Patent ID: 7602556

Claim:
A microscope comprising: an oil immersion system objective used under a condition where oil is charged between a cover glass and a most sample-side lens surface of the oil immersion system objective; and an imaging lens, wherein a front focal length and a front focal position of the oil immersion system objective are made adjustable so that a predetermined depth position in a sample is focused on in a state where a working distance WD between the cover glass and the most sample-side lens surface is set to satisfy a condition, 0<WD<0.03 mm, wherein the oil immersion system objective comprises, in order from a sample side: a first lens unit, a most image-side surface of which is convex, having positive refracting power as a whole; a second lens unit, a most image-side surface of which is convex, having positive refracting power as a whole; a third lens unit constructed with a cemented lens, having positive refracting power as a whole; and a fourth lens unit constructed with a cemented lens, having negative refracting power as a whole, and wherein when the working distance WD is changed from 0.03 mm <WD to 0<WD≦0.03 mm, a spacing between the first lens unit and the second lens unit is widened, a spacing between the second lens unit and the third lens unit is narrowed, and a spacing between the third lens unit and the fourth lens unit is narrowed, to thereby adjust the front focal length and the front focal position so that the predetermined depth position in the sample is focused on.