Device for detecting the relative position between opposed first and second objects
US5160848A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 12, 1992 |
| Grant date | Nov 3, 1992 |
| Priority date | — |
| Expiry date | Feb 12, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7049
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A device, usable with first and second opposed objects each having at least one diffraction grating, for detecting a positional relationship between those objects in a direction perpendicular to the direction in which they are opposed, is disclosed. The device includes a light source for projecting light to a diffraction grating of one of the first and second objects and a first detecting system for detecting, in a first plane, first light diffracted by diffraction gratings of the first and second objects. The position of incidence of the first light on the first plane is changeable with a change in the relative position of the first and second objects in the perpendicular direction. A second detecting system detects, in a second plane, second light diffracted by a diffraction grating of the first and second objects, wherein a change in the position of incidence of the second light on the second plane due to a change in the relative position of the first and second objects in the perpendicular direction is different from the change in the position of incidence of the first light. A position detecting system detects the relative position of the first and second objects, in accordanc…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.