ALMA band 2 optics: Design, constraints, implementation and measurements

This paper describes the development, construction, and measurement of the optics of a receiver operating between 67-90 GHz prototyped by the National Radio Astronomy Observatory (NRAO). The intent is to install this receiver on the Atacama Large Millimeter/submillimeter Array (ALMA) as a new band increasing the capability of ALMA. ALMA is an international radio telescope in the Atacama Desert of northern Chile [1]. The array consists of 54 12-meter and 12 7-meter high precision antennas operating in the 0.3 to 10 mm wavelength range. The instrument provides both interferometric and total-power astronomical information on atomic, molecular and ionized gas and dust in our galaxy, the solar system and the nearby to high-redshift universe.