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US 4,281,894 AGranted
Very low absorption, low efficiency laser beamsampler
AssigneeThe Perkin-Elmer Corporation
InventorJayanta K. Guha
Life of this patent
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Abstract
A very low absorption beamsampler for diffracting a very small fraction of a laser beam while specularly reflecting substantially all of the main beam with minimal absorption. The beamsampler comprises a plane mirror surface coated with a high-reflectivity multilayer dielectric coating, the topmost dielectric of which is grooved into a grating and coated with a transparent dielectric having a refractive index very similar, but not the same, as the grooved layer to form a weak phase grating for diffracting a weak first order sampling beam.
Claims6
A very low absorption, low efficiency, laser beamsampler comprising:
- a plane reflective surface;
- a plurality of dielectric pairs overlying said reflective surface, each of said pairs comprised of a first layer of dielectric material having a high refractive index and a second layer of dielectric material having a low refractive index, said first and second layers being deposited in one-quarter wavelength optical thicknesses;
- a shallow groove diffraction grating formed in the top surface of the top layer of the top dielectric pair;
- and
- a protective layer of a third dielectric material applied over said diffraction grating, said third material applied to an optical thickness of substantially one-half wavelength, said third material having an index of refraction similar to, but different than, that of the dielectric material of said top layer of said top dielectric pair.
2 more elements
Dependencies are inferred from the claim text.