| 摘要 |
PURPOSE:To enable a simple and accurate detection of differences between graphics required to be the same originally drawn on two light transmitting thin plates by comparing signals generated corresponding to each graphic by two photoelectric systems after they are piled up together. CONSTITUTION:Two light transmitting thin plates on which graphics required to be the same originally are drawn with non-light transmitting material are piled up together and signals are compared from two photoelectric conversion systems focusing on the position of each graphic to detect differences between the graphics. For example, glass base plates 11 and 11' on which graphics required to be the same originally are drawn with non-light transmitting materials 12 and 12' are piled up together to match one graphic with the other and two optical systems comprising a light source 15, an opaque mirror 16, a lens 17 and the like are focused on the position of each image moving it by a stage drive system 14. Two outputs of photoelectric converters 18 and 18' are compared with a comparator 19 whose outputs are sent to an evaluation system with a coordinate signal to detect the position showing a difference. |
