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Interference Filters and Antireflection Coatings for the Ultraviolet

IP.com Disclosure Number: IPCOM000079210D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Spiller, EA: AUTHOR

Abstract

This description relates to two optical devices for the ultraviolet range between 1100 and 2500 angstroms, both of which use low-loss mirrors. The low-loss mirrors consists of multilayer structures composed, for example, of Al and MgF(2). Low loss is obtained by positioning the Al film into nodes of the standing wave produced by the structure.

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Interference Filters and Antireflection Coatings for the Ultraviolet

This description relates to two optical devices for the ultraviolet range between 1100 and 2500 angstroms, both of which use low-loss mirrors. The low- loss mirrors consists of multilayer structures composed, for example, of Al and MgF(2). Low loss is obtained by positioning the Al film into nodes of the standing wave produced by the structure.

In the first device, two of these mirrors are combined to form an interference filter. Due to the reduced losses in the mirrors, interference filters of very small bandwidth and large-peak transmission become possible.

In the second device, such a mirror is used to produce an antireflective coating for substrate materials which are used as photodetectors (such as Si), Spacer material such as MgF(2) is used between the substrate and the mirror coating, with the thickness of the spacer material and the reflectivity of the mirror adjusted in such a way that a device with zero reflectivity is obtained. A large fraction (more than 85%) of the incident light is absorbed in the photosensitive substrate, if a single film of Al is used as a mirror; this fraction can be increased if more layers are used for the mirror.

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