# CC fw flow 3D (gauss)
# Forward cross-correlation function including flow for confocal setups with
# a free 3D diffusing species. 
# This file was gladly provided by Thomas Kuckert, Schwille Lab, Biotec,
# Tatzberg 47-51, 1307 Dresden, Germany.

# For more information about this model function, see:
#    Staroske, Wolfgang:
#    In Vitro and In Vivo Applications of Fluorescence
#    Cross-Correlation Spectroscopy, TU Dresden, Diss., June 2010#
#
#    Brinkmeier, M. ; Dörre, K. ; Stephan, J. ; Eigen, M.: Two-beam cross-
#    correlation: A method to characterize transport phenomena in micrometer-
#    sized structures. In: Anal Chem 71 (1999), Feb, Nr. 3, 609?616. http://dx.
#    doi.org/10.1021/ac980820i. ? DOI 10.1021/ac980820i

## Parameters
# Diffusion coefficient
D [10 µm²/s] = 10.0

# Structural parameter
w = 6.5

# Waist of the lateral detection area
a [100 nm] = 3.25

# Particle number
n = 10.0

# Focal distance
R [100 nm] = 5.0

# Flow velocity
v [100 µm/s] = 0.5

# angular difference to Flow for Foci Vector
alpha = 0.000001

## Calculation fo correlation function
gFlowT = (v**2)*(tau**2)+R**2
gAng = 2*R*v*tau*cos(alpha)
gC1Flow = exp(-(gFlowT-gAng)/(a**2+4*D*tau))
gTwoD = 1./(1.+4*D*tau/a**2)
gOneD = 1./sqrt(1.+4*D*tau/(w*a)**2)
gThrD = gTwoD * gOneD

G = 1./n * gThrD * gC1Flow

