PRECISION CALIBRATION AND DIGITAL RECORDING TECHNIQUES FOR AN INFRARED SPECTROMETER

Author Institution: Block Engineering, Incorporated; Air Force Cambridge Research Laboratories, (CRO) L. G. Hanscom FieldPrecision calibration and digital recording of spectra have been achieved with the White spectrometer by utilizing techniques which retain simplicity and yet have a high degree of accuracy. The standards used for the calibration are the higher order lines of the visible neon spectrum. A filter which reflects infrared and transmits visible radiation is used to combine both the neon and infrared beams so that both the neon and infrared radiations traverse the same optical path in the grating section of the spectrometer. A similar filter beyond the exit slit allows separate detectors to be used for the visible and infrared radiations. The main advantage of such a system is that infrared spectra can be calibrated directly by using visible wavelengths. Digitization of the spectral data is accomplished with angle encoders which are connected to the pen drives of a two-pen strip chart recorder. Fringes from an interferometer connected to the grating drive are used as signals for the transfer of the digitized data onto paper tape. In this form the data is directly amenable to computer techniques