Structures, Pointing, And Control Engineering Laboratory



  • The secondary mirror is a six-sided pyramidal aluminum mirror located 2.4 m above the primary mirror. The mirror has a diamond fly cut in itÂ’s reflecting surface at an angle of 5.15 deg that allows it to split the incoming laser beam into six sub-beams.
  • The shape of the mirror was developed by performing a geometric study of the trace of the laser beam. A suitable geometry was found that would reflect the incoming beam from the laser source to a point on the panels. Furthermore, the returning beam is reflected back to the optical sensors at the center of the primary mirror.
  • A series of springs suspend the secondary from the secondary mirror housing. The secondary mirror has three degrees of freedom in the form of a tip, a tilt, and a piston motion.
  • It is equipped with 3 reluctance actuators to provide 3-axis active control and 3 inductive position sensors that provide information about the secondary mirror attitude.