| 摘要 |
PROBLEM TO BE SOLVED: To provide a miniaturized AF survey machine that has no eclipse of light fluxes passing through a pair of different pupil ranges set on an objective lens, does not cause degradation of aberration or degradation of AF performance caused by the degradation of aberration, and is inexpensive. SOLUTION: This AF survey machine comprises a collimation telescope for collimating a measured object and a focus detecting means for detecting the focus state through the collimation telescope. The focus detecting means is a phase difference type focus detecting means for detecting a focus position based on a pair of images formed on a focus detecting surface equivalent to an image forming surface of the objective lens using the light fluxes passing through the pair of different pupil ranges set on an objective lens of the collimation telescope. The focus detecting means comprises a condenser lens group common to the light fluxes passing through the pair of different pupil ranges and a pair of separator lens groups for forming, on line sensors, respective image of the light fluxes passing through the pair of different pupil ranges, and the condenser lens group comprises two or more subgroups.
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