Electron energy loss spectra (EELS) are collected by a CCD camera in which vertical pixel rows are integrated to construct the energy channels.
A “parallel EELS spectrometer” does not use a
pair of slits, but instead uses a scintillator and a position–sensitive photon detector
such as a linear photodiode array. It is typical to use a set of postfield lenses to
magnify the energy dispersion before the electrons reach the scintillator. A parallel
spectrometer has an significant advantage over a serial spectrometer in its rate of data
Data acquisition of EELS is slow due to two main reasons:
i) The slow shutter/readout rates of diode array/CCD cameras.
ii) The low signal of many loss features.
The modern CCD spectrometers provide rapid and/or multiple readout bins and/or continuous readouts so that the collection speed of EELS and thus spatially resolved mapping are faster.