Photometer for gas or liquid analysis - has filter in common path of two beams, whose transmission is reciprocal to sample background absorption

摘要

A photometer is used for analysis of gas or liquid, and it uses two beams of light. Measurement and reference radiation from the source at closely adjacent frequency ranges is periodically and consecutively passed through the sample and is applied to a receiver. Quotients of the two signals generated by the measurement and reference radiation beams serves as a measure for concentration of the component to be measured. A filter (4, 5) is provided in the common path of the two beams. Its transmission as a function of wavelength is reciprocal to that of the background absorption of the sample.