Abstract: Various controllers herein detect a remote object's change of position. A controller emits a laser through a laser emitter at the remote object and measures an intensity of light reflected back to the controller through a photosensor disposed in proximity to the laser emitter. The surface of the remote object comprises a retroreflective portion, which reflects most of the laser beam's light in the direction it came from. A change in the remote object's position is detected when the intensity of light measured is substantially different after altering a factor of the laser emitter, such as power state.

Abstract: Various controllers detect whether or not a remote object is in a predetermined position. A controller emits a laser through a laser emitter at the remote object and measures an intensity of light reflected back to the controller through a photosensor disposed in close proximity to the laser emitter. The surface of the remote object may comprise a retroreflective portion, which reflects most of the laser beam's light in the direction from which it came. A predetermined position of the remote object is detected when the intensity of light measured by the photosensor reaches a threshold level. The controller and retroreflective portion are configured such that when the remote object is not in the predetermined position, the intensity of the reflected laser light diminishes due to a scattering of the light when the laser beam is incident on any non-retroreflective portion of the remote object.