IMAGING OPTICAL SYSTEM AND OPTICAL DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a high-performance imaging optical system which is made accurate and much more miniaturized and thinned than the conventional miniaturized and thinned optical system, and copes with the change of the size of a spot caused by using a prism, and also to provide an optical device using the same. SOLUTION: The imaging optical system has a front group G1 having at least one rotationally asymmetric reflection surface having power, an aperture diaphragm 2, and a rear group G2 having at least one rotationally asymmetric reflection surface having power in order from an object side, and is constituted so that Fno may be different in two directions orthogonal to each other on a plane orthogonal to an optical axis. It is constituted to be eccentric in one direction out of two directions, and the Fno in a direction perpendicular to the eccentric direction is set to be brighter than the Fno in the eccentric direction. Assuming that the Fno in the eccentric direction is FNY and the Fno in the direction perpendicular to the eccentric direction is FNX, the imaging optical system satisfies a conditional expression: 1.1