| 摘要 |
PROBLEM TO BE SOLVED: To switch the focal distance with high accuracy by reducing the withdrawal space. SOLUTION: A fold-back optical system includes a first lens group 11, a prism 12, a second lens group 13, and an imaging lens system 14. The first lens group 11, the prism 12 and the second lens group 13 are assembled integrally in a holding member 26. The holding member 26 rotates around the rotation axis 27 orthogonal to the surface including first and second optical axes 16, 24 between a first position and a second position. At the first position, a slope inner surface 18 of the prism 12, and the first and second lens groups 11, 13 are inserted onto the optical axes 16, 24 together. At the second position, a slope outer surface 19 of the prism 12 is inserted and at the same time the first and second lens groups 11, 13 are withdrawn from the optical axes 16, 24. COPYRIGHT: (C)2009,JPO&INPIT
|
