5. Operating the INFINITE M1000 PRO
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Instructions for Use for INFINITE M1000 PRO No. 30064852 Rev. No. 1.0
2011-09
5.5.2
Light Level Attenuation
When using photon-counting detection, optical attenuation of higher
luminescence light levels (> 10,000,000 counts per second) is necessary. In that
case, too many photons entering the PCT at a time cannot be distinguished as
distinct exit pulses. Count rates would even fall behind values at lower light
levels. Therefore, values >10,000,000 counts/s (without attenuation) are marked
as “INVALID” on the result sheet.
‘The OD2 neutral density filter serves to attenuate high light levels by a factor of
100. The resulting values are automatically scaled to counts per second and
displayed accordingly in the software result output.’
Luminescence Scan
Results of luminescence scans may be optimized by selecting appropriate
instrument parameters. In comparison to fluorescence intensity scans, longer
integration times are necessary to detect luminescent signals. Long signal
integration combined with very high gain values may result in excessive noise
from the detector. The
INFINITE M1000 PRO
instrument offers a default gain
value to keep noise levels low at maximum signal integration. Of course, gain
value and integration time may be optimized in assays by the user according to
the demands of the application. Gain optimizations are also necessary if
temperature-dependent experiments are performed.
A company preset gain value for the luminescence measurement is provided.
Especially if measurements at temperatures well below 30°C are performed, it
may be useful to increase the sensitivity by increasing the gain value relative to
the company preset gain. On the other hand, if measurements well above 30°C
are performed it may be necessary to decrease the gain value, in order to avoid
a dark signal overflow.
Standard or dual-color luminescence measurements are performed by the
luminescence module, whereas luminescence scans are performed by the
fluorescence intensity module (refer to chapter 4.1.4 Luminescence Scan).
Various detector types with completely different technical specifications are
installed on the different modules. The luminescence module is equipped with a
single photon-counting detector and the results of standard or dual-color
luminescence measurements are given in counts per second (refer to chapter
4.4.2 Luminescence Detection). Luminescence scanning results are given in
relative luminescence units (RLU). Direct data comparison of measured
intensities between standard/dual-color luminescence measurements and
luminescence scan measurements are therefore not possible.
