Fourier spectroscopy with a transputer-based standard image processing system

ABSTRACT A CCD camera setup is introduced which can be used to digitize the interferogram data of the Fizeau fringes of a Fourier spectrometer. To decrease costs we use a standard CCD chip (frame type) for digitization.It is cooled by a Peltier element which allows to work even with relative faint light sources. The frame grabberas well as the llnal analysis processor are Inmos T800 transputer based modules. Using this electronics theinstrument is even capable to measure spectra of slightly pulsed light sources. INTRODUCTION Fourier Spectroscopy has the advantage that a complete interferogram of a light emitting source can be taken, thus allowing a full analysis of the examined material. The data acquisition and the final analysis however need improved computing performance. Here a CCD camera setup is introduced which is used todigitize the Fizeau fringes of a Fourier spectrometer within milliseconds.The resolution ofthe spectrometer data depend strongly on the resolution of the digitizing media. Since thepixel size of CCD-chips can only vary in limited boundaries, a good choice would therefore be to take selectedCCD-chips with the greatest number of pixels available using a special optical focussing system. This howeverwould also implement a specialised and therefore cost intensive electronics which would finally result in a veryexpensive instrument. Taking standard CCD's has the advantage of a remarkable cost reduction concerningthe digitization electronics, the disadvantage however is the necessity to correct for all kinds of distortionsof these chips which leads to the need of a powerfull processor capable to perform all these corrections in a