Arrangement for determining the concentration of a substance in a mixture of substances

US4449819A · kind A · utility

Assignee

• Erwin Sick GmbH Optik-Elektronik · DE

Inventor

• Gerhard Krause · Rosenheim, DE

Key dates

• Filing date: Jul 30, 1981
• Grant date: May 22, 1984
• Expiry date: Jul 30, 2001

Classification

• Technology area (CPC G): Physics
• CPC primary: G01J3/433
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A mixture of substances is analyzed by spectral analysis to establish the concentration of one component of the mixture. For this purpose signals U.sub.1 (.lambda.) representative of the spectrum of the substance under investigation and U.sub.2 (.lambda.) representative of the spectrum of the mixture of substances are manipulated electronically so as to remove the effects of cross-sensitivity and to yield an accurate value for the concentration of the substance in the mixture of substances. This concentration is normally difficult to determine because of the effects of cross-sensitivity, i.e. because other components in the mixture of substances have similar spectral lines to those of the substance under investigation. In one arrangement the two signals U.sub.1 (.lambda.) and U.sub.2 (.lambda.) are first differentiated in respective differentiating stages 13 and 14 and the differentiated signals are multiplied in a multiplier 17. The output signal from the multiplier is subsequently integrated in an integrator 20 and the output of the integration is a measure of the concentration of the substance under investigation. The signal F derived from the multiplier 17 has two components F.…