SISTEMA PARA HACER DIFERENCIACIONES CONTRA ARTEFACTOS EN PRUEBAS OPTICAS

A chamber (15) for accommodating a test tube (24) holding the solution to be tested is located in a light-tight housing (12). A laser (13) is arranged such that the laser beam (14) can penetrate into the solution through an opening (28, 29). Situated as a light trap opposite the said opening is a recess (31) which is lined with light-absorbing material. Located at the external end of a light-passing channel (32) extending at approximately 45 DEG relative to the direction of the laser beam is a photodetector (36) for receiving the scattered light emanating from the solution. A NOT element is used to negate the output signal of the photodetector and to add to the negated signal by means of a circuit a constant signal of the same polarity as the interference signals but having a value exceeding the amplitude of the interference signals. Furthermore, a comparator and an electronic switch are provided for eliminating the negated interference signals. A filter element for smoothing the output signal is connected at the output of the electronic switch. The smooth output signal is fed to a digital display via an amplifier.