project TMT Secondary Mirror Support System and Positioner

The TMT International Observatory (TIO) contracted AMOS to design and manufacture the secondary mirror support system and positioner (M2SSP) of the future extremely large Thirty Meter Telescope (TMT). Once constructed, the TMT telescope will have a 30-meter primary mirror and be the largest ground-based, optical telescope in the northern hemisphere.

With its preferred site on Maunakea in Hawaii, TMT is one of three extremely large telescopes under construction in the world. Building such a telescope is a major challenge. Engineers must design and build large moving structures capable of holding the telescope’s various mirrors in place with nanometric precision.

AMOS is contracted for a critical piece of the telescope: the M2SSP system. The M2SSP will carry and adjust the position of the telescope’s secondary mirror. Located at the top of the telescope, the secondary mirror receives the light collected by the primary mirror, sends it towards the tertiary mirror, and then to the telescope’s various instruments.

The M2SSP system is composed of two elements:

• A system to support the secondary mirror (with a 3.2-meter diameter) facing downward, in the direction of the tertiary mirror of the telescope. This system maintains the 2-ton mirror in such a way that its surface keeps its optimal shape with a precision in the order of a fraction of a micrometer.
• A positioning mechanism that allows the mirror to move with 6 degrees of freedom within micrometric accuracy to compensate the deformation of the structures, the effect of gravity, some thermal effects on the telescope’s structure, etc.