Concentration measuring device, concentration measuring arrangement and concentration measuring method

A concentration measuring device for determining a concentration of gas or particles in a measurement volume, comprising at least one housing having an opening for communication with the measurement volume;

• a light source for transmitting measurement light through the at least one housing into the measurement volume;
• a light receiver for receiving the measurement light after its passage through the measurement volume, wherein the light receiver is arranged either in the same housing as the light transmitter or in a second housing having an opening for communication with the measurement volume;
• and an evaluation unit which is designed to determine the concentration of gas or particles from the measurement light received at the light receiver, wherein at least one body of solid material is arranged in the at least one housing such that the measurement light path largely passes through the at least one solid body within the at least one housing, with the portion of the measurement light path within the at least one housing not passing through the at least one solid body having a total length which is smaller than a length SL, where SL=2GML/K and G is the desired accuracy of the concentration determination on a measurement length ML in the measurement volume for a gas to be measured or particles to be measured within the dead volumes occurring in the housing having a concentration amounting to K.