25 June 2003 High-sensitivity scatterometer with a bidirectional ring laser
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Proceedings Volume 4969, Laser Resonators and Beam Control VI; (2003) https://doi.org/10.1117/12.502747
Event: High-Power Lasers and Applications, 2003, San Jose, CA, United States
Abstract
We present a technique for the absolute measurement of very low-level scattering. The method is absolute in that it relies on fundamental physics and does not require calibration against standards maintained by the National Institute of Standards. In a bi-directional mode-locked ring laser, a difference in longitudinal mode frequency between the two senses of circulation of the intracavity pulses can be measured as a beat note between the corresponding outputs. A very small amount of light backscattered by a sample (located at the pulse crossing) from one sense of circulation into the other, causes the beat note to vanish. The threshold in mode frequency difference that causes locking is a measure of the scattering amplitude.
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Rafael Quintero-Torres, Rafael Quintero-Torres, M. Navarro, M. Navarro, Mark R. Ackermann, Mark R. Ackermann, Jean-Claude Diels, Jean-Claude Diels, } "High-sensitivity scatterometer with a bidirectional ring laser", Proc. SPIE 4969, Laser Resonators and Beam Control VI, (25 June 2003); doi: 10.1117/12.502747; https://doi.org/10.1117/12.502747
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