Design and test of a high-resolution EUV spectroheliometer

The High-Resolution EUV Spectroheliometer (HiRES) is a sounding rocket instrument designed to obtain very high spatial, spectral and temporal resolution images of the solar outer atmosphere. The main components of the instrument are a 45-cm Gregorian telescope feeding a 1-m normal-incidence stigmatic EUV spectrometer with an imaging Multi-Anode MicroChannel Array (MAMA) detector system together with a 1-m Wadsworth IR spectrometer with an imaging CCD detector system. The stigmatic EUV spectrometer utilizes a single toroidal diffraction grating which is fabricated by a recently developed method employing an elastically deformable substrate. An additional 0.25-m normal-incidence spectrometer with a MAMA detector system is included in order to record atmospheric extinction data over the 280 to 1270 A wavelength range. This paper summarizes the expected performance of the telescope and 1-m EUV spectrometer system including the effects of vibrational misalignments and despaces due to the sounding rocket flight environment. Finite element analyses of the telescope primary mirror mounting concepts are presented and discussed. In addition, results of ray tracing and laboratory spectrograph measurements from the toroidal grating test program are presented and discussed.