Prism coupling methods with improved mode spectrum contrast for double ion-exchanged glass

Patent metadata

Field	Value
Publication number	US-9442028-B2
Application number	US-201514794067-A
Country	US
Kind code	B2
Filing date	Jul 8, 2015
Priority date	Jun 17, 2013
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

Methods of capturing improved-contrast mode spectra of a double ion-exchanged (DIOX) glass sample using prism coupling of index n p . The DIOX glass sample has a refractive index profile with a first region adjacent the surface that satisfies
0.0005 ≤  λ n ⁢ ⅆ n ⅆ x  ≤ 0.0009 ,
where λ is a wavelength of measuring light. The prism-sample interface includes an interfacing liquid of index n f that differs from n p by no more than 0.03, and that can exceed n p . The mode spectra have a contrast that is higher than that obtained by conventional prism coupling by using gradient illumination or partially blocked illumination that reduces the amount of background reflected light from the coupling prism. The improved-contrast mode spectra can be processed using conventional means to determine at least one stress characteristic of the DIOX glass sample.

First claim

What is claimed is:

1. A method of characterizing a refractive index profile of an ion-exchanged (IOX) glass sample having a surface and a base refractive index n s , comprising:
wetting either a coupling surface of a coupling prism of refractive index n p or the IOX sample surface with an interfacing fluid having a refractive index n f ;
interfacing the coupling prism to the surface of the IOX sample to define a prism-sample interface having input and output ends, with the interfacing fluid residing between the coupling prism and the IOX sample surface, wherein n f differs from n p by no more than 0.03, and wherein the sample has a refractive index profile with a region adjacent the surface that satisfies

0.0004
≤



λ
n

⁢

ⅆ
n

ⅆ
x



≤
0.0013

,

 where λ is a wavelength of measuring light;
illuminating the prism-sample interface with the measurement light; and characterizing the refractive index profile using measured mode spectrum of reflectivity of the prism-sample interface.

2. The method of claim 1 , wherein the mode spectrum comprises one or both of TE and TM.

3. The method of claim 2 , wherein the ion-exchanged (IOX) glass sample comprises a double ion-exchanged (DIOX) glass sample.

4. The method of claim 3 , further comprising, digitally capturing the mode spectrum reflected from the prism-sample interface; and processing the mode spectrum to determine an aspect of a refractive index profile or an aspect of a stress profile of the DIOX sample.

5. The method of claim 2 , further comprising, digitally capturing the mode spectrum reflected from the prism-sample interface; and processing the mode spectrum to determine an aspect of a refractive index profile or an aspect of a stress profile of the IOX sample.

6. The method of claim 5 , the aspect of a refractive index profile comprises depth of the refractive index profile and the aspect of a stress profile comprises depth of the compressive stress profile.

7. A method of characterizing a refractive index of an ion-exchanged (IOX) glass sample having a surface and a base refractive index n s , comprising:
wetting either a coupling surface of a coupling prism of refractive index n p or the IOX sample surface with an interfacing fluid;
interfacing the coupling prism to the surface of the IOX sample to define a prism-sample interface having input and output ends, with the interfacing fluid residing between the coupling prism and the IOX sample surface, and wherein the sample has a refractive index profile with a region adjacent the surface that satisfies

0.0004
≤



λ
n

⁢

ⅆ
n

ⅆ
x



≤
0.0013

,

 where λ is a wavelength of measuring light;
illuminating the prism-sample interface with the measurement light, wherein the measurement light has an intensity gradient that increases in the direction from the input to the output end of the prism-sample interface, and
input to the output end of the prism-sample interface: and
characterizing the refractive index using measured mode spectrum of reflectivity of the prism-sample interface.

8. The method of claim 7 , wherein the mode spectrum comprises one or both of TE and TM.

9. The method of claim 8 , wherein the ion-exchanged (IOX) glass sample comprises a double ion-exchanged (DIOX) glass sample.

10. The method of claim 9 , further comprising, digitally capturing the mode spectrum reflected from the prism-sample interface; and processing the mode spectrum to determine an aspect of a refractive index profile or an aspect of a stress profile of the DIOX sample.

11. The method of claim 8 , further comprising, digitally capturing the mode spectrum reflected from the prism-sample interface; and processing the mode spectrum to determine an aspect of a refractive index profile or an aspect of a stress profile of the IOX sample.

12. The method of claim 11 , the aspect of a refractive index profile comprises depth of the refractive index profile and the aspect of a stress profile comprises depth of the compressive stress profile.

13. A method of characterizing a refractive index of an ion-exchanged (IOX) glass sample having a surface and a base refractive index n s , comprising:
wetting either a coupling surface of a coupling prism of refractive index n p or the IOX sample surface with an interfacing fluid having a refractive index n f ;
interfacing the coupling prism to the surface of the IOX sample to define a prism-sample interface having input and output ends, with the interfacing fluid residing between the coupling prism and the IOX sample surface, wherein n f differs from n p by no more than 0.03, and wherein the sample has a refractive index profile with a region adjacent the surface that satisfies

0.0004
≤



λ
n

⁢

ⅆ
n

ⅆ
x



≤
0.0013

,

 where λ is a wavelength of measuring light;
illuminating the prism-sample interface with the measurement light; and characterizing the refractive index using measured mode spectrum of reflectivity of the prism-sample interface, wherein a portion of the measurement light at the input end of the prism-sample interface is either partially or completely blocked.

14. The method of claim 13 , wherein the coupling prism has an output surface and further including either partially or completely blocking a portion of the measurement light that exits the output surface.

15. The method of claim 13 , wherein the measurement light is passes through a light-blocking member having a graded transmittance.

16. The method of claim 13 , wherein the mode spectrum comprises one or both of TE and TM.

17. The

Assignees

• Corning Inc

Inventors

• Roussev Rostislav Vatchev
• Young Emily Elizabeth

Classifications

• G01N21/00

  Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light (G01N3/00 - G01N19/00 take precedence) · CPC title

• G01L1/24 Primary

  by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis {using infrared, visible light, ultraviolet} · CPC title

• G01N21/23

  Bi-refringence · CPC title

• G01N21/41

  Refractivity; Phase-affecting properties, e.g. optical path length (G01N21/21 takes precedence) · CPC title

• C03C21/002

  to perform ion-exchange between alkali ions (C03C21/005 takes precedence) · CPC title