Atmospheric Emitted Radiance Interferometer AERI

Open-loop Mode

• Open-loop Mode (also know as Align Mode) is a diagnostic mode where the interferometer swing-arm operates without fringe-counting feedback from the metrology laser
• This mode can be used to align the metrology laser and quadrature detector to peak the signal
• Three values are displayed in real time
  • F:  Fringe, amplitude (%) of laser signal
  • D:  Dephase, amplitude (%) of laser signal
  • Phase:  Phase (degrees) between the two signals
• Nominal values are
  • F/D > 5% (absolute minimum), >10% (preferred)
  • Phase ~ 45 degrees

Closed-loop Mode

• Closed-loop Mode is a diagnostic mode where the interferometer swing-arm operates with fringe-counting feedback from the metrology laser
• This mode can be used to align the white light source to peak the signal
• Four values are displayed in real time
  • WL:  White Light, amplitude (%) of white light signal and fringe counts in brackets
  • F:  Fringe, amplitude (%) of laser signal
  • D:  Dephase, amplitude (%) of laser signal
  • Phase:  Phase (degrees) between the two signals

Procedure

1. Make sure the AERI is powered ON, and a computer is connected
2. Close any AERI software that is running (Ingest, FTSW)
3. Open an internet browser and go to the address of the interferometer
   • http://169.254.44.127
   • Open the ‘Service’ page in the left bar (Fig. 1)
   • Type the password:  @Bb
4. Alternatively, go straight to
   • http://169.254.44.127/admin-bin/production.cgi
5. This opens the Production Menu (Fig. 2) from which you can select to enter either Open-loop Mode (Fig. 3) or Closed-loop Mode (Fig. 4) in the left bar
6. After completing diagnostics, make sure to take the instrument out of Open/Closed-loop Mode by clicking ‘Open/Closed-loop Mode OFF’

Figure 1. Interferometer Menu

Figure 2. Production Menu

Figure 3. Open-loop Mode

Figure 4. Closed-loop mode