ABSTRACT
Optical sensors are indispensable for the precise control of mechatronic systems as well as other electronic and mechanical sensors. Optical sensors are especially preferable in noncontact measurements because light transmission and reflection can be used without contacting the object surface. Moreover, measurements using light as a means of detection are essentially the fastest in response because of their inherent propagation velocity, although the response time is limited by the detection electronics. In the case of displacement sensing using light waves, optical sensors are essentially high precision as the wavelength can be utilized as a unit length for the measurement, which is in the submicron region of visible light.
