Distributed optical sensor surface concept for planar object detection

Abstract

With the ever-increasing demand for a more efficient production process, the thickness of silicon wafers for the solar cell industry has shown a decreasing trend over the years. This makes the substrates more and more fragile, with an increasing breakage rate as a result. Research at the TU Delft has been done on contactless handling, using air bearings and actuators. A suitable and integrated sensor system in the air bearings would complete the package of actuator and sensor. The sensor should be able to detect and track objects floating above an air bearing transport system. Previous work on this subject investigated the possibilities of using optical fibers as a vision distributor for a camera sensor. This proved to be a promising concept, but the optical fibers showed to have a limited reach. This research focusses on increasing the detection range of an individual optical fiber. A commercial light diffuser plate is used to increase the vision of an optical fiber. The effect of the light diffuser is experimentally tested with a test setup that can simulate the motion of a moving rectangular object that resembles a solar cell. Different transmission trends observed by the optical fiber are received for various angles of motion of the moving object. The detection range of an individual optical fiber is increased up to an 8mm radius around the optical fiber, dependant on the angle of motion of the object. The distributed sensor concept is verified by tracing the observed signals from the optical fiber back to object position and angle of motion.