Patent ID: 8576483

Claim:
A microscope, comprising: an illumination optical system provided with an illumination field diaphragm, and one or a plurality of illumination optical devices to serve as an optical system configured to radiate illumination light to a sample placed on a stage; a first image creation optical system provided with a first image taking device configured to take an image based on transmitted light passing through said sample, and one or a plurality of first optical devices configured to create said image based on said transmitted light on said first image taking device; a second image creation optical system provided with a light-beam splitting section configured to split said transmitted light propagating in said first image creation optical system in order to get a partial light beam from said transmitted light, a second image taking device configured to take a phase-difference image based on said partial light beam, and one or a plurality of second optical devices configured to create said phase-difference image based on said partial light beam on said second image taking device; an illumination-field-diaphragm focus adjustment section configured to adjust an image creation position at which an image of said illumination field diaphragm is created; and a characteristic-quantity computation block configured to compute a characteristic quantity, which represents a focus shift degree of said illumination field diaphragm, on the basis of an output signal generated by said second image taking device, wherein said illumination-field-diaphragm focus adjustment section adjusts said image creation position for said illumination field diaphragm on the basis of said characteristic quantity computed by said characteristic-quantity computation block; said phase-difference image includes first and second images created on said second image taking device in accordance with the shape of said illumination field diaphragm, and said characteristic-quantity computation block computes said characteristic quantity by making use of a difference in intensity between an output signal of said first image and an output signal of said second image at every pixel on said second image taking device; a position control section configured to control the position of said stage; and a thickness-change computation block configured to compute a change of the thickness of a slide glass on which said sample is mounted, wherein said phase-difference image includes first and second images created on said second image taking device in accordance with the shape of said illumination field diaphragm, said thickness-change computation block computes a change of said thickness by making use of a difference in intensity between an output signal of said first image and an output signal of said second image at every pixel on said second image taking device, and said position control section changes the position of said stage toward said illumination optical system on the basis of said thickness change computed by said thickness-change computation block.