Two axis encoder head assembly
US9243896B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 12, 2013 |
| Grant date | Jan 26, 2016 |
| Priority date | — |
| Expiry date | Feb 12, 2034 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70775
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A measurement system for measuring the position of a work piece (28) includes a stage grating (234) and an encoder head (236). A first measurement beam (38A) is directed at the stage grating (234) at a first angle, the first measurement beam (38A) being at a first wavelength. A second measurement beam (38B) is directed at the stage grating (234) at a second angle that is different than the first angle, the second measurement beam (38B) being at a second wavelength that is different than the first wavelength. At least a portion of the first measurement beam (38A) and at least a portion of the second measurement beam (38B) are interfered with one another to create a measurement signal along a signal axis.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.