Illumination apparatus, microscope apparatus, and cartridge

A transmitted illumination apparatus for a microscope having an objective, the apparatus comprising:

• a surface light source disposed on an optical axis of the objective of the microscope such that at least a portion of illumination light emitted by the illumination apparatus enters the objective, the surface light source having a light emission plane configured to emit the illumination light;
• a transparent mount on which a sample is placed;
• a cartridge that includes an optical member and a mechanical structure, the optical member blocking at least a portion of the illumination light emitted from the light emission plane of the surface light source, and the mechanical structure moving the optical member so as to change a position or posture of the optical member within the cartridge;
• a supporting base that supports the cartridge between the surface light source and the transparent mount in an attachable/detachable manner;
• and
• means for reporting information on the position or posture of the optical member;
• wherein:
• the optical member includes a micro louver film configured to limit components of a divergence of the illumination light that are parallel to the light emission plane of the surface light source, and
• the following conditional expression is satisfied:
• 20°≤A≤60° (1)
• where A indicates, with reference to a direction for which the micro louver film limits the divergence of the illumination light, a maximum spread angle of the illumination light having passed through the micro louver film, the maximum spread angle being symmetrical about the optical axis of the objective.