Thermo Scientific Accela PDA, Руководство по оборудованию

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Xcalibur Diagnostics for the PDA Detector
Adjusting the Light Throughput with the Xcalibur Data System
42 Accela PDA Detector Hardware Manual Thermo Scientific
Adjusting the Light Throughput with the Xcalibur Data System
The first time that you adjust the attenuators, you must create a display method. After you
create the method for adjusting the attenuators, save it with a name that you can associate
with adjusting the attenuators and store it for future use.
Decreasing light throughput increases baseline noise. Increasing light throughput can saturate
the diode array. When the array is saturated, the response from the PDA detector is a flat
baseline.
During the deuterium lamp’s lifetime of approximately 2000 hours (see “Lamp Lifetime and
Detector Noise” on page 5 ), the lamp’s light output decreases. Adjust the attenuators as the
light output from the deuterium lamp decreases and whenever you do the following:
• Replace either lamp (see “Replacing the Lamps” on page 89 )
• Replace the LightPipe flowcell (see “Installing the LightPipe Flowcell” on page 17 )
• Change the configured diode array scan rate (see “Thermo Foundation Instrument
Configuration” on page 28 )
Y To adjust the attenuators while viewing the light intensities
1. Prepare the PDA detector to monitor an intensity scan (see “Preparing the PDA Detector
to Monitor Lamp Performance” on page 38 )
2. If you have not already done so, create a display method that scans from diode 2 to diode
511 with a diode step of 1 and that displays the default discrete channel wavelengths
(see
“Creating a Display Method to View Light Intensity” on page 38 ).
Tip The integrated light intensity viewed on the Display page is a function of the light
throughput to the diode array and diode array scan rate. When you change the diode array
scan rate, you must adjust the light throughput.
• If you increase the diode array scan rate (for example, from 20 Hz to 80 Hz), you
must increase the light throughput to achieve the same intensity counts.
• If you reduce the diode array scan rate (for example, from 80 Hz to 20 Hz), check the
intensity counts, and if necessary reduce the light throughput to avoid saturating the
array.
Adjusting the position of the attenuator tabs changes the light throughput to the diode
array: up increases and down decreases the light throughput to the diode array (see
Figure 20 on page 25 ).