Reflective overcoat for replicated diffraction gratings

Details Reflective overcoat for replicated diffraction gratings Reflective overcoat for replicated diffraction gratings

1999-03-09

1999-12-07

Henry, Jon

Optical: systems and elements

Diffraction

From grating

359576, 427162, G02B 518, G02B 506

Patent

active

059993189

ABSTRACT:
An extra step for a conventional replica forming process for diffraction gratings used in lasers is described herein. Applicant has discovered that the deterioration of a replica diffraction grating, when used with intense laser light, is accelerated due to small quantities of the radiation leaking through minute fractures in the aluminum reflective coating. Applicant has identified the source of this problem as occurring during the removal of the replica from the master grating. Applicant's improvement to this conventional process is to deposit a thin reflective overcoat of aluminum on the surface of the replica after the replica has been removed from the master and cleaned. The overcoating is performed in a vacuum chamber by sputtering or evaporation. This overcoat is not subjected to any subsequent destructive forces and hence remains relatively opaque. A typical thickness of the overcoat is around 100 nm. An oxide layer is formed over the aluminum and a third layer of aluminum is formed over the oxide.

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