Non-contact near infrared principle. Several molecular bonds absorb near infrared light at wave-lengths proportional to the quantity of the specified constituent (water, oil, proteins).

Infrared filters within the sensor generate a sequence of light pulses; one is selected at the specific constituent's absorbency rate, the others are selected to gauge the reflectance properties of the material.

Reflected light is processed in a ratio to provide a value that is proportional to the constituent.