WO2004111575B1 - Interferometric absolute and real-time surface curvature sensor insensitive to tilt, translation and vibration - Google Patents
Interferometric absolute and real-time surface curvature sensor insensitive to tilt, translation and vibrationInfo
- Publication number
- WO2004111575B1 WO2004111575B1 PCT/US2004/018401 US2004018401W WO2004111575B1 WO 2004111575 B1 WO2004111575 B1 WO 2004111575B1 US 2004018401 W US2004018401 W US 2004018401W WO 2004111575 B1 WO2004111575 B1 WO 2004111575B1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- sample surface
- beams
- curvature
- lens
- reflector
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
- G01B11/306—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces for measuring evenness
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Instruments For Measurement Of Length By Optical Means (AREA)
Abstract
An apparatus and a method are disclosed to characterize curvature of a surface (16) of a sample. The apparatus (10) includes a reflector (14), a lens (12) characterized by having two focal planes and an optical source, such as a laser (20), that outputs measurement light that is directed to pass through the lens and to be reflected by the reflector. The reflector and lens are arranged so that when a sample surface of interest is positioned relative to the reflector such that the reflector and the sample surface are each located at one of the two focal planes of the lens, the sample surface becomes the image plane of itself for the lens, and beams bl and b2 of the measurement light are reflected at least twice from the sample surface and accumulate a path length difference, Δ, that is proportional to the curvature, κ, of the sample surface. The apparatus further includes a detector (30) for detecting the path length difference.
Claims
1. Apparatus to characterize curvature of a surface of a sample, comprising: a reflector; a lens characterized by having two focal planes; a source assembly for providing measurement light as beams bl and b2 and for directing said beams bl and b2 to pass through said lens and to be reflected by said reflector; where said reflector and lens are arranged so that when a sample surface of interest is positioned relative to said reflector such that said reflector and the sample surface are each located at one of the two focal planes of said lens, the sample surface becomes the image plane of itself for said lens, and said beams bl and b2 of the measurement light are reflected at least twice from the sample surface and accumulate a path length difference, Δ, that is proportional to the curvature, K, of the sample surface; and a detector for detecting the path length difference.
2. Apparatus as in claim 1, where the curvature, K, of the sample surface is equal to 1/R, where R is the radius of curvature of the sample surface, and beams bl and b2 develop a path length difference of 2(y -yB), where yA 
.yflare the normal positions of points A and B, with respect to the focal plane of said lens, and where reflections from points D and C result in a path length difference of 2(yD -yc), and where a total path length difference, Δ, between beams bl and b2 is
Δ a 2(yΛ - yB) + 2(yD - yc) a 2{yΛ + ya) - 2(yB + yc) . 18
3. Apparatus as in claim 2, where a lateral distance, d, between points A and B is equal to a lateral distance between points C and D; where a distance between midpoints of the positions (A,B) and (C, D) is represented by c, and the curvature of the sample surface, K, is expressed in terms of the total path length difference, Δ, and the distances, c and d, as s_. - l ^ . VD - VC VB - VA ) _ Δ R dx2 c[ d d ) 2cd
4. Apparatus as in claim 3, where the optical path difference, Δ, corresponds to a phase difference of 2πA k between beams bl and b2, where λ is the wavelength of the measurement light, and where said detector measures the phase difference from the interference between beams bl and b2 after reflecting from points C and D, and where the curvature, K, of the sample surface is determined from the measured phase difference.
5. Apparatus as in claim 1, where the curvature, K, of the sample surface changes with time, and where a real time curvature variation, κ(t), is monitored by measuring a variation of the path length difference, Δ(/).
6. Apparatus as in claim 3, where one of the lateral distance, d, between beams bl and b2 changes by an amount, δd, and the distance, c, between the midpoints of positions (A, B) and (C, D) changes by an amount, he, then the absolute curvature, K, of the sample surface is expressed as
where δΔ. is the change of the path difference due to the change in distance d or c.
7. Apparatus as in claim 1, wherein said source assembly further comprises a first beam splitter disposed relative to said lens, said reflector and the sample surface for splitting said measurement light into said beams bl and b2 and directing said beams bl and b2 towards the sample surface and towards said reflector. 19
8. Apparatus as in claim 7, wherein said source assembly further comprises a second beam splitter disposed relative to said lens, said reflector and the sample surface for directing at least twice reflected beams bl and b2 towards said detector.
9. Apparatus as in claim 1, where said lens comprises a convex lens, and where said optical source is comprised of a laser.
10. Apparatus as in claim 1, where said detector is responsive to receiving twice reflected beams bl and b2 for determining interference fringes between the at least twice reflected beams bl and b2.
11. A method to characterize curvature of a surface of a sample, comprising:
providing a reflector, a lens characterized by having two focal planes, and an optical source assembly outputting measurement light as beams bl and b2 and directing said beams bl and b2 to pass through said lens and to be reflected by said reflector;
arranging said reflector and said lens so that when a sample surface of interest is positioned relative to said reflector, such that said reflector and the sample surface are each located at one of the two focal planes of said lens, the sample surface becomes the image plane of itself for said lens, and said beams bl and b2 of the measurement light are reflected at least twice from the sample surface and accumulate a path length difference, Δ, that is proportional to the curvature, K, of the sample surface; and
detecting the path length difference to determine the curvature, K, of the sample surface.
12. A method as in claim 11, where the curvature, K, of the sample surface is equal to 1/R, where R is the radius of curvature of the sample surface, and beams bl and b2 develop a path length difference of 2(yΛ -yB), where ^and .yflare the normal positions of points A and B, with respect to the focal plane of said lens, and where reflections from points D and C result in a path length difference of 2(yD -yc), and where a total path length difference, Δ, between beams bl and b2 is 20
Δ = 2(yΛ - ya) + 2(yD - yc) = 2(yΛ + yD) - 2(yB + yc).
13. A method as in claim 12, where a lateral distance, d, between points A and B is equal to a lateral distance between points C and D; where a distance between midpoints of the positions (A,B) and (C, D) is represented by c, and the curvature of the sample surface, K, is expressed in terms of the total path length difference, Δ, and the distances, c and d, as
- Vc VD - VA d ) 2cd
14. A method as in claim 13, where the optical path difference, Δ, corresponds to a phase difference of 2πΔ/λ between beams bl and b2, where λ is the wavelength of the measurement light, and where said detector measures the phase difference from the interference between bl and b2 after reflecting from points C and D, and where the curvature, K, of the sample surface is determined from the measured phase difference.
15. A method as in claim 11, where the curvature, K, of the sample surface changes with time, and where a real time curvature variation, κ(t), is monitored by measuring a variation of the path length difference, Δ(t).
16. A method as in claim 13, where one of the lateral distance, d, between beams bl and b2 changes by an amount, δd, and the distance, c, between the midpoints of positions (A, B) and (C, D) changes by an amount, δc, then the absolute curvature, K, of the sample surface is expressed as
1 -& I δA K " 2c d ' θr" K 2 δe ' -
where δΔ. is the change of the path difference due to the change in distance d or c.
17. A method as in claim 11, wherein said beams bl and b2 are directed towards the sample surface and towards said reflector by said optical source assembly. 21
18. A method as in claim 11, wherein said optical source assembly further comprises a combining beam splitter for directing the at least twice reflected beams bl and b2 towards a detector.
19. A method as in claim 1 1, where providing said lens provides a convex lens, and where providing said optical source provides a laser.
20. A method as in claim 1 1, where detecting comprises receiving the at least twice reflected beams bl and b2 for determining interference fringes between said at least twice reflected beams bl and b2.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US47792003P | 2003-06-12 | 2003-06-12 | |
| US60/477,920 | 2003-06-12 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| WO2004111575A2 WO2004111575A2 (en) | 2004-12-23 |
| WO2004111575A3 WO2004111575A3 (en) | 2005-05-19 |
| WO2004111575B1 true WO2004111575B1 (en) | 2005-06-16 |
Family
ID=33551782
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US2004/018401 WO2004111575A2 (en) | 2003-06-12 | 2004-06-10 | Interferometric absolute and real-time surface curvature sensor insensitive to tilt, translation and vibration |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO2004111575A2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102798491A (en) * | 2011-05-23 | 2012-11-28 | 同济大学 | Thin film residual stress separating and measuring device |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100454000C (en) * | 2006-10-12 | 2009-01-21 | 上海交通大学 | Long term monitoring sensor for steel bar corrosion in steel concrete member |
| CN111895989A (en) * | 2020-06-24 | 2020-11-06 | 浙江大华技术股份有限公司 | Robot positioning method and device and electronic equipment |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4884697A (en) * | 1988-06-21 | 1989-12-05 | Takacs Peter Z | Surface profiling interferometer |
| US5248889A (en) * | 1990-08-14 | 1993-09-28 | Tencor Instruments, Inc. | Laser apparatus and method for measuring stress in a thin film using multiple wavelengths |
| US5523582A (en) * | 1992-04-30 | 1996-06-04 | Ann F. Koo | Method and apparatus for measuring the curvature of wafers with a laser source selecting device |
-
2004
- 2004-06-10 WO PCT/US2004/018401 patent/WO2004111575A2/en active Application Filing
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102798491A (en) * | 2011-05-23 | 2012-11-28 | 同济大学 | Thin film residual stress separating and measuring device |
| CN102798491B (en) * | 2011-05-23 | 2014-04-16 | 同济大学 | Thin film residual stress separating and measuring device |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2004111575A3 (en) | 2005-05-19 |
| WO2004111575A2 (en) | 2004-12-23 |
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