Lens mounting technique

A lens mounting system that is self-centering at an operating temperature, said system comprising:

• a lens mount having a cylindrical inner surface defining an internal cavity;
• an annular mounting shoulder projecting into the cavity having a fixed forward facing mounting surface;
• a mounting ring having a movable rearward facing mounting surface, said mounting ring being operably engaged with said inner surface for selective movement of said movable mounting surface between a withdrawn position distant from said mounting shoulder and an advanced position adjacent said mounting shoulder;
• a lens including:
• a forward facing first optical surface;
• a rearward facing second optical surface;
• an annular mounting member at an interface between said first optical surface and said second optical surface, said annular mounting member including:
• a first forward facing mounting surface for flush mating engagement with said movable mounting surface of said mounting ring;
• and
• a second rearward facing mounting surface spaced from said first mounting surface for flush mating engagement with said fixed mounting surface of said mounting shoulder;
• said lens becoming rigidly supported on said lens mount as said mounting ring is moved from said withdrawn position toward said advanced position;
• said lens mount and said lens having different rates of thermal expansion such that said lens mount contracts and forces said lens into a centering position when the system is cooled to the operating temperature.