Enhanced performance metallic based optical mirror substrates

Patent metadata

Field	Value
Publication number	US-9971073-B2
Application number	US-201514679339-A
Country	US
Kind code	B2
Filing date	Apr 6, 2015
Priority date	Apr 14, 2014
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

A method for coating substrates is provided. The method includes diamond turning a substrate to a surface roughness of between about 60 Å and about 100 Å RMS, wherein the substrate is one of a metal and a metal alloy. The method further includes polishing the diamond turned surface of the substrate to a surface roughness of between about 10 Å and about 25 Å to form a polished substrate, heating the polished substrate, and ion bombarding the substrate with an inert gas. The method includes depositing a coating including at least one metallic layer on the ion bombarded surface of the substrate using low pressure magnetron sputtering, and polishing the coating to form a finished surface having a surface roughness of less than about 25 Å RMS using a glycol based colloidal solution.

First claim

What is claimed is:

1. A method for coating substrates, the method comprising:
diamond turning a substrate to a surface roughness of between about 60 Å and about 100 Å RMS, wherein the substrate is one of a metal and a metal alloy;
polishing the diamond turned surface of the substrate to a surface roughness of between about 10 Å and about 25 Å to form a polished substrate;
heating the polished substrate;
ion bombarding the polished substrate with an inert gas;
depositing a coating comprising at least one metallic layer on the ion bombarded surface of the polished substrate using low pressure magnetron sputtering; and
polishing the coating to form a finished surface having a surface roughness of less than about 25 Å RMS using a glycol based colloidal solution.

2. The method of claim 1 , wherein the substrate is selected from the group consisting of aluminum, aluminum alloys, magnesium and magnesium alloys.

3. The method of claim 1 , wherein the metallic layer comprises a material selected from the group consisting of aluminum, aluminum alloys, magnesium and magnesium alloys.

4. The method of claim 1 , wherein the coating has a thickness of between about 2.0 μm and about 10 μm.

5. The method of claim 1 , wherein the glycol based colloidal solution has a pH of between about 8.5 and about 9.5.

6. The method of claim 1 , wherein the finished surface has a peak to valley (PV) roughness of less than about 30 nm.

7. The method of claim 1 , wherein depositing a coating further comprises depositing an adhesion layer on the ion bombarded surface of the polished substrate and depositing the metallic layer on the adhesion layer.

8. The method of claim 7 , wherein depositing a coating further comprises depositing an intermediate layer on the adhesion layer, the intermediate layer comprising a material selected from the group consisting of an aluminum oxide, aluminum nitride and aluminum oxynitride.

9. The method of claim 1 , further comprising depositing at least one smoothing layer, the at least one smoothing layer comprising aluminum oxide.

10. The method of claim 1 , wherein the polished substrate is heated to a temperature between 50° C. and 150° C. for a time period between 1.0 hour and 2.0 hours.

11. The method of claim 1 , wherein the polished substrate is ion bombarded with the inert gas for a time period between 15 min and 30 min.

Assignees

• Corning Inc

Inventors

• Crifasi Joseph Charles
• Hart Gary Allen
• Walton Robin Merchant
• Wamboldt Leonard Gerard
• Wang Jue

Classifications

• C23C14/028

  Physical treatment to alter the texture of the substrate surface, e.g. grinding, polishing · CPC title

• C23C14/165

  by cathodic sputtering · CPC title

• G02B1/14

  Protective coatings, e.g. hard coatings · CPC title

• C23F3/03

  with acidic solutions · CPC title

• C23C14/588 Primary

  by mechanical treatment · CPC title