Phase retrieval holography and surface adjustment of SEST using the LES-8 satellite

Phase retrieval holography has been used to determine the surface profile of the Swedish-ESO Sub-millimetre Telescope (SEST). The measurement was performed using a signal transmitted from the geosynchronous LES-8 satellite over a range of elevation angles. The results of the measurements have been used to reset the reflector thus reducing the surface errors from the initial 80 m r.m.s. to 51 m r.m.s. The improvement in the surface accuracy has been confirmed by telescope efficiency measurements at 232–250 GHz.