# US 6,720,081 B2 · UV-reflective interference layer system

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- Number: US 6,720,081 B2
- Document ID: US6720081B2
- Status: Granted
- Kind: B2
- Application number: 10/168,491
- Filed: 2002-10-21
- Published: 2003-04-24
- Granted: 2004-04-13
- Earliest claimed: 1999-12-22
- Assignees: Schott Spezialglas GmbH
- Inventors: Bruno Vitt; Juergen Blankenburg; Werner J. Behr; Karl-Heinz Dasecke; Birgit Lintner
- Web page: https://patentgrep.com/patent/US6720081B2

## CPC

- G02B 5/283: {designed for the ultraviolet}
- C03C 17/3417: {all coatings being oxide coatings}
- C03C 2217/734: comprising an alternation of high and low refractive indexes
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS

## Abstract

There is provided a UV-reflective interference layer system for transparent substrates with broadband anti-reflection properties in the visible wavelength range. The interference layer system includes at least four individual layers. Successive layers have different refractive indices and the individual layers contain UV and temperature-stable inorganic materials.

## Claims

### Claim 1

A UV-reflective interference layer system for transparent substrates with broadband antireflection in the visible wavelength range, the interference layer system comprising at least five individual layers, wherein consecutive layers of the five individual layers have different indices of refraction and the five individual layers have UV and temperature-stable inorganic materials, characterized in that the interference layer system has the following structure:
substrate/M1/T1/M2/T2/S, wherein substrate designates the transparent substrate, M1, M2 denote layers with intermediate index of refraction, T1, T2 denote layers with high index of refraction, S denotes a layer with low index of refraction, and for a reference wavelength of 550 nm the indices of refraction of the individual layers lie in the following range:
nlow≦1.6
1.6>nintermediate<1.8
1.9≦nhigh
and the thickness of the individual layers lies in the following range:
for the layer M1: 70 nm≦dM1≦100 nm
for the layer T1: 30 nm≦dT1≦70 nm
for the layer M2: 20 nm≦dM2≦40 nm
for the layer T2: 30 nm≦dT2≦50 nm
for the layer S: 90 nm≦dS≦110 nm.

### Claim 2 (depends on 1)

The interference layer system according to claim 1, wherein the inorganic materials are inorganic oxides.

### Claim 3 (depends on 1)

The interference layer system according to claim 1, wherein the inorganic oxides are largely transparent above a wavelength of light of 320 nm.

### Claim 4 (depends on 1)

The interference layer system according to claim 1, wherein the five individual layers comprise a material selected from the group consisting of TiO2, Nb2O5, Ta2O5, CeO2, HfO2, SiO2, MgF2, Al2O3, ZrO2, and any combinations thereof.

### Claim 5 (depends on 1)

The interference layer system according to claim 1, wherein the five individual layers comprise the following materials:
the high-refracting layer with nhigh, TiO2
the low-refracting layer with nlow, SiO2
and the intermediate-refracting layer with nintermediate, a mixture of TiO2 and SiO2.

### Claim 6 (depends on 1)

The interference layer system according to claim 1, wherein the T1, T2 layers with nhigh comprise one or more of the following materials: Nb2O5, Ta2O5, CeO2, HfO2, or mixtures of these with TiO2, the S layer comprise the following materials:
MgF2 or mixtures of MgF2 with SiO2, and the M1, M2 layers comprise one or more of the following materials: Al2O3, ZrO2.

### Claim 7 (depends on 1)

The interference layer system according to claim 1, wherein the transparent substrate is soft glass.

### Claim 8 (depends on 1)

The interference layer system according to claim 1, wherein the transparent substrate is a hard glass.

### Claim 9 (depends on 1)

The interference layer system according to claim 1, wherein the transparent substrate is quartz glass.

### Claim 10

A UV-reflective thermal protection glass, comprising at least one transparent substrate, wherein the substrate has a heat-reflecting coating on at least one side, which has a surface resistance <20 Ω,
wherein the substrate, which has a heat-reflecting coating on at least one side, has at least one UV-reflective interference layer system disposed thereon, said at least one UV-reflective interference layer system comprising at least five individual layers in the following structure:
M1/T1/M2/T2/S, wherein M1, M2 denote layers with intermediate index of refraction, T1, T2 denote layers with high index of refraction, S denotes a layer with low index of refraction, and for a reference wavelength of 550 nm the indices of refraction of the individual layers lie in the following range:
nlow≦1.6
1.6>nintermediate<1.8
1.9≦nhigh
and the thickness of the individual layers lies in the following range:
for the layer M1: 70 nm≦dM1≦100 nm
for the layer T1: 30 nm≦dT1≦70 nm
for the layer M2: 20 nm≦dM2≦40 nm
for the layer T2: 30 nm≦dT2≦50 nm
for the layer S: 90 nm≦dS≦110 nm.

### Claim 11 (depends on 10)

The UV-reflective thermal protection glass according to claim 10, wherein the UV-reflective interference layer system is deposited onto the heat reflecting interference layer system.

### Claim 12 (depends on 10)

The UV-reflective thermal protection glass according to claim 10, wherein the UV-reflective interference layer system is deposited directly on the substrate, and a heat-reflecting layer with a surface resistance <20 Ω is deposited on the UV-reflective interference layer.

### Claim 13 (depends on 10)

The UV-reflective thermal protection glass according to claim 10, wherein the UV transmission of the thermal protection glass in the UV range of 280-380 nm is less than 8% and in the visible wavelength range it is greater than 90%.

### Claim 14 (depends on 10)

The UV-reflective thermal protection glass according to claim 10, wherein the heat-reflecting coating comprises one or more of the following materials:
SnO2:F,Sb
ZnO:Al
In2O3:Sn
Ag-based coating.

### Claim 15 (depends on 10)

The UV-reflective thermal protection glass according to claim 10, wherein the heat transfer value of the thermal protection glass is smaller than 3.5 W/m2K.

### Claim 16 (depends on 10)

The UV-reflective thermal protection glass according to claim 10, wherein the UV thermal protection glass comprises two transparent substrates yielding a double-pane insulated glass, wherein at least one side of one of the transparent substrates has a heat-reflecting layer and at least three sides of the two substrates comprise the reflective interference layer system.

### Claim 17 (depends on 16)

The UV-reflective thermal protection glass according to claim 16, wherein the double-pane insulated glass has a small k-value of less than 1.0 W/m2K, a UV transmission of less than 4%, and a visible transmission in the visible wavelength range of greater than 85%.

### Claim 18

A UV-reflective interference layer system for a transparent substrate, comprising:
a first layer disposed on the transparent substrate, said first layer having an intermediate index of refraction;
a second layer disposed on said first layer, said second layer having a high index of refraction;
a third layer disposed on said second layer, said third layer having said intermediate index of refraction;
a fourth layer disposed on said third layer, said fourth layer having said high index of refraction; and
a fifth layer disposed on said fourth layer, said fifth layer having a low index of refraction, said first through fifth layers combining to transmit less than 8% of light having an UV wavelength while transmitting greater than 90% of light having a visible wavelength.

### Claim 19 (depends on 18)

The UV-reflective interference layer system as in claim 18, wherein said intermediate index of refraction is between about 1.6 and about 1.8 for a reference wavelength of 550 nm, said high index of refraction of greater than or equal to 1.9 for said reference wavelength, and said low index of refraction of less than or equal to 1.6.

### Claim 20 (depends on 18)

The UV-reflective interference layer system as in claim 18, wherein the transparent substrate is glass selected from the group consisting of a hard glass, a soft glass, and quartz glass.

### Claim 21 (depends on 18)

The UV-reflective interference layer system as in claim 18, further comprising a heat-reflecting coating disposed either on said fifth layer or between the transparent substrate and said first layer.

### Claim 22 (depends on 18)

The UV-reflective interference layer system as in claim 18, wherein said heat-reflecting coating provides a heat transfer value less than 3.5 W/m2K.

### Claim 23 (depends on 18)

The UV-reflective interference layer system as in claim 18, wherein said first through fifth layers combine to provide broadband antireflection at a viewing angle in a range of between 12.5 degrees to about 50 degrees.