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On Resolution Enhancement of Line Spectra by Deconvolution

Volume 27, Number 1 (Feb. 1973) Page 50-51

Goldman, A.; Alon, P.


In a recent paper, G. Horlick described resolution enhancement studies of emission line spectra by deconvolution. Recently we have been using a similar technique to study the resolution enhancement of digitized infrared solar spectra obtained with a balloon-borne grating spectrometer. For these studies, a number of solar spectra in the 550 cm−1 region were taken from the ground at Denver, Colorado on 19 January, 1971. The spectra were taken with a number of different slit widths, so that the deconvoluted spectra could be compared with the actual higher resolution spectra. Various slit functions were tried in order to reduce the sidelobes introduced by the transforms, and good apodization effects were obtained from asymmetric slit functions with a linear rise and a Gaussian decay. Fig. 1 shows a portion of the observed spectrum with a slit width of 1.0 mm. The corresponding deconvoluted spectrum is shown in Fig. 2 and can be compared with another spectrum observed with a slit width of 0.70 mm (Fig. 3). Deconvolution of the spectrum presented in Fig. 3 is shown in Fig. 4, again with significant improvement in resolution. The number of data points in the digitized spectra shown in Figs. 1 to 4 is 1024, and the corresponding number of points defining the slit function is 20. The transforms were taken using the FFT algorithm. No experimental spectrum was available for comparison, but based on Figs. 1 to 3 and on the known atmospheric lines it is apparent that most of the line structure recovered is real and originates from some faint features in the observed spectrum.