diodes that were mounted in a bridge circuit with their bias batteries. One diode was illuminated by a single beam, and a second was illuminated by a reference beam. The bridge circuit output forms the difference in the two laser intensities. Using pulsed lasers with 8-ns widths, we observed that the error in subtraction was 0.01% of the pulse area. This was only 1.5 times the shot noise of the pulses. The technique is examined for application to Raman-induced Kerr-effect spectroscopy, in which difficulties arise because of the use of polarization-sensitive detection.
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