Introduction

The Temporal Point Spread Function (TPSF) is key to determining the attenuation characteristics of ascattering sample. Examples of TPSFs when scattering is dominant can be readily produced via, forexample, Monte Carlo (MC) modelling. Of course non-scattering samples still possess a TPSF but it issimply a pulse with all photons being ballistic and arriving at the same time that is determined by thesource to detector distance and speed of light in the sample.

The Task

Your task is to explore, and compile a report on, the evolution of the TPSF from the ‘delta function'of a non-scattering sample through to its familiar form obtained from highly scattering samples. Thisshould include comparison of your results with those from the literature (see below).

It is suggested that the MC code provided as part of this module can be adapted for this purpose.Modelling of light transport, and hence the TPSF, need only be in two dimensions.

It is likely that consideration of the number of times that a photon has scattered in the sample (for low numbers ofscattering events) will be helpful in understanding the process (e.g. see Rodmell et al. below(Also note that some information can be determined without recourse to MC modelling.

This includesthe number of ballistic photons obtainable from the exponential distribution used in MC modeling that gives the probability of a certain path length being exceeded. Considering single scatter eventsmay also be of value. Note that the results will depend upon the size of the detector.

Article reference:-

1. Representation of the photon pathlength distribution in a cloudy atmosphere using ?nite elements

Ralf Bennartz and
Rene Preusker

2. Light path-length distributions within the retina

Paul I. Rodmell, John A. Crowe, Alastair Gorman, Andrew R. Harvey, Gonzalo Muyo, David J. Mordant, Andy I. McNaught, Stephen P. Morgan

3. Channel capacity study of underwater wireless optical communications links based on Monte Carlo simulation

Jing Li, Yong Ma, Qunqun Zhou, Bo Zhou and Hongyuan Wang1

Attachment:- MC.rar