Abstract

An improved system for quantitative chemical analysis incorporates a chromatographic column. A radiation source of a predetermined range of wavelengths is in optical communication with an emerging specie from the chromatographic column by of a first optical path whereby radiation is modified by characteristic of the specie. A detector is in optical communication with the emerging specie by a second optical path whereby a first output signal reflective of the detected radiation is generated. An acousto-optic tunable filter system is disposed in one of either the first or second optical paths. The radiation is passed through the crystal at a predetermined angle relative to the crystal's optic axis. An acoustic transducer is coupled to the crystal to launch acoustic waves into the crystal to interact with a selected narrow bandwidth portion of the radiation to make it distinguishable from the remaining radiation. A computer to which the detector output signal is applied determines the emerging specie by the identifiable characteristics. An auxiliary detector responsive to the emerging specie can be associated with the chromatographic column. A parallel optical path can also be included to define a reference cell. A second output signal reflective of the detected radiation passing through the parallel optical path is generated. The difference between the first and second output signals represents a measure of the emerging specie's absorption characteristic. In an alternative embodiment, an acoustooptic dispersive light filter can be inserted in the system.

Other References

• Wiczer et al., "Influence of Electro-Static Field on the Properties of Acoustically Tuned Optical Filters," Applied Physics, vol. 30, No. 9 (1977)
• G. Schmidke et al., VDI-Berichte 509, 293, (1984), "Nir-Prozeb-specktrometer: Zuzammensetzung von Gasen and Flussigkeiten", pp. 293-295