On top of this, there are the choices to be made on interfacing to other systems, as well as how the environment where the sensor is to be used will impact housing choice.
Many situations simply require the detection of an object, for example on a conveyor belt, table or transport trolley. However, it may not be possible to fit a reflector to use in conjunction with a retro-reflective sensor, or the receiving end of a through beam sensor. If the object to be detected lies in front of an interfering background, a diffuse sensor with background suppression could be the answer.
Such sensors use the principle of triangulation to measure the light intensity reflected by the desired target as well as the distance is it away. The minimum size of the object is then defined by the dimensions of the light beam being used. The distance to the object is configured by set screw, although some more advanced solutions have a “Teach-in” method that can be used. Featuring a red light emitter, this visible light source makes it simple to adjust, even in conjunction with small objects. Laser-based sensors are capable of detecting objects with a size of just 0.1mm, while pinpoint diode-based sensors have a 2mm diameter spot of light at their focus. Their design is such that the object being detected can vary in both colour and material without detriment to the detection capability, while objects moving in the background do not trigger unwanted detection.