Focal optical spectrometer

For a point source, z is zero, and from equ. (10.6b) it follows that tp = const. This means that the electrons ejected from the source move in a plane which contains the z-axis. Hence, the focal point must also be in this plane, and this fact considerably facilitates the discussion of the optical properties of the spectrometer. Due to the conservation conditions, one is left with only one differential equation which describes the radial movement of the electron, i.e.,... 

In parallel with the development of the EOID for focal plane mass spectrometers of the Mattauch-Herzog type, similar devices were developed for use with conventional sector-type mass spectrometers (15, 16, 17, 18). A schematic representative of this type detector, versus that implemented on a CEC type 21-490 single focusing mass spectrometer, is shown in Fig. 8. The main differences between these two applications of the EOID are a result of the differences in the ion optics of the two types of mass analyzers, as shown in Fig. 1. First, the detector of a sector type instrument resides outside the magnetic fringe field, thus eliminating the need for angling the primary ion sensors. 

Another electro-optical ion detector, which is called the electro-optical array detector, allows the simultaneous measurement of ions spatially separated along the focal plane of the mass spectrometer. It combines the microchannel plate and Daly detector. The ions are converted in a microchannel plate into electrons that are amplified. The released secondary electrons finally strike a phosphorescent screen that emits photons. These photons are then detected with a photodiode array or CCD detector. This array detector acts as electronic photoplates. 

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