Abstract: The mold source of a bottle provided with one or more sectors spanning a circumferential zone with prism-like timing marks thereon is identified by an on-line programmed microcomputer. The bottle is identified by a laser beam and sensor. The sensor generates a series of digital pulses in response to the passage of the laser beam through the timing marks. The leading and trailing edges of the pulses are time stamped by the microcomputer. A microcomputer program identifies the mold source of the bottle based on the time stamped information. The identification of the bottle and its status are stored in the microcomputer memory. A running log of the numbers of defective and acceptable bottles produced by the mold source is printed out based on the contents of the microcomputer memory.