IR absorbing reflector

• US 20070013998A1
• Filed: 07/12/2005
• Published: 01/18/2007
• Est. Priority Date: 07/12/2005
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Gupta, Anurag, Wu, Kuohua
• Granted Patent: US 7,349,151 B2
• Time in Patent Office: Days
• US Class Current: 359/361
• CPC Class Codes: F21V 7/24 characterised by the material
• CPC Class Codes: F21V 7/28 characterised by coatings
• CPC Class Codes: F21W 2131/406 for theatres, stages or film studios
• CPC Class Codes: G02B 5/281 designed for the infrared light
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361

Abstract

A IR absorbing reflector is formed with a substrate that supports a first IR absorptive multilayer part having multiple layers of partial IR absorbing thin films. The first IR (infrared) absorptive multi-layer part supports a second visible light reflecting multilayer part.

Claims

1. A reflector comprising:

a substrate;

a first multilayer part having multiple layers of partial IR absorbing thin films supported by the substrate; and

a second multilayer part reflecting visible light supported by the first IR absorptive multilayer part.

2. The IR absorbing reflector of claim 1 wherein the second multilayer part comprises dielectric layers of alternate relative high and low index material.

3. The IR absorbing reflector of claim 2 wherein the dielectric layers absorb UV (ultraviolet radiation).

4. The IR absorbing reflector of claim 3 wherein the dielectric layers provide a reflectance of at least approximately 95% in the visible spectrum (400 nm˜

800 nm).

5. The IR absorbing reflector of claim 2 wherein the dielectric layers are selected from the group consisting of TiO₂, SiO₂, ZrO₂, HfO_x, Ta₂O₃, Nb₂O₅, and Al₂O₃.

6. The IR absorbing reflector of claim 2 wherein the dielectric layers comprise approximately 20 to 40 layers.

7. The IR absorbing reflector of claim 1 wherein the first multilayer part comprises IR absorptive matching layers of dielectric, metal or semi-metal thin films.

8. The IR absorbing reflector of claim 7 wherein the matching layers are selected from the group consisting of W, Ni, Ti, Si, Ta, Al₂O₃, Cr₂O₃, and SiO₂.

9. The IR absorbing reflector of claim 7 wherein the matching layers are indexed matched to provide low reflectance for most of the IR region.

10. The IR absorbing reflector of claim 1 further comprising an adhesive layer disposed between the substrate and the first multilayer part.

11. A IR absorbing reflector comprising:

a substrate;

means for absorbing particular wavelengths of IR (infrared) to obtain an overall absorption that is substantially uniform from the near IR to the far IR disposed on the substrate; and

means for reflecting visible light while passing IR to the means for absorbing.

12. The IR absorbing reflector of claim 11 wherein the means for reflecting includes means for absorbing UV (ultraviolet).

13. The IR absorbing reflector of claim 11 further including means for adhering the means for absorbing to the substrate wherein the means for adhering further includes means for absorbing visible or non-visible incident light.

14. A IR absorbing reflector comprising:

a substrate;

an IR (infrared) absorptive multilayer part including multiple layers of deposited thin-films formed directly on the substrate; and

a visible light reflecting, IR transmissive, and UV (ultraviolet) absorbing multilayer part formed directly on the IR absorptive multilayer part.

15. The IR absorbing reflector of claim 14 further comprising an adhesion layer having light absorption properties disposed between the substrate and the IR absorptive multilayer part.

16. A light projector comprising:

a light source;

a reflector positioned to receive light from the light source, said reflector including,

a substrate;

a first IR (infrared) absorptive part of multiple thin-films supported by the substrate; and

a second visible light reflecting part of multiple thin-films supported by the IR absorptive multilayer part; and

a lens coupled to the reflector and positioned to transmit reflected visible light in a desired direction.

17. The light projector of claim 16 and further comprising a heat removal layer coupled to the IR absorptive part.

18. A method comprising:

forming an IR (infrared) absorptive part of multiple thin-films supported by a substrate; and

forming a visible light reflecting part of multiple thin-films supported by the IR absorptive part.

19. The method of claim 18 wherein the visible light reflecting part comprises dielectric layers of alternate relative high and low index material.

20. The method of claim 18 wherein the dielectric layers include UV (ultraviolet) absorptive material.

21. The method of claim 18 wherein the dielectric layers provide a reflectance of at least approximately 95% in the visible region.

22. The method of claim 19 wherein the dielectric layers are selected from the group consisting of TiO₂, SiO₂, Ta₂O₃, HfO_x, Al₂O₃, Nb₂O₅, and ZrO₂.

23. The method of claim 19 wherein the dielectric layers comprise approximately 20 to 40 layers.

24. The method of claim 18 wherein the IR absorptive part comprises IR absorptive matching layers of dielectric, metal or semi-metal thin films.

25. The method of claim 24 wherein the matching layers are selected from the group consisting of W, Ni, Ti, Ta, Si, Al₂O₃, Cr₂O₃, and SiO₂.

26. The method of claim 24 wherein the matching layers provide low reflectance for most of the IR region.

27. The method of claim 21 wherein the matching layers are index and thickness matched to provide substantial uniform absorption from the near IR to the far IR.

28. The method of claim 18 wherein the substrate is formed in a substantially concave shape.

29. A method of using multiple layers of QWT (quarter wave thickness) thin films to form an IR (infrared) absorbing reflector, the method comprising:

illuminating UV (ultraviolet), visible, and IR light on the IR absorbing reflector;

reflecting greater than 95% of the visible light with a first set of QWT thin films;

transmitting the IR light to a second set of QWT thin-films that absorb particular wavelengths of IR to obtain an overall absorption of IR that is substantially uniform from the near IR to the far IR;

absorbing the UV in at least one of the first set of QWT thin-films, the second set of QWT thin-films, or an adhesion/absorption layer; and

transmitting the absorbed IR and UV to a metallic substrate supporting the adhesion/absoption layer and first and set sets of QWT thin-films.

30. An IR (infrared) absorbing reflector, comprising:

a metallic substrate;

a first set of QWT (quarter wave thickness) thin-films having small differential indices of refraction to minimize reflectance of IR disposed on the metallic substrate and wherein the first set of QWT thin-films absorbs particular wavelengths of IR to obtain a substantially uniform IR absorption from the near IR to the far IR; and

a second set of QWT thin-films having large differential indices of refraction disposed on the first set of QWT thin-films to maximize reflection of visible light and to minimize reflection of non-visible light.

31. The IR absorbing reflector of claim 30 wherein the first set of QWT thin-films comprise alternating layers of Ti and SiO₂, and the second set of QWT thin-films comprise alternating layers of TiO₂ and SiO₂.

32. The IR absorbing reflector of claim 31 wherein the Ti and SiO₂ layers of the first set of QWT thin-films have refractive indices of approximately 1.7 and 1.5 respectively, and the alternating layers of TiO₂ and SiO₂ of the second set of QWT thin-files have refractive indices of approximately 2.5 and 1.5 respectively at a reference wavelength of 510 nm.

33. The IR absorbing reflector of claim 31 wherein the first set of QWT thin-films comprise four layers of Ti and four layers of SiO₂, and the second set of QWT thin-films comprise thirteen layers of TiO₂ and twelve layers of SiO₂.

34. The IR absorbing reflector of claim 31 wherein the first and second sets of QWT thin-films have a combined thickness of approximately 3200 nm.

35. The IR absorbing reflector of claim 30 wherein the first set of QWT thin-films comprise alternating layers of Ni and SiO₂, and the second set of QWT thin-films comprise alternating layers of TiO₂ and SiO₂.

36. The IR absorbing reflector of claim 35 wherein the Ni and SiO₂ layers of the first set of QWT thin-films have refractive indices of approximately 1.7 and 1.5 respectively, and the alternating layers of TiO₂ and SiO₂ of the second set of QWT thin-files have refractive indices of approximately 2.5 and 1.5 respectively at a reference wavelength of 510 nm.

37. The IR absorbing reflector of claim 35 wherein the first set of QWT thin-films comprise five layers of Ni and four layers of SiO₂, and the second set of QWT thin-films comprise thirteen layers of TiO₂ and twelve layers of SiO₂.

38. The IR absorbing reflector of claim 35 wherein the first and second sets of QWT thin-films have a combined thickness of approximately 4100 nm.

39. The IR absorbing reflector of claim 30 wherein the first set of QWT thin-films comprise alternating layers of W and Cr₂O₃, and the second set of QWT thin-films comprise alternating layers of TiO₂ and SiO₂.

40. The IR absorbing reflector of claim 39 wherein the W and Cr₂O₃ layers of the first set of QWT thin-films have refractive indices of approximately 3.4 and 2.2 respectively, and the alternating layers of TiO₂ and SiO₂ of the second set of QWT thin-files have refractive indices of approximately 2.5 and 1.5 respectively at a reference wavelength of 510 nm.

41. The IR absorbing reflector of claim 39 wherein the first set of QWT thin-films comprise five layers of W and five layers Cr₂O₃, and the second set of QWT thin-films comprise thirteen layers of TiO₂ and twelve layers of SiO₂.

42. The IR absorbing reflector of claim 39 wherein the first and second sets of QWT thin-films have a combined thickness of approximately 4200 nm.