Optical fibers are being increasingly used in sensing various parameters in industrial and other environments due to their virtues of immunity to Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI), chemical passivity, small size, low weight, etc; and their ability to interface with a wide variety of measurands. This paper briefly reviews the fiber-optic techniques of sensing temperature using fluorescence emitted by certain materials, normally phosphors.
In recent years, fiber-optics has found major applications in sensor technology, due to the
inherent advantages of optical fibers, e.g., immunity to Electromagnetic Interference (EMI)
or Radio Frequency Interference (RFI), electrical isolation, chemical passivity, small size, low
weight, and their ability to interface with a wide variety of measurands.
A Fiber-optic Sensor (FOS) is a device, which uses light guided within an optical fiber to
detect any external physical, chemical or biomedical parameter. A generalized configuration
of a fiber-optic sensor is shown as a block diagram in Figure 1. It consists of an optical source,
optical fiber(s), a modulating element, an optical detector, a signal processor, and a read-out
device.
The measurand (which may be displacement, force, pressure, temperature, etc.) modulates
the intensity, phase or spectral distribution of light propagating through the optical fiber and
the modulating element combination. The modulated light changes the detector output,
which can be further processed and calibrated to give the value of the measurand. A variety
of schemes have been suggested for this kind of modulation. |
