Resolution system for interferometer
US4583856A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 27, 1983 |
| Grant date | Apr 22, 1986 |
| Priority date | — |
| Expiry date | Jun 27, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B9/02083
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Analog-to-digital conversion and a computer produce finer resolution for interferometer distance measurement. The system applies to a laser interferometer producing two detected signals with voltages 19 and 20 that vary to form two sine waves in quadrature as interference fringes occur. A pair of analog-to-digital converters 21 and 22 converts each of these signals into digital values subdividing each sine wave fringe cycle into a plurality of increments. An up/down counter 25 supplied with a significant digit from each of the converters counts fringes corresponding to changes in path lengths. A computer 30 arranged with access to the fringe count and the digital increments determines a distance measurement based on the fringe count and a fine resolution of the distance measurement based on final values of the signals at any subdivided fringe cycle increments after changes in the path lengths.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.