First FTIR Spectrum

Monday, March 13, 2017

Initial test spectrum at 12cm Optical Path Difference (OPD) of a globar source (1200ºC Blackbody), Indium Antimonide (InSb) detector at 5µm taken in <5 seconds.  The instrument employs a novel time-based two channel acquisition system for the Helium Neon (HeNe) metrology laser and the Infrared (IR) signals.  The first post-acquisition process converts these to functions of optical path distance.  Below is the Fourier transform of the corrected signal that shows fairly high Signal to Noise Ratio (SNR) >200, flat baseline and carbon dioxide (CO2) and water vapor (H2O) absorptions in the lab air.  This is a first demonstration of the instrument's ability to measure signals similar to those expected during the total solar eclipse.

First FTIR Spectrum Acquired by NCAR