Method and apparatus for detecting surface defects in mechanical workpieces
US4448527A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 8, 1982 |
| Grant date | May 15, 1984 |
| Priority date | — |
| Expiry date | Feb 8, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/88
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The detection of surface defects in mechanical parts is effected by the analysis of diffracted light coming from these defects. The detection method includes the steps of illuminating the surface of the part to be examined with incoherent light and forming a flat image of the said surface in a transparent photosensitive layer of a spatial light modulator. The spatial distribution of the intensity of the incoherent light reflected by the said surface produces a corresponding and proportional spatial distribution of values of refractive index in the photosensitive layer. This layer is illuminated with plane polarized, coherent light by frame scanning in elementary areas. During the scanning operation, the variations in at least one of the polarization components of the coherent light are detected by a matrix of converters after the light has traversed the said transparent photosensitive medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.