Optical method of detecting defect and apparatus used therein
US5894345A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 20, 1997 |
| Grant date | Apr 13, 1999 |
| Priority date | — |
| Expiry date | May 20, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/8903
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An array light source 1 with semiconductor laser sources disposed one-dimensionally and a projective lens 2 are used to illuminate an inspected object so that light beams projected from the array light source form a dotted line on the object. A line sensor is used to receive through an objective lens 3 light emitted from an imaging area 11 away from an illuminated area 12. An image signal, fed to an image processing unit 8 through a pre-processing unit 7 producing an image from signals from the line sensor 4 and a stage 5 is processed, while the stage 5 bearing the object 6 is being gradually moved, to inspect the object 6 for crack defects 9 and 10 by detecting an optically nonhomogeneous portion of the object. The method allows a crack defect of an object, such as a ceramic substrate or a sintered metal product, to be detected fast with high accuracy.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.