Atacama sub-millimeter telescope experiment polarimeter (APol) I: design and lab-test result

The Atacama Submillimeter Telescope Experiment (ASTE), a 10-m aperture telescope, hosts a camera equipped with the Transition Edge Sensor (TES). We developed a fore-optics module—“APol,” to convert the 271 pixels of the TES working at 350 GHz into a sensitive imaging polarimeter without sacrificing the image quality and the 7.5 ′ field of view. Here, we describe the detailed optical design of APol and present the results of the preliminary test in a laboratory.