Optical system for discussion-microscope

An optical system for a discussion-microscope comprising a first ray flux dividing element for dividing a ray flux through an objective lens from an object into a first ray flux passing along the optical axis of the said objective lens and a second ray flux passing in a direction different from the said optical axis, a first optical element for directing the said second ray flux to approximately the same direction as the said first ray flux, a second ray flux dividing element designed for further dividing the said second ray flux and disposed in the passage of the said second ray flux, a second optical element for directing a third ray flux divided by the said second ray flux dividing element to approximately the same direction as the said first ray flux, and at least one relay lens disposed in the passage of the ray flux directed by the said first ray flux dividing element to a direction different from the optical axis of the said first ray flux, and the said second ray flux dividing element, the said first ray flux dividing element, said first optical element, the said relay lens and the said second optical element being disposed in the common plane.