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US 4,229,066 AGranted
Visible transmitting and infrared reflecting filter
AssigneeOptical Coating Laboratory, Inc.
InventorsJames D. Rancourt, William T. Beauchamp
Life of this patent
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AssigneeOptical Coating Laboratory, Inc.
InventorsJames D. Rancourt, William T. Beauchamp
Estimating the term…
Visible transmitting and infrared reflecting filter having a substrate formed of a material capable of transmitting visible light or absorbing visible light and having a surface and a coating carried by the surface of the substrate. The coating comprises at least one period of a multilayer stack which is reflecting in the infrared and transmitting at shorter wavelengths. The period is formed of a plurality of layers of high and low index materials with alternate layers being formed of materials having a high index of refraction and the other layers being formed of materials having a low index of refraction. At least one anti-reflection layer is disposed between adjacent layers of the period for matching the layers of the period to each other in the visible so that the transmission of the filter is relatively high over a relatively wide wavelength band at shorter wavelengths while maintaining high reflection and low absorption at the longer wavelengths.
In a filter which is reflecting at a longer wavelength region and transmitting over a wide band shorter wavelength region, a substrate having a surface, and a coating carried by the surface comprising at least one period which is reflecting at longer wavelengths and transmitting in a wide band of shorter wavelengths, each period being formed of a plurality of thick layers of high and low index materials with alternate layers being formed of a material having a high index of refraction and other layers being formed of a material having a low index of refraction, at least one thin anti-reflection layer disposed between adjacent thick layers for matching the thick layers of the period to each other in the shorter wavelength region so that the transmission of the filter is relatively high in the shorter wavelength region while maintaining high reflection and low absorption in the longer wavelength region.
Dependencies are inferred from the claim text.