Abstract

By combining two well-established techniques—multispectral imaging with a tunable filter and regularized data inversion—a fast and accurate method for measuring, at each pixel of a CCD array, the spectrum emitted by a radiating object is obtained. The method is demonstrated with ruby $R_1$- and $R_2$-line fluorescence, using a narrowband tilt-tunable Fabry–Perot interference filter for data acquisition. Since the data inversion problem is badly ill conditioned, regularization is essential to obtain meaningful results. The reconstruction is capable of a peak wavelength accuracy of $0.01\mathrm{nm}$, sufficient to measure the small wavelength shifts encountered in rubylike materials due to changes in the local crystal lattice stress. Thus, the technique presents a novel approach to piezospectroscopic imaging and offers 2 to 3 orders of magnitude faster mapping of local stress than current techniques.

© 2007 Optical Society of America

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