US3748047A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of detecting surface defects of material surfaces
Assignee: Rederi Nordstjernan AB
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Filing: 1971-10-19
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Granted: 1973-07-24
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Expires: 1991-10-19
Abstract
Abstract The apparatus and method of the invention are directed to photoelectrically observing differences in diffraction and reflection, for light scanning a surface to be inspected for defects, the comparison being between a pattern for the unknown surface and a pattern for a tolerably acceptable smooth surface. In application to inspection of a surface of continually moving sheet material, a flying-spot scanner is caused to scan generally transverse to sheet motion, and the photoelectric response is a measure of light scattered by transiently observed abnormalities in the moving surface.
Inventors
- 👤 L Millgard
- 👤 U Sjolin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:40
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/89; G01N21/8901
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
110 words
The method of detecting surface defects of preferably smooth material, which comprises: a directing electromagnetic radiation from a radiation source to a surface of the material to be examined; b. relatively moving said surface and radiation in a first general direction; c. causing said radiation to periodically scan said surface along an alignment generally transverse to said relative movement; d. producing a stationary image of diffraction patterns from reflections of electromagnetic radiation reflected from said surface; e. filtering out image elements deriving from the normal structure of said surface; and f. detecting image elements which survive such filtering, whereby the detected output is a measure of defects in said surface.
Claim 2
Independent Claim
110 words
The method of detecting surface defects of preferably smooth material, which comprises: a directing electromagnetic radiation from a radiation source to a surface of the material to be examined; b. relatively moving said surface and radiation in a first general direction; c. causing said radiation to periodically scan said surface along an alignment generally transverse to said relative movement; d. producing a stationary image of diffraction patterns from reflections of electromagnetic radiation reflected from said surface; e. filtering out image elements deriving from the normal structure of said surface; and f. detecting image elements which survive such filtering, whereby the detected output is a measure of defects in said surface.
Claim 3
Dependent Claim
15 words
The method of claim 1, wherein an opaque material is used in said filtering step.
Claim 4
Dependent Claim
26 words
The method of claim 1, in which said filtering step is accomplished by attenuating image elements deriving from the normal structure of said surface being examined.
Claim 5
Dependent Claim
27 words
Apparatus according to claim 3, wherein said photoelectric means comprises a plurality of detector elements, each sensitive to scratches with an orientation within a certain angular range.
Claim 6
Dependent Claim
220 words
Apparatus for continuous inspection of surface quality in a straight presumptively smooth surface of a given body, comprising an optical flying-spot scanner having a straight-line scan path in a scanning surface in which the scan spot is swept in periodic recycling succession, means for supporting the given body with its smooth surface in a plane intersected by said scanning surface at an angle of incidence such that intersection of said surfaces defines the alignment of the scan path, said last-defined means including means for relatively displacing said body and scanner in a direction generally transverse to the scan path, whereby the light spot is reflected from the surface along a correspondingly swept axis of reflection within a predominant surface of reflection, with dispersed light within a range of angles near said surface of reflection, focusing optical means positioned to collect the substantial range of light reflected in the course of scanning, and focusing optical means being adapted to converge collected directly reflected light at a single focal point, an optical attenuator in substantially the focal surface of said focusing optical means, said attenuator having an area-function of attenuation selected essentially only to attenuate a substantial fraction of the total light flux attributable to reflection from a surface tolerably free from defects, and photoelectric means responsive to light passing said attenuator.
Claim 7
Dependent Claim
220 words
Apparatus for continuous inspection of surface quality in a straight presumptively smooth surface of a given body, comprising an optical flying-spot scanner having a straight-line scan path in a scanning surface in which the scan spot is swept in periodic recycling succession, means for supporting the given body with its smooth surface in a plane intersected by said scanning surface at an angle of incidence such that intersection of said surfaces defines the alignment of the scan path, said last-defined means including means for relatively displacing said body and scanner in a direction generally transverse to the scan path, whereby the light spot is reflected from the surface along a correspondingly swept axis of reflection within a predominant surface of reflection, with dispersed light within a range of angles near said surface of reflection, focusing optical means positioned to collect the substantial range of light reflected in the course of scanning, and focusing optical means being adapted to converge collected directly reflected light at a single focal point, an optical attenuator in substantially the focal surface of said focusing optical means, said attenuator having an area-function of attenuation selected essentially only to attenuate a substantial fraction of the total light flux attributable to reflection from a surface tolerably free from defects, and photoelectric means responsive to light passing said attenuator.
Claim 8
Dependent Claim
24 words
Apparatus according to claim 5, wherein said optical attenutator includes a photographic film exposed with said diffraction patterns from a surface free from defects.
Claim 9
Dependent Claim
35 words
Apparatus according to claim 5, in which said flying-spot scanner comprises a laser generating a beam of coherent light, and means including a continuously rotating prism mirror for sweeping said beam in said scanning surface.
Claim 10
Dependent Claim
25 words
Apparatus according to claim 5, wherein said optical attenuator includes an adaptive optical filter with transmission properties automatically adapted to the surface to be examined.
Claim 11
Dependent Claim
15 words
Apparatus according to claim 8, wherein the adaptive optical filter consists of a photochromous material.
Claim 12
Dependent Claim
182 words
Apparatus for continuous inspection of surface defects in a moving sheet, comprising means for supporting and conveying sheet material to be inspected, an optical flying-spot scanner supported above the sheet-supporting and conveying means, said scanner translating a light spot in a scanning surface intersecting said sheet in a line across a given width of the sheet in periodic recycling succession, whereby the light spot is reflected from the sheet along a coRrespondingly swept axis of reflection within a predominant surface of reflection, with diffracted and diffused light within a range of angles near said axis, focusing optical means positioned to collect the substantial range of light reflected and diffracted in the course of scanning, said focusing optical means being adapted to converge collected directly reflected light at a single focal point, an optical attenuator in substantially the focal surface of said optical means, said attenuator having an area-function of attenuation selected essentially only to attenuate a substantial fraction of the toral light flux attributable to reflection from a surface tolerably free from defects, and photoelectric means responsive to light passing said attenuator.
Claim 13
Dependent Claim
182 words
Apparatus for continuous inspection of surface defects in a moving sheet, comprising means for supporting and conveying sheet material to be inspected, an optical flying-spot scanner supported above the sheet-supporting and conveying means, said scanner translating a light spot in a scanning surface intersecting said sheet in a line across a given width of the sheet in periodic recycling succession, whereby the light spot is reflected from the sheet along a coRrespondingly swept axis of reflection within a predominant surface of reflection, with diffracted and diffused light within a range of angles near said axis, focusing optical means positioned to collect the substantial range of light reflected and diffracted in the course of scanning, said focusing optical means being adapted to converge collected directly reflected light at a single focal point, an optical attenuator in substantially the focal surface of said optical means, said attenuator having an area-function of attenuation selected essentially only to attenuate a substantial fraction of the toral light flux attributable to reflection from a surface tolerably free from defects, and photoelectric means responsive to light passing said attenuator.
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) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |