Optical Sensors

Description

Optical sensors are devices used to measure temperature, pressure, strain, vibration, acoustics, rotation, acceleration, position, and water vapor content. The principle of an optical sensor is based on the variation of the propagating light wave characteristics such as intensity, polarization, time of flight, frequency (color), modal cross talk and phase, as the light wave passes through an optical fiber. The change in the parameter values can be measured from the detector.

Types

Various types of optical sensors are listed below:

• Point optical sensors
• Integrated optical sensors
• Quasi distributed or multiplexed optical sensors
• Distributed optical sensors

Specifications

The various industrial specifications for optical sensors are:

• Wavelength range
• Power range
• Sensor element used
• Optical input form
• Measurement accuracy
• Dimensions and mass
• Polarization dependence
• Noise level

Advantages

Some of the advantages of the optical sensors are:

• Optical sensors have high sensitivity, range and resolution
• Since optical sensors are highly immune to electromagnetic interference they can be used for various microwave applications
• Being resistant to high temperatures and chemically reactive environment makes them suitable for harsh and hostile environment
• Due to their small size, optical sensors are widely used for embedding and surface mounting applications
• Optical sensors are electrically passive that makes them suitable for explosive environment
• Optical sensors provide absolute electrical insulation from high electrostatic potential

Applications

Following are the applications of optical sensors:

• Used to monitor the conditions within the wings of the plane, in wind turbines, bridges and oil wells
• Integrated optical sensors are used in building structures to monitor and obtain information on the strain applied to the building due to aging phenomenon, vibrations, etc
• Used in meteorology departments for measurement of temperature, water vapor content, etc.
• Used in medical applications such as intra-aortic balloon pumping
• Used for accurate measurement of plastic film thickness