The 50-metre Large Millimeter Telescope (LMT) successfully completed first light observations in June 2011, operating
with an initial 32.5-metre diameter collecting area. This reduced-area primary surface consists of 84 reflector panels
measuring approximately 3x5m. During the construction phase, individual panels were assembled and adjusted to the
specified rms surface error off-site, then installed and aligned on the antenna using a total station. Prior to first-light
observations, panels were fine-tuned in piston, tip-tilt and twist using full-surface holography measurements to direct the movement of electromechanical actuators located at the four corners of each panel.
In preparation for the next observing season the 32.5m primary is being refurbished and re-aligned on-site, using a
commercial laser tracker for surface adjustment of each panel. For this task we have opted for the transfer of panels from the antenna surface to the telescope basement for adjustment, offering an enclosed environment with stable temperature, followed by reinstallation and measurement on the open-air antenna surface at night.
In this paper we present our experiences on the use of a laser tracker to conduct panel surface measurement and
adjustment on-site, at an isolated location 4,700m (15,000ft) above sea level and in the absence of dedicated metrology
facilities. In section 2 we present the primary surface concept deployed at the LMT. Section 3 discusses the laser tracker
equipment and data processing for panel surface measurement. Section 4 describes the panel adjustment process carried out in the site basement and presents examples of indoor panel metrology using the laser tracker. In section 5, we present our experiences to date of open-air measurement of panels installed on the antenna. Some conclusions are offered in section 6.