The sheet is cemented onto the surface of the object being explored so that they will be compressed or stretched together. Proximity sensors detect objects without actually touching them. Some sensors check for the presence of magnetic fields, some create blasts of air and record the pressure in the immediate surroudings, some emit sound waves, still others employ nuclear beams. Beam detectors are the most basic of machine vision devices if they can be called by such. A light source and a detector are aligned on the robot arm, so that interruption of the beam announces the pressence of an object.
Different surfaces reflect light differing in brightness levels.
This is the princlple of a light-level detector, which analyzes reflections until the desired one has been found. Video cameras collect the light scattered by objects and stores it as electrical information. The non-conductivity of the sensors allow the formation of small capacitor elements when shine on by light. Each cell then receives an intense beam of energy, causing movement of electrons, and eventually the image is reassembled and transfered. The computer proceeds to process the images, determining their orientation, dimensions, location, etc.