Patent ID: 7843634

Claim:
A microscope system comprising: an observation optical system including an objective lens; an illumination light source for autofocusing that is disposed around the perimeter of an end of a lens barrel of the objective lens, emits infrared or near-infrared light, and converges the light at a focus position of the objective lens; a dark field illumination system for autofocusing that obliquely casts illumination light emitted from the illumination light source for autofocusing onto a biological sample stored in a container so that the illumination light for autofocusing does not pass through the objective lens; an image-capturing device that captures a dark field image of the sample through the objective lens; an adjustment device that adjusts a distance between the sample and the objective lens; a storage device that stores a plurality of detected distances between the biological sample and the objective lens as position information; and a computation device that compares a plurality of brightness signals of a predetermined number of dark field images each captured while changing the distance between the sample and the objective lens by the adjustment device and determines a specific dark field image having a maximum brightness signal; wherein the focus position, at which the objective lens is in focus on the biological sample, is detected based upon the maximum brightness signal, the dark field illumination system includes an epi-illumination system in which a part of an optical path of the epi-illumination system is parallel to an optical axis of the objective lens, the epi-illumination system includes an epi-fluorescence illumination device that includes an excitation light source emitting ultraviolet rays onto the sample through the objective lens so as to cause emission of fluorescence, the fluorescence being observed through the objective lens, and casting the excitation light emitted from the excitation light source to the biological sample is started up after the focus detection is performed according to images formed by the illumination light for autofocusing cast to the sample without passing through the objective lens and captured by the image-capturing device through the objective lens under dark field illumination using the infrared or near infrared light from the dark field illumination system for autofocusing.