caltheta: calibrate theta zero-point
"caltheta" is a program to calibrate the "theta" zero setting on the
KappaCCD by analysis of 5 360 degree phi scans of an ambi crystal at
different dx.
Usage
caltheta [options] [make] [filenames]
Without any argument, the "caltheta" program will analyze any images
named "thetacal01f01" through "thetacal09f36.kcd" in the current
directory. With the argument "make" it will make five 4x90 degree phi
scans at dx=70, 90, 110, 130 and 150 mm first, and then analyze these.
The program can analyze any images specified on the command line instead.
Possible options are:
- frametime=f
-
Sets the time to spend per frame. In seconds. Default frametime=15
- frameangle=f
-
Sets the frame angle. In degrees. Default frameangle=90
By studying the center of all quadruplets of reflection at two
different distances, the absolute theta zero is determined, and if
it is significantly offset, the program will print instructions on how
to re-calibrate the theta on the server PC.
WARNINGS:
- Caltheta needs a distortion correction and a good guess at
the primary beam position to be able to work. Please run
makedistor and either
makedetalign or
caldx before running caltheta. Since
"makedetalign" depends on a good theta calibration whereas
"caldx" does not, the order "makedistor", "caldx", "caltheta",
"makedetalign" is advised for first-time
calibrations of a machine.
- Running "caltheta" is harmless, but if mistakes are made during
the actual recalibration on the server PC, the KappaCCD might be
damaged.
- If the offset printed by "caltheta" is not absolutely reasonable,
do not recalibrate the server PC, but warn your
Bruker Nonius service contact instead.
- It is advisable to check after a recalibration whether the result
of a retest comes out correctly.
