Scanning laser microscope with aperture alignment

A scanning laser microscope comprising a laser which emits a laser beam, a first optical system which is disposed between said laser and a specimen so as to focus the laser beam on the specimen, specimen movement means for moving the specimen, a second optical system which is arranged with one focal position thereof held in agreement with a focal position of said first optical system on the specimen in order to focus the laser beam transmitted through the specimen or reflected therefrom, an aperture which is arranged at the other focal position of said second optical system and which is provided at a predetermined position within a plane of a photomask including rectilinear pattern edges orthogonal to each other formed on a transparent substrate, optical detection means for detecting the laser beam passed through said aperture, aperture movement means for moving said aperture, control means for controlling a movement of said aperture movement means in order to bring the position of said aperture into agreement with a focused position of the laser beam in such a way that coordinate positions at which the laser beam traverses the respective rectilinear pattern edges orthogonal to each other are found on the basis of output signals from said optical detection means, and display means for displaying the output signals of said optical detection means in correspondence with impinging positions of the laser beam on the specimen.