Wide angle optical filters
First Claim
1. A thin-film optical interference filter having high-transmission of blue light and high-reflectance of infrared light, said filter having a predetermined design wavelength, said filter comprising:
- (a) a glass substrate;
(b) a first or bottom coating of a high-refractive index material applied on said substrate, said first coating having a first thickness of less than one-sixteenth of said design wavelength;
(c) a second coating of a low-refractive index material applied on said first coating, said second coating having a second thickness greater than one-sixteenth and less than three-sixteenths of said design wavelength;
(d) a third coating of a high-refractive index material applied on said second coating, said third coating having a third thickness of less than one-sixteenth of said design wavelength; and
(e) a quarterwave stack applied on said third coating, said quarterwave stack including a plurality of layers of alternating high- and low-refractive index materials, said quarterwave stack having a design wavelength being matched approximately to said predetermined design wavelength of said filter.
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Accused Products
Abstract
A thin-film optical interference filter designed and manufactured to have high transmission of blue light and high reflectance of infrared light. The novel feature of this filter rests in the thin-film layer design at the top and bottom of a quarterwave stack and the manufacturing technique by which this thin-film design is deposited. The thin-film layer design suppresses the so called halfwave holes which occur at wide angles of incidence of the incoming light. This desirable effect is achieved by the proper layer thickness and refractive index control in the manufacturing process.
40 Citations
7 Claims
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1. A thin-film optical interference filter having high-transmission of blue light and high-reflectance of infrared light, said filter having a predetermined design wavelength, said filter comprising:
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(a) a glass substrate; (b) a first or bottom coating of a high-refractive index material applied on said substrate, said first coating having a first thickness of less than one-sixteenth of said design wavelength; (c) a second coating of a low-refractive index material applied on said first coating, said second coating having a second thickness greater than one-sixteenth and less than three-sixteenths of said design wavelength; (d) a third coating of a high-refractive index material applied on said second coating, said third coating having a third thickness of less than one-sixteenth of said design wavelength; and (e) a quarterwave stack applied on said third coating, said quarterwave stack including a plurality of layers of alternating high- and low-refractive index materials, said quarterwave stack having a design wavelength being matched approximately to said predetermined design wavelength of said filter. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification