US3706485A
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Multi-layer anti-reflection coatings using intermediate layers having monotonically graded refractive index
Assignee: Rank Organization Ltd
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Filing: 1971-02-04
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Granted: 1972-12-19
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Expires: 1991-02-04
Abstract
Abstract An anti-reflection multiple layer coating is formed on a transparent substrate by successive deposition of an inner layer, at least three intermediate layers and an outer layer, the optical thicknesses of the inner and outer layers being approximately lambda /4 and the overall optical thickness of the coating being approximately lambda , where lambda is a reference wavelength within the band of wavelengths over which reflection is to be reduced. The intermediate layers are formed with progressively decreasing refractive indices from the innermost to the outermost intermediate layers, either as a number of separate layers or as a single layer of graded refractive index.
Inventors
- 👤 John Anthony Fawcett
- 👤 William Hugh Gray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:49
CPC Classifications
C; C03; C03C; C03C17/00; C03C17/34; C03C17/3411; C03C17/3417; C03C17/3429; C03C17/3447; C03C17/3452; G; G02; G02B; G02B1/00; G02B1/10; G02B1/11; G02B1/113; G02B1/115
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
22 words
A coating according to claim 1, wherein said reference wavelength lies at or close to the harmonic mean of said wavelength band.
Claim 2
Dependent Claim
18 words
A coating according to claim 1, wherein the outer layer has a refractive index between 1.25 and 1.45.
Claim 3
Dependent Claim
23 words
A coating according to claim 1, wherEin the difference between the refractive indices of any two adjacent intermediate layers is substantially the same.
Claim 4
Dependent Claim
40 words
A coating according to claim 1, wherein the refractive index of the inner layer is approximately equal to ng1/2 .nL , where ng is the refractive index of the substrate and nL is the refractive index of the outer layer.
Claim 5
Dependent Claim
23 words
A coating according to claim 5, wherein the refractive index of the inner layer lies between 0.9 ng1/2 .nL and 1.1 ng1/2.nL inclusive.
Claim 6
Dependent Claim
88 words
An anti-reflection coating on a transparent substrate, said coating comprising an inner layer closest to said substrate, an outer layer farthest from said substrate, and an inhomogeneous intermediate layer having a graded refractive index which increases progressively from the outer to the inner layer, the optical thicknesses of the outer and inner layers being each substantially lambda /4, and the overall optical thickness of the coating being substantially lambda , where lambda is a reference wavelength lying within a wavelength band over which reflection is to be reduced.
Claim 7
Dependent Claim
18 words
A coating according to claim 7, in which said substrate has a refractive index between 1.40 and 2.00.
Claim 8
Dependent Claim
24 words
A coating according to claim 7, wherein the said reference wavelength is at least approximately equal to the harmonic mean of said wavelength band.
Claim 9
Dependent Claim
18 words
A coating according to claim 7, wherein the outer layer has a refractive index between 1.25 and 1.45.
Claim 10
Dependent Claim
39 words
A coating according to claim 7, wherein the refractive index of the inner layer is approximately equal to ng1/2.nL , where ng is the refractive index of the substrate and nL is the refractive index of the outer layer.
Claim 11
Dependent Claim
94 words
An anti-reflection coating on a transparent substrate, said coating comprising an inner layer closest to said substrate, an outer layer farthest from said substrate, and a number N of at least three and less than six intermediate layers designated L1, L2 . . . LN, starting from the outermost intermediate layer L1 immediately adjacent the outer layer Lo, the successive intermediate layers between the outer and inner layers having progressively increasing refractive indices nL , nL , . . . , nL and the outer layer having a refractive index nL , such that:
Claim 12
Dependent Claim
104 words
An anti-reflection coating on a transparent substrate, said coating comprising an inner layer closest to said substrate, an outer layer farthest from said substrate and a number N greater than five intermediate layers designated L1, L2 . . . LN, starting from the outermost intermediate layer L1 immediately adjacent the outer layer Lo, the successive intermediate layers between the outer and inner layers having progressively increasing refractive indices nL , nL , . . . , nL and the outer layer having a refractive index nL , such that: 3.33(1.24nL -1.00)>nL >2.72(1.24nL - 1.00) (2) 3.55(1.16nL - 1.00)>nL >2.90(1.16nL - 1.00)(4)0.30>(nL -nL )>0.05 (6)
Claim 13
Dependent Claim
20 words
A coating according to claim 12, wherein the refractive index nL of the outer layer is between 1.25 and 1.45.
Claim 14
Dependent Claim
20 words
A coating according to claim 13, wherein the refractive inDex nL of the outer layer is between 1.25 and 1.45.
Claim 15
Dependent Claim
23 words
A coating according to claim 12, wherein the refractive index of the inner layer lies between 0.9 ng1/2.nL and 1.1 ng 1/2.nL inclusive.
Claim 16
Dependent Claim
22 words
A coating according to claim 13, wherein the refractive index of the inner layer lies between 0.9 ng1/2.nL and 1.1 ng1/2.nL inclusive.
Claim 17
Dependent Claim
17 words
A coating according to claim 12, wherein said substrate has a refractive index between 1.40 and 2.00.
Claim 18
Dependent Claim
17 words
A coating according to claim 13, wherein said substrate has a refractive index between 1.40 and 2.00.
Claim 19
Dependent Claim
88 words
An anti-reflection coating according to claim 13, wherein the outer layer has refractive index nL of 1.38 and there are eleven intermediate layers L1 to L11 with refractive indices nL to nL as follows: nL 1.95 nL 1.97 nL 1.99 nL 2.01 nL 2.03 nL 2.05 nL 2.07 nL 2.09 nL 2.11 nL 2.13 nL 2.15 each intermediate layer having a thickness of 0.0455 lambda ( lambda 495nm), and wherein the inner layer has a refractive index of 1.66, and said substrate has a refractive index of 1.45.
Claim 20
Dependent Claim
88 words
An anti-reflection coating according to claim 13, wherein the outerlayer has a refractive index nL of 1.38 and there are eleven intermediate layers L1 to L11 with refractive indices nL to nL as follows: nL 1.95 nL 1.97 nL 1.99 nL 2.01 nL 2.03 nL 2.05 nL 2.07 nL 2.09 nL 2.11 nL 2.13 nL 2.15 each intermediate layer having a thickness of 0.0455 lambda ( lambda 495nm), and wherein the inner layer has a refractive index of 1.86 and said substrate has a refractive index of 1.81.
Claim 21
Dependent Claim
92 words
An anti-reflection coating according to claim 13, wherein the outer layer has a refractive index nL of 1.38 and there are thirteen intermediate layers L1 to L13 with refractive indices nL to nL as follows: nL 2.08 nL 2.10nL 2.12 nL 2.14 nL 2.16 nL 2.18 nL 2.20 nL 2.22 nL 2.24 nL 2.26 nL 2.28 nL 2.30 nL 2.32 each intermediate layer having a thickness of 0.0385 lambda ( lambda 495nm) and wherein the inner layer has a refractive index of 1.75, and said substrate has a refractive index of 1.52.
Claim 22
Dependent Claim
85 words
An anti-reflection coating according to claim 13, wherein the outer layer has a refractive index nL of 1.38 and there are nine intermediate layers L1 to L9 with refractive indices nL to nL as follows: nL 1.97 nL 1.98 nL 1.99 nL 2.00 nL 2.01 nL 2.02 nL 2.03 nL 2.04 nL 2.05 each intermediate layer having a thickness of 0.0556 lambda ( lambda 495nm) and wherein the inner layer has a refractive index of 1.66, and said substrate has a refractive index of 1.52.
Claim 23
Dependent Claim
92 words
An anti-reflection coating according to claim 12, wherein the outer layer has a refractive index nL of 1.38 and there are three intermediate layers 1L1 to L3 with refractive indices nL to nL as follows: nL 1.98 nL 2.05 nL 2.12 the first intermediate layer L1 having a thickness of 0.14 lambda ( lambda 495nm) and the other two intermediate layers L2 and L3 having equal thicknesses of 0.18 lambda , and wherein the inner layer has a refractive index 1.75, the coating being applied to a substrate of refractive index 1.60.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-19 | 1976-06-19 | 1976-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-19 | 1980-06-19 | 1980-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-19 | 1984-06-19 | 1984-12-19 | $7700.00 | Window Closed / Lapsed |