A photometer used for the photometric analysis consists principally consists of a light source, a filter, a cuvette and a detector. Furthermore there are additional screens and mirrors in this kind of device. The light from the light source is incident on the filter, wherein the wavelength at which is to be measured is determined. Subsequently, the light passes through the sample solution, which is located in the sample cuvette and then to the detector. Logically speaking, the smaller the amount of light, the higher the concentration of the sample must be (basically, light transmittance of the sample).
The different units of the manufacturers vary in terms of the basic design and quality of the optical components - these affect the quality of the measurement and the application range.