Fiber-Optic Presence Sensor
An increasingly popular version of the reflective proximity sensor is presented.
In this sensor system, fiber optics are used as Light conduits. They are to tight what a waveguide is to microwaves.
The fiber efficiently transfers light from its input end to the output end. Thus, light introduced into fiber A will be transmitted with only a small loss to the output end, where it is aimed at the object's pathway.
When an object is close to the ends of the fiber optic cords, tight is reflected from its surface into the end of fiber B. This tight is transferred through fiber B, where it impinges on a photosensor device.
Background light is a continual problem in some photosensor-based proximity detector systems.
The obvious solution is to reduce the background light level to a point where the sensor is dominated by the light source.
But the simple solution is elegant, appealing, low cost, and wrong.
Fiber-optic presence sensor