Fluorometric system, method and test article

Claim 1

In apparatus for analyzing a sample by fluorometric techniques, a carrier member having a surface portion adapted for receiving said sample and including means for supporting said sample thereon as an exposed layer presenting a surface for analysis, test stage means for supporting said member at an analysis location in said apparatus, said carrier member and said stage means being constructed and arranged so that said member is removably insertable into said stage means, illumination means including a source of excitation radiation and means forming a first optical system intersecting said analysis location for delivering said radiation to the surface thereat, optical fluorescence collection means including a photodetector and means forming a second optical system intersecting said analysis location for receiving the fluorescence emitted from the exposed layer thereat, emission filter means associated with said fluorescence collection means for restricting the sensitivity thereof to a frequency band overlapping the emission spectra of said fluorometrically active substance and being substantially non-responsive to the band of excitation radiation, means juxtaposed with said excitation filter means for forming a beam splitter for removing a portion of the light therefrom for developing a reference channel in parallel with the illumination means, means for alternating said illumination means and said reference means during mutually exclusive periods of time, sensing means for developing a signal indicative of sample illumination on-times when said photodetector is activated by sample fluorescence and for developing a second signal indicative of the period when said reference means is detected, a demultiplexer response to said signal for alternately delivering outputs indicative of said sample signal or said reference signal, a sample signal processor for receiving said sample signal, a reference signal processor for receiving said reference signal, said processors serving to develop signal outputs, the strength of which is proportional to the amount of light signal received at said photodetector during said sample and reference periods, respectively, a ratio circuit for obtaining the ratio S/R where S equals sample signal and R equals said reference signal, and display means responsive to said ratio circuit for displaying the value of said ratio.