Enhancement of low-resolution Raman spectra by simplex projection

We demonstrate the enhancement of low-resolution spontaneous Raman spectra by simplex projection which extrapolates the high-frequency components that are lost when the entrance slit width,w of the grating spectrometer is wid ened to increase the optical throughput. The improvement in the signal-to-n oise ratio of the measured Raman spectrum is accompanied by an unwanted but inevitable decrease in the resolving power of the spectrometer. Spectral e xtrapolation by simplex projection [Opt. Commun. 176 (2000) 373] is applied to the linearly deconvolved low-frequency Fourier transform of the measure d Raman spectrum, to recover accurately and rapidly the information (peak l ocations and profiles) that are lost. The weak Raman spectrum of CCl4 is ut ilized as the test signal. In terms of the Linfoot's criteria, the combinat ion of simplex projection and linear deconvolution succeeded in enhancing a low-resolution Raman spectrum (w = 150 mum) to obtain information that are available in raw spectra measured at w = 75 mum. The recovery performance is superior to what could be achieved via linear deconvolution alone. (C) 2 000 Elsevier Science B.V. All rights reserved.