Problem: General Noise

Common causes:
  • Beam blocked
  • Low throughput accessory
  • Poor environment
  • Failing source
  • Fogged beamsplitter
  • Poorly tuned moving mirror control
  • Failing detector
  • Electronic fault

  • Follow the infrared beam (conceptually, as it is not visible). Make sure path is unobstructed. Does problem exist with accessories removed?
  • Reduce environmental vibrations.
  • Inspect beamsplitter for fogging, replace if necessary.
  • If poorly controlled moving mirror is suspected, try a different scanning velocity. However, if using a detector that has a considerable frequency response dependence, such as a DTGS detector, results may be ambiguous.
  • As last resort, swap detector/electronics/power supplies, one at a time.

Problem: Frequency Dependent Noise

Common causes:
  • Noise is greater at higher frequency: interferometer component missaligned
  • Misaligned focusing mirror
  • Scattering sample

  • Align fixed interferometer mirror or other interferometer component with alignment capability.

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