Focus information generating device and focus information generating method

A focus information generating device comprising:

• an objective lens that condenses a light beam on a focal point;
• a focal point shifting unit that shifts the focal point in an optical axis direction of the light beam relative to a pathology glass slide in which a sliced biological tissue is placed on a setting surface of a glass slide and the biological tissue is covered with an embedding medium and a cover glass;
• a splitting unit that splits a reflected light beam, which is obtained by reflecting the light beam from the pathology glass slide, into a first reflected light beam and a second reflected light beam;
• a first light-receiving unit that receives the first reflected light beam and generates a first light-reception signal;
• an irregularly-reflected component removing unit that removes an irregularly-reflected component included in the second reflected light beam;
• a second light-receiving unit that receives the second reflected light beam passing through the irregularly-reflected component removing unit and generates a second light-reception signal;
• and
• a focus information generating unit that calculates a cover distance from a predetermined reference point set on the pathology glass slide to the biological tissue on the basis of the first light-reception signal and the second light-reception signal when the focal point is shifted by the focal position adjusting unit and generates focus information of the pathology glass slide on the basis of the cover distance.