Fiber optic sensor for detecting very small displacements of a surface
US4572949A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 14, 1983 |
| Grant date | Feb 25, 1986 |
| Priority date | — |
| Expiry date | Dec 14, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/268
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A light source (10) coupled to a first fiber optic waveguide (14) which is coupled by a first directional coupler (22) and a second directional coupler (24) to a second waveguide (20). The first waveguide (14) has a phase modulator (60), a delay loop (62) and a polarization controller (68) therein to cause a differential delay time T on counterpropagating coherent light waves phase modulated at a frequency 1.sub.M. The first directional coupler (22) has one part connected to a photodector (28) and the second directional coupler (24) has a probe (20D) coupled to the first fiber (14) and the second fiber (20). The probe directs light toward a surface (18) whereupon the counterpropagating waves are shifted in phase by an amount proportional to the amplitude of displacement of the surface 18.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.