Optoelectronic system for determining surface irregularities of a workpiece having a nominally plane reflective surface
US5003615A · kind A · utility
15Cited by
5References
16Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Dec 1, 1988 |
| Grant date | Mar 26, 1991 |
| Priority date | — |
| Expiry date | Dec 1, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/306
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
By comparing the distorted image of an edge pattern, such as a checker board pattern, reflected from the surface of a work piece, such as a silicon wafer, and received by a solid state television camera, with a similar image, reflected from the optically flat surface of a calibration piece substituted for the work piece, surface height irregularities, such as warpage, of the work piece can be measured with a high sensitivity and a large dynamic range at relatively low cost.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.