Coating, composed of an optically effective layer system, for substrates, whereby the layer system has a high anti-reflective effect, and method for manufacturing the coating

Claim 2

A coating for a front side of a substrate, which side faces an observer, said coating being composed of an optically effective layer system, said layer system having a high anti-reflective effect, said layer system being composed of four layers with a first layer with a layer thickness of 100ű10% being arranged on the front side of the substrate and comprising a highly refractive material, a second layer of the four layers being arranged on the first layer, said second layer having a thickness of 400ű5% and comprising a low-refracting material, a third layer of the four layers being arranged on the second layer, said third layer having a thickness of 1040ű2% and comprising a highly refractive material, and the fourth layer of the four layers being arranged on the third layer, said fourth layer having a thickness of 940ű2% and comprising a low-refracting material.

Claim 3

A coating according to claim 1, wherein the first and third layers are of TiO 2 , said second layer is Al 2 O 3 and said fourth layer is SiO 2 .

Claim 4

A coating according to claim 1, wherein the first layer comprises a compound selected from a group consisting of TiO 2 , ZnS, Bi 2 O 3 , and mixtures of TiO 2 , ZnS, Bi 2 O 3 .

Claim 5

A coating according to claim 1, wherein the second layer comprises oxides selected from a group consisting of Al 2 O 3 , MgO, SiO 2 , SiAl-oxide, NiSi-oxide and mixtures of these oxides.

Claim 6

A coating according to claim 1, wherein the third layer comprises a compound selected from a group consisting of TiO 2 , ZnS, Bi 2 O 3 and mixtures of these compounds.

Claim 7

A coating according to claim 1, wherein the fourth layer comprises a compound selected from a group consisting of SiO 2 and MgF 2 and mixtures of SiO 2 and MgF 2 .

Claim 8

A coating according to claim 1, wherein the first layer is composed of a material with a refractive coefficient n≧2.2; the second layer is composed of a material with a refractive index n=approximately 1.6; the third layer is composed of a material with a refractive index n≧2.2; and the fourth layer is composed of a material with a refractive index of n≦1.5.

Claim 9

A coating according to claim 7, wherein the index of refraction for the first and third coatings is n=2.4 and the index of refraction for the fourth coating is n=1.48.

Claim 10

A coating for a front surface of a substrate when viewed by an observer, said coating being composed of an optically effective layer system, said layer system having a high anti-reflective effect and being composed of four layers, a first layer of the four layers being arranged next to the front surface of the substrate and being highly refracting, said first layer being a TiO 2 layer with a thickness of 100 angstrom ±10%, a second layer of the four layers being arranged on the first layer and being a low-refracting material, said second layer being an Al 2 O 3 layer with a thickness of 400 angstrom ±5%, a third layer of the four layers being arranged on said second layer and comprising a highly refractive material, said third layer being a TiO 2 layer with a layer thickness of 1040 angstrom ±2%, a fourth layer of the four layers being arranged on the third layer and being a low-refracting material, said fourth layer being an SiO 2 layer with a layer thickness of 940 angstrom ±2%.

Claim 11

A coating for a front surface of a substrate when viewed by an observer, said coating being composed of an optically effective layer system, said layer system having a high anti-reflective effect and being composed of four layers, a first layer of the four layers being arranged next to the front surface of the substrate and being highly refracting, said first layer being a TiO 2 layer with a thickness of 100 angstrom ±10%, a second layer of the four layers being arranged on the first layer and being a low-refracting material, said second layer being an Al 2 O 3 layer with a thickness of 400 angstrom ±5%, a third layer of the four layers being arranged on said second layer and comprising a highly refractive material, said third layer being a TiO 2 layer with a layer thickness of 1040 angstrom ±2%, a fourth layer of the four layers being arranged on the third layer and being a low-refracting material, said fourth layer being an SiO 2 layer with a layer thickness of 940 angstrom ±2%.

Claim 12

A coating for a front surface of a substrate, which surface faces an observer, said coating being composed of an optically effective layer system, said layer system having a high anti-reflective effect for a visible range of light having a wavelength λ, said layer system being composed of four layers with each layer having an optical density being defined by the refractive index (n) times an actual layer thickness (d), a first layer of the four layers being arranged on the front side of the substrate and comprising a highly refractive material with n 1 being between 1.8 and 2.56 and the optical density of n 1 ×d 1 being approximately equal to 0.05λ, a second layer of the four layers being arranged on the first layer and comprising a low-refracting material with n 2 being between 1.55 and 1.75 and the optical density n 2 ×d 2 being approximately equal to 0.12λ, a third layer of the four layers being arranged on the second layer and comprising a highly reflective material with n 3 being between 1.8 and 2.58 and the optical density n 3 ×d 3 being approximately equal to 0.5λ, and a fourth layer of the four layers being arranged on the third layer and comprising a low-refracting material with n 4 being between 1.3 and 1.63 and the optical density n 4 ×d 4 being approximately equal to 0.25λ.

Claim 13

A coating for a front surface of a substrate, which surface faces an observer, said coating being composed of an optically effective layer system, said layer system having a high anti-reflective effect for a visible range of light having a wavelength λ, said layer system being composed of four layers with each layer having an optical density being defined by the refractive index (n) times an actual layer thickness (d), a first layer of the four layers being arranged on the front side of the substrate and comprising a highly refractive material with n 1 being between 1.8 and 2.56 and the optical density of n 1 ×d 1 being approximately equal to 0.05λ, a second layer of the four layers being arranged on the first layer and comprising a low-refracting material with n 2 being between 1.55 and 1.75 and the optical density n 2 ×d 2 being approximately equal to 0.12λ, a third layer of the four layers being arranged on the second layer and comprising a highly reflective material with n 3 being between 1.8 and 2.58 and the optical density n 3 ×d 3 being approximately equal to 0.5λ, and a fourth layer of the four layers being arranged on the third layer and comprising a low-refracting material with n 4 being between 1.3 and 1.63 and the optical density n 4 ×d 4 being approximately equal to 0.25λ.

Claim 14

A coating according to claim 10, wherein λ is approximately 555 nm.

Claim 15

A coating according to claim 11, wherein the first and layers are TiO 2 , the second layer is Al 2 O 3 and the fourth layer is SiO 2 .

Claim 18

A method according to claim 13, wherein the method used for applying the layers is a DC-reactive sputtering from a target with a magnetron.

Claim 19

A method according to claim 13, wherein one of the first and third layers of the four layer system is a layer composed of TiO 2 , and the method includes DC-reactive sputtering from a Ti-target with a magnetron while providing sputtering gas mixtures comprising Ar and O 2 at a pressure of approximately 5×10 -3 mbar.

Claim 20

A method according to claim 13, wherein a second layer of the four-layer system is an Al 2 O 3 layer and said method includes DC-reactive sputtering with a sputtering gas mixture from an aluminum target with a magnetron, said sputtering gas mixture comprising Ar and O 2 at a pressure of approximately 8×10 -3 mbar.

Claim 21

A method according to claim 13, wherein the fourth and outermost layer of the four-layer system is a layer composed of SiO 2 and said method includes DC-reactive sputtering from a silicon target with a magnetron in a sputtering gas mixture, said sputtering gas mixture comprising Ar and O 2 at a pressure of approximately 1.2×10 -2 mbar.

Claim 22

A method according to claim 13, wherein the method of applying the layers is a vacuum-metallization method.

Claim 25

A method according to claim 19, wherein the first and third layers are composed of TiO 2 , the second layer is composed of Al 2 O 2 , and the fourth layer is composed of SiO 2 .