Abstract: A machine for refunding the deposit on empty containers such as bottles or cans for encouraging their return is disclosed. The machine includes an access door through which an empty container is introduced to an inspection station whereupon an inspection device determines if the empty container is marked with a proper identifying mark unique to that brand of container. The inspection device includes an ultraviolet light source which directs ultraviolet radiation onto an identifying mark on the container and causes fluorescent emmission of a narrow band of light. The radiation detection scheme of the present invention employs at least a pair of photodetectors, one which detects the very narrow band of radiation emitted from the fluorescent identifying mark, and the other which monitors whether or not any adjacent light bands are emitted from the object to a significant degree.