Dual band 550/1200 GHz wideband spectrometer for planetary observation

摘要

NASA and ESA are planning missions to Jupiter and its moons. There is strong interest in a submillimeter/Terahertzspectroscopic heterodyne instrument covering the bands 520 to 600 GHz and 1100 to 1300 GHz. Therefore, we aredeveloping a prototype instrument incorporating unique features not previously developed for planetary instrumentation.These include (1) extremely wide, rapid tunability. The Herschel/HIFI astronomical instrument, is also wideband, but farlarger. It incorporates a 3.5 meter telescope on a spacecraft massing over three tons orbiting near Earth, versus our 20 kgJupiter spectrometer. Hence, we have developed a wideband low-phase-noise synthesizer pumping two Schottky diodeLO multiplier chains outputting 520 to 600 and 550 to 650 GHz. Also based on Schottky diodes are (b) 550 and 1200GHz room temperature mixers. The high frequency mixer is subharmonically pumped; the lower balanced fundamental.To analyze the IF signals from the mixers, (c) ASIC based digital polyphase spectrometers consuming only a few Wattseach are being incorporated into the instrument. Finally, since signals for both receivers come from one telescope, weinclude a new (d) compact dual band low-loss optical bench. It uses the fact that each receiver accepts one polarization,making a polarizing beam splitter sufficient to split the beam with minimal loss.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.