| 摘要 |
PROBLEM TO BE SOLVED: To enable precisely detecting a surface position at a high speed without being affected by a base pattern, when the surface position of a substrate in which the base pattern having directivity is formed is detected, by constituting an optical element wherein the refracting power is different in the longitudinal direction of a slit image which is to be formed again and in the direction rectangular to the longitudinal direction. SOLUTION: A column lens 23 is arranged between a first relay lens 22 and a second relay lens 24. The lens 23 is so arranged that the direction of a bus line rectangularly intersects the longitudinal direction of the image of a slit type pattern which is formed on a one-directional scanning type image sensing element (CCD). Images of an exposure surface WS and the slit pattern 13a are again formed on the one-dimensional CCD on an image sensing surface 25 with optical systems 17, 19-23, 14. The image of the slit pattern 13a has a specific inclination angle to the scanning line of the onedimensional CCD. Along the longitudinal direction of the inclined slit image, the direction wherein power of the column lens 23 exists is set. Thereby the width direction of the slit image is clearly formed, and the longitudinal direction is defocussed. |
