US Patent 7164111 Device for detecting invisible light beam

A light beam detection device includes a light-receiving element for receiving a light beam and outputting a detection signal. A light detection circuit generates and outputs a light-emission signal based on the detection signal. A light-emitting element emits light based on the light-emission signal. The light-receiving element and the light-emitting element are arranged on a detection member. A supporting member supports the detection member. A driving device moves the supporting member in a reciprocative manner in an X axis direction and a Y axis direction to form a detection region with the detection member. The light-emitting means forms an afterimage on the detection region when the light beam irradiates the detection region.