Opto-mechanical design of primary mirror assembly for free gyro stabilized seeker

In Free Gyroscopic Stabilized Seekers, the Primary Minor has the multiple functions of a magnetic rotor, the primary rotating mass and the primary reflector for the optical train. The introduction of rare-earth magnetic alloys to this class of seeker has provided increased flexibility in materials selection, opto-mechanical design and cost of manufacture. Along with superior magnetic properties, the rare-earth alloy Neodymium-Iron-Boron (NdFeB) comes with the undesirable properties of anisotropic CTE, high susceptibility to corrosion and manufacturing challenges. This paper discusses the opto-mechanical design, structural and optical modeling and analysis of a primary mirror assembly utilizing an NdFeB insert with centrifugal, linear acceleration and thermal loading as well as the optical test results, qualification testing of long-term figure stability and validation of the mechanical/magnetic/optical design model.