Optical device

An optical device comprising:

• an image forming lens disposed in an optical path between an objective lens and an imaging device, the image forming lens forming an image of light incident via the objective lens on an imaging surface of the imaging device;
• a beam splitter disposed along an optical axis of the objective lens;
• a coaxial epi-illumination optical system configured to be able to illuminate an imaging target via the beam splitter, the coaxial epi-illumination optical system being arranged in an optical path different from the optical path in which the image forming lens is arranged;
• and
• an optical damper having a damper surface, wherein
• the beam splitter, the image forming lens, and the imaging device are arranged along the optical axis of the objective lens,
• an optical axis of the coaxial epi-illumination optical system is perpendicular to the optical axis of the objective lens,
• the beam splitter and the optical damper are arranged along the optical axis of the coaxial epi-illumination optical system, and
• a normal direction of the damper surface is perpendicular to the optical axis of the objective lens and inclines with respect to the optical axis of the coaxial epi-illumination optical system without being perpendicular to the optical axis of the coaxial epi-illumination optical system.