No Signal, but Scanning

Problem: No signal, but scanning

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.

  • 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.

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