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Proceedings Paper

Low cost plane parallel plate lateral shearing interferometer for infrared laser beam diagnostics
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Paper Abstract

Few cost-effective methods exist for measuring the wave front of mid- and long-wave infrared beams that span 3-5 and 8-12 μm, respectively. One obvious need within the infrared laser community is the ability to measure the degree of collimation of an infrared laser beam, e.g. that formed by a beam expanding telescope used with a CO2 laser or a system of lenses used to collimate a Quantum Cascade Laser (QCL). An ideal approach for this type of metrology is the use of a lateral shearing interferometer (LSI). An LSI uses various methods to displace ("shear") a beam with respect to itself to create an interferogram that can subsequently be used for diagnosing the wavefront quality of the beam. Since this type of interferometer is of the common path variety, it is insensitive to vibration making it ideal for field applications, where vibration isolation may neither be possible nor practical. In this paper we present and demonstrate, through laboratory measurements and computer ray tracing simulations, a low-cost LSI using a single commercial off-the-shelf uncoated ZnSe window in conjunction with an infrared camera. This plane parallel plate LSI configuration was used to interactively collimate a LWIR beam and also provide quantitative transmitted wavefront error data using static fringe analysis software. We also present a self-contained review of the theory of lateral shearing interferometry, including the necessary design equations as applicable to this LSI configuration, to enable researchers to construct a similar beam diagnostic shearing interferometer from readily available components.

Paper Details

Date Published: 9 May 2009
PDF: 10 pages
Proc. SPIE 7325, Laser Technology for Defense and Security V, 73250X (9 May 2009); doi: 10.1117/12.817416
Show Author Affiliations
Bruce E. Bernacki, Pacific Northwest National Lab. (United States)
Kannan Krishnaswami, Pacific Northwest National Lab. (United States)
Norman C. Anheier, Pacific Northwest National Lab. (United States)

Published in SPIE Proceedings Vol. 7325:
Laser Technology for Defense and Security V
Mark Dubinskii; Stephen G. Post, Editor(s)

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