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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 acquisition.

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.