User_Manual-PILATUS-V1_2.doc 47/57
11 Creating a flat field correction
image
Intensity correction images are created with the glossary
"trim_gls/p2_make_flat.gl" or using the TVX command: MkFlatCorr
First set up a very uniform x-ray illumination and verify that it is as
flat as possible. This can very difficult, but is critical to success
Start this glossary in TVX by issuing the command get
"trim_gls/p2_make_flat.gl".
Follow the instruction in the TVX window. You will be asked to supply a
module number, this will create a directory under your images directory with
the name you supply; ensure that this is a new directory.
A 'rbd' image will be taken followed by a 'calibdet' image, if these images are
correct continue.
You are now asked to load the trim-files, start the load trim files procedure, set
'flag=1' and continue.
Now enter the trim file directory you wish to trim the module with, this
procedure is described in 10.3 Loading trim files.
After the trim loading section has completed you will be given an opportunity
to change the DAC settings if necessary.
The X-ray testing section will now begin, and you will be asked to turn on your
X-ray source. A 1 second exposure will be taken and a mean count rate for
the detector will be obtained. You are given the opportunity to redefine the
area being used to obtain the mean value. Using this number an exposure
time will be calculated to obtain a 10,000 X-ray count image. You are given
the opportunity to change the exposure time if required.
The longer the exposure time, the better the statistics.
After the data has been taken you will be shown a histogram and asked if you
would like to change the cutoff levels that have been set. These levels will be
used to create a mask image. Both a mask file and a flat field correction
image will be created and copied into the directory ~/p2_det/correct.
The final step will delete the working directory created under the images
directory.
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