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US 5,398,133 AGranted
High endurance near-infrared optical window
AssigneeIndustrial Technology Research Institute
InventorsRung-Ywan Tsai, Fang-Chuan Ho
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Abstract
Multilayers of low refractive index amorphous silicon nitride and high refractive index amorphous silicon are interleaved to construct a near-infrared optical filter. For an edge filter, the structure is transparent to near-infrared light and opaque to visible light. For a band-pass filter, the low-pass filter is superimposed with a high-pass filter. Anti-reflection coating can be added to improve the transmittance. These multilayers are deposited with Plasma Enhanced Chemical Vapor Deposition technique.
Claims14
A near infrared optical filter, comprising:
- a substrate which is transparent to visible and near infrared light;
- a first set of refractive index layers composed of amorphous silicon nitride (a-SiNx:H) which is transparent to visible and near-infrared light;
- a second set of layers, having a refractive index greater than that of said first set of layers, composed of material which is transparent to near-infrared light but absorptive to visible light;
- said first set of layers and said second set of layers being interleaved and deposited over said substrate.
1 more element
Dependencies are inferred from the claim text.