AQ-00275-000, Rev. 3
40
Note:
Ordinary compressed air systems typically carry microscopic oil droplets that may con-
taminate Spectralon.
Troubleshooting the DRA-CA-3300
If the instrument does not initialize properly even after the accessory has been optically aligned, or
if the instrument displays an error message such as "D
2
Calibration Failure", try the troubleshoot-
ing steps provided below.
1. Check the optical alignment of the accessory.
2. Make sure that the beams are not blocked by the detector cable, a transmittance sam-
ple, or any other object within the accessory. The accessory cannot be initialized with
a center-mount sample holder or attenuation screen in place.
3. Make sure that the Spectralon reflectance standards entirely cover the reflectance port
and the reference port.
4. Turn the instrument power switch OFF and unplug the accessory detector cable.
Inspect the detector cable connector for any obvious damage to the pins or to the
plastic rings surrounding the high voltage contacts on the sides of the connector. If
either of these rings are pushed-in, the instrument will not initialize.
If initialization problems persist after checking the items described above, contact the Labsphere
Customer Service Department at
(603) 927-4266
for assistance.
Your DRA-CA-3300 accessory should deliver years of accurate and consistent reflectance mea-
surement results. If your reflectance measurements become inconsistent, you should first check the
operation of the spectrophotometer. Most problems that develop when using an accessory can be
traced back to the instrument itself - check that your instrument light source is operating satisfacto-
rily. Check that the accessory cord is securely attached to the DRA connector at the instrument. If
your instrument checks out OK, you should run the diagnostic scans discussed in this manual and
compare the results with the original scan data. When running these scans, make sure you use the
same scan parameters used in the original scans. Remember that during corrected baseline scans
the sample beam is sensed, for all practical purposes, at the same time as the reference beam. Keep
in mind the following short list of possible accessory failures.
• The reflectance characteristics of the internal sphere coating may deteriorate.
• The reflectance characteristics of your reflectance standard may deteriorate.
• The transfer optics in the accessory may be damaged or dirty.
• The detector may be defective.
The reflectance characteristics of Spectralon deteriorate very slowly and it is unlikely this will
affect your measurements. If deterioration of the sphere wall does occur equally across the wave-
length spectrum, your reflectance measurements will be completely unaffected. To determine if the
spectral reflectance characteristics of your sphere has occurred, run a
Sample Beam Energy Scan
on the accessory and compare the results to the original diagnostic scan.
Damage to the reflectance standard is more likely because this device is most often handled by
operators on a routine basis. Even so, the impact of a defective standard on reflectance measure-
ments will be minimal in a double beam accessory. If you suspect the reflectance of your standard