Actuator, image capturing unit and electronic device

An actuator, configured to drive an imaging lens system, and the actuator comprising:

• a frame portion, configured to accommodate the imaging lens system;
• a supporting portion, disposed on the frame portion, wherein the supporting portion is configured to support the imaging lens system and give the imaging lens system at least one degree of freedom of movement with respect to the frame portion;
• a driving portion, configured to move the imaging lens system along a direction of the at least one degree of freedom;
• an optical mark structure, configured to be disposed on the imaging lens system, wherein the optical mark structure faces part of at least one of the frame portion, the supporting portion and the driving portion, the optical mark structure comprises a plurality of optical mark units arranged side by side, and each of the plurality of optical mark units comprises a first optical mark surface;
• and
• an intermediate layer, disposed on the optical mark structure, wherein the intermediate layer is in physical contact with one of the frame portion, the supporting portion and the driving portion that is adjacent to the optical mark structure;
• wherein an area of each of the first optical mark surfaces is A, a distance between center points of adjacent two of the first optical mark surfaces is D, and the following conditions are satisfied:
• 0.001[mm2]≤A≤0.5[mm2];
• and
• 0.03[mm]≤D≤1.0[mm].