Optimization of the Hot-electron Bolometer and a Cascade Quasiparticle Amplifier for Space Astronomy

Ultra low noise bolometers are required for space based astronomical observations. Extremely sensitive detectors are necessary for a deep full-sky survey of distant extragalactic sources in the submillimeter-wave region corresponding to the extraterrestrial background spectrum minimum. A deep full-sky survey is the main goal of the Submillimetron project of the cryogenically cooled telescope on the International Space Station [1,2], project CIRCE (NASA) and other projects. Detection of faint sources involvves wide-band continuum observation using direct detectors (bolometers) that are not restricted by the quantum noise of indirect heterodyne receivers. Theoretical estimations and preliminary experiments show that it is possible to realize the necessary sensitivity of 10 10 W/Hz with a novel concept of the antenna-coupled microbolometers [3,4] at temperatures ≤0.1 K (Fig. 1). Additional advantages of such detectors are the possibility to operate with a wide range of background load, easy integration in arrays, and direct possibility of polarization measurements.