2. General Description
2016-04
IFU for Infinite 200 PRO No. 30052730 Rev. No. 1.6
29
Fluorescence Intensity Detection
The fluorescence detection system is used for both measuring modes:
fluorescence from above (top) and below the microplate wells (bottom).
The fluorescence light is focused onto the entrance slit of the Emission
Monochromator. After passing the monochromator the light is focused onto the
detector (PMT). A filter wheel is located between the monochromator and the
PMT.
The Fluorescence Detection system is built from the following components:
•
Emission Double Monochromator
•
Filter Wheel PMT
•
PMT Detector
Emission Double Monochromator
Similar to the Excitation Double Monochromator, the Emission Double
Monochromator is used to select any wavelength of the fluorescence signal.
It acts like an adjustable filter to discriminate scatter of excitation light and
nonspecific fluorescence. The wavelength range is selectable from 330 – 600 nm
in the standard instrument and from 280 – 850 nm in the spectrally enhanced
instrument. The bandwidth is 20 nm.
Filter Wheel PMT
The filter wheel contains wavelength specific optical filters, which are necessary
to block undesired diffraction orders produced by the optical gratings. The filters
are set automatically.
PMT Detector
A photo-multiplier tube (PMT) is used for the detection of such low light levels
associated with fluorescence. The Infinite M200 PRO is available in two versions:
The PMT of the standard version is sensitive up to 600 nm. The PMT of the
spectrally enhanced version of the Infinite M200 PRO is sensitive up to the near
infrared (NIR) while still having low dark current. Electronic circuitry uses analog
to digital conversion of PMT output current. Adjusting the PMT gain enables
measurement of a wide range of concentrations in lower or higher concentration
domains. For details, see Section 5.5.1 Instrument Parameters.
