| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus detector which adapts itself to an objective lens form a low power to a high power and can widen the AF capturing range of the high-power objective lens and an optical microscope or optical inspection apparatus having the same. SOLUTION: This focus detector has a condensing optical system 8' for condensing an incident luminous flux and a photodetector having two photodetecting sections A and B disposed apart one boundary line intersecting with the optical axis, is arranged with the condenser optical system and the photodetector in optical paths divided by means of a beam splitting member and is arranged with the photodetector in the condensing position of the condensing optical system, in which the condensing optical system 8' is so formed as to vary the focal length in the boundary line X-Y direction of the two photodetecting sections A and B and the focal length in the direction perpendicular to the boundary line X-Y and to align the imaging direction of the boundary line X-Y direction and the imaging position in the direction perpendicular to the boundary line X-Y. |
