Bounce {MCBackscattering}

Bounce Photon Interaction with Surface

Description

This function is applied when photon trajectory goes out of the media or reaches the surface (z <= 0). The photon flux is summarized upon leaving semi-infinite media through the surface.

Usage

Bounce(myObject)

Arguments

myObject

The mandatory parameter of this function is the MCBS class created by MCBS constructor function.

Details

The Bounce function, alias Bounce.MCBS, calculates internal reflection if incident angle to surface boundary was higher than critical angle. In all other cases, Fresnel reflection is calculated according to the direction and refractive index of media. Remaining photon weight that leaves the media is collected and summarized by the position. Position is calculated as distance from incident point. This way, radial averaging is performed with rigns of width of the spatial resolution. The internally reflected part of photon energy still follows trajectory until reaches limiting energy or expected trajectory length.

Value

The Bounce function returns an MCBS object as class. Typically the same object is used in argument and result. The function collects photon flux in an array:

heat

vector of photon flux scattered back from media. One element represent a ring of width of the spatial resolution. The center of the ring is the incident point.

Note

Please note thet this is an internal function of Simulation. Do not use it separately, unless you build your own simulation procedure. The function uses the coordinates c(x,y,z) of the current photon and the c(u,v,w) direction of its last move.

See Also

MCBS for construction of object with initial input parameters. Simulation for running the simulation with adjusted parameters. Chart for plot of calculated photon flux profile. Export for export of photon flux with corresponding radii. Setup for initial computation of specular reflection and transport albedo. Launch for start position of single photon and initial direction in media. Move for moving single photon forward. Absorb for absorption of single photon energy in interaction with media. Scatter for single photon scattering interaction with media. Randomize for adjustment of random trajectory vectors.

Examples

## Apple simulation data according to Qin and Lu (2006).
## DOI: 10.13031/2013.20862

# create object
cfgMedia <- c(0.63,30,0,1.4)
cfgSimulation <- c(1e6,0.05,1e-9,3,0.012)
apple <- MCBS(cfgMedia,cfgSimulation)
apple <- Setup(apple)
apple <- Randomize(apple)

# launch and move first photon
apple$idx <- 1
apple <- Launch(apple)
# first move
apple$midx <- 1
apple <- Move(apple)
if (apple$z <= 0) {
 apple <- Bounce(apple)
}