Inspico High Resolution Analysis
Dedicated Instruments:  Field Ion Microscopy & Atom Probe Tomography

# Classic Module

To be able to reconstruct the obtained data correctly the tip radius R has to be known.  Two different ways to determine R are often used. A very common way is to calculate R using eq. 2‑1. A constant evaporation field strength E is assumed and thus the radius can be determined [Blavette1995]. This assumption is mostly valid for pure materials or alloys made of constituents with similar evaporation field strengths. Problems may occur in heterogeneous materials or at interfaces, resulting in reconstruction artifacts. If the evaporation field strength varies, the shape of the tip will vary suddenly, leading to a wrong density at the interface. This is very critical for multilayer systems

/* Classic Algorithm

w = 0;

if(α is checked)
w = sin(α)/(1-sin(α))
apert = ϴ
if(ϴ is not checked)
ang = sqrt(A/π)
apert = ang/(L * κ)

U = Ub + c * Up (for event 0)
a = sin(apert) * sin(apert) - w * (1 -cos(apert)) * (1 -cos(apert))
T = 0
foreach(event)
Ui = Ubi + c * Upi
if(β is Constant)
βi = β
if(β is Linear)
βi = β + dβdV * (Ui - U0)
if(β is NonLinear)
βi = LinearInterpolationFromTable

Ri = Ui/(βi * E) phi = atan2(Yd,Xd)
theta = sqrt(Xd *Xd + Yd * Yd)/L)/κ
Xi = Ri * sin(theta) * cos(phi)
Yi = Ri * sin(theta) * sin(phi)
Zi = T + Ri * (1 - cos(theta))
if(theta < ϴ AND d =! 0)
T = T + 1/(π * R * R * p * d * a)

*/