Spectrophotometer and optical system therefor

Abstract

The photometer of the present invention includes an optical system in which an emission beam generated by pulsed ultra violet radiation from a source is split into a sample beam and a reference interference beam by spectrally selective mirrors arranged in series. These mirrors reflect a beam having a wavelength range corresponding to an absorption wavelength of the gas to be detected onto one solid state detector and to pass a beam to a second spectrally selective mirror where a beam having second range of wave lengths corresponding to an interfering gas is reflected onto a second solid state detector. This second beam serves to measure the interfering gas and also as an imperfect reference channel. In a preferred embodiment the radiation from the source is split prior to entering the sample cell. One beam is directed through an optical path which avoids the sample cell but which is otherwise identical to the optical path described above, including series arranged spectrally selective mirrors to be further split the beam into two beams having wavelength ranges corresponding to the wavelength ranges of the sample and reference gases. These beams are directed to solid state detectors and the signals derived therefrom are combined with a second set of similar signals derived from the sample and reference beams which have passed through the sample cell.