Laser Radiance Measurements.
Research and development rept. 1 Jul 68-1 Jul 69,
NAVAL ELECTRONICS LAB CENTER SAN DIEGO CA
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Beam radiance or radiant brightness for a laser is defined and discussed, and the radiometric quantities required to discuss radiance measurement are defined. The importance of etendue is emphasized. The divergence and etendue of a fundamental spatial mode for a laser cavity are found and expressions for the near field and far field of this spatial mode are given. The etendue of higher order spatial modes is compared to the fundamental. The far-field divergence and etendue are given for various aperture illumination functions, and the conceptual fuzziness in comparison of beam divergence to that of a diffraction-limited beam is pointed out. The elegant divergence measurement technique of Boyden is discussed and applied to determine the radiance of a Q-switched Nd glass laser with a peak radiance of the order of 10 to the 14th power Wsq cm sr and an integrated peak radiance of 10 to the 7th power Jsq cm sr. Author
- Lasers and Masers