GB1214518A - A photometer - Google Patents

Abstract

1,214,518. Photo-electric apparatus. SPETSIALNOE KONSTRUKTORSKOE BJURO PO AVTOMATIKE V NEFTEPERERABOTKE I NEFTEKIMII. April 30, 1968, No.20365/68. Heading G1A. The absorption of light by a sample 8 in container 9 is measured by a two-path photo-electric system comprising radiation source 1, collimating system 2, 3, filters 5, 5<SP>1</SP> respectively passing the portion of the spectrum which will be absorbed by sample 8 and the portion that is transmitted, a diaphragm 6 and a rotating barrel shutter 7 which causes the output of detector 4 to be an A.C. signal having a phase displacement, with respect to the reference signal associated with the rotation of the shutter, which is proportional to the absorption by the sample. The barrel shutter detailed in Figs.2-4 (not shown) comprises a cylinder with two rows of apertures, the apertures in one row being misaligned with those of the other row. The misalignment can be chosen to change the sensitivity of the apparatus, as explained with reference to Fig. 6 (not shown). The rotation of the shutter is used to generate a reference signal by induction generator 10, this signal being amplified at 14 and 16 and applied to phase discriminator 21, its amplitude being maintained constant by limiter 15. The detector signal comprises variations due to the parts of the beam absorbed and transmitted by the sample and is amplified at 17, 18 and 19 and applied to discriminator 21, its amplitude being maintained constant by automatic gain control 20. The phase difference due to the absorption by the sample is displayed on an instrument 22.