Ballistic photon

Ballistic Photons are the light photons that travel through the scattering (turbid) media in straight line. If laser pulses are sent through a turbid media (e.g. fog, body tissue), most of the photons are either randomly scattered or absorbed. However, across short distances, a few photons pass through the scattering medium in straight lines. These coherent photons are referred to as the ballistic photons. Note that another class of photons, those that are slightly scattered, retaining some degree of coherence, are commonly referred to as snake photons.