Surveying instrument having a phase-difference detection type focus detecting device and a beam-splitting optical system

摘要

A surveying instrument includes a sighting for sighting an object; a beam-splitting optical system positioned between an objective lens and an eyepiece, and having a wavelength selection mirror which reflects light with specific wavelengths while allowing light having wavelengths other than the specific wavelengths to pass therethrough; an optical distance meter which includes a light-transmitting optical system for transmitting measuring light toward the object, and a light-receiving optical system for receiving light reflected by the object; and a phase-difference detection type focus detecting device which detects a focus state from a correlation between a pair of images respectively formed by two light bundles which are passed through two different pupil areas on the objective lens and the wavelength selection mirror. The two different pupil areas are positioned so that the two light bundles are incident on the wavelength selection mirror at the same incident angle.