Laue Master Pattern Simulation - EMsoft-org/EMsoft GitHub Wiki

Laue Master Pattern Simulation

While EMsoft focuses primarily on electron scattering modalities, there are a few programs that address X-ray diffraction. The EMLauemaster program produces a master pattern, similar to the EMEBSDmaster program, that can be used to compute individual transmission and reflection Laue patterns for a given detector geometry using the EMLaue program.

Using the standard command line approach, the template file can be obtained; this file contains the following parameters:

&LaueMasterData
! number of pixels along semi-edge of square Lambert pattern
 npx = 500,
! number of pixels along semi-edge of reflection patch
 patchw = 5,
! minimum wave length [nm]
 lambdamin = 0.10,
! maximnum wave length [nm]
 lambdamax = 0.16,
! concentration parameter for von Mises-Fisher distribution
 kappaVMF = 50000.D0,
! intensity truncation factor; any reflection with intensity less than intfactor * I(000) will be ignored
 intfactor = 0.0001D0,
! crystal structure file name
 xtalname = 'undefined',
! output file name [relative to EMdatapathname, .h5 extension]
 hdfname = 'undefined',
! output file name [relative to EMdatapathname, .tiff or .tif extension]
 tiffname = 'undefined',
 /

Most of the parameters are easily interpreted. The forward model employs the von Mises-Fisher distribution on the 2-sphere to compute the intensity distribution of individual pattern spots. A kappaVMF value between 10,000 and 100,000 produces reasonably small spots; smaller values will produce larger spots, and when too small a value is used the spots will take on an angular shape.

 &LaueMasterData
 npx = 500,
 patchw = 5,
 lambdamin = 0.10,
 lambdamax = 0.16,
 intfactor = 0.0001D0,
 kappaVMF = 50000.D0,
 xtalname = 'grt.xtal',
 hdfname = 'Laue/test.h5',
 tiffname = 'Laue/test.tiff',
 /