Interferometric appts. for measuring physical parameters - uses conversion from linear to circular polarisation to give directional information

摘要

The interferometric arrangement for measurement of physical parameters contains a monochromatic light source (1), a beam divider (2) producing measurement and reference light beams for measurement (7) and reference (10) paths, and a recording arm with two photoreceivers (5,6) associated with the two beams. The arrangement can produce information about deformation, ie extension or compression, enabling unambiguous detection of the direction of the loaded optical fibre (8). It may be used to measure temp. force, expansion etc. An element (13) directly in the beam from the source (1) converts the linearly polarised light into circularly polarised light. A further element (14) in the measurement or reference arm converts the circularly polarised light into light polarised linearly perpendicular to the original light polarisation direction. An optical analyser (15,16) is placed in front of each receiver (5,6).