Patent ID: 6657782
Filing Date: 2003-12-02
Classification: G02B

Abstract:
A microscope episcopic illumination device comprising:a light source to supply light; a collector lens system to convert said light from said light source into substantially parallel light flux; an aperture diaphragm; a light source image forming lens system having a variable finite focal distance to condense said substantially parallel light flux from said collector lens system and form an image of said light source in the vicinity of said aperture diaphragm; a pupil relay lens system to re-form said image of said light source formed in the vicinity of said aperture diaphragm in the vicinity of a pupil plane of an object lens system; and a field stop being provided between said aperture diaphragm and said pupil plane of said objective lens system, wherein said light source image forming lens system varies a protection magnification of a ratio of the size of said re-formed image of said light source in the vicinity of said pupil plane of said objective lens system to the size of said light source by changing said focal distance of said light source image forming lens system, wherein said light source image forming lens system comprises in order from the side of said light source: a first lens group with positive refracting power; a second lens group with negative refracting power; and a third lens group with a positive refracting power, and wherein at least said second lens group is shifted along an optical axis to vary said focal distance of said light source image forming lens system successively.