Optical determination of cross-sectional profile of continuous bars

摘要

Four slit sources (10), preferably linear xenon flash tubes with collimated beams, sequentially illuminate a steel bar (12) with planar beams of light. The light is diffusely reflected from the steel bar and received by four cameras (14) connected to image processing equipment (16) and a numerical and graphic output device (40) such as a video screen. A known reference datum for calibration purposes is located on the roll table on which the bars to be examined will travel. This enables data to be obtained, which will be used in performing transformation to compensate for perspective distortion due to the viewing geometry of the cameras. The known reference datum takes the form of a steel bar having a cross-shaped cross-section. It enables at least three non-co-linear reference locations to be defined with calibration parameters being determined from them.