Development and testing of EUV multilayer coatings for the atmospheric imaging assembly instrument aboard the Solar Dynamics Observatory

The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO)

“…Different multilayer coatings were applied to each half of each telescope optic to achieve the desired central wavelength (see Table 3). Reflective X-ray Optics applied the 94-, 131-, and 335-Å flight coatings and LLNL applied the 171-, 193-, 211-Å flight coatings (Soufli et al, 2005). LLNL led the reflectance calibration and mapping of all AIA EUV flight mirrors, using the reflectometer at beam line 6.3.2 of the Advanced Light Source synchrotron at Lawrence Berkeley National Laboratory (Underwood et al, 1997;Gullikson, Mrowka, and Kaufmann, 2001).…”

EUV reflectance characterization of the 94/304 ? flight secondary AIA mirror at beamline 6.3.2 of the Advanced Light Source

“…The individual layer thicknesses are determined by controlling the rotational velocity of the substrate as it passes over each cathode. For the coatings described here, the base pressure in the chamber was less than 2 x 10 -7 Torr, the sputter gas (Ar) pressure was maintained at 1.6 Torr, and the cathodes were operated in constant power mode: SiC was deposited at 400 W, Mg at 400 W, Mo at 200 W and Y at 200 W. The development and optimization of the Mo/Y and SiC/Mg coatings for AIA has been discussed earlier 3 .…”

Initial Calibration of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO)

“…Variations in the accuracy of the beam normalization due to changes or errors in the calibration of the microchannel plate or proportional counter are the dominant source of uncertainty in the QE measurement (< 5% for the proportional counter, and around 10% for the cross-calibrated MCP). After accounting for the effect of the CCD-camera system gain (see below), the measurements were used to constrain a model of the detector quantum efficiency (Stern et al, 1994(Stern et al, , 2004. The measurements of the four flight CCDs all agreed to within 5 -6%, less than their error bars, so the mean CCD QEs were fit to the same CCD model, which was used for all channels.…”

“…Multilayer coatings are necessary in order to render the mirrors efficient reflectors in the EUV region. The multilayer coating development for the seven EUV AIA channels is discussed in Soufli et al (2005). Multilayer coatings on the AIA flight-mirror substrates were applied at Reflective X-ray Optics (RXO), LLC for the 94 (Mo/Y), 131 (Mo/Si), 304 and 335 (SiC/Si) Å channels and at LLNL for the 171, 193 and 211 (Mo/Si) Å channels.…”

“…The uncertainties in both the optical constants that go into the model and the QE measurements are larger in the UV range. Therefore, instead of the formal model of the QE that was used for the EUV channels based upon an estimated implant distribution (see Stern, Shing, and Blouke (1994) for the description of the formal and empirical model approaches), we used an empirical fit to the CCD measurements in the calibration of the UV channels. In addition, the CCD response is flat over the bandpass of the AIA UV channels, so the accuracy of the CCD calibration for the UV channels can likely be improved by on-orbit cross-calibration with instruments such as TIMED/SEE (Woods et al, 2005).…”