Introduction to Near-Infrared Spectroscopy 

Absorption & scattering contrast

Physiological contrasts

Functional contrasts 

fNIRS history

Light propagation in biological tissue

Quantifying hemoglobin changes:

Modified Beer-Lambert law

NIRS modalities

Cerebral Oximetry

CW-, FD-, & TD- NIRS

Broadband

DCS 

Imaging

2D mapping = topography

3D reconstruction = tomography

Atlas head model 

Challenges

Sensitivity to brain

Systemic physiology contamination

Motion artifacts

More Challenges

Differential path-length & partial volume error

Potential for hemoglobin crosstalk

Focal changes, spatial resolution

Additional consideration

Use in clinical applications

Use in neuroscience applications

Devices choices

SNR & Dynamic range

Short separation channels

High density

Safety

ANSI standards