Dissimilar superimposed grating precision alignment and gap measurement systems
US4596467A · kind A · utility
33Cited by
5References
10Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Mar 16, 1984 |
| Grant date | Jun 24, 1986 |
| Priority date | — |
| Expiry date | Mar 16, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7049
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A substrate having a diffraction grating of a first periodicity formed thereon, a mask having a diffraction grating of a second periodicity formed thereon, the mask and substrate being positioned such that the respective mask and substrate gratings are generally parallel opposing one another on the mask and substrate, means for providing collimated coherent light directed so as to impinge on the mask and substrate gratings, and means for separately collecting, recombining, and detecting the intensity of at least a first given order of diffracted light beams as respectively diffracted by the mask and substrate gratings.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.