Fiber Optic Temperature Sensor How It Works

Light is sent to the end of a fiber via a fiber coupler and received by a photodiode phototransistor.

Fiber optic temperature sensor how it works.

A fiber optic sensor is a sensor that uses optical fiber either as the sensing element intrinsic sensors or as a means of relaying signals from a remote sensor to the electronics that process the signals extrinsic sensors. This allows a single sensor to both illuminate and view an object through the same fiber optic assembly. It consists of a laser source to emit light. They are basically just a regular fiber with a diaphragm on the end that is normal to the fiber.

Dts systems contain a pulsed laser which sends in an approximately 1m pulse equivalent to a 10ns time into the fibre optic. If an object appears in front of the sensing end of a bifurcated fiber optic light from one branch will be reflected off the object and back to the receiver through the other branch. Depending on the application fiber may be used because of its small size or because no electrical power is needed at the. The fibre optic cable can be 30 km in length is passive in.

Fiber optic sensors work based on the principle that light from a laser or any superluminescent source is transmitted via an optical fiber experiences changes in its parameters either in the optical fiber or fiber bragg gratings and reaches a detector which measures these changes. Intensity based fiber optic sensors require more light and these sensors use a multi mode large core fibers the shown figure gives an idea about how the light intensity work as a sensing parameter as well as how this arrangement makes the fiber to work as a vibration sensor. Distributed temperature sensing dts measures temperature distribution over the length of an optical fiber cable using the fiber itself as the sensing element. It depends on the type of sensor.

As the pulse travels along the length of the fiber optic it interacts with the glass. It is based on the principle of interference between the beams emerging out from the reference fiber and the fiber kept in the measuring environment. Figure 1 schematic of step index optical fibre. Fibers have many uses in remote sensing.

The temperature measuring system consists of a controller laser source pulse generator for otdr or code generator for code correlation or modulator and hf mixer for ofdr optical module receiver and micro processor unit and a quartz glass fibre as line shaped temperature sensor. Fiber optic temperature sensor how it works. Optical fibres an optical fibre consists of a thin low loss glass wire with a centre or core region having a slightly higher refractive index than its surrounding region or cladding. Unlike traditional electrical temperature measurement thermocouples rtd the length of the fiber optic cable is the temperature sensor.