Lens barrel

1. A lens barrel in which a first movable member holding a first lens group and a second movable member holding a second lens group are arranged in a direction of an optical axis and made movable with respect to a fixing frame, said lens barrel comprising:

a first actuator including a first coil, a first magnet opposed to the first coil, and a first yoke with a U-shaped cross section, wherein the first actuator is configured to move the first movable member in the direction of the optical axis by a first magnetic circuit formed by the first coil, the first magnet and the first yoke;

a second actuator including a second coil, a second magnet opposed to the second coil, and a second yoke with a U-shaped cross section, wherein the second actuator is configured to move the second movable member in the direction of the optical axis by a second magnetic circuit that is formed by the second coil, the second magnet and the second yoke and that is magnetically independent of the first magnetic circuit; and

an intermediate member located between the first movable member and the second movable member and including a diaphragm of an optical system, that includes the first lens group and the second lens group, and a collision preventing member that prevents the first movable member and the second movable member from colliding with each other,

wherein an opening of the first yoke with the U-shaped cross section is opposed to an opening of the second yoke with the U-shaped cross section, the opening of the first yoke and the opening of the second yoke being provided away from each other by a predetermined distance and being opposed to each other along the direction of the optical axis.

2. The lens barrel according to claim 1 , further comprising:

a first shock absorbing member that is located on a side of the intermediate member which faces the first movable member and that is configured to absorb a shock applied by collision of the first movable member; and

a second shock absorbing member that is provided on the fixing frame and that is located at an end of a movable range of the second movable member which is close to the intermediate member, the second shock absorbing member being configured to absorb a shock applied by collision of the second movable member.

3. The lens barrel according to claim 1 , wherein the intermediate member has a black surface.

4. The lens barrel according to claim 1 , wherein the diaphragm has an opening edge which defines an opening that has a predetermined diameter, and which blocks one of (i) an undesired light component traveling through a gap between the first coil and the first yoke or a gap between the second coil and the second yoke and (ii) an undesired light component reflected by the first yoke or the second yoke.

5. The lens barrel according to claim 1 , further comprising a third yoke arranged inside the opening of the first yoke or the opening of the second yoke such that the third yoke closes the opening of the first yoke or the opening of the second yoke, wherein the intermediate member is arranged inside the third yoke.

6. The lens barrel according to claim 5 , wherein the third yoke is provided with a nonmagnetic member having a uniform thickness.

7. The lens barrel according to claim 6 , wherein the third yoke includes a narrow central portion and upper and lower wide areas, and the nonmagnetic member is a rectangular sheet-like member provided on the upper and lower wide areas.

8. The lens barrel according to claim 1 , wherein the intermediate member includes a rib for providing the intermediate member with rigidity.