US Patent 7794397 Endoscope having an illumination lens subjected to light diffusion process

An endoscope includes an insertion unit; an observation optical system arranged at an end surface of the insertion unit in an inserting axis direction and having a wide viewing angle for observing a body cavity; and a plurality of illumination optical systems arranged on an axis slanted with respect to the inserting axis direction of the insertion unit and used when illuminating the body cavity. An illumination lens of at least one of the illumination optical systems is subjected to light diffusion process.