Agilent Technologies 1100 Series Reference Manual page 277

8
Theory of Operation
Raw Signal Acquisition (PMT and Reference Diode)
Each raw data value of the PMT and the reference diode signal is measured
synchronized to the flashes of the xenon flash lamp with a 16-bit
analog-to-digital converter.
Dark Subtraction
The dark value of the PMT and the reference signal are measured during any
power cycle of the detector without flash lamp on. These values are stored and
subtracted from any PMT and reference diode value
Normalize Reference Diode Signal
The reference diode, located behind the flow cell, measures the excitation
(EX) light within the flow cell and corrects flash lamp fluctuations. Because of
a non-linear output of the diode (depending on the EX-wavelength), the
measured data are now normalized to get better real light level values within
the flow cell.
Divide PMT/Reference Diode
With this calculation the output of the detector will suppress lamp effects like
lamp flash fluctuations or lamp lifetime.
Filtering
FIR-filters (finite-impulse-response) are used to filter the given raw data and
output it to a the digital data bus and the analog outputs.
Spectra: Collect data to complete spectra
All flashes that are measured to get spectral information are collected to get
one spectra.
1100 Series FD Reference Manual 279