Abstract An improved correlation spectrometer is provided which may be used for the quantitative measurement of the amounts of such gases as SO2, CO2, NO, NO2, and N2O3, in a gaseous discharge. The invention has particular utility, for example, in the measurement of sulphur dioxide (SO2) in a flue discharge so that the sulphur dioxide level may at all times be maintained below acceptable ecological thresholds. The correlation spectrometer of the invention includes a piezoelectric transducer which effectively causes filters to be selectively and cyclically introduced into the optical path between an ultravoilet light source and a photoelectric transducer, so that the percent transmittance may be measured successively and repeatedly at two distinct wavelengths. The two wavelengths respectively correspond to an oabsorption line of the particular gas being measured, and to a wavelength displaced from the absorption line to provide a reference.
A correlation spectrophotometer including: optical filter means having a first section constructed to pass light at a selected first wavelength and having a second section constructed to pass light at a second wavelength displaced a particular increment from said first wavelength; piezoelectric transducer means supporting said optical filter means in an optical path to cause said first and second filter sections to be successively and cyclically positioned in said optical path, an oscillator electrically coupled to said piezoelectric transducer means to cause said transducer means to oscillate at a predetermined frequency, photoelectric transducer means disposed in said optical path and responsive to light passed successively and cyclically through said first and second sections of said optical filter means, and an electronic detection system electrically coupled to said photoelectric transducer and responsive to the signal therefrOm for producing an output signal representative of the percent transmittance of a particular gas traversing the aforesaid optical path.
Claim 2
Dependent Claim
154 words
A correlation spectrophotometer including: optical filter means having a first section constructed to pass light at a selected first wavelength and having a second section constructed to pass light at a second wavelength displaced a particular increment from said first wavelength; piezoelectric transducer means supporting said optical filter means in an optical path to cause said first and second filter sections to be successively and cyclically positioned in said optical path, an oscillator electrically coupled to said piezoelectric transducer means to cause said transducer means to oscillate at a predetermined frequency, photoelectric transducer means disposed in said optical path and responsive to light passed successively and cyclically through said first and second sections of said optical filter means, and an electronic detection system electrically coupled to said photoelectric transducer and responsive to the signal therefrOm for producing an output signal representative of the percent transmittance of a particular gas traversing the aforesaid optical path.
Claim 3
Dependent Claim
39 words
The correlation spectrophotometer defined in claim 1, and which includes a source of ultraviolet light; and lens means for forming the ultraviolet light from said source into a beam and for directing the beam along the aforesaid optical path.