A camera for a narrow and deep welding groove

摘要

In this paper welding seam imaging in a very narrow and deep groove is presented. Standard camera optics can not be used as it does not reach the bottom of the groove. Therefore, selecting suitable imaging optics and components was the main challenge of the study. The implementation is based on image transmission via a borescope. The borescope has a long and narrow tube with graded index relay optics inside. To avoid excessive heating, the borescope tube is enclosed in a cooling pipe. The performance of the imaging system was tested by measuring its modulation transfer function (MTF)and visually evaluated its distortion. The results show that a borescope providing VGA resolution is adequate for the application. The spectrum of the welding processes was studied to determine optimum window to observe the welding seam and electrode. Optimal bandwidth was found in region of 700nm-1000nm.