| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an optical system for taking an image having a full 360°-direction angle of view or projecting an image at a full 360°-direction angle of view, which is not influenced by flare light and which is reduced in size and improved in resolving power. <P>SOLUTION: The optical system is equipped with: a front group 10 that is rotationally symmetric about a center axis 1 and includes two reflecting surfaces and two transmitting surfaces; a rear group 20 that is rotationally symmetric about the center axis and has positive power; and an aperture 5 arranged coaxially to the center axis. Luminous flux incident on the front group passes through the 1st transmitting surface 11, is reflected to an opposite side to an image plane by the 1st reflecting surface 12 arranged on the same side as the 1st transmitting surface relative to the center axis, reflected to the image plane side by the 2nd reflecting surface 13 arranged on an opposite side to the 1st transmitting surface, passes through the 2nd transmitting surface 14 arranged on the same side as the 2nd reflecting surface and exits from a transparent medium to the outside, then passes through the rear group 20 so as to form an image on the image plane 30. Then, the positions of entrance pupils 6Y and 6X on a cross section including the center axis 1 and a cross section orthogonal to the cross section and including the center light beam 2<SB>0</SB>of the luminous flux are different. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
