Common causes:

• Incorrect detector selected
• Detector not properly connected
• Detector power not proper
• Beam blocked
• Low throughput accessory
• Failed source
• Fogged beamsplitter
• Liquid nitrogen cooled detector not cold
• Failed detector
• Electronic fault
• Small aperture selected.

Suggestions:

Verify correct detector for spectral range, scan speed, is selected in software. Slow response detectors, such as DTGS detectors, will not response well at high scan speeds.

Verify detector is positioned correctly and connected. Check power at detector.

Follow infrared beam (conceptually, as it is not visible). Make sure path is unobstructed. Does problem exist with accessories removed?

Verify source is on. If not on, remove and test for open source element. If source is OK, suspect power supply is bad.

Inspect beamsplitter for fogging, replace if necessary.

Cool liquid nitrogen detector.

Swap detector/electronics/power supplies, one at a time.

Select larger aperture size.