Surface detect test apparatus
US4162126A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 9, 1977 |
| Grant date | Jul 24, 1979 |
| Priority date | — |
| Expiry date | Dec 9, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/952
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus and method for testing surface defect on an object are disclosed, which comprise an illumination means for illuminating collimated lights onto a surface of the object obliquely to the surface and from two symmetrical directions, a sensor composed of a TV camera or a linear image sensor for sensing diffused reflected lights from the surface of the object in the direction perpendicular to the surface, a classification means for discriminating the sensed image signal by a threshold level which is higher than an average level of the image signal and a threshold level which is lower than the average level to determine the surface defect pattern as a broken cavity pattern or a pit or crack pattern by the discriminated signals, and a discrimination means for calculating L.sup.2 -4.pi.S, where S is an area of the defect and L is a length of the contour, when signal discriminated by the lower threshold level is produced to discriminate the pit pattern and the crack pattern by determining whether L.sup.2 -4.pi.S exceeds a predetermined value or not. In this manner, the defects that exist on the surface of the object can be classified and evaluated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.