Mechanical design of an infrared imaging system for DIII-D

Two infrared imaging units have been designed to monitor temperature changes on the protective armor tile inside the DIII-D vacuum vessel. Each imaging unit includes an optical system (lenses, mirrors, and infrared camera), a support structure, and a magnetic-shield enclosure. Each optical system requires a 45° field of view to monitor a large area within the vacuum vessel. The quality of the image produced by the infrared camera is very sensitive to mechanical vibrations. A rigid support structure has been designed to minimize the motion of the optical system and camera image during a plasma experiment. The vibration characteristics of an existing DIII-D imaging-unit support structure were measured. The structural properties of the proposed imaging-unit supports were then determined using CAD/CAM modeling and finite-element analysis and were modified until their stiffnesses matched or exceeded the stiffness of the existing structure. This method eliminated a detailed static and dynamic analysis of all the forces acting on the proposed structures