US4428676A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical system for oblique viewing
Assignee: International Business Machines Corp
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Filing: 1981-10-23
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Granted: 1984-01-31
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Expires: 2001-10-23
Abstract
Abstract An optical system for the oblique viewing of an object includes a specific embodiment for quantitatively determining the volume of solder mounds on chips and wafers without the introduction of keystone distortion and anamorphosis. The optical system includes means for directing an image of the solder mounds at an angle to a diffraction grating to provide a diffracted beam normal to the grating. The diffracted beam is then processed in a conventional manner to yield the sought-after information. In a preferred embodiment the directing means is an afocal lens system having a magnification of one.
Inventors
- 👤 Jean C. A. Chastang
- 👤 Robert F. Koerner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:30
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/4205; G01; G01B; G01B11/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
120 words
An optical system for the oblique viewing of a substrate comprising means for reflecting an image of the surface of the substrate at a first angle of θ 2 with the perpendicular to the substrate, a diffraction grating, directing means for projecting said reflected image on said grating at a second angle of θ 3 with the perpendicular to said grating to provide a diffracted beam normal to said grating, said grating having a period a=λ/sin θ where λ is the wavelength of the diffracted beam, said directing means providing a magnification of one, lens means for projecting said diffracted beam, and means for detecting said projected diffracted beam wherein a high resolution distortion-free image of said substrate is obtained.
Claim 2
Dependent Claim
120 words
An optical system for the oblique viewing of a substrate comprising means for reflecting an image of the surface of the substrate at a first angle of θ 2 with the perpendicular to the substrate, a diffraction grating, directing means for projecting said reflected image on said grating at a second angle of θ 3 with the perpendicular to said grating to provide a diffracted beam normal to said grating, said grating having a period a=λ/sin θ where λ is the wavelength of the diffracted beam, said directing means providing a magnification of one, lens means for projecting said diffracted beam, and means for detecting said projected diffracted beam wherein a high resolution distortion-free image of said substrate is obtained.
Claim 3
Dependent Claim
24 words
The optical system of claim 1 wherein said detecting means comprises means to analyze the contrast in the image of said projected diffracted beam.
Claim 4
Dependent Claim
16 words
An optical system as described in claim 1 wherein said directing means is a dioptric system.
Claim 5
Dependent Claim
15 words
An optical system as described in claim 1 wherein said directing means is a lens.
Claim 6
Dependent Claim
16 words
An optical system as described in claim 1 wherein said directing means is a catadioptric system.
Claim 7
Dependent Claim
17 words
An optical system as described in claim 1 wherein said directing means is an afocal optical system.
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) | 1987-01-30 | 1987-08-01 | 1988-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-30 | 1991-08-01 | 1992-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-30 | 1995-08-01 | 1996-01-31 | $7700.00 | Window Closed / Lapsed |