Introduction

We are also investigating the phenomenon that as the order increases in the diffraction pattern, the dots smear out until after the 10th or so order, we are seeing double dots, as shown in Fig. 7. This happens because the filter lets through a small range of wavelengths around 173 Å, from about 170 to 175 Å, and there are two major wavelengths coming through, Fe IX at 171.06 Å and Fe X at 174.52 Å. Over many orders, the images separate through dispersion, because the longer wavelength is diffracted more than the shorter one.

Figure 7: The dispersion effect: Higher orders separate into double dots because the filter lets through two major wavelengths, Fe IX at 171.06 Å and Fe X at 174.52 Å, and the longer wavelength is diffracted more than the shorter one.