Light for Health

Picosecond Laser Pulses

Single-photon Detectors

Advanced Data Processing



TD-NIRS (Time-Domain Near-Infrared Spectroscopy) is a non-invasive technique that uses low power light pulses to monitor functional hemodynamics in human tissues, such as our brain and muscles.

The propagation of the light pulses in the tissue modifies their temporal shape, which is reconstructed photon by photon by our detection system, which can measure their individual arrival times with picosecond resolution.

Exploiting mathematical fitting procedures of the obtained data, thanks to a diffusion equation approximation [1], it is possible to retrieve the absorption and reduced scattering coefficient of the tissue under investigation, that can lead us to the estimation of important physiological parameters like its absolute concentrations of oxy- and deoxy-hemoglobin and the oxygen saturation level [2].


The strong relationship between tissue penetration depth and photon’s arrival times makes it possible to select the depth at which we want to retrieve the information. This unique feature of TD-NIRS makes us able to better estimate deep functional variations in te brain, lowering the contribution of unwanted superficial systematic changes happening for example in the skin.​

Compared to standard Continuous-Wave NIRS systems, TD-NIRS is able to penetrate deeper in tissues, approximately at 3 cm depth over a surface of a couple of cm2.

At PIONIRS, we were able to overcome the bulkiness of old generation TD-NIRS systems and we can now present our innovative, compact, and easy to use, new generation TD-NIRS devices.


Selected Scientific Publications:

A review on Neuroimage Journal about the state of the art of TD-NIRS technique and its future.

Here you will see the system prototipe in to action … showing some applications of the compact TD-NIRS device invivo and on phantoms. Published on Biomedical Optics Express.

Monitoring functional cerebral activation of freely moving subject. Hemodynamic Response Function (HRF) from the motor cortex of walking human subjects. Published on Neurophotonics