US5343290A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Surface particle detection using heterodyne interferometer
Assignee: International Business Machines Corp
•
Filing: 1992-06-11
•
Granted: 1994-08-30
•
Expires: 2012-06-11
Abstract
Abstract A heterodyne interferometer is combined with darkfield surface particle detection for improved surface particle detection sensitivity. The probe beam and the reference beam have different wavelengths. The reference beam may either be a real reference beam or a virtual reference beam. The probe beam may be incident at the surface at either a grazing angle or at an angle substantially normal to the surface. The real reference beam is incident at the surface at a grazing angle. The detection may either be conventional heterodyne detection or a combination of heterodyne and Lloyd's mirror detection.
Inventors
- 👤 John S. Batchelder
- 👤 Donald M. DeCain
- 👤 Philip C. D. Hobbs
- 👤 Marc A. Taubenblatt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:17
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/94; G01J; G01J9/00; G01J9/04; G01N21/8806; G01N2021/8822; G01N21/17; G01N21/47; G01N21/95; G01N21/9501
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
152 words
A surface particle detection apparatus comprising: means for generating a probe beam and a reference beam at different wavelengths and for illuminating a surface with said probe beam; and detector means for detecting a scattered probe beam arising from said probe beam intersecting a particle on the surface, and for simultaneously detecting a second beam spatially coherent with said scattered probe beam, said second beam comprising one of: (a) a real reference beam arising from said reference beam intercepting the surface at a grazing angle, and (b) a virtual reference beam arising from said reference beam bypassing the surface when at least one of said probe beam and scattered probe beam intercepts the surface at a grazing angle, said detector means generating a beat frequency signal resulting from interference of the detected beams at the detector means, said beat frequency signal being indicative of the presence of a particle on the surface.
Claim 2
Dependent Claim
152 words
A surface particle detection apparatus comprising: means for generating a probe beam and a reference beam at different wavelengths and for illuminating a surface with said probe beam; and detector means for detecting a scattered probe beam arising from said probe beam intersecting a particle on the surface, and for simultaneously detecting a second beam spatially coherent with said scattered probe beam, said second beam comprising one of: (a) a real reference beam arising from said reference beam intercepting the surface at a grazing angle, and (b) a virtual reference beam arising from said reference beam bypassing the surface when at least one of said probe beam and scattered probe beam intercepts the surface at a grazing angle, said detector means generating a beat frequency signal resulting from interference of the detected beams at the detector means, said beat frequency signal being indicative of the presence of a particle on the surface.
Claim 3
Dependent Claim
20 words
A surface particle detection apparatus as set forth in claim 1 wherein said detector means comprises a Lloyd's mirror detector.
Claim 4
Dependent Claim
68 words
A surface particle detection apparatus as set forth in claim 2 wherein said means for generating causes said probe beam to be incident at the surface at an angle of incidence substantially normal to the surface and said reference beam to be incident at the surface at a grazing angle and said probe beam and said reference beam to intersect at substantially the same location at the surface.
Claim 5
Dependent Claim
52 words
A surface particle detection apparatus as set forth in claim 2 wherein said means for generating causes said probe beam and said reference beam to be incident at the surface at respective grazing angles and said probe beam and said reference beam to intersect at substantially the same location at the surface.
Claim 6
Dependent Claim
21 words
A surface particle detection apparatus as set forth in claim 4, wherein said means for generating further comprises hyper-telecentric scanning means.
Claim 7
Dependent Claim
20 words
A surface particle detection apparatus as set forth in claim 5, wherein is said hyper-telecentric scanning means comprises galvo-mirror means.
Claim 8
Dependent Claim
21 words
A surface particle detection apparatus as set forth in claim 6 wherein said hyper-telecentric scanning means further comprises spherical mirror means.
Claim 9
Dependent Claim
36 words
A surface particle detection apparatus as set forth in claim 4, wherein said means for generating further comprises means for causing said probe beam and said reference beam to intersect at a substantially orthogonal azimuthal angle.
Claim 10
Dependent Claim
46 words
A surface particle detection apparatus as set forth in claim 2 wherein said means for generating causes said probe beam to be incident at the surface at an angle substantially normal to the surface and said reference beam to be detected as a virtual reference beam.
Claim 11
Dependent Claim
42 words
A surface particle detection apparatus as set forth in claim 2 wherein said means for generating causes said probe beam to be incident at the surface at a grazing angle and said reference beam to be detected as a virtual reference beam.
Claim 12
Dependent Claim
19 words
A surface particle detection apparatus as set forth in claim 1 wherein said detector means is a heterodyne detector.
Claim 13
Dependent Claim
42 words
A surface particle detection apparatus as set forth in claim 11 wherein said means for generating causes said probe beam to be incident at the surface at a grazing angle and said reference beam to be detected as a virtual reference beam.
Claim 14
Dependent Claim
35 words
A surface particle detection apparatus as set forth in claim 1 wherein said means for generating is selected from the group consisting of a laser and Bragg cell, a Zeeman split laser and two lasers.
Claim 15
Independent Claim
142 words
A method of surface particle detection comprising the steps of: generating a probe beam and a reference beam at different wavelengths; illuminating a surface with said probe beam; and detecting a scattered probe beam arising from said probe beam intercepting a particle on the surface and detecting simultaneously a second beam spatially coherent with said scattered probe beam, said second beam comprising one of (a) a real reference beam arising from said reference beam intercepting the surface at a grazing angle, and (b) a virtual reference beam arising from said reference beam bypassing the surface when at least one of said probe beam and said scattered probe beam intercepts the surface at a grazing angle, and generating a beat frequency signal from interference of the detected beams, said beat frequency signal being indicative of the presence of a particle on the surface.
Claim 16
Independent Claim
142 words
A method of surface particle detection comprising the steps of: generating a probe beam and a reference beam at different wavelengths; illuminating a surface with said probe beam; and detecting a scattered probe beam arising from said probe beam intercepting a particle on the surface and detecting simultaneously a second beam spatially coherent with said scattered probe beam, said second beam comprising one of (a) a real reference beam arising from said reference beam intercepting the surface at a grazing angle, and (b) a virtual reference beam arising from said reference beam bypassing the surface when at least one of said probe beam and said scattered probe beam intercepts the surface at a grazing angle, and generating a beat frequency signal from interference of the detected beams, said beat frequency signal being indicative of the presence of a particle on the surface.
Claim 17
Dependent Claim
22 words
A method of surface particle detection as set forth in claim 14 wherein said detecting comprises the step of Lloyd's mirror detection.
Claim 18
Dependent Claim
67 words
A method of surface particle detection as set forth in claim 15 wherein said illuminating a surface comprises the step of illuminating the surface with said probe beam at an angle of incidence substantially normal to the surface and illuminating the surface with said reference beam at a grazing angle and said probe beam and said reference beam intersecting at substantially the same location at the surface.
Claim 19
Dependent Claim
53 words
A method of surface particle detection as set forth in claim 15, wherein said illuminating a surface comprises the steps of illuminating the surface with said probe beam and said reference beam at respective grazing angles and said probe beam and said reference beam intersecting at substantially the same location at the surface.
Claim 20
Dependent Claim
31 words
A method of surface particle detection as set forth in claim 17, wherein said illuminating a surface comprising reflecting said probe beam and said reference beam from a hyper-telecentric scanning means.
Claim 21
Dependent Claim
31 words
A method of surface particle detection as set forth in claim 18, wherein said illuminating a surface further comprises reflecting said probe beam and said reference beam from an oscillating galvo-mirror.
Claim 22
Dependent Claim
32 words
A method of surface particle detection as set forth in claim 19 wherein said illuminating a surface further comprises reflecting said probe beam and said reference beam from a spherical mirror surface.
Claim 23
Dependent Claim
33 words
A method of surface particle detection as set forth in claim 17, wherein said illuminating a surface further comprises said probe beam and said reference beam intersecting at a substantially orthogonal azimuthal angle.
Claim 24
Dependent Claim
43 words
A method of surface particle detection as set forth in claim 15 wherein said illuminating a surface comprises illuminating the surface with said probe beam at an angle substantially normal to the surface and wherein said detecting comprises detecting a virtual reference beam.
Claim 25
Dependent Claim
38 words
A method of surface particle detection as set forth in claim 15, wherein said illuminating a surface comprises illuminating the surface with said probe beam at a grazing angle and said detecting comprises detecting a virtual reference beam.
Claim 26
Dependent Claim
21 words
A method of surface particle detection as set forth in claim 14, wherein said detecting comprises the step of heterodyne detection.
Claim 27
Dependent Claim
38 words
A method of surface particle detection as set forth in claim 24 wherein said illuminating a surface comprises illuminating the surface with said probe beam at a grazing angle and said detecting comprises detecting a virtual reference beam.
Claim 28
Dependent Claim
44 words
A method of surface particle detection as set forth in claim 14 wherein said generating comprises generating said probe beam and said reference beam by means selected from the group consisting of a laser and Bragg cell, a Zeeman split laser and two lasers.
References Cited (Backward Citations)
US4669875A
Cited
US4610541A
Cited
JPS6067845A
Cited
US4848908A
Cited
JPS60224044A
Cited
JPS6361152A
Cited
US4740708A
Cited
US5030842A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-08-29 | 1998-02-28 | 1998-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-29 | 2002-02-28 | 2002-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-29 | 2006-02-28 | 2006-08-30 | $7700.00 | Window Closed / Lapsed |