The EUV monitor is designed to measure the solar irradiance in three broad bands in the soft xray
         and extreme ultraviolet wavelength range. It consists of three filter radiometers that each
         have a limiting aperture, bandpass limiting filter, silicon photodiode detector, and an
         electrometer to measure the current in the detector. A fourth detector-electrometer combination
         that is blocked from receiving any light input is used as a ?dark? detector to monitor changes in
         the thermal and radiation induced background signals. A temperature diode is also included in
         the EUV instrument. There is also a mechanism to place or remove additional fused silica
         windows in front of the three science apertures. These filters block the EUV and X-ray sunlight,
         but still allow longer wavelength light (primarily visible) through into the radiometers. This
         allows for a measurement of the out-of-band contribution to the signals from the science
         channels.