Acousto-optical spectrometer for spaceborne application

Acousto optical spectrometers (AOS) have become an attractive alternative to filterbanks or autocorrelators for applications in radioastronomy and in heterodyne as well as in laboratory spectroscopy. Due to continuous improvements, AOSs have now achieved a performance and reliability level that makes this technology applicable for airborne or spaceborne missions. A first fully space qualified AOS was built at the University of Cologne for the Submillimeter Wave Astronomy Satellite (SWAS) to be launched in fall 1995. The SWAS-AOS has a large bandwidth of 1.4 GHz covered by 1365 channels, with a center frequency of 2.1 GHz. Only 11 mW rf white noise input power is required for simultaneous saturation of all channels. The design is optimized for very high stability and allows operation within a temperature range from minus 5 to plus 30 degrees Celsius at temperature variations of up to 2 degrees Celsius/hour. The total weight is 7.2 kg including electronics, the power consumption is 5.4 watts including data pre-averaging electronics and dc-dc converter losses. The performance was verified also after complete vibrational and thermal vacuum environmental testing. For future projects with large bandwidth requirements or with multichannel systems the AOS technology can also be used to fabricate array spectrometers. Such array AOS offers the unique option to multiply the available bandwidth without multiplying the hardware accordingly. Especially for spaceborne applications this is an extremely useful development because weight, power consumption as well as costs increase only very moderately. At present the first prototype with four independent 1 GHz channels is in development. This array AOS will have a total bandwidth of 4 GHz covered by 4000 channels, and will be available in 1996.