Actuator and object detecting apparatus

An actuator, comprising:

• a torsion spring fixed to a support member, the torsion spring having a folded shape with a straight folded peak, a rotational axis of the torsion spring being parallel to a ridge direction of the folded peak;
• a permanent magnet having an N-pole and an S-pole and being coupled to the torsion spring such that the N-pole and the S-pole are disposed on opposite sides of the folded peak from each other;
• a driving coil facing the permanent magnet and located such that the driving coil and the torsion spring are disposed on opposite sides of the permanent magnet from each other;
• a driving circuitry configured to apply a drive signal with periodically varying voltage or current;
• and
• a mirror unit fixed to the torsion spring and located such that the mirror unit and the permanent magnet are disposed on opposite sides of the torsion spring from each other, the mirror unit comprising a first reflecting surface disposed over the folded peak and a second reflecting surface disposed on both sides of the folded peak and parallel to the first reflecting surface, a second plane including the second reflecting surface being closer to the rotational axis of the torsion spring than a first plane including the first reflecting surface, and the mirror unit being configured to reciprocate in accordance with application of the drive signal.