Diagnostic Test for FT-IR Spectrometers
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
An ODD-OVER-EVEN test produces a spectrum from which one can assess the "health" of an FT-IR (Fourier Transform-Infrared) spectrometer. This test spectrum is similar in both appearance and interpretation to a 100% line. Features in these spectra, such as peak-to-peak noise, unexpected bands and interference patterns, can be related to signal-to-noise, spectrometer instability and digital/electronic considerations, respectively, for both tests. Although these diagnostic aids are similar in many respects, they differ in some important ways. The ODD-OVER-EVEN test forms the ratio of the spectra derived from ODD interferogram points with the spectrum derived from EVEN interferogram points. By oversampling the original interferogram by a factor of two, the Nyquist requirement is satisfied for both spectra.