Optical filter comprising solar blind dyes and UV-transparent substrates

• US 20050084666A1
• Filed: 11/03/2004
• Published: 04/21/2005
• Est. Priority Date: 02/08/2002
• Status: Active Grant

• Current Assignee: Navy The USA As Represented By The Secretary of The
• Original Assignee: Navy The USA As Represented By The Secretary of The
• Inventors: Pong, Richard G.S., Shirk, James S., Flom, Steven R.
• Granted Patent: US 6,994,885 B2
• Time in Patent Office: Days
• US Class Current: 428/304.400
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G02B 5/208 for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10S 977/70 Nanostructure
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/249956 Void-containing component is inorganic
• CPC Class Codes: Y10T 428/249969 Of silicon-containing material [e.g., glass, etc.]
• CPC Class Codes: Y10T 428/249975 Void shape specified [e.g., crushed, flat, round, etc.]

Abstract

The invention provides an optical filter comprising: a. an organic, solar blind filter dye; and b. a UV-transparent, non-scattering and chemically stable substrate. The substrate may be a UV-transparent nanoporous silica glass solid having pores that are substantially filled with a UV-transparent solvent, which has been selected to dissolve said dye and also to match the refractive index of the nanoporous silica glass solid. Alternatively, the substrate may be a UV-transparent inorganic salt compressed to form a solid body. The invention also provides for methods of making these embodiments and an optical device comprising such an optical filter. The filter provides an efficient solar blind filter that is chemically and dimensionally stable.

Claims

1. An optical filter comprising:

a. an organic, solar blind filter dye; and

b. a UV-transparent, non-scattering and chemically stable substrate

wherein said filter dye is incorporated directly into said substrate.

2. The filter of claim 1 wherein said filter dye is a cyanine dye.

3. The filter of claim 1 wherein said filter dye is a cyclic cyanine dye.

4. The filter of claim 1 wherein said filter dye is a 2,7-dialkyl-3,6-diazacyclohepta-1,6-diene complexed with a counterion.

5. The filter of claim 1 wherein said filter dye is 2,7-dimethyl-3,6-diazacyclohepta-1,6-diene perchlorate.

6. The filter of claim 1 wherein said filter dye is salt of a dithioic acid having the formula RCS₂⁻

X⁺, wherein R is H or alkyl and X is a cation.

7. The filter of claim 6 wherein the alkyl group is a methyl, ethyl, isopropyl or tertiary butyl group, and the cation X is selected from the group consisting of Na⁺, N(C₂H₅)₄⁺ and C₅H₁₀NH₂⁺ (piperidine).

10. The filter of claim 1 wherein said substrate comprises a UV-transparent inorganic salt compressed to form a solid body.

11. The filter of claim 10 wherein said inorganic salt is a halide salt of an alkali metal (Group 1a) or an alkaline earth metal (Group 2a).

12. The filter of claim 11 wherein said halide salt is a fluoride, chloride, bromide or iodide salt.

13. The filter of claim 11 wherein said alkali metal is K or Cs, and said alkali earth metal is Ca.

14. The filter of claim 1 wherein said filter absorbs UV radiation having wavelengths between about 300 and 400 nm, and transmits UV radiation having a wavelength below about 300 nm.

8-9. -9. (canceled)

15. A method of making an optical filter comprising:

a. an organic, solar blind filter dye; and

b. a UV-transparent, non-scattering and chemically stable substrate, comprising the steps of;

(1) selecting a nanoporous silica glass solid that is substantially UV-transparent;

(2) dissolving said dye in a UV-transparent solvent, which has been selected to form a solution of said dye and to match the refractive index of the nanoporous silica glass solid;

(3) allowing said solution to permeate said porous glass solid to form a UV-transparent, non-scattering substrate incorporating said dye.

16. The method of claim 16 wherein said UV-transparent solvent comprises dibutyl phthalate or dibutyl succinate.

17. A method of making an optical filter comprising:

a. an organic, solar blind filter dye; and

b. a UV-transparent, non-scattering and chemically stable substrate, comprising the steps of;

(1) selecting a nanoporous silica glass solid that is substantially UV-transparent;

(2) dissolving said dye in a relatively volatile solvent to form a volatile solution;

(3) allowing said volatile solution to permeate said nanoporous glass solid;

(4) evaporating off the relatively volatile solvent, leaving behind microparticles of said dye in the pores of the nanoporous silica glass solid; and

(5) allowing a relatively non-volatile, UV-transparent solvent, which has been selected to match the refractive index of the nanoporous glass solid, to permeate the nanoporous glass solid containing microparticles of said dye until said dye is dissolved in the non-volatile solvent, thus forming a UV-transparent, non-scattering substrate incorporating said dye.

18. The method of claim 17 wherein said relatively volatile solvent is an alkanol, a halogenated hydrocarbon or water.

19. The method of claim 17 wherein said non-volatile, UV-transparent solvent comprises dibutyl phthalate or dibutyl succinate.

20. A method of making an optical filter comprising:

a. an organic, solar blind filter dye; and

b. a UV-transparent, non-scattering and chemically stable substrate, comprising the steps of;

(1) grinding together a UV-transparent inorganic salt with said dye to form a mixture;

(2) compressing said mixture to form a solid body.

21. The method of claim 20 wherein said UV-transparent inorganic salt is a halide salt of an alkali metal (Group 1a) or an alkaline earth metal (Group 2a).

22. The method of claim 20 wherein said inorganic salt is the fluoride, chloride, bromide or iodide salt of K, Cs or Ca.

23. The method of claim 20 wherein said compressing step takes place at a pressure ranging from about 10,000 psi to about 50,000 psi.

24. The method of claim 20 wherein said method further comprises the step of coating the solid body with a sealant to ensure chemical and dimensional stability.

25. (canceled)