© Steffen Weber, July 1997, (update 10/24/01)

*I am in the process of updating this applet ..., so this is
a beta version*

This applet simulates *X-ray Diffraction patterns* for
the *Laue method* (transmission/backreflection mode). **NOTE
on the quasicrystal systems:**

-you may select among the octagonal (8fold), decagonal (10fold),
dodecagonal (12fold) and icosahedral systems

-the capital letters 'S:' and 'Y:' indicate the usage of
STEURER's or YAMAMOTO's lattice matrices

** Film size and Film distance**The Film size is set as 120 x 120 mm. The film-sample-distance (FSD) is
set as 50 mm. Therefore in transmission mode reflections with theta<=25 deg
and in backreflection mode reflections with theta>=65 deg are plotted.

**NOTE on STEURER and YAMAMOTO matrices:**

- the two leading authorities on numerical structure analysis of quasicrystals
are Dr.Akiji Yamamoto and Prof.Walter Steurer

- they use different lattice matrices

- their lattice constants 'a' are not the same

**NOTE on the OCTAGONAL, DECAGONAL, DODECAGONAL system:**

- do use 5 integers for the orientation vector (separate
components by SPACE)

- give 'a' & 'c' as lattice constant

**NOTE on the ICOSAHEDRAL system:**

- do use 6 integers for the orientation vector (separate
components by SPACE)

- give 'a' as lattice constant

**NOTE on the maximum order:**

-due to the loop over 5 or 6 integer indices the number of
generated poles might be high. I reseved arrays for upto 10.000
poles. The calculation might be very time consuming though.
Therefore I recommend not to exceed max.oder=1 (icosahedral
system) or max.order=2 (for the other systems).

**NOTE on the indices:**

- just click the poles to get their indices.

**NOTE on max. q**_{i}**:**

You may limit the number of generated reflections by setting
smaller values for the internal space component of the
diffraction vector *q*. This is reasonable since reflections
with large internal space components are weak and often not
observable. **NOTE on spot radii:**

You may select fixed spotsizes or use a rough approximation for
the intensities, which is *Intensity is proportional to the
inverse of the internal space component of the diffraction vector*.
[spot radii ~1/qi]