| 摘要 |
PROBLEM TO BE SOLVED: To provide an autofocus device in which a deterioration in performance other than at pattern projection is prevented and the efficiency of an illumination system, the edge contrast and the yield of a pattern image can be improved. SOLUTION: The autofocus device is equipped with: an objective lens to condense light on the measured surface of an object to be measured; an observation optical system to observe the image of the object to be measured based on light emitted from the objective lens; and a driving mechanism to displace the objective lens in its optical axis direction based on the contrast of the image of the object to be measured obtained by the observation optical system. The autofocus device is further provided with a pattern projection means 40 including a pattern projection plate 41 on which a specified pattern is formed and projecting the pattern formed on the plate 41 to the measured surface of the object to be measured. The pattern projection means includes an advance/retreat mechanism 43 for advancing/retreating the plate 41 in the optical path of the pattern projection means. COPYRIGHT: (C)2004,JPO |
