There are four common causes for bad readings on LI-8xxx instruments:
- Incorrect zero and span calibration parameters.
- IR light source that is failing or has failed.
- Contamination (dirt, corrosion, liquids) in the optical path.
- Failed detector.
1) Incorrect zero and span calibration parameters:
Check these values using the LI-COR interface software for each instrument by going to:
For LI-820 and LI-840, LI-840A: View – Calibration – Advanced
For the LI-8100, LI-8100A: Utilities…