INTERFEROMETRIC MEASUREMENT OF FLUORESCENCE EXCITATION-SPECTRA

A Michelson interferometer has been adapted as an excitation source fo r fluorescence spectroscopy. A moving fringe pattern was generated by linear displacement of the movable mirror of the Michelson interferome ter coupled to a xenon-are lamp. This spectrally modulated source was monitored by a reference photomultiplier and used for exciting a Rhoda mine B solution. The fluorescence emission at >645 nm was detected by a second photomultiplier. The two interferograms were acquired by a du al-channel digital oscilloscope, and their discrete Fourier transforms and corresponding power spectra were generated in a computer. The pow er spectrum of the emission signal represented the excitation spectrum , as was confirmed by comparison with the absorption spectrum of Rhoda mine B. This optical arrangement is well suited for acquiring fluoresc ence excitation spectra in the optical microscopy of biological specim ens. (C) 1998 Optical Society of America.