Diffractive Effects in the Determination of Damage Thresholds Using Focused Top Hat Beams
Final rept. for period ending Jan 2003
ARMY RESEARCH LAB ADELPHI MD
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An accurate determination of damage thresholds for focal plane elements must correctly account for diffractive effects. This technical note reviews the physics of Fraunhofer diffraction of a top hat beam. It presents a new result. accurate to second order in the subtended solid angle for the encircled energy. It describes in detail the computation of peak and average fluences in the presence of diffraction and it includes a compilation of practical formulae for workers measuring damage threshold fluences.