Illumination optical system and fluorescent microscope

An illumination optical system which irradiates a sample surface with light through an illuminating lens, comprising:

• a light source;
• a condensing optical system receiving the light emitted from the light source, the condensing optical system comprising a collector lens and a reflector reflecting the light emitted from the light source toward the collector lens;
• and
• a lens array optical system including a first lens array surface and a second lens array surface each formed by a plurality of lens elements;
• wherein:
• the first lens array surface has a conjugate relation with a focal position of the illuminating lens;
• the second lens array surface is placed at a back focal position of the lens array optical system and has a conjugate relation with a pupil position of the illuminating lens;
• the light source and the condensing optical system are arranged to form an image of the light source on the first lens array surface;
• and
• the reflector functions as a switching unit for switching between a third illuminating state in which the collector lens forms a plurality of images of the light source on the second lens array surface and a fourth illuminating state in which the collector lens forms an image of the light source on the first lens array surface and a plurality of images of the light source on the second lens array surface.

An illumination optical system which irradiates a sample surface with light through an illuminating lens, comprising:

• a light source;
• a condensing optical system receiving the light emitted from the light source;
• and
• a lens array optical system including a first lens array surface and a second lens array surface each formed by a plurality of lens elements;
• wherein:
• the first lens array surface has a conjugate relation with a focal position of the illuminating lens;
• the second lens array surface is placed at a back focal position of the lens array optical system and has a conjugate relation with a pupil position of the illuminating lens;
• the light source and the condensing optical system are arranged to form an image of the light source on the first lens array surface;
• the illuminating lens includes a plurality of illuminating lenses having different optical specifications;
• and
• the illumination optical system is used with the plurality of illuminating lenses one of which is selectively inserted into an optical axis of the illumination optical system.