Plate thickness measuring method and apparatus
US4564296A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 24, 1981 |
| Grant date | Jan 14, 1986 |
| Priority date | — |
| Expiry date | Sep 24, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A plate thickness measuring method and apparatus, is provided wherein a fine pattern is projected on the front and rear surfaces of an object to be measured via object lenses oppositely provided on the front and rear surfaces of the object to be measured in its thickness. The image of the projected pattern on the object to be measured is formed via said object lenses, and the contrast of the formed pattern image is detected. Then the object lenses are moved slightly to achieve the maximum of the contrast, or to perform an automatic focusing control. The thickness of the object to be measured can then be estimated from the difference of the positions of the object lenses at which the maximum contrast, or the focused condition, are obtained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.