Fluorometric analyzer including shutter means for simultaneously shielding sample and photodetector during sample change

Claim 1

A head assembly for a fluorometric analyzer for measuring fluorescence in a liquid sample element contained within a test cell, wherein the analyzer includes, an excitation lamp element for applying radiation to the sample, and a photodetector element for detecting light produced as a result of fluorescence in the sample; said head assembly comprising, in combination: a housing defining a bore-shaped chamber, and further defining a first optical passageway between the excitation lamp element and the test cell, and a second optical passageway between the test cell and the photodetector element, said optical passageways being arranged at generally right angles to each other and to the axis of the bore-shaped chamber; shutter means comprising a cylindrical sleeve member slidably received within said bore-shaped chamber for simultaneously controlling the passage of light through said first and second optical passageways, said sleeve being mounted for rotation about the axis of said bore-shaped chamber between first and second positions and including a central recess for slidably receiving the test cell, said test cell rotating about said axis with rotation of said sleeve; and said sleeve further including first and second apertures arranged for alignment with said first and second optical passageways and said sample-receiving recess for establishing light communication between the excitation lamp element, the sample element, and the photodetector element when said sleeve is in said first position, and arranged for non-alignment with said first and second optical passageways for blocking light communication between said elements when said sleeve is in said second position.