(under subclass 154) Subject matter wherein an optical transmitter and receiver system is used to determine if an object is present within the range of the optical beam.
SEE OR SEARCH CLASS
342, Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation),
27+, for radio frequency presence detection.
356, Optics: Measuring and Testing,
3+, for range or remote distance (e.g., height) finding, which is useful in identifying the actual location of an object.
