Python package for FTIR interferogram and spectrum analysis

ftirobs is a python library for interfergram analysis in Fourier-transform infrared spectroscopy (FTIR). It aims at providing a modern toolkit for analyzing observations made in the framework of the ground-based remote sensing networks NCDACC-IRWG, TCCON and COCCON.

Key Features are

1. Mathematical Utilities

• Implements real-to-complex DFT
• Pre-defines several apodizations
• The definition of an interferogram IFG is closely related to the Bruker® OPUS format (metadata mapping is preserved, e.g. APT for aperture).
• Convolution operations

2. Phase Correction

• Mertz & Forman Methods: Standard algorithms for phase correction of asymmetric interferograms.
• ZPD Detection: Automated identification of the Zero Path Difference (ZPD) point, including fractional shift compensation.
• Diagnostic Phase Spectrum tools: Visualization and polynomial fits (analytical phase)

3. DC-filtering

Contains the two methods developed in the TCCON and COCCON to correct for source brightness fluctuations.

4. Correction for non-linear detector response

Correction for non-linearities in MCT, InSb and InGaAs detectors. This method uses autocorrelations of the in-band spectrum to fit with out-of-band artifacts.