4-24 | IPS-4 Dual Bench (UV / IR) Analyzer
The neutral density filter (NDF) is an optical diagnostics tool that can be
used to check the response and alignment of the IPS-4’s UV Optical Bench
pathway. This user-initiated feature provides additional diagnostics and
preventive diagnostics on the UV Optical Bench, which can help avoid
timely and costly repairs. The filter verification, which can only be started
manually, only needs to be performed if the process readings are outside
the expected values, or if “Failed Calibration” is displayed on the UIP.
When the filter verification routine is initiated, the NDF is inserted into
the optical path. The optical intensity response is compared against a fac-
tory generated Reference. The peak areas should remain relatively constant
and only generate an error if they rise above or fall below the factory-
defined tolerance.
Next, the physical alignment of the Optical Bench will be confirmed. Even
though the Xenon lamp output will decrease over time, the emission
peaks’ relative positions should remain the same because the wavelength
mapping is independent of the lamp’s age. If the peak positions are not
within the factory specification, the analyzer will display a “Failed Cali-
bration” message on the UIP to alert you that there is an issue with the
wavelength positioning on the diode array. Further diagnostics is then
required to determine the exact cause. Review the “Neutral Density Filter
Verification Diagnostic Chart.“ In some cases, the analyzer Optical Bench
may need to be returned to the factory for service.
To initiate a filter verification:
1. From the SETUP menu, select Calibration Control and press Enter.
Select Calibration Actions and press Enter, then scroll down and se-
lect Start Filter Verification. Press Enter to start the verification (Figure
4-18a). After the filter verification routine has been started, you can
view the Display Filter Verification screen (Figure 4-18b).
2. The analyzer will perform the Zero read. The length of this period is
dependent on the factory-set number of measurements to be averaged
during the Zero read.
3. The analyzer then performs a two-fold optical diagnostic routine.
First, the wavelength mapping is verified. Next, the filter is moved
into position by a rotary solenoid. The length of time the filter remains
in the activated position is factory set (1 minute). The Reference value
is factory set, based on the provided filter, and should not be adjusted.
The filter absorbance is measured at four wavelengths.
Figure 4-18a.
Calibration Actions
screen.
Manual Zero Calibration
Manual Span Calibration
►Start Filter Verication
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