Patent US4725139A successfully refreshed from Google Patents.
US4725139A
Expired / Lapsed
US
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Method and apparatus for detecting defects in transparent materials
Assignee: Schott AG
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Filing: 1985-05-08
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Granted: 1988-02-16
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Expires: 2005-05-08
Abstract
Abstract A method of detecting defects present at the surface and/or internally in transparent materials, particularly of detecting included foreign bodies or bubbles in glass, is disclosed. The test material is scanned with an electromagnetic radiation of a single wavelength which is set to the penetration depth in the test material. The intensity reflected by the defects is picked up and analyzed. By this method only defects located up to a specified depth in the material are detected. Visible light as well as UV- or IR radiation may be applied. The associated test rig comprises a tunable Laser (2), a conveyor belt (6) carrying the test material (5), a fast rotating mirror-wheel (3) which directs the light beam (4) at high speed over the test material (5), and an optical sensor (7) connected with an analyzer unit (8).
Inventors
- 👤 Hrabanus Hack
- 👤 Rainer Haspel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 21:36
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/30; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/89; G01N21/892; G01N21/896; G01N21/8806; G01N2021/8845
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
137 words
A method of detecting defects in a test material by the use of incident electromagnetic radiation which is incident on the test material comprising the steps of: I. selecting the wavelength of the incident electromagnetic radiation such that defects of the test material within a characteristic penetration depth of said incident electromagnetic radiation is scattered such that the scattered electromagnetic radiation will reach a detector; and II. scanning the test material with the incident electromagnetic radiation thus selected; and III. detecting the scattered electromagnetic radiation from defects in said test material by use of the detector; and whereby, when the incident electromagnetic radiation is scanned relative to the test material the detector will receive a sensible variation in the intensity of the scatterd electromagnetic radiation in accordance with the presence of defects within the characteristic penetration depth.
Claim 2
Independent Claim
137 words
A method of detecting defects in a test material by the use of incident electromagnetic radiation which is incident on the test material comprising the steps of: I. selecting the wavelength of the incident electromagnetic radiation such that defects of the test material within a characteristic penetration depth of said incident electromagnetic radiation is scattered such that the scattered electromagnetic radiation will reach a detector; and II. scanning the test material with the incident electromagnetic radiation thus selected; and III. detecting the scattered electromagnetic radiation from defects in said test material by use of the detector; and whereby, when the incident electromagnetic radiation is scanned relative to the test material the detector will receive a sensible variation in the intensity of the scatterd electromagnetic radiation in accordance with the presence of defects within the characteristic penetration depth.
Claim 3
Dependent Claim
23 words
Method according to claim 1, characterised in that the incident electromagnetic radiation has a wavelength within the visible region of the electromagnetic spectrum.
Claim 4
Dependent Claim
23 words
Method according to claim 1, characterised in that the incident electromagnetic radiation has a wavelength within the invisible region of the electromagnetic spectrum.
Claim 5
Dependent Claim
19 words
Method according to claim 3, characterised in that the incident electromagnetic radiation has a wavelength within the ultraviolet region.
Claim 6
Dependent Claim
19 words
Method according to claim 3, characterised in that the incident electromagnetic radiation has a wavelength within the infrared region.
Claim 7
Dependent Claim
25 words
Method according to claim 1, characterised in that the incident electromagnetic radiation has a wavelength in respect to which the test material has reduced transmissivity.
Claim 8
Dependent Claim
21 words
Method according to claim 1, characterised in that the test material is successively scanned by incident electromagnetic radiation of different wavelengths.
References Cited (Backward Citations)
US4297587A
Cited
US4555179A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-15 | 1991-08-17 | 1992-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-15 | 1995-08-17 | 1996-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-15 | 1999-08-17 | 2000-02-16 | $7700.00 | Window Closed / Lapsed |