Abstract
The need for fiber optic based rotary displacement sensors is becoming more apparent as commercial and military applications (such as aircraft throttle controls) use of optical fibers increases.1 In this paper, an angular displacement extrinsic fiber optic sensor is described which utilizes variable retardation wavelength encoding of sensed information. The encoding scheme involves the modulation of an intensity minimum in wavelength in a broadband signal by the parameter of interest. The system presented here represents a hybrid adaptation of Goldberg’s rotating waveplate intensity modulator 2 and Jones and Spooncer’s photoelastic pressure sensor.3 The differences between this rotary displacement sensor and those earlier systems are that while Goldberg did utilize a rotating waveplate, no fiber optics were incorporated and its ultimate use was as an intensity modulator not a sensor. Jones and Spooncer’s pressure sensor was based on modulation of wavelength encoded intensity maxima and did not use rotating waveplates. The rotary displacement sensor described here uses wavelength encoded intensity minima, a procedure which allows the detector combination to be operated at maximum sensitivity without recalibration for source intensity variations.
© 1988 Optical Society of America
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