A Low-Cost Lighting System For Fast Line Scan Cameras

A low-cost lighting system for line scan camera has been developed with conventional AC fluorescent lamps. If the fluctuation period of illumination is longer than exposure time of a line scan camera, gray value variation between successive image lines appears. To suppress such variation, the proposed lighting system employs 3 fluorescent lamps spaced with some fixed distance between each lamp. By adjusting the distance between the lighting pack and the object surface, illumination with suppressed fluctuation is obtained. Once the inspection distance is properly determined, a line scan camera is able to get stable images without fluctuation. The principle of the proposed lighting system has been explained analytically. Some experiments have been done to prove its usefulness.