WIDE ANGLE LENS AND ENTIRE CELESTIAL SPHERE TYPE IMAGING APPARATUS

• Main Authors: TANAKA TOMONORI, SAWAGUCHI SATOSHI, TAKENAKA HIROICHI, IMAE NOZOMI, SATO HIROYUKI, TERAO NORIYUKI, IRINO YOSHIAKI, MASUDA KENSUKE, YAMAMOTO HIDEAKI, HARADA TORU, BESSHO DAISUKE
• Format: Patent
• Language: English
• Published: 04.02.2013
• Subjects: OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

PROBLEM TO BE SOLVED: To realize a wide angle lens suitable as a wide angle lens used in the entire celestial sphere type imaging apparatus, which achieves a combined image of fewer parallaxes, and ensures optical performance.SOLUTION: The wide angle lens comprises, in order from an object side to an image side, a front group, a reflecting face, and a rear group, and is equal to or greater than 180 degrees in an angle of view. The front group is composed of three lenses LA1 to LA3 and has negative refractive power. The reflecting face bends an optical axis of the front group 90 degrees toward the rear group. The rear group is composed of four lenses LA4 to LA7 and has positive refractive power. A principal point is set in a position between the second lens LA2 and the third lens LA3 in order from the object side in the front group. A focal distance f of the entire system and a distance d between the intersection of the optical axis of the front group and the reflecting face and the front principal point satisfy the following conditional expression (1): 7.0<d/f<9.0.