OPTICAL SYSTEM, LENS BARREL, IMAGING DEVICE, AND ADAPTER FOR IMAGING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an optical system capable of adjusting focus in an extremely minute unit.SOLUTION: An optical system is made of a transparent parallel flat plate containing an optical medium. The transparent parallel flat plate can deform in a width direction; and as the thickness of the transparent parallel flat plate changes, a difference in optical path length occurs to light passing the transparent parallel flat plate. Accordingly, an imaging surface of an image caused by the light passing the transparent parallel flat plate is moved along an optical axis direction.