Optical and fiber-optic sensors (review)

Abstract

Kvantovaya Elektron. (Moscow) 12, 901-944 (May 1985)Optical, fiber-optic, and integrated optical sensors of physical effects are reviewed. The sensors are classified in accordance with their operating principle: amplitude, interference, and polarization sensors are considered. Descriptions are given of the construction of the sensors (or of their sensitive elements) which can react to mechanical quantities (displacement, force, acceleration), acoustic vibrations and pressure, electric and magnetic fields, electric current, temperature, angular velocity, etc. Some of their principal characteristics are described. Important parameters of known sensors are presented in a classified reference table.

A fiber optic temperature sensor based on the combination of epoxy and glass particles with different thermo-optic coefficients

“…Density (g/cm³) 1.1 (1) 3.19 (1) Total Transmission (%) 91.28 (2) internal transmittance at 546 nm (10 mm): 99.8 (1) Coefficient of thermal expansion [m/(mK)]…”

“…Fiber optic temperature sensing enables monitoring in particular surroundings such as microwaves or explosion sensitivity [1][2][3][4]. Commercially, available fiber optic temperature sensors often use a semiconductor-chip, which has an absorption edge that moves with the temperature [5,6].…”

A fiber-optic interferometric seismometer

“…That is, first.the mechanical deformation of the fiber is converted into an optical phase shift (e.g., radians per gram or radians per micrometer), then the optical phase shift is converted into an analogous electrical signal by an interferometric demodulator, which consists of photodiodes, amplifiers, signal processing electronics, etc., to produce a given voltage per radian of optical phase shift. Although both of these processes introduce noise into the measurement, only the electrooptic demodulation noise has been treated in the literature [ 11 , [2], [5] , [9]-[ 1 11. This deficiency has not caused any difficulty to date because the optical sensitivity of the sensors has not been large and most sensor systems have been plagued by other noise problems and measurements in low noise environments have not been attempted.…”

“…The promise of high sensitivity was not based on the intrinsic sensitivity of optical fibers to physical stimuli but on the fact that optical phase shifts on the order of microradians could be resolved and optical path lengths of tens or hundreds of meters could be incorporated in sensors of modest physical dimensions. That combination of high interferometric demodulator resolution and long optical path length led to the possibility of measurements with resolutions on the order of a part in 10" to In addition to measurement of conventional physical parameters [l], [2] such as temperature, pressure, etc. , fiber-optic sensors were suggested for such unusual measurements as the detection of cosmologically generated gravitational waves [3].…”

Self-referenced temperature sensor based on a polymer optical fiber macro-bend

“…Many optical fiber sensors have been developed based on amplitude or phase techniques [1]. Different interferometric configurations have been proposed as temperature sensors such as Mach-Zehnder [2] and Fabry-Perot [3].…”