SYMPOSIA PAPER Published: 01 January 1988

Wavelength Dependence of Edge Filter Absorption


Laser isotope separation and free electron laser programs have driven the need for optical coatings which function in environments of high average power density. Low absorption is the key requirement for these coatings to prevent catastrophic laser damage and to minimize wavefront deformation caused by localized heating of the coating and substrate. Dichroic edge filters have been utilized in wavelength separation applications; however, the intrinsic absorption of these designs at the edge limits their power handling capability for closely spaced wavelengths. In order to fully understand the absorption behavior and to optimize the performance of these designs, measurement of absorption as a function of wavelength has been undertaken, with particular emphasis on the transition region.

The absorption measurements have been performed with a calorimeter which utilizes a matched thermistor bridge and an ultra-precision instrumentation amplifier in conjunction with both discrete and tunable laser sources. Several types of edge filter coatings have been measured. These measurements have been performed over the wavelength region from the stopband through the edge region into the passband. This empirical data is compared to theoretical predictions.

Author Information

Basegio, LJ
von Gunten, MK
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Developed by Committee: F01
Pages: 257–264
DOI: 10.1520/STP24430S
ISBN-EB: 978-0-8031-5033-1
ISBN-13: 978-0-8031-4481-1