Microscope corrections
Introductions
These corrections need to be computed after the installation of a new microscope, or when the support plate is changed (for example, OPERA-like or SND-like emulsion size).
List of corrections
flimgen
cormtx (This is a correction of uneven magnification distortion along the field of view)
slope (This is a correction of spherical distribution)
flatview (Correction allowing to transfer the spherical field of view into a flat one)
grainvol (Correction of grain volume/brightness)
Pixel size determination and flimgen
Stretching the image from the camera on two monitor screens, select a point, run it from left to right - record x coordinate, run back - record x coordinate. Repeat at least 3 times, get average value, divide 1 by number of pixels: Nx = 2336
Repeat the procedure for y axis. Divide the average value by the number of pixels: Ny = 1728
Check the results are 0.345 and 0.346
Enter the resulting values in
Modules -> Processor -> img_pixel_size
Make a test scan (flimgen) and convert into clusters
Cormtx
Create two directories: /bot and /top
Launch copied files from previous directory
Select scan parameters x 90 y 70
img_cor_mat_0 and img_cor_mat_1 should be empty in first correction!
Set thickness of bot (top) with a distance of 10-15 μm from base.
Make test scans, convert them into raw.root files
Send them to Y: folder (visibile by nusrv)
Insert Xpix and Ypix in viewdist.rootrc
On Linux server, copy directories to disk Y:
viewdist -f=clust.raw.root
obtain correction map
send the correction map back to LASSO
create folders bot_1 and top_1
Fill these 2 maps in img_cor_mat_0 and img_cor_mat_1. Both the same file, bot if you scan bot, top if you scan top
Repeat the scan and conversion
N.B. When building following maps, remember to build them on top of previous corrections!
Example: (for bot_1 from bot)
Repeat until map converge. It may complain about EdbViewMatch::CalculateCorr: WARNING: null dxy: ic=43 i=367065 cx,cy: 397.868652 43.176414. This means nothing will be added as correction here. What is the reason?
Obtained files need to be moved to C:\LASSO_x64, renaming them in order to replace already existing files.
Slope
It is only a fast scan
launch run.bat
launch scans
launch OpGrnProc.bat
launch fit.C:
Flatview and grainvol
They use the same scan:
copy folders
Scanning (measure glass, bottom, base and top, check light level, to have gray level about 190)
OpGrainProc.bat
run_flatview.bat
run_grain_vol.bat (from folder 5.grainvol)
check plots with .C scripts
copy flatview_0.vfm and flatview_1.vfm in C:\LASSO_x64
copy grnvol_mtx_0.grv and grnvol_mtx_1.grv in C:\LASSO_x64
gfind
copy fit values in link_corr, link_cor_0, link_cor_1
Note: the last corrections (the 5th, in particular), should be performed with a sampling emulsion film from the OPERA experiment, not one with SND@LHC beam.
Angular offset
This correction cannot be applied before scanning, must be performed a posteriori.
Each microscopes has not an exactly planar stage. Therefore, an angular offset can be observed, depending on the singolar microscope (about 10 mrad in TX and TY).
The proposed solution to correct it is to analyze a plate scanned twice: first normally, second rotated of 180°.
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