HIFI: Heterodyne Instrument for the Far Infrared

Herschel Space Observatory (HSO)

The Herschel Space Observatory (formerly called FIRST, Far InfraRed and Submillimeter Telescope) is the fourth of the original Cornerstone missions in the ESA Horizon 2000 science plan. It will perform imaging photometry and spectroscopy in the 60-670 µm range. The Herschel satellite will have three instruments on board:

• HIFI (Heterodyne Instrument for the Far Infrared)
• SPIRE (Spectral and Photometric Imaging REceiver)
• PACS (Photodetector Array Camera & Spectrometer)

Overview of the HIFI instrument

HIFI will consist of three major sub-systems and an instrument controller.

• The Focal-Plane sub-system (FPU) containing relay optics, mixers, low-noise IF HEMT pre-amplifiers, a focal-plane chopper, a calibration source and the FPU control unit (FCU).
• The local oscillator sub-system consisting of the Local Oscillator Unit (LOU) and the Local oscillator Control Unit (LCU). It will generate the LO signal which is coupled into the FPU.
• A back-end sub-system containing the IF-processor, the High Resolution Spectrometer (HRS) and the Wide Band Spectrometer (WBS).

Our Contribution to HIFI

The Wide Band Spectrometer is one back-end of HIFI consisting of an Acoustic-Optical Spectrometer, its electronic and the associated IF-processor. The electronics, the IF-processors, and the acousto-optical units are developed by Max-Planck-Institut für Sonnensystemforschung, Miteq and I.InstPhys/KOSMA, respectively.

The Mixer unit for Band 2 provides a mixer with a SIS junction covering the RF-frequency range of 640-800 GHz. The IF-frequency range is 4-8 GHz.