With the colorimeter or spectrophotometer PCE-CRM 40, important photometric factors in the field of light measurement can be determined. These include the tristimulus values of XYZ, the u´ and v´ color location coordinates according to CIE 1976, and the xy color location coordinates according to CIE 1931. Moreover, further color statistics are measured as absolute values and differences. The user can determine the dominant wavelength within the sensitivity range of the spectrophotometer, which is 360 … 780 nm, as well as the color density (Pe) and the correlated color temperature (CCT) in Kelvin. Also, the spectrophotometer can measure the illuminance in lux (lx) or foot-candle (fcd) as well as the light flux in lumens (lm) and show the color location in the RGB color space. Due to the ergonomic single-handed operation, the large display, memory, data interface and software, measurements with the spectrophotometer can be carried out quickly and the results are reproducible. The test results can be recorded by means of the software. Its specifications make the spectrophotometer perfectly suitable to classify and optimize lighting installations and conditions in various fields of application.