US4674875A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for inspecting surface defects on the magnetic disk file memories
Assignee: Hitachi Ltd
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Filing: 1984-12-07
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Granted: 1987-06-23
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Expires: 2004-12-07
Abstract
Abstract Method and apparatus for inspecting surface defects of a sample in which oblique illumination is applied onto a surface of the sample and in which illuminance of reflected beams generated from the surface is measured. Shading plate having double pinholes or double slits is used as means for shading a scattered beam from aventurine prominences of the sample surface to fully shade the scattered beam so that the inspection is accurately executed.
Inventors
- 👤 Mitsuyoshi Koizumi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:11
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/95; G01N21/9506
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
123 words
A method for inspecting surface defects of magnetic disks comprising: applying parallel coherent in space oblique illumination beams onto a surface of a plate at a oblique angle; measuring the illuminance distribution of reflected beams generated from said surface by using photoelectric transducer means having stray-light-stop optical means, scattered beams being cut off by said stray-light-stop optical means, said photoelectric transducer means including a photoelectric transducer element and at least two plates, each plate having an aperture therein and arranged for introducing the reflected beams to said photoelectric transducer element; and detecting defects distributed over said surface having minute averturine dents and prominences based upon said measured illuminance distribution, each of said defects having a depth (or height) significantly smaller than its size.
Claim 2
Independent Claim
123 words
A method for inspecting surface defects of magnetic disks comprising: applying parallel coherent in space oblique illumination beams onto a surface of a plate at a oblique angle; measuring the illuminance distribution of reflected beams generated from said surface by using photoelectric transducer means having stray-light-stop optical means, scattered beams being cut off by said stray-light-stop optical means, said photoelectric transducer means including a photoelectric transducer element and at least two plates, each plate having an aperture therein and arranged for introducing the reflected beams to said photoelectric transducer element; and detecting defects distributed over said surface having minute averturine dents and prominences based upon said measured illuminance distribution, each of said defects having a depth (or height) significantly smaller than its size.
Claim 3
Dependent Claim
56 words
A method for inspecting surface defects of magnetic disks according to claim 1, wherein said photoelectric transducer means includes said photoelectric transducer element and one of said plates with said aperture being a pinhole and arranged behind said stray-light-stop optical means and wherein said photoelectric transducer means is so disposed so as to detect craterlike defects.
Claim 4
Dependent Claim
48 words
A method for inspecting surface defects of magnetic disks according to claim 1, wherein said photoelectric transducer means includes said photoelectric transducer element and a cylindrical lens arranged behind said stray-light-stop optical means and wherein said photoelectric transducer means is so disposed so as to detect stripe defects.
Claim 5
Dependent Claim
65 words
A method for inspecting surface defects of magnetic disks according to claim 1, wherein said photoelectric transducer means includes said photoelectric transducer element in addition to said stray-light-stop optical means, and stray-light-stop optical means includes said at least two plates with said apertures in the form of pinholes, and wherein said photoelectric transducer means is so disposed as to detect craterlike defects or stripe defects.
Claim 6
Dependent Claim
65 words
A method for inspecting surface defects of magnetic disks according to claim 1, wherein said stray-light-stop optical means includes said at least two plates with said apertures in the form of slits and wherein said photoelectric transducer means includes a cylindrical lens and said photoelectric transducer element behind said stray-light-stop optical means, and said photoelectric transducer means is so disposed as to detect strip defects.
Claim 7
Dependent Claim
41 words
A method for inspecting surface defects of magnetic disks according to claim 1, wherein said stray-light-stop optical means includes two convex lenses and one of said plates with said aperture in the form of a pinhole inserted between said convex lens.
Claim 8
Dependent Claim
34 words
A method for inspecting surface defects of magnetic disks according to claim 6, wherein said photoelectric transducer means includes a cylindrical lens inserted between said stray-light-stop optical means and another of said two plates.
Claim 9
Dependent Claim
27 words
A method for inspecting surface defects of magnetic disks according to claim 1, wherein said stray-light-stop optical means includes two of said plates having said apertures therein.
Claim 10
Dependent Claim
44 words
A method for inspecting surface defects of magnetic disks according to claim 8, wherein said photoelectric transducer means includes a cylindrical lens and a third plate having an aperture therein, said cylindrical lens being arranged between said stray-light-stop optical means and said third plate.
Claim 11
Independent Claim
70 words
An apparatus for inspecting surface defects of magnetic disks comprising: a parallel coherent oblique illumination unit; a photoelectric transducer unit having a stray-light-stop optical system, scattered beams being cut off by said stray-light-stop optical system, said photoelectric unit including a photoelectric transducer element and at least two plates, each plate having an aperture therein for enabling introduction of light beams to said photoelectric transducer unit; and a sample feeding stage.
Claim 12
Independent Claim
70 words
An apparatus for inspecting surface defects of magnetic disks comprising: a parallel coherent oblique illumination unit; a photoelectric transducer unit having a stray-light-stop optical system, scattered beams being cut off by said stray-light-stop optical system, said photoelectric unit including a photoelectric transducer element and at least two plates, each plate having an aperture therein for enabling introduction of light beams to said photoelectric transducer unit; and a sample feeding stage.
Claim 13
Dependent Claim
41 words
An apparatus for inspecting surface defects of magnetic disks according to claim 10, wherein said stray-light-stop optical system includes two convex lenses and one of said plates with said aperture in the form of a pinhole inserted between said convex lenses.
Claim 14
Dependent Claim
46 words
An apparatus for inspecting surface defects of magnetic disks according to claim 11, wherein said photoelectric transducer unit includes a cylindrical lens and another of said plates having said aperture, said cylindrical lens being arranged between said stray-light-stop optical system and said another of said plates.
Claim 15
Dependent Claim
43 words
An apparatus for inspecting surface defects of magnetic disks according to claim 10, wherein said photoelectric transducer unit includes said photoelectric transducer element and one of said plates with said aperture in the form of a pinhole arranged behind said stray-light-stop optical system.
Claim 16
Dependent Claim
33 words
An apparatus for inspecting surface defects of magnetic disks according to claim 10, wherein said photoelectric transducer unit includes said photoelectric transducer element and a cylindrical lens arranged behind said stray-light-stop optical system.
Claim 17
Dependent Claim
27 words
An apparatus for inspecting surface defects of magnetic disks according to claim 10, wherein said stray-light-stop optical system includes two of said plates having said apertures therein.
Claim 18
Dependent Claim
47 words
An apparatus for inspecting surface defects of magnetic disks according to claim 15, wherein said photoelectric transducer unit includes a cylindrical lens and another of said plates having an aperture therein, said cylindrical lens being arranged between said stray-light-stop optical system and said another of said plates.
Claim 19
Independent Claim
64 words
An apparatus for inspecting surface defects of magnetic disks comprising: a coherent oblique illuminating unit which illuminates substantially in a parallel beam; a photoelectric transducer unit having a stray-light-stop optical system, scattered beams being cut off by said stray-light-stop optical system, said photoelectric transducer unit including a cylindrical lens and a photoelectric transducer element behind said stray-light-stop optical system; and a sample feeding stage.
Claim 20
Independent Claim
64 words
An apparatus for inspecting surface defects of magnetic disks comprising: a coherent oblique illuminating unit which illuminates substantially in a parallel beam; a photoelectric transducer unit having a stray-light-stop optical system, scattered beams being cut off by said stray-light-stop optical system, said photoelectric transducer unit including a cylindrical lens and a photoelectric transducer element behind said stray-light-stop optical system; and a sample feeding stage.
Claim 21
Dependent Claim
25 words
An apparatus for inspecting surface defects of magnetic disks according to claim 17, wherein said stray-light-stop optical system includes a plurality of plates having pinholes.
Claim 22
Dependent Claim
25 words
An apparatus for inspecting surface defects of magnetic disks according to claim 17, wherein said stray-light-stop optical system includes a plurality of plates having slits.
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) | 1990-06-22 | 1990-12-22 | 1991-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-22 | 1994-12-22 | 1995-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-22 | 1998-12-22 | 1999-06-23 | $7700.00 | Window Closed / Lapsed |