Opto-electronic soln. density or concn. determn. - with two=stage temperature correction of emitter and receiver characteristics

摘要

A method of optoelectronically determining the density or concentration of a soln. consists of reflecting the light emitted from a luminescence diode through a succession of prisms immersed in the liq. using angles of reflection close to the limiting angle to total reflection and of measuring the intensity of the reflected light by an optoelectronic receiver. After temp. compensation, the result is displayed on an indicator device to give the density. The temp. compensation is carried out in two electronic stages in the first stage the fluctuation in emmission of the luminescence diode and the temp.-dependence of the optoelectronic receiver are eliminated, while in the second stage the stilling remaining temp.-dependence of the variable is balanced out sufficiently for a display of the density or concentration to be obtd. which is virtually independent of temp. Used e.g. for monitoring the electrolyte in electrochemical cells and indicating the acid density in accumulators. By employing a first stage to compensate the luminescence diode and first receiver almost the entire non-linearity of the curve is eliminated, giving a straight line possessing a defined slope. The second stage adjusts the slope of this line to zero.