Verfahren und Vorrichtung zum Nachweisen von ungelösten Teilchen in einem Fluid

The invention relates to a method and a device for detecting undissolved particles in a flowing fluid, which fluid has the density p and the viscosity [mu]. The fluid with the particles is transported through a measuring channel (60) and flows through an excitation zone (76), in which it is recorded by a radiation source, and a measuring zone (80), in which an emission emanating from the particles as a result of the excitation and/or scattered light emanating from the particles is recorded by a detector (82). A mask (84) arranged between the measuring channel (60) and the detector (82) modulates the emission or the scattered light, and the modulated signal is evaluated by means of a correlation analysis. The fluid is transported through the measuring channel (60) at an average flow velocity (a) at which the channel Reynolds number (b) assumes values between 0.1 and 500, wherein the particles assume a velocity distribution of which the half width is less than 4% of the average particle velocity.