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Proceedings Paper

Identification and removal of high-frequency temporal noise in a Nd:YAG macro-pulse laser assisted with a diagnostic streak camera
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Paper Abstract

This paper discusses the use of a reference streak camera (RSC) to diagnose laser performance and guide modifications to remove high frequency noise from Bechtel Nevada’s long-pulse laser’s output. The upgraded laser used now exhibits less than 0.1% high frequency noise in cumulative spectra, exceeding NIF calibration specifications. ICF experiments require full characterization of streak cameras over a wide range of sweep speeds (10 ns to 480 ns). This paradigm of metrology poses stringent spectral requirements on the laser source for streak camera calibration. Recently, Bechtel Nevada worked with a laser vendor to develop a high performance, multi-wavelength Nd:YAG laser to meet NIF calibration requirements. For a typical NIF streak camera with a 4096x4096 pixel CCD, flat field calibration at 30 ns requires a smooth laser spectrum over 33 MHz to 68 GHz. Streak cameras are the appropriate instrumentation for measuring laser amplitude noise at very high frequencies since the upper end spectral content is beyond the frequency response of typical optoelectronic detectors for a single shot pulse. The SC was used to measure a similar laser at its second harmonic wavelength (532 nm) establishing baseline spectra for testing signal analysis algorithms. The RSC was then used to measure the custom calibration laser. In both spatial-temporal measurements and cumulative spectra, 6~8 GHz oscillations were identified. The oscillation was diagnosed as inter-surface reflections between amplifiers. In addition, RSC spectral data changes were found due to temperature instabilities in the seeding laser. Upgrades were made on the findings and high frequency noises were removed from the laser output.

Paper Details

Date Published: 17 March 2005
PDF: 12 pages
Proc. SPIE 5580, 26th International Congress on High-Speed Photography and Photonics, (17 March 2005); doi: 10.1117/12.567582
Show Author Affiliations
Kent A. Marlett, Bechtel Nevada (United States)
Ke-Xun Sun, Bechtel Nevada (United States)

Published in SPIE Proceedings Vol. 5580:
26th International Congress on High-Speed Photography and Photonics
Dennis L. Paisley; Stuart Kleinfelder; Donald R. Snyder; Brian J. Thompson, Editor(s)

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