Characterisation of instrumental line shape distortions due to path difference dependent phase errors in a Fourier transform spectrometer

In Fourier transform spectroscopy, path di€erence dependent misalignments, such as those due to imperfect me- chanical movement of the scanning mirror, can be modelled as path di€erence dependent apodisation and phase errors. The theoretical model that relates the mirror drive characteristics to the path di€erence dependent error is used to verify the consistency of the optical instrument line shape with the measurements of the mechanical drive quality. This procedure can be used as a diagnostic and qualiÆcation tool.