Mechanical alignment of tertiary mirror and positioner on the LMT telescope - art. no. 70183M

The Large Millimeter Telescope (LMT) at Cerro La Negra in Central Mexico is Currently being fitted Out with optical, mechanical and control systems. The tertiary mirror is a 1.1 x 1.7m ellipse, mounted oil a positioner which provides tracking in elevation and 180 degrees image direction switching between detectors. Installation and alignment of mirror and positioner must be achieved with high accuracy in a construction-site environment, at an altitude of 4600m. Alignment equipment should be intuitive to use, easy to install, and have minimum interference with other site tasks. Alignment will be achieved with small diameter, well-collimated laser beams, pre-aligned to the telescope elevation and primary reflector (optic) axes. Although a total station and laser tracker are available, the laser beam method has theoretically higher accuracy, gives faster, more intuitive results and requires no time-sharing with the former instruments. This paper describes the alignment concept, equipment to be used, pre-installation testing, and alignment procedures to be carried out at the telescope.