BD FACSCanto II, Reference Manual, Page: 114 / 158

114 BD FACSCanto II Flow Cytometer Reference Manual
Detectors
Detectors convert light signals into electrical signals that can be processed by the
electronics system and a computer and then displayed on a plot.
There are two types of signal detectors in the BD FACSCanto II flow cytometer:
the photodiode and the photomultiplier tube (PMT). The photodiode is used to
detect the stronger FSC signal (generated by light from the blue laser). The more
sensitive PMTs are used to detect the weaker signals generated by SSC and all
fluorescence channels.
In BD FACSCanto clinical software, the fluorochrome (or cell parameter) to be
measured at each PMT is preset.
In BD FACSDiva software, you can use the Instrument Configuration dialog to
specify the fluorochrome that will be measured at each PMT detector. You can
also add additional parameters to your configuration and choose the appropriate
fluorochrome within your software experiment.
Detector Arrays
On BD FACSCanto II flow cytometers, PMTs are organized onto an octagon and
one or two trigons. The octagon has five or six PMTs. The trigons have two or
three PMTs. These arrays efficiently direct the emitted light from each
fluorochrome to a specific PMT, through placement of LP mirrors and BP filters.
When the collected light leaves the fiber optic cable at the octagon, it first meets a
735 LP dichroic mirror (Figure A-9 on page 115). The mirror allows light with
wavelengths greater than 735 nm to pass and reflects light with lower
wavelengths to the next PMT.