Patent ID: 7821705

Claim:
A microscope comprising: an objective lens; an afocal variable-magnification optical system, disposed at an exit side of the objective lens, for variably magnifying the size of an image of the objective lens; an image-forming optical system, disposed at an exit side of the afocal variable-magnification optical system, for imaging the image of the objective lens; a splitting member, disposed at an exit side of an image-forming lens, for selectively splitting into an observation optical path or an image-acquisition optical path; and an observation optical system, disposed in the observation optical path, for visually observing an image split-off from the image-acquisition optical path; wherein the observation optical path comprises: a relay optical system for relaying a pupil of the objective lens to a pupil conjugate position; an optical-path-splitting member, disposed at the object side of the pupil conjugate position for splitting an optical axis of an incident beam into two optical axes for observation by both eyes, one for the left and one for the right; and an aperture stop, disposed in the observation optical path and disposed at an exit side of the image forming lens, the position of which is toward the object side with respect to the position of the image closest to the observer and is in the vicinity of a conjugate position of the objective lens pupil relayed by the relay optical system, for stopping down a numerical aperture thereof to a numerical aperture smaller than a numerical aperture of the image-acquisition optical path, and wherein the microscope satisfies the following conditional expression: D>18 mm where symbol D represents an exit beam diameter of the afocal variable-magnification optical system.