PROCEDIMENTO PER LA MISURAZIONE FOTOOTTICA DEL COMPORTAMENTO ASSORBENTE DI MEZZI SOLIDI,LIQUIDI E GASSOSI

摘要

A process and apparatus for the photo-optical measurement of the absorption behavior of solid, liquid and gaseous media. The analysis medium and a comparison medium are exposed to two light beams. The light beams are broken up by a chopper means into a periodical sequence of light pulses and the measured difference of the beam attenuations in the analysis medium and comparison medium is evaluated in a circuit which is adjustable with regard to the intensity of the radiation from the optical light source and the sensitivity of the light receiver. The light pulses are divided by defined variation of their intensity into two different pulse series of which one series comprises measuring light pulses and the other series comprises control pulses. The evaluation of the measuring light pulses is periodically interrupted by the control pulses for a relatively short time period and the actual value of the control pulses is compared with a standard value during said time period, and the circuit is adjusted during said time period in accordance with the difference between the actual value and the standard value so that said difference is decreased to as small a value as possible, whereupon the following measuring light pulses are again evaluated for the purpose of a measurement.