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US3936136A
Expired / Lapsed
US
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Multilayer anti-reflection film for ultraviolet rays
Assignee: Nikon Corp
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Filing: 1973-11-19
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Granted: 1976-02-03
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Expires: 1993-11-19
Abstract
Abstract A three-layer anti-reflection film for ultraviolet range comprises a first layer having a refractive index n 1 determined so as to provide a great dispersion effect in the peripheral range, a second layer having a refractive index n 2 , and a third layer having a refractive index n 1 . The three layers are arranged symmetrically. The first and third layers are provided with an asymmetry so that an intended refractive index n* for the ultraviolet range from 200mμ to 400mμ may be obtained. The film has a predetermined optical thickness.
Inventors
- 👤 Hideo Ikeda
- 👤 Hideki Akasaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:25
CPC Classifications
G; G02; G02B; G02B1/00; G02B1/10; G02B1/11; G02B1/113; G02B1/115; G02B5/00; G02B5/20; G02B5/28; G02B5/285; G02B5/286; G02B5/283
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
277 words
An anti-reflection film for ultraviolet rays comprising: a substrate having a refractive index in the range of 1.6- 1.4 and being transparent to the ultraviolet range; and a three-layer film consisting of a. a first-layer having a refractive index n 1 in the range of 1.3- 1.5 and an optical thickness n 1 d 3 and being adjacent to air, where d 3 is a physical thickness of the first layer, b. a second layer adjacent to said first layer and having a refractive index n 2 in the range of 1.6-1.7 and an optical thickness n 2 d 2 , where d 2 is a physical thickness of the second layer, and c. a third layer disposed between said substrate and said second layer and having a refractive index (n 1 + Δn) and an optical thickness (n 1 + Δn)d 1 , wherein Δn has the relation: ##EQU30## n.sub.1 d.sub.3 = (n.sub.1 + Δn)d.sub.1, and Δn > 0, and d 1 is a physical thickness of the third layer, said optical thickness of said three layers satisfying the following relation: ##EQU31## where λs is the center wavelength within the ultraviolet range and m is integer (1,2, 3 . . . . . . . . . . ), and the following relation: ##EQU32## where ##EQU33## and λ is a specific wavelength in the far peripheral range of 450mμ-500mμ or 150mμ-180mμ, wherein an equivalent refractive index N of said three-layer film is in the range of 1.35-1.3 for the central ultraviolet range (225mμ - 350mμ), less than 1.3 for the peripheral range (200mμ - 225mμ and 350mμ -400mμ) and nearly zero at the specific wavelength λ.
Claim 2
Dependent Claim
277 words
An anti-reflection film for ultraviolet rays comprising: a substrate having a refractive index in the range of 1.6- 1.4 and being transparent to the ultraviolet range; and a three-layer film consisting of a. a first-layer having a refractive index n 1 in the range of 1.3- 1.5 and an optical thickness n 1 d 3 and being adjacent to air, where d 3 is a physical thickness of the first layer, b. a second layer adjacent to said first layer and having a refractive index n 2 in the range of 1.6-1.7 and an optical thickness n 2 d 2 , where d 2 is a physical thickness of the second layer, and c. a third layer disposed between said substrate and said second layer and having a refractive index (n 1 + Δn) and an optical thickness (n 1 + Δn)d 1 , wherein Δn has the relation: ##EQU30## n.sub.1 d.sub.3 = (n.sub.1 + Δn)d.sub.1, and Δn > 0, and d 1 is a physical thickness of the third layer, said optical thickness of said three layers satisfying the following relation: ##EQU31## where λs is the center wavelength within the ultraviolet range and m is integer (1,2, 3 . . . . . . . . . . ), and the following relation: ##EQU32## where ##EQU33## and λ is a specific wavelength in the far peripheral range of 450mμ-500mμ or 150mμ-180mμ, wherein an equivalent refractive index N of said three-layer film is in the range of 1.35-1.3 for the central ultraviolet range (225mμ - 350mμ), less than 1.3 for the peripheral range (200mμ - 225mμ and 350mμ -400mμ) and nearly zero at the specific wavelength λ.
Claim 3
Dependent Claim
76 words
An anti-reflection film according to claim 1, wherein the first layer of said three-layer film is made of a material selected from the group consisting of MgF 2 and LiF; the second layer is made of a fluoride selected from the group consisting of NdF 3 and LaF 3 ; the third layer is made of cryolite; and the substrate is made of a material selected from the group consisting of CaF 2 and Silica glass.
Claim 4
Dependent Claim
34 words
An anti-reflection film according to claim 1, wherein a fourth layer having an optical film thickness λs/4 is inserted between said third layer and said substrate for correcting the refractive index of said substrate.
Claim 5
Dependent Claim
267 words
An anti-reflection film for comprising a substrate having a refractive index of 1.6-1.4 and being transparent to ultraviolet rays; and a three-layer film consisting of a. a first-layer being adjacent to air, and having a refractive index n 1 in the range 1.3-1.5 and optical index thickness n 1 d 3 , where d 3 is a physical thickness of the first layer, b. a second layer being adjacent to said first layer and having a refractive index n 2 in the range 1.6-1.7 and an optical thickness n 2 d 2 . where d 2 is a physical thickness of the second layer, and c. a third layer disposed between said substrate and said second layer and having a refractive index (n 1 + Δ n) and an optical thickness (n 1 + Δ n)d 1 , where Δn satisfies the relation ##EQU34## n 1 d 3 = (n 1 + Δ n) d 1 and Δn ≢ 0, and d 1 is an optical thickness of the third layer, each layer of said three-layer film satisfying the following relation: ##EQU35## where λ s is the central wavelength within the ultra-violet range, m is an integer, and the following relation: |cosG|.sup.≳ n.sub.1 /(n.sub.1 + n.sub.2) where ##EQU36## λ is a specific wavelength in the far peripheral range of 450mμ-500mμ and 150mμ -180mμ, and wherein an equivalent refractive index N of said three-layer film is in the range of 1.35-1.3 for the central ultraviolet range (225mμ-350mμ) and less than 1.3 in the peripheral range (200mμ - 225mμ and 350mμ-400mμ) and nearly zero at the specific wavelength λ.
Claim 6
Dependent Claim
267 words
An anti-reflection film for comprising a substrate having a refractive index of 1.6-1.4 and being transparent to ultraviolet rays; and a three-layer film consisting of a. a first-layer being adjacent to air, and having a refractive index n 1 in the range 1.3-1.5 and optical index thickness n 1 d 3 , where d 3 is a physical thickness of the first layer, b. a second layer being adjacent to said first layer and having a refractive index n 2 in the range 1.6-1.7 and an optical thickness n 2 d 2 . where d 2 is a physical thickness of the second layer, and c. a third layer disposed between said substrate and said second layer and having a refractive index (n 1 + Δ n) and an optical thickness (n 1 + Δ n)d 1 , where Δn satisfies the relation ##EQU34## n 1 d 3 = (n 1 + Δ n) d 1 and Δn ≢ 0, and d 1 is an optical thickness of the third layer, each layer of said three-layer film satisfying the following relation: ##EQU35## where λ s is the central wavelength within the ultra-violet range, m is an integer, and the following relation: |cosG|.sup.≳ n.sub.1 /(n.sub.1 + n.sub.2) where ##EQU36## λ is a specific wavelength in the far peripheral range of 450mμ-500mμ and 150mμ -180mμ, and wherein an equivalent refractive index N of said three-layer film is in the range of 1.35-1.3 for the central ultraviolet range (225mμ-350mμ) and less than 1.3 in the peripheral range (200mμ - 225mμ and 350mμ-400mμ) and nearly zero at the specific wavelength λ.
Claim 7
Dependent Claim
36 words
An anti-reflection film according to claim 4, wherein the optical thickness n 1 d 3 , n 2 d 2 , (n 1 + Δn)d 1 of said first, second and third layers are λs/4, respectively.
Claim 8
Dependent Claim
59 words
An anti-reflection film according to claim 5, wherein said first layer is made of a material selected from the group consisting of LiF, cryolite, MgF 2 and CaF 2 ; said second layer is made of a fluoride selected from the group consisting of LaF 3 and NdF 3 ; said third layer is made of ThF 3 .
Claim 9
Dependent Claim
194 words
An anti-reflection film for ultraviolet rays comprising: a first layer having a refractive index n 1 in the range 1.3- 1.5 and an optical thickness n 1 d 1 equal to λs/4, where d 1 is a physical thickness of the first layer and λ s is the center wavelength within the ultraviolet range, a second layer adjacent said first layer and having a refractive index n 2 in the range 1.6- 1.7 and an optical thickness n 2 d 2 equal to λs/2, where d 2 is a physical thickness of the second layer, a substrate adjacent to said second layer and having a refractive index equal to n 1 , wherein the optical film thickness satisfy the relation: ##EQU37## cosG ≈ √ n 1 / (n 1 + n 2 ) where ##EQU38## and λ is a specific wavelength in the peripheral range of 450mμ - 550mμ and 150mμ - 180mμ, wherein an equivalent refractive index N of said anti-reflection film is in the range of 1.35-1.3 for the central ultraviolet range (225mμ-350mμ) and less than 1.3 for the peripheral range (200mμ-225mμ and 350mμ-400mμ), and nearly zero at the specific wavelength λ.
Claim 10
Dependent Claim
194 words
An anti-reflection film for ultraviolet rays comprising: a first layer having a refractive index n 1 in the range 1.3- 1.5 and an optical thickness n 1 d 1 equal to λs/4, where d 1 is a physical thickness of the first layer and λ s is the center wavelength within the ultraviolet range, a second layer adjacent said first layer and having a refractive index n 2 in the range 1.6- 1.7 and an optical thickness n 2 d 2 equal to λs/2, where d 2 is a physical thickness of the second layer, a substrate adjacent to said second layer and having a refractive index equal to n 1 , wherein the optical film thickness satisfy the relation: ##EQU37## cosG ≈ √ n 1 / (n 1 + n 2 ) where ##EQU38## and λ is a specific wavelength in the peripheral range of 450mμ - 550mμ and 150mμ - 180mμ, wherein an equivalent refractive index N of said anti-reflection film is in the range of 1.35-1.3 for the central ultraviolet range (225mμ-350mμ) and less than 1.3 for the peripheral range (200mμ-225mμ and 350mμ-400mμ), and nearly zero at the specific wavelength λ.
References Cited (Backward Citations)
US3738732A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-02-02 | 1979-08-04 | 1980-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-02 | 1983-08-04 | 1984-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-02 | 1987-08-04 | 1988-02-03 | $7700.00 | Window Closed / Lapsed |