MgF2: extends UV to VUV
SB: Solar Blind
BB: Broadband
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The incoming light first meets the
photocathode of the ICCD cameras image
intensifier. The photocathode
converts the incoming
photons to photo electrons by collisional ionization. To obtain a
maximum signal to noise ratio in the images the spectral sensitivity of
the photocathode should be well fitted to the applications light
spectrum. A maximum number of photoelectrons per incoming photon is
generated in this way, i.e. a maximum integral quantum efficiency is
achieved. The
photocathode of the image intensifier will therefore be selected
according to
the specific requirements of your application. A selection of popular
photocathode materials is shown in the according diagram.
Before the
photons
meet
the photocathode, they have to pass the entrance window. Quarz is used
as standard
material for the window. However, for UV
applications a MgF2 window may be applied. The ultraviolet
transmission factors of both materials are shown in the appropriate
diagram.
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