To reduce loss of light quantity in the peripheral part of a wide-angle lens apparatus using a ball lens.

A ball lens 1 converges light from a plane-shaped object plane 2 on a curved surface-shaped image surface 3 and the image of the image surface 3 is transferred to a plane-shaped image plane 5 by a fiber optic field flattener 6. The fiber optic field flattener 6 is constituted of an optical fiber bundle in which tapered optical fibers 6a having opening ends at the image surface 3 are bundled and the fiber optic field flattener 6 is arranged so that respective optical fibers 6a have tapered shapes and longitudinal directions of all optical fibers 6a are in agreement with directions of the center of a ball of the ball lens 1. Thus, a high-performance camera and a high-performance projector can be realized by reducing the shortage of light quantity while preventing the incident light from becoming inclined in the peripheral part of the the fiber optic field flattener 6.

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