Dual wavelength spectrophotometer for ampoule leak detection and content

Abstract

A dual wavelength spectrophotometer for ampoule content inspection, in particular for ampoule leak detection wherein leaks are initially 'flagged' via the dye bath immersion technique. Light transmitted through the ampoule is received by a bifurcated fiber optic cable providing via a random mix arrangement substantially identical ampoule optical signature signals. Each is directed through preselected interference filters, chosen on the one hand on the basis of the dye being used and the glass ampoule and its contents on the other hand. Associated with the filters are respective photodetectors, the output signals of which are connected to a difference amplifier stage. The output (if any) of the latter is compared to a preestablished (dye) threshold signal, which represents the minimum level (of dye) from which to effect a reject status. The ampoule contents or a particular component thereof may also be investigated in this manner. The photodetector outputs are also summed and the resultant compared to a second preestablished threshold in order to provide a failsafe system capability against optical failure and the like. The difference signal/comparison circuit leg may be constructed to provide logrithmic function capability and thus produce an output which a proportional to concentration. Therefrom the concentration of the ampoule contents (or the dye) can be determined, for example to lie within a preestablished 'window'.