An inexpensive reflective displacement sensor with optical fibre links has two light output levels which switch when the measurand reaches a preset value. An autoreferencing unit monitors the light from the sensor at one level and continuously updates the system gain to compensate for intensity changes. Prototypes have been built; the paper presents results of repeatability trials.
M. R. Oliver,
R. C. Spooncer,
M. H. Ghezelayagh,
"An Autoreferenced Two-State Optical Fibre Reflective Sensor", Proc. SPIE 0630, Fibre Optics '86, (6 October 1986); doi: 10.1117/12.963612; https://doi.org/10.1117/12.963612