Multiwire Laboratories, Ltd.

Step 1 - Mount cut (but not polished) GaAs crystal at a 113 mm film to specimen distance. Enter a Collect time of 5 seconds into the Parameters box for integrating a Laue pattern into the computer memory. For 13 kV operation of a Tungsten x-ray tube, only Miller indices up through 7 are needed.

Step 2 - Collect image for 10 seconds and display it.

Step 3 - Load indexing file "Si100A.idx" which contains a table of angles between planes for cubic crystals (such as GaAs). With Add Points, select 4 to 6 points in the displayed image by positioning the cursor over the point and left clicking with the mouse. The NorthStar program selects suitable HKLs  for the first two points from the table and calculates the Miller indices of the remaining points.

Step 4 - Indexed solution reveals the Miller indices of all the spots in the image. The complete orientation of the crystal relative to the x-ray beam is now completely described by an orientation matrix. This matrix can be used to compute a stereographic projection of this particular orientation. A Move-to feature calculates the angles needed to bring any hkl into orientation.

Orienting Quartz Single Crystals

Quartz Laue pattern and its indexing - A quartz crystal was mounted 150 mm from the detector and the Laue pattern integrated into the computer for 5 seconds. The indexing file "quartz_c.idx" was loaded from disk and a 4 Miller indices feature turned on before the image was indexed.

Then the image was brought into orientation with the motorized 3-axis stage.