A laser trimming apparatus calibration system including controlling a laser beam positioning mechanism to move a laser beam to a desired nominal laser position, imprinting a mark on a medium to establish an actual laser position, comparing the imprinted mark with the desired nominal position and producing a result indicative of the difference between the actual position and the desired nominal position. The system further including providing an illuminated mark at a desired illuminated mark nominal position, controlling the laser beam positioning mechanism to direct an optical path to the desired illuminated mark position, establishing an actual illuminated mark position by directing light from the desired illuminated mark nominal position along the optical path to the detection device and comparing the actual illuminated mark position with the nominal illuminated mark position.