Estimating and correcting interference fringes in infrared spectra in infrared hyperspectral imaging
G. Azarfar, E. Aboualizadeh, N. M. Walter, S. Ratti, C. Olivieri, A. Norici, M. Nasse, A. Kohler, M. Giordano, C. J. Hirschmugl
Short-term acclimation response of individual cells of Thalassiosira weissflogii was monitored by Synchrotron FTIR imaging over the span of 75 minutes. The cells, collected from batch cultures, were maintained in a constant flow of medium, at an irradiance of 120 μmol m−2 s−1 and at 20 °C. Multiple internal reflections due to the micro fluidic channel were modeled, and showed that fringes are additive sinusoids to the pure absorption of the other components of the system. Preprocessing of the hyperspectral cube (x, y, Abs(λ)) included removing spectral fringe using an EMSC approach. Principal component analysis of the time series of hyperspectral cubes showed macromolecular pool variations (carbohydrates, lipids and DNA/RNA) of less than 2% after fringe correction.