An optical element mounting includes a frame, and a shuttle that is translatable relative to the frame. The shuttle includes inner and outer portions that are mechanically coupled together by a plurality of flexures that effectively bending and twisting of the shuttle from being transmitted to an optical element, such as an optical window, that is mounted on the inner portion of the shuttle. The flexures may be thin linking strips of material between the outer and inner portions. The flexures may have a thickness that is greater in an expected load direction, than in a direction perpendicular to the load direction. The optical mounting may include a locking mechanism, for example including a shape memory alloy wire, to lock the shuttle in a predetermined location relative to the frame.