Apparatus for actuating objective lens

In an apparatus for actuating an optical element along an axis:

• stationary means having a pair of inner and outer surfaces spaced apart from each other in a radial direction relative to the axis, the inner and outer surfaces extending in the axial direction to define therebetween a magnetic gap effective to induce therein a magnetic force;
• movable means disposed in the magnetic gap to undergo movement in the axial direction for supporting thereon the optical element;
• actuating means mounted on the movable means within the magnetic gap for movement therewith and cooperative with the magnetic gap to receive a magnetic driving force in the axial direction for actuating the movable means in the axial direction;
• and retaining means mounted on the movable means within the magnetic gap for movement therewith and cooperative with the magnetic gap during other than the actuation of the movable means to receive a magnetic retaining force in the axial direction for retaining the movable means in the axial direction, the retaining means being spaced from both the radially innermost portion of the stationary means outer surface and the radially outermost portion of the stationary means inner surface in the radial direction to thereby allow the movable means to freely move in the axial direction during the actuation thereof.