| 摘要 |
PURPOSE:To execute comparison and observation with high accuracy as to an object to be inspected, such as a mask negative, by placing the first and second objective lenses so as to be opposed to each other, and providing both objects to be observed, in parallel with each other, between both the objective lenses. CONSTITUTION:The first objective lens 11a and the second objective lens 11b are provided so that the respective optical axes 10a, 10b are made to coincide, and also the lenses are opposed to each other. Between both the objective lenses 11a, 11b the first and second IC printing masks 4a, 4b as objects to be observed are placed in parallel so as to be vertical to the respective objective lenses. A light beam which is emitted to the upper part from a pattern 5a of the first mask 4a is reflected 4 times in all, and forms an image of the pattern 5a of the first mask on an image surface 37 on a common optical axis 30, and on the other hand, a luminous flux which is emitted to the lower part from the pattern 5b of the second mask 4b forms an image of the pattern 5b of the second mask on the image surface 37 in the same way. In this case, since two objective lenses are located on the same optical axis and the respective observation points are on the same straight line, no measuring error is caused. |
