FOCUS DETECTION UNIT AND MICROSCOPE PROVIDED WITH THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a focus detection unit using an interposing system simplified in an optical system. SOLUTION: The focus detection unit is constituted so that a double slit mask 12 is arranged on the optical axis of a lamp 10 and a single slit mask 16 is arranged on an optical axis from a lamp 14. Then, a sight double beam and a sight single beam are respectively formed. A prism 18 constituting a triangle pole by a first and a second side surfaces forming the ridge of an optional angle and a plane surface faced to the ridge is arranged at a position where the sight double beam and the sight single beam are respectively made incident on the first and the second side surfaces so as to reflect both incident sight beams ahead of the ridge. A projection lens 20 is disposed in front of the ridge of the prism 18 so that the images of both sight beams which are reflected by the prism 18 and separated to luminous flux by a mask 22 are formed on an image forming position for both sight beams 100 and projected on an examinee which is observed.