FT-IR interferogram sampling validation and correction

A commercial digital signal processor (DSP) board with custom software monitors the operation of an FT-IR spectrometer. The DSP board acquires interferogram data simultaneously from both the infrared and reference laser channels of the FT-IR spectrometer. This approach permits post-processing of the signals to obtain conventional spectra as well as a variety of diagnostics. Such diagnostics include extraction of interferometer mirror velocity and the combined transfer functions of the detectors, amplifiers and filters. The DSP board resides in the accessory bus of a personal computer (PC), allowing use of the PC and its peripherals for data display, storage and post-processing. A method for extracting the transfer functions of the laser and infrared channels by the use of solid state emitters is presented. These are the key elements required to monitor and correct the effects of velocity error. The simultaneous digitization of both interferometer channels may be a trend in FT-IR spectrometer design which shifts signal processing further towards software implementations.