| CPC G02B 26/0833 (2013.01) [G02B 27/0172 (2013.01); G02B 2027/0178 (2013.01)] | 14 Claims |

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1. A projection optical system comprising:
a base;
a mirror; and
a pair of first actuators provided between the base and the mirror, the pair of first actuators configured to face each other in a first direction,
wherein each of the pair of first actuators comprises a first electroactive polymer film having structural flexibility such that a size of the first electroactive polymer film is changeable based on an applied voltage,
wherein the mirror is adjustable based on a change in the size of the first electroactive polymer film,
wherein the first electroactive polymer film has a first surface and a second surface, and
wherein each of the pair of first actuators further comprises:
a first electrode provided on the first surface;
a second electrode provided on the second surface;
a first stretch maintaining film provided to surround the first electrode; and
a pair of first hinge elements provided on the first stretch maintaining film.
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