An optical apparatus for machine vision inspecting both top and bottom surfaces of the TEC components

摘要

In this paper, a novel optical inspection apparatus was studied which enables one to inspect both top and bottom surfaces of the thermoelectric cooler (TEC) components. In the optical inspection apparatus, a right angle prism reflector located beneath the glass stage was used to image the bottom surface of the TEC component on top of the stage. In order to obtain the clear images of two surfaces of the TEC component simultaneously, a proper telecentric imaging lens with sufficient large depth of field needs to be selected to address their optical path difference. A telecentric optical imaging lens DH110-03F50 with depth of field of around 6mm together with a right angle prism reflector with solpe side length of 3.6mm was chosen for this experimental setup. With this apparatus three groups of components were inspected in the experiments and each group has some typical samples with specially selected Passed and Failed features on the surfaces to be examined. The experimental results indicate that the images of both top and bottom surfaces obtained using the optical inspection system are sufficiently clear and well resolved which meets the requirements for the following image processing. The results show that the proposed technique allow us to inspect both top and bottom surfaces of the component with simplified configuration and effective cost. This novel inspecting technique will find applications in the automatic optical inspection systems for the TEC components.