EMHOLZ

Program: EMHOLZ

This is an older command line program, written around 2001, that allows the user to produce a map of HOLZ lines inside the central disk of a CBED pattern. The program does not use a name list file for input; the user must enter the individual parameters manually based on the program's prompts.

The program is executed by typing EMHOLZ on the command line. This will produce a few lines of information followed by the following prompt:

  Enter xtal file name :

Assuming that you have an aluminum structure file, enter Al.xtal. Then the program asks for the accelerating voltage in kV (as a real number, so make sure you include the decimal point):

 Enter the microscope accelerating voltage [kV, R] :

Use 200.0 as input. You will then see the following prompt:

 The following scattering factor sets are available :

  [1] Doyle-Turner/Smith-Burge (no absorption)
  [2] Weickenmeier-Kohl (no absorption)
  [3] Weickenmeier-Kohl (with absorption)

  Which set do you want to use [1/2/3] ?

You can basically chose any one of them, but 3 provides a better model for the structure's Fourier coefficients. The program will return a number of parameters and then asks for the camera length:

  Camera length L  [mm, real]

Type 500.0; then you will be prompted for the name of a PostScript output file

  Enter Postscript file name : 

Enter test.ps; some more information will be printed to the command line, and then you will be prompted for the zone axis orientation [uvw]:

 Enter u,v,w :

Enter 1,1,1. For the foil thickness:

  Enter foil thickness [nm, R] (to get relrods of proper length) :

enter 20.0. The program will print the largest size for the central CBED disk without overlapping any other disks (4.3785 in this case), and then asks for the beam convergence/divergence angle:

  Enter the beam divergence angle [mrad, R] 

Enter 4.3. The program prompts you for the foil normal as a direction:

 Enter u,v,w :

Enter 1,1,1 to have the foil normal parallel to the zone axis. Somce additional information follows, and then the user is prompted for the coordinates of the Laue center (for slightly off-axis illumination):

  Enter the coordinates of the Laue center with respect to g1 and g2

Enter 0.0,0.0 if you don't want to have any beam tilt. Information follows on the HOLZ ring radii in the field of view (basically, the field of view is determined from the camera length and is represented at the correct scale in the output as an old fashioned micrograph). The program then asks if you want to do another one; for now, type 0.

Then you can look at the PostScript output file with any program that can read this file type. The result will look like this:

Please refer to section 3.9.5 in the "Introduction to Conventional Transmission Electron Microscopy" textbook (M. De Graef, Cambridge University Press, 2003) for detailed information on HOLZ patterns and the various quantities of importance.