Patent ID: 7800839

Claim:
An optical system adapted to form an image having a full 360°-direction (full-panoramic) angle of view on an image plane or project an image located on an image plane at a full 360°-direction angle of view, comprising: a front unit having two reflecting surfaces, each rotationally symmetric about a center axis, a rear unit that is rotationally symmetric about the center axis and has positive power, and an aperture located coaxially with the center axis, wherein: said front unit comprises a transparent medium that is rotationally symmetric about the center axis and comprises a first transmitting surface, a first reflecting surface, a second reflecting surface and a second transmitting surface; said first reflecting surface is located on an image plane side with respect to said first transmitting surface, said second reflecting surface is located in opposition to an image plane with respect to said first reflecting surface, and said second transmitting surface is located more on the image plane side than said first transmitting surface; and in order of travel of light rays in the case of an imaging system or in reverse order of travel of light rays in the case of a projection system, a light beam incident onto said front unit enters the transparent medium via said first transmitting surface, is reflected at said first reflecting surface located in opposition to said first transmitting surface with the center axis between them in a direction away from the image plane and then reflected at said second reflecting surface located on the same side with respect to the center axis in a direction toward the image plane side, and leaves said transparent medium via said second transmitting surface, forming an image at a position of the image plane off the center axis by way of said rear unit, wherein in a section including the center axis and in a section orthogonal to said section and including a center ray of said light beam, a position of an entrance pupil differs such that said entrance pupil in the section including said center axis is positioned near said second reflecting surface.