Patent ID: 6649893
Filing Date: 2003-11-18
Classification: G02B

Abstract:
A focus detecting device for a microscope comprising:a beam splitting member that has a surface for reflecting or transmitting an incident light beam, said beam splitting member being located at an intersection of an optical axis of a first optical path with an optical axis of a second optical path; a multi-beam producing member for emitting a plurality of light beams, said multi-beam producing member being placed in the first optical path; a light-blocking member that is placed in the first optical path at a position between said beam splitting member and said multi-beam producing member, said light-blocking blocks a part of each of said plurality of light beams, the plurality of light beams with the part thereof being blocked by said light-blocking member pass said beam splitting member to enter the microscope; a light-condensing optical system that is placed in the second optical path at a position on an exit side of said beam splitting member, said light-condensing optical system condenses the plurality of light beams, which have been reflected at a sample surface of the microscope and have passed said beam-splitting member; and a photodetector having at least two light-receiving sections, said photodetector being placed in the second optical path at a position on which a light beam is converged by said light-condensing optical system, wherein said position is on an exit side of said light-condensing optical system.