Double beam intracavity laser spectrometers I. Flash lamp pumped

We describe a double beam intracavity dye laser spectrometer which is capable of a direct quantitative measurement of the absorbance of weak absorbers. The instrument is sensitive to broad band absorptions. The spectrometer can be modeled to allow a prediction of its sensitivity. Experimentally, the spectrometer reported here is about as sensitive as earlier flash lamp pumped intracavity spectrometers.