A photothermal velocimeter using an optical fibre heterodyne interferometer free from external disturbance
Abstract
The phase variation induced by the photothermal effect is measured by means of an optical fiber heterodyne interferometer to increase sensitivity and to understand the phenomena directly. This interferometer can be remotely operated, is extremely sensitive, and has a linear relation between the phase-meter output and the measuring phase. The phase fluctuation in the fiber due to external disturbance is eliminated by constructing a system of two Michelson type interferometers that have common paths in two fibers. The relations of phase variation induced by the photothermal effect to concentration and laser pulse duration are examined experimentally and theoretically.
- Publication:
-
Laser Anemometry - Advances and Applications
- Pub Date:
- 1990
- Bibcode:
- 1990laaa.proc..255N
- Keywords:
-
- Laser Anemometers;
- Michelson Interferometers;
- Optical Fibers;
- Optical Heterodyning;
- Temperature Effects;
- Velocity Measurement;
- Flow Velocity;
- Laser Beams;
- Optical Paths;
- Phase Shift;
- Instrumentation and Photography