We are currently working on a design to be put forward as the High Resolution Imager on board SO.  A proposed design is one based upon the MOSES (Multi-Order Slittless Spectrograph) sounding rocket which is to be launched in 2004. 

The MOSES instrument is a combined imaging spectrograph that images over three orders.  The lack of rastering a slit, as done in a conventional slit spectrometer, allows for high cadence and co-temporal imaging, while spectral data is obtained by deconvolving Lambda and X in the outer two orders.

Rather than having a large passband, the system concentrates on a dual-line wavelength selection with a narrowband multilayer.  For the proposed design, there are a number of possible passbands that can be considered.

Design options include having a single instrument concentrating on a dual-line selection, or a multiple three-order system, with each subsystem focusing on a single line.

Illustration of the MOSES three order imaging spectrograph