Elemental semiconductor mirror
First Claim
1. A high luminous reflectance mirrored substrate comprising:
- a glass substrate having first and second surfaces;
a reflector coated upon said second surface of said glass substrate, said second surface adapted to face away from a source of light to be reflected;
said reflector comprising a multilayer thin film stack comprising a first thin film layer of an elemental semiconductor which is farthest from said second surface of said glass substrate and has a refractive index of greater than 3.0, a second thin film layer which is closest to said second surface of said glass substrate, a third thin film layer disposed between said first thin film layer and said second thin film layer, said third thin film layer having a refractive index between about 1.3 and 2.7, said second thin film layer having a refractive index greater than said third thin film layer;
said reflector having a light reflectance of at least about 60% of light incident thereon at the wavelength region of about 550 nanometers and being achromatic; and
a light absorbing coating disposed on said reflector coated second surface of said glass substrate.
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Abstract
An elemental mirror having a high luminous reflectance of at least about 60% of incident light at the wavelength region of about 550 nanometers and being acromatic includes a substrate coated with a reflector comprising a multilayer thin film stack. The thin film stack comprises a first thin film layer of an elemental semiconductor which is closest to the first surface of the glass substrate and has a refractive index of greater than 3.0, a second thin film layer which is farthest from the first surface of the glass substrate, and a third thin film layer disposed between the first thin film layer and the second thin film layer, the third thin film layer having a refractive index between about 1.3 and 2.7, the second thin film layer having a refractive index greater than the third thin film layer. A light absorbing coating is included on at least one surface of the substrate and a layer of the reflector, the light absorbing coating absorbing light transmitted by the reflector coated substrate. Alternately, the multilayer thin film stack may be coated on the second surface of the glass substrate with the light absorbing coating disposed on the reflector coated second surface of the glass substrate. The elemental semiconductor may comprise silicon or germanium. The light absorbing coating may comprise one of a paint, a lacquer, a tape, a ceramic, a hot melt plastic, a resinous plastic, a plastisol, or an epoxy material.
339 Citations
29 Claims
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1. A high luminous reflectance mirrored substrate comprising:
a glass substrate having first and second surfaces; a reflector coated upon said second surface of said glass substrate, said second surface adapted to face away from a source of light to be reflected; said reflector comprising a multilayer thin film stack comprising a first thin film layer of an elemental semiconductor which is farthest from said second surface of said glass substrate and has a refractive index of greater than 3.0, a second thin film layer which is closest to said second surface of said glass substrate, a third thin film layer disposed between said first thin film layer and said second thin film layer, said third thin film layer having a refractive index between about 1.3 and 2.7, said second thin film layer having a refractive index greater than said third thin film layer; said reflector having a light reflectance of at least about 60% of light incident thereon at the wavelength region of about 550 nanometers and being achromatic; and a light absorbing coating disposed on said reflector coated second surface of said glass substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
Specification