Claims
- 1. A non-contact method for evaluating stress, the method comprising:
non-uniformly introducing an impurity into at least one region of a crystalline substrate; subjecting the crystalline substrate to physical stress; directing fluorescence producing energy at the crystalline substrate; measuring a fluorescence produced by the crystalline substrate; and correlating the fluorescence with the stress on the crystalline substrate.
- 2. The method according to claim 1, wherein the crystalline substrate comprises at least one of sapphire and yttria.
- 3. The method according to claim 1, wherein the crystalline substrate comprises monocrystalline sapphire.
- 4. The method according to claim 1, wherein the impurity is introduced into a region in the vicinity of a surface of the crystalline substrate.
- 5. The method according to claim 4, wherein the region where the impurity is introduced has a depth of up to 200 nm.
- 6. The method according to claim 4, wherein the impurity has a peak concentration of about 1020 to about 1022 ions/cm2 at a depth of about 10nm to about 200 nm.
- 7. The method according to claim 1, wherein the impurity has a peak concentration of about 1022 cm−3 at a depth of about 70 nm.
- 8. The method according to claim 1, wherein the physical stress comprises at least one of mechanical force, non-uniform heating or cooling, and elevated temperature.
- 9. The method according to claim 8, wherein the physical stress comprises mechanical force of about 50 MPa to about 10 GPa.
- 10. The method according to claim 8, wherein the physical stress comprises elevated temperature of about 22 degrees C. to about 600 degrees C.
- 11. The method according to claim 8, wherein the physical stress comprises mechanical stress applied to the center of the sapphire window.
- 12. The method according to claim 1, wherein the impurity comprises at least one of chromium ions and neodymium ions.
- 13. The method according to claim 1, wherein the impurity is introduced by high energy ion implantation.
- 14. The method according to claim 13, wherein the impurity is introduced at about 1000 degrees C. with a beam energy of about 150 keV and an ion flux of about 1017 cm−2.
- 15. The method according to claim 1, wherein the fluorescence producing energy has a wavelength of about 532 nm and an energy of about 10 mW.
- 16. The method according to claim 1, wherein the method measures surface stress.
- 17. The method according to claim 1, wherein the impurity is introduced into a single region in the vicinity of one surface of the crystalline substrate.
- 18. The method according to claim 1, wherein the impurity is introduced into plurality of regions in the vicinity of opposite surfaces of the crystalline substrate.
- 19. A method for manufacturing a structure for non-contact evaluation of stress in the structure, the method comprising:
non-uniformly introducing an impurity into at least one region of a crystalline substrate.
- 20. The method according to claim 19, wherein the crystalline substrate comprises at least one of sapphire and yttria.
- 21. The method according to claim 19, wherein the crystalline substrate comprises monocrystalline sapphire.
- 22. The method according to claim 19, wherein the impurity is introduced into a region in the vicinity of a surface of the crystalline substrate.
- 23. The method according to claim 22, wherein the impurity is introduced into a region having a depth of up to 200 nm.
- 24. The method according to claim 22, wherein the impurity is introduced such that it has a peak concentration of about 1020 to about 1022 ions/cm2 at a depth of about 10 nm to about 200 nm.
- 25. The method according to claim 19, wherein the impurity is introduced to have a peak concentration of about 1022 cm−3 at a depth of about 70 nm.
- 26. The method according to claim 19, wherein the impurity comprises at least one of chromium ions and neodymium ions.
- 27. The method according to claim 19, wherein the impurity is introduced by high energy ion implantation.
- 28. The method according to claim 27, wherein the impurity is introduced at about 1000 degrees C. with a beam energy of about 150 keV and an ion flux of about 1017 cm−2.
- 29. The method according to claim 19, wherein the impurity is introduced into a single region in the vicinity of one surface of the crystalline substrate.
- 30. The method according to claim 19, wherein the impurity is introduced into plurality of regions in the vicinity of opposite surfaces of the crystalline substrate.
- 31. A structure for non-contact evaluation of stress in the structure, the structure comprising:
a crystalline substrate comprising at least one impurity non-uniformly distributed in the substrate.
- 32. The structure according to claim 31, wherein the crystalline substrate comprises at least one of sapphire and yttria.
- 33. The structure according to claim 31, wherein the crystalline substrate comprises monocrystalline sapphire.
- 34. The structure according to claim 31, wherein the at least one impurity containing region is arranged in the vicinity of a surface of the crystalline substrate.
- 35. The structure according to claim 34, wherein the impurity is introduced into a region having a depth of up to 200 nm.
- 36. The structure according to claim 31, wherein the at least one impurity containing region has a peak concentration of about 1020 to about 1022 ions/cm2 at a depth of about 10 nm to about 200 nm.
- 37. The structure according to claim 31, wherein the at least one impurity containing region has a peak concentration of about 1022 cm−3 at a depth of about 70 nm.
- 38. The structure according to claim 31, wherein the at least one impurity comprises at least one of chromium ions and neodymium ions.
- 39. The structure according to claim 31, wherein the substrate comprises one impurity containing region in the vicinity of one surface of the crystalline substrate.
- 40. The structure according to claim 31, wherein the substrate comprises a plurality of impurity containing regions in the vicinity of at least one surface of the crystalline substrate.
- 41. A device for non-contact evaluation of stress in a substrate, the device comprising:
a hollow cylindrical window support operable to support the substrate; a source of fluorescence producing energy operable to direct the fluorescence producing energy at the substrate; a heat source operable to subject the substrate to elevated temperature; a mechanical loading assembly operable to subject the substrate to a mechanical load; and a sensor operable to detect fluorescence emitted from the substrate.
- 42. The device according to claim 41, wherein the mechanical loading assembly comprises a substrate contacting surface.
- 43. The device according to claim 41, wherein the mechanical loading assembly comprises a shaped force application member operable to contact a surface of the substrate.
- 44. The device according to claim 41, wherein the device applies tensile and compressive forces to the substrate.
- 45. The device according to claim 41, wherein the supporting cylinder has a circular cross-section having a diameter small than a smaller of a length and a width of the substrate.
- 46. The device according to claim 45, wherein the load assembly applies the mechanical load to the substrate centered with respect to the cylinder.
- 47. The device according to claim 41, further comprising:
a cooling assembly for cooling at least the source of fluorescence producing energy and the sensor.
- 48. A non-contact method for evaluating stress in a sapphire window, the method comprising:
subjecting to a physical stress a sapphire window comprising an impurity non-uniformly distributed in a region in the vicinity of a surface of the sapphire window; directing fluorescence producing energy at the sapphire window; measuring a fluorescence produced by the sapphire window; and correlating the fluorescence with the stress on the sapphire window.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional application No. 60/292,254, filed on May 18, 2001, which is hereby incorporated by reference in its entirety.
STATEMENT OF GOVERNMENTAL INTEREST
[0002] This invention was made with Government support under Naval Sea Systems Command contract no. N00024-98-D-8124, Arlington, Va. The Government has certain rights in the invention.
Provisional Applications (1)
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Number |
Date |
Country |
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60292254 |
May 2001 |
US |