<title>CHAMP: the Carbon Heterodyne Array of the MPIfR</title>

Terahertz Heterodyne Array Receivers for Astronomy

“…CHAMP/CHAMP + CHAMP [15] was a 4 × 4 pixel array for the 625 μm atmospheric window first installed at the Caltech Submillimeter Observatory [28] on Mauna Kea, Hawaii in 1999. The array was composed of two polarization split interleaving subarrays of 8 pixels each, which reduced the beam spacing by a factor of √ 2.…”

“…At even higher frequencies, each mixer requires an individual optical element to collimate its beam, before it is injected into the common array optics. This can be achieved by a simple lens (e.g., [15]) or with a fully reflective design like the CHARM [44] setup.…”

“…At higher frequencies, it can be achieved by a succession of beam splitters, which extract appropriate fractions of power from the LO beam [20] or by a phase grating. Originally designed as Dammann gratings [15,96], the preferred grating type soon became the Fourier grating [19,97].…”

CHAMP+: a powerful array receiver for APEX

“…The cryogenic and mechanical concept follows the design of CHAMP [8] . For the commissioning and first observing runs cooling will be provided by a Daikin 3-stage closed-cycle cooler, consisting of a two-stage Gifford-McMahon cooler with an additional Joule-Thomson stage to operate at 4 K. The replacement of this aged cooler by a Sumitomo 3-stage Gifford-McMahon cooler is scheduled for the near future.…”

“…To make best use of these unique conditions, CHAMP + , a dual-color heterodyne array for spectroscopy in the 450 and 350 µm atmospheric windows is under development. The instrument is a re-furbished version of the former 16-pixel 625 µm carbon heterodyne array CHAMP [8] , which was successfully operated for several years at the Caltech Submillimeter Observatory (CSO).…”