ABSTRACT
This chapter discusses several other types of sensors including optical sensors, ultrasonic sensors, magnetostrictive sensors, acoustic emission sensors, thermofluid sensors, and sensors that are useful in monitoring the quality of water e.g., pH value, dissolved oxygen, and oxidation–reduction potential. There are many sensors that use light or laser as the basis of measurement. Also, camera images are widely used for sensing purposes. The characteristic component in a fiber-optic sensor is a bundle of glass fibers that can carry light. Each optical fiber may have a diameter on the order of a few µm to about 0.01 mm. There are two basic types of fiber-optic sensors. The advantages of fiber optics include insensitivity to electrical and magnetic noise ; safe operation in explosive, high-temperature, corrosive, and hazardous environments; and high sensitivity. Furthermore, mechanical loading and wear problems do not exist because fiber-optic position sensors are noncontact devices with no moving parts.
