With a corner mount, the center of the mirror is intentionally located at the xy intersection of the pitch and yaw adjusters, i.e., at the virtual fourth point of the square formed by the ball points of the three actuators. To achieve gimbal movement, two adjacent adjustment screws must be actuated the exact same distance. For gimbal pitch adjustment, the adjuster normally used for yaw adjustment must be actuated along with the corner adjuster the exact same distance. For gimbal yaw adjustment, the adjuster normally used for pitch adjustment must be actuated along with the corner adjuster the exact same distance. In this way, the mirror is being rotated about two virtual axes that intersect at the center of the optic, aka gimbal movement. Adjust one actuator at a time and the mount acts as a standard kinematic optical mount. Adjust all three actuators to translate the optic in Z-axis.
 

Another benefit of the corner mount design is the additional space between the optic and the adjustment knobs. This allows for sharper beam splitting angles and easier access to the adjustment screws.
 

Since grease can migrate, causing long-term creep, these mounts are exclusively fitted with thread-matched adjustment screws which need almost no grease.  The result is actuators that have very smooth movement, and mounts with exceptional long-term and thermal stability.