Sol-Gel composite AR coating for IR applications

• US 7,572,512 B2
• Filed: 03/02/2007
• Issued: 08/11/2009
• Est. Priority Date: 03/02/2006
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Missiles & Fire Control (Martin Marietta Corporation), University of Central Florida Research Foundation Inc. (State University System of Florida)
• Original Assignee: Lockheed Martin Missiles & Fire Control (Martin Marietta Corporation), University of Central Florida Research Foundation Inc. (State University System of Florida)
• Inventors: Braunstein, Edit, Brinley, Erik, Seal, Sudipta, Kramer, Leslie
• Primary Examiner(s): Speer; Timothy M
• Assistant Examiner(s): ROBINSON, LAUREN E
• Application Number:
  US11/681,469
• Publication Number:
  US 20070207325A1
• Time in Patent Office: 893 Days
• Field of Search: 428/215, 428/688, 428/690, 428/696, 428/432, 428/482, 428/428, 427/162, 427/164, 427/165, 359/621, 350/166
• US Class Current: 428/432
• CPC Class Codes: C03C 1/008 for the production of films or coatings
• CPC Class Codes: C03C 17/256 Coating containing TiO2
• CPC Class Codes: C03C 2217/212 TiO2
• CPC Class Codes: C03C 2217/213 SiO2
• CPC Class Codes: C03C 2217/23 Mixtures
• CPC Class Codes: C03C 2218/113 by sol-gel processes
• CPC Class Codes: C03C 4/10 for infrared transmitting glass
• CPC Class Codes: G02B 1/111 using layers comprising organic materials

Abstract

An infrared transmissive article includes an infrared transmissive substrate and a single layer anti-reflective (AR) composite broadband sol gel coating on a surface of the substrate. The AR coating includes a first chalcogenide including compound, and a second chalcogenide including compound intermixed with the first chalcogenide including compound. The percentages of the first chalcogenide and the second chalcogenide in the AR coating are selected to provide a refractive index of the AR coating that approximates the square root of a refractive index of the substrate.

Claims

1. An infrared transmissive article, comprising:

an infrared (IR) transmissive substrate, and

a single layer anti-reflective (AR) sol-gel composite broadband coating on a surface of said substrate, said single layer AR coating comprising;

a first metal or semiconductor chalcogenide comprising compound, said first metal or semiconductor chalcogenide compound being essentially all in a metal or semiconductor chalcogenide form;

a second chalcogenide comprising compound different from said first chalcogenide comprising compound intermixed with said first chalcogenide comprising compound, said second metal or semiconductor chalcogenide compound being essentially all in a metal or semiconductor chalcogenide form;

wherein percentages of said first chalcogenide and said second chalcogenide in said single layer AR coating are selected provide a refractive index of said single layer AR coating that approximates the square root of a refractive index of said substrate, and

wherein said AR coating is in a highly amorphous state.

2. The article of claim 1, wherein a thickness of said AR coating is <

200 nm.

3. The article of claim 1, wherein said first metal or semiconductor chalcogenide comprising compound is silica and said second metal or semiconductor chalcogenide comprising compound is titania.

4. The article of claim 1, wherein a primary particle size distribution in said AR coating has a peak at between about 2-10 nm.

5. The article of claim 1, wherein said substrate is a chalcogenide glass substrate.

6. The article of claim 5, wherein said chalcogenide glass substrate comprises a substrate having a refractive index of around 2.7, wherein said refractive index of said AR coating in a wavelength range from 1 to 5 microns is from 1.62 to 1.66.

7. The article of claim 5, wherein a % transmissivity of said coated substrate averages at least 70% over a majority of a wavelength range from 1.5 to 5 micrometers.

8. The article of claim 1, wherein said AR coating has a gradient of said refractive index across its thickness, wherein said refractive index of said AR coating is lower at its surface as compared to a bulk of said coating.

9. The article of claim 8, wherein gradient comprises a difference in said refractive index from 1 to 5% from said surface to said bulk of said AR coating.