An optical element and a lens unit each includes: a liquid container transmitting light at least in a predetermined optical axis direction, the liquid container containing an insulating liquid and an ionic liquid being mutually immiscible and optically transparent, and having different refractive indices; a first electrode contacting the ionic liquid in the liquid container; and a second electrode insulated from the ionic liquid in the liquid container. The ionic fluid is not subject to electrolysis and does not evaporate easily even at high temperature. Accordingly, the optical element, the lens unit and an image taking apparatus having the optical element can maintain high light-transmission and optical characteristics over a long period even in a high temperature environment.
光学元件和透镜单元各包括:至少在预定光轴方向上透光的液体容器,液体容器中含有互不相溶、光学透明且折射率不同的绝缘液体和
离子液体;与液体容器中
离子液体接触的第一电极;以及与液体容器中
离子液体绝缘的第二电极。
离子液体不会发生电解,即使在高温下也不易蒸发。因此,即使在高温环境下,光学元件、透镜单元和具有该光学元件的图像拍摄装置也能长期保持较高的透光率和光学特性。