Similar to a pulse oximiter, an fNIR imager sends pulses of near infrared light into the body and records the intensity of the reflection to determine blood oxygen levels. At these frequencies bone is nearly transparent so sensors placed on the head can measure oxygen levels in the outer layers of the brain. These tend to correspond over time with the levels of activity of those regions.

This fNIR system has 8 groupings of transmitter LEDs and 10 receivers clustered around them which provides 16 measurement channels. Each LED cluster can illuminate the brain with either of two frequencies, one which reflects strongly off oxygenated hemoglobin and the other non-oxygenated. Calculating the ratio between the two yields the target's oxygen concentration.

The sensors are meant to be installed in a headband which can target the frontal lobe (short term memory, complex thought), primary motor cortex (voluntary movement), or even the broca's area or visual cortex.