The present invention provides an optical element switching mechanism that overcomes
many of the disadvantages found in the prior art. The switching mechanism uses
a balanced arm, with an optical element attached at one end of the arm. The arm
is suspended on a axis that allows it to rotate from a first position to a second
position. The arm is balanced to provide low force disturbance during this movement.
A spring is coupled to the arm that provides the rotational energy to move the
arm. The spring is coupled such that its neutral position is between the first
and second positions, and thus the spring provides the energy to move the arm from
the first position to the second position and vice versa. A latch mechanism is
also provided for selectively holding the arm in the first position or second position.
Additionally, the latch mechanism can provide additional energy needed to catch
and move the arm into final position.