Focus tracking system
US4626103A · kind A · utility
12Cited by
6References
16Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Mar 29, 1984 |
| Grant date | Dec 2, 1986 |
| Priority date | — |
| Expiry date | Mar 29, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7026
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method and apparatus are disclosed for tracking the position of surfaces during certain processing such as optical projection printing. Light from a line or point source is made incident on the surface at a small angle to produce interference fringes between the reflected light and a reference beam. Any movement of the surface causes a shifting of the fringe pattern which can be detected by appropriate means such as a slit or grating and photodiode combination.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.