M1
VISTA will be a quasi-Ritchey-Chretien telescope equipped with a Cassegrain focus. The design is based on a ~f/1, 4.1 m primary mirror, in the form of a meniscus and a rigid light-weighted secondary mirror of 1.24 m diameter. The desired intrinsic image quality is obtained by means of a field corrector physically included in the IR Camera. In addition, the IR Camera will be equipped with wavefront sensors to measure the image quality. This allows periodic corrections of the primary mirror, telescope focussing and collimation. This is achieved through an active primary mirror cell that includes 84 axial supports, 24 lateral supports and a 5 axis M2 support system. A view of the Telescope Optical layout is shown here.
The M1 blank was produced by Schott in Germany and is made from Zerodur. The mirror was transported to Moscow where JSC LZOS took responsibility for the rest of the manufacturing process. The picture below shows the blank finally completed at Schott whilst the next picture shows the mirror after LZOS had added all the support pads to the side and rear surface of the blank.
Vista M1 Blank completed by Schott
Vista M1 Rear surface with axial support pads
The mirror is now undergoing polishing at LZOS and is expected to be completed in late summer 2005.
Vista M1 Asperhirsation Proccess
VISTA M1 polishing