Patent ID: 7800821

Claim:
A microscopic illumination apparatus comprising: a light source section having a light source, to emit a beam of substantially parallel rays; a field lens for collecting the beam of substantially parallel rays; a condenser lens for introducing the beam of rays collected by the field lens to an illumination target surface; and an aperture stop disposed at an entrance-side focal position of the condenser lens, the aperture stop and the light source being arranged at substantially conjugate positions, wherein an optical element having a plate shape and having different transmittances or different diffusion angles between a central region and an outer region is arranged in a path of the beam of substantially parallel rays, and wherein the optical element is arranged between the field lens and the light source section at a position that is conjugate with a position distant from the illumination target surface by L satisfying the following condition: 0.03 <|L/f CD |<0.4 where f CD is a focal length of the condenser lens, and L is a distance from the illumination target surface to a position that is, of positions on which the optical element is projected, closest to the illumination target surface.