Apparatus and method for analyzing particles

A method for analyzing particles, comprising:

• providing a measuring cell in the form of a glass capillary with a hollow channel having a hollow-channel longitudinal axis and a hollow-channel wall;
• introducing a test sample containing the particles into the hollow channel, wherein the test sample has a refractive index ΔnM;
• generating a light beam using a light source;
• coupling the light beam into the hollow channel by means of an optical input device at an input point for the purpose of illuminating the test sample;
• and
• detecting scattered light exiting the hollow channel using a detector;
• wherein a glass capillary is used in which the hollow channel has an internal diameter DH in the range of 10 μm to 60 μm;
• wherein the light beam has a radial light intensity distribution with a minimum beam diameter DL, wherein the following applies to the diameter ratio DL/DH:
• 0.05<DL/DH<2.0;
• and
• wherein the light beam has an angle of incidence (Ψ) of less than 2 degrees in relation to the hollow channel's longitudinal axis on entering the hollow channel.