Sub reflector with supporting structure


According to the selected optical scheme – Cassegrain optical scheme – “Millimetron” telescope includes sub reflector. Sub reflector is mounted on the supporting truss and located in the primary mirror cup in order to meet the requirements for temperature regimes (Figure 2). Sub reflector adjustment with primary mirror is provided by a special adaptation. In case of "Millimetron" telescope a hexapod is used for this purpose. Thus, sub reflector consists of secondary mirror and hexapod, which provides the secondary mirror movement along three linear and two angular coordinates during the adjustment process.

The secondary mirror has a shape, backed by a system of stiffening bars. Secondary mirror surface serves as a reflecting surface. To ensure the space telescope operation in the infrared wavelength ranges the required accuracy of the secondary mirror reflective surface as the standard deviation (RMS) of its reflective surface normal to the theoretical surface must not exceed 1 micron. Currently it expected to manufacture the secondary mirror from silicon carbide. The secondary mirror is mounted on the supporting truss ring through a hexapod.

Sub reflector supporting structure is six rod farm with three bearing pads, mounted on the cooled container power panel. To mount this construction, the primary mirror has openings to arrange the passage for supporting structure to the power panel.

Sub reflector with its supporting truss is cooled down to 4.5 K by active cooling system in order to ensure the telescope operation at the highest sensitivity.