The Multiple Mirror Telescope uses six 1.8 m diameter folded Cassegrain telescopes to achieve the collecting area equivalent to that of a single 4.5 m telescope. However, for some applications, this capability is realized only if the images are brought to a common focus and coaligned in such a way that the overlapping images appear to result from a single primary. The method of adjustment used at the MMT to coalign the six images does not involve the primaries or the tertiaries; instead, the cassegrain secondary mirrors are tilted in orthogonal axes. Since the SPIE Conference on Advanced Technology Optical Telescopes in March 1982, the MMT has rebuilt the optical configuration used to sense image positions at the focal plane (the top box) so that image stacking, automatic guiding, and star acquisition can be made fully operational procedures. This report describes the coalignment system and the results of tests to date.
|