System for absolute measurements by interferometric sensors

Douglas A. Norton

doi:10.1117/12.141267

5 March 1993 System for absolute measurements by interferometric sensors

Douglas A. Norton

Proceedings Volume 1795, Fiber Optic and Laser Sensors X; (1993) https://doi.org/10.1117/12.141267
Event: Fibers '92, 1992, Boston, MA, United States

Abstract

The most common problem of interferometric sensors is their inability to measure absolute path imbalance. Presented in this paper is a signal processing system that gives absolute, unambiguous reading of optical path difference for almost any style of interferometric sensor. Key components are a wide band (incoherent) optical source, a polychromator, and FFT electronics. Advantages include no moving parts in the signal processor, no active components at the sensor location, and the use of standard single mode fiber for sensor illumination and signal transmission. Actual absolute path imbalance of the interferometer is determined without using fringe counting or other inferential techniques. The polychromator extracts the interference information that occurs at each discrete wavelength within the spectral band of the optical source. The signal processing consists of analog and digital filtering, Fast Fourier analysis, and a peak detection and interpolation algorithm. This system was originally designed for use in a remote pressure sensing application that employed a totally passive fiber optic interferometer. A performance qualification was made using a Fabry-Perot interferometer and a commercially available laser interferometer to measure the reference displacement.

Citation Download Citation

Douglas A. Norton "System for absolute measurements by interferometric sensors", Proc. SPIE 1795, Fiber Optic and Laser Sensors X, (5 March 1993); https://doi.org/10.1117/12.141267

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