The sensitive area of the Echelle detector is 40mm x 40mm. The Echelle spectrum is mapped as bright stripes onto the detector. Each stripe is one order of the Echelle spectrum. Orders 40 and 60 are marked in the image, also some wavelegth positions are marked within these orders. Additionally the hydrogen Ly-beta absorption line is marked.
Absorption lines are visible as dark spots within the bright stripes of the individual orders.
The image shows a simulated Echelle spectrum. For extraction of the spectrum the brightness along each stripe is measured and each position on the detector is associated a certain wavelength. This graphics shows the efficiencies of the individual optical components of the Echelle spectrometer and the resulting total efficiency of the whole instrument. The values given are the pure quantum effiency values without electronical losses due to selection or dead time effects. Dead time losses are count rate dependent, the dead time is about 13 microseconds per photon pulse.