| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem wherein much time needs to be spent for aligning an aperture, precise measurement cannot be made since the relative position relationship between the aperture and a lens slightly differs for each measurement, and it is difficult to cope with the unexpected deviation and aging of an aperture position in a prior art. SOLUTION: There are provided: an aperture 24 limiting nearly parallel light entering an objective lens 20 and a peripheral pattern 26 provided around the aperture; an auxiliary aperture 23 shielding light to the aperture 24 when measuring the aberration of the objective lens 20; and an optical system for receiving the images of light generated by the peripheral pattern 26 and that generated by the objective lens 20 in the same optical path. By adjusting the relative position of the objective lens 20 to the aperture 24 based on the received light, the relative position relationship between the aperture 24 and the objective lens 20 can be maintained continuously and precisely. COPYRIGHT: (C)2008,JPO&INPIT
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