Provided is an actuator for scanning detecting light, comprising an optical
element for emitting detecting light, a moveable part supporting the
optical element, a sheet spring having a fixed end and a moveable end
supporting the moveable part; and drive means for driving the moveable
part so as to scan the detecting light. Thus, a spring-mass system is
formed in which the moveable part retaining the optical device acts as the
mass, and the first order resonant frequency of the system may be selected
so as to be higher than the operating frequency (scanning frequency). A
bearing for a sliding part is not required, and the resistance loss can be
thereby eliminated. These factors contribute to a favorable
responsiveness. Also, by properly designing the sheet spring, a lighter
and more compact design is enabled than would be possible with the
conventional arrangement. A plurality of drive force generating units
disposed on either side of the optical element in such a manner that the
combined force of the drive force produced by the drive force generating
units acts substantially onto the gravitational center of the moveable
part. Thus, the drive efficiency can be improved while saving energy and
achieving a high level of responsiveness.
