US4988198A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for measuring microlevel difference
Assignee: Dainippon Screen Manufacturing Co Ltd
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Filing: 1988-06-22
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Granted: 1991-01-29
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Expires: 2008-06-22
Abstract
Abstract An apparatus for measuring a very small difference comprises a stage for receiving a sample to be measured, a light source illuminating the sample, an optical system for condensing light reflected from the sample, structure for intercepting a portion of the reflected light, a spectroscope for analyzing the condensed reflected light and a detector for detecting spectrum of the analyzed light. Light reflected only from a main surface of the sample is intercepted by the intercepting structure. Thus, the signal to noise ratio of the reflected light is reduced to enhance measurement capability.
Inventors
- 👤 Noriyuki Kondo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:15
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/02; G01B11/06; G01B11/0616; G01B11/0625; G01B11/22
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
185 words
An apparatus for measuring the distance between an upper surface and a lower surface of a sample, said apparatus comprising: means for holding said sample; a light source for illuminating said upper and lower surfaces in such a manner that light is reflected off of said surfaces, said light source impinging light substantially vertically onto said upper surface, said reflected light having a first component which is regularly reflected from said upper surface and a second component which represents interfered light reflected from said upper and lower surfaces; an optical system for condensing said reflected light, said optical system including an optical axis; reducing means for reducing said first component relative to said second component, said reducing means including means for intercepting said first component near said optical axis, said intercepting means including a mirror which includes: (1) a central portion and other portions; (2) a light intercepting portion formed at said central portion; and (3) transmissive portions formed at said other portions; a spectroscope for analyzing reflected light condensed by said optical system; and means for detecting spectrum of light analyzed by said spectroscope.
Claim 2
Independent Claim
185 words
An apparatus for measuring the distance between an upper surface and a lower surface of a sample, said apparatus comprising: means for holding said sample; a light source for illuminating said upper and lower surfaces in such a manner that light is reflected off of said surfaces, said light source impinging light substantially vertically onto said upper surface, said reflected light having a first component which is regularly reflected from said upper surface and a second component which represents interfered light reflected from said upper and lower surfaces; an optical system for condensing said reflected light, said optical system including an optical axis; reducing means for reducing said first component relative to said second component, said reducing means including means for intercepting said first component near said optical axis, said intercepting means including a mirror which includes: (1) a central portion and other portions; (2) a light intercepting portion formed at said central portion; and (3) transmissive portions formed at said other portions; a spectroscope for analyzing reflected light condensed by said optical system; and means for detecting spectrum of light analyzed by said spectroscope.
Claim 3
Dependent Claim
37 words
An apparatus according to claim 1, wherein: said light source includes a diaphragm and said diaphragm includes a first aperture; said optical system includes a second aperture; and said first aperture is smaller than said second aperture.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-01-28 | 1994-07-30 | 1995-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-28 | 1998-07-30 | 1999-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-28 | 2002-07-30 | 2003-01-29 | $7700.00 | Window Closed / Lapsed |