US Patent 7154684 Optical element holding apparatus

An optical element holding apparatus provided with a holding portion for holding a flange portion of an optical element. The holding portion includes a bearing surface block having a bearing surface, which contacts the flange portion, and a bearing surface block support mechanism, which rotatably supports the bearing surface block about a tangential axis of the optical element. This structure holds the optical element with the optical element holding apparatus in a kinematical manner and maintains satisfactory imaging performance in the optical element.