Rapid fluorescence excitation-emission matrix measurements using hybrid configuration of Michelson interferometer and grating spectrometer.

A technique for rapid fluorescence excitation-emission matrix (EEM) measurements is proposed, which leverages the high optical throughput and tunable resolution of a scanning Michelson interferometer and the fast acquisition of a grating spectrometer. In this technique, a broadband excitation light beam is modulated by a galvanometer-scanning Michelson interferometer, and the resulting interferometrically modulated light excites the sample. By synchronizing fluorescence detection with galvanometer scanning, fluorescence spectra corresponding to different optical path differences are separated. This configuration enables the tradeoff between the excitation module's spectral resolution and measurement speed, while enabling high throughput excitation light focused into a small spot on the sample. It is demonstrated that with excitation and emission spectral resolutions of 10 nm and 0.44 nm, respectively, the system can acquire the EEM of an 8.34 μM Rhodamine 6 G solution in ethanol in only 977 ms.