Defocussing correction

[Madhavan Radhakrishnan]

Hello,

I need to do defocussing correction for my pole figure data. Till now I could not succeed in generating a complete random texture powder sample and still trying to make one. In the mean time, I thought of incorporating theoretical defocussing correction using Schulz reflection formula. Do mtex 3.3.0 have any provision for incorporating Schulz formula? If yes, how?

Madhavan R,
IISc, Bangalore, India.

[Ralf Hielscher]

Dear Madhavan,

you can incorporate defocussing correction according to Schulz formula by

the constant - adjust them according to you setup

mu = 1 % absorption coefficient
t  = 1 % penetration dept
theta = 45*degree  % theta angle depends on the pole figure (hkl)

extract the polar angles of the pole figures

alpha = get(pf(1),'polar')

compute the correction coefficients

def0 = 1-exp(-2*mu*t/sin(theta))
defalpha = 1-exp(-2*mu*t/sin(theta)./cos(alpha))

apply correction to the pole figure intensities

pf(1) = pf(1) .* def0 ./ defalpha

Note that the above code applies correction only to the first pole figure. Repeat these step, e.g. in a loop, for all other pole figures.

I hope this helps.

Ralf.