The NIR Smart Sensor makes 20 measurements per second. Water molecules contain O-H bonds which absorb light energy in a specific region of the NIR spectrum. The more water that is present, the greater the energy that is absorbed.
The NIR Smart Sensor houses a quartz halogen lamp which channels energy through a rotating wheel containing NIR filters, one positioned at a wavelength where water absorbs and others positioned at reference wavelengths where there is no absorption by water.
Pulses of light illuminate the product and the diffused reflected light is collected by a concave mirror and focused onto a single temperature-controlled Lead Sulfide detector. Process Sensors employs a state-of-the-art detector system that allows multiple simultaneous measurements to be made with the use of only one detector. This technique lends significant stability to the measurement over time, especially with changing temperature conditions.
Detector signals are processed to give a read-out proportional to the concentration of water.