Image detector, simultaneous fluorescence

In thTs communication, we will illustrate the application of the Video Fluorometer to simultaneous analysis of polycyclic aromatic hydrocarbons and warfarin and its metabolite 7-OH warfarin. We hope to convince the reader of the utility of "higher-order" strategies in fluorescence analysis made practicable by imaging detector based instrumentation. 

Fig. 3.9. Principle of a wide field FLIM system with simultaneous detection of two time gates. The fluorescence image is split into two images and one of the images is optically delayed with respect to the other. Both images are detected simultaneously with the same time-gated detector.

To make multispectral time-resolved fluorescence measurements into a diagnostic tool, the technique must be combined with imaging. Direct imaging techniques by position-sensitive TCSPC are optically easy. They can be used with wide-field illumination and are easily integrated into endoscopes. However, it is difficult to obtain simultaneous spectral and temporal resolution. Several detectors must be used or several images of different wavelength be projected on one detector. True multispectral resolution cannot be obtained this way. 

For this purpose, the system uses a Raman shifter pumped by the fourth harmonic of an Nd YAG laser to generate multiple laser beams simultaneously in the UV-visible region of the spectrum. Ten beams are separated by a set of prisms and launched into separate silica-clad silica optical fibers and delivered to the sample. Separate collection fibers deliver the fluorescent signals to specific positions on an imaging spectrographic detector. 

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