The Metrohm NIRS Analyzer PRO can analyze granules, powders, slurries, or opalescent substances without damaging them. The interfaces are based on reflectance or transmittance technology. Measurements are gathered directly on the moving sample in the process stream. The sample is illuminated by the backup lamp in the dual lamp system either directly or through an optical fiber, and the light reflected or transmitted is measured by the diode array sensor. The backup lamp also ensures unchanged uptime and measurement accuracy despite a switch to a new lamp. Highly accurate measurements on moving subjects are ensured through instantaneous wavelength frequency measurement.