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Laser beam diagnostics : BEAMDIAG program.

Laser beam diagnostics : BEAMDIAG program. Stéphan Del Burgo CERN PS/LP 30 January 1998. DBS 01/98-101. Laser beam diagnostics : BEAMDIAG program. What is it for and where is it used ? How does it work ?

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Laser beam diagnostics : BEAMDIAG program.

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  1. Laser beam diagnostics :BEAMDIAG program. Stéphan Del Burgo CERN PS/LP 30 January 1998 DBS 01/98-101

  2. Laser beam diagnostics : BEAMDIAG program. • What is it for and where is it used ? • How does it work ? • The analysis with the main functions : barycentre, contours, profiles, widths, fits, 3-D… • Conclusion - Next developments. DBS 01/98-102

  3. What is it for ? • For laser beam diagnostics and analysis. • To improve laser adjustments and beamgeometry. • For every kind of beams that a video camera can see with or without a screen. • Where is it used ? • In the CTF Laser room. • In the photocathodes laboratory. • In the new laser laboratory. DBS 01/98-103

  4. How does it work ? Depending on the wavelength, a video camera looks at a screen or directly at the beam. The video camera is triggered. The pulse ( a few ns or ps ) is seen only during one frame ( two interlaced frames usually ! ). DBS 01/98-104

  5. How does it work ? The data are acquired by a frame grabber in the PC. The frame grabber subtracts the noise from the picture. The frame grabber output is a TIFF file matrix in the PC. Each line of the matrix corresponds to one line of one frame, one line of the CCD matrix out of two. All these developments have been done by Eric CHEVALLAY. DBS 01/98-105

  6. How does it work ? My work begins here with the calculations on the matrix. The size of the matrix can be very large ( e.g. 512x256 ). The calculations are made with Matlab, Matlab 5 for the last version. The program is called BEAMDIAG ( or BEAMCTF ). This program contains around 80 files . The main loop is : Data Acquisition ( TIFF file ) Conversion into an Intensity Matrix 1 loop : ~15 s Calculations and Analysis Display DBS 01/98-106

  7. R G B LUT • Calculations and Analysis : • The projections from the beam to the screen and the camera are compensated ( X scale = Y scale ). • Matrix conversion and normalization : 0 0 0 0 11 16 35 5 1 0.1 0 0 3 125 78 11 2 0.2 0 0 204 204 12 16 ... ... ... ... 202 251 121 11 254 1 1 0.9 TIFF Matrix 255 1 1 1 Video picture : 2 frames Pixels Pixels 0.2 0.3 0.33 0.1 100 100 Histogram Histogram 0.05 0.5 0.6 0.2 Normalization 0.9 0.9 0.23 0.3 0.7 0.95 0.42 0.2 DBS 01/98-107 1 0 1 0 Level Level Intensity Matrix

  8. Analysis - video matrix, contours, barycentre, profiles DBS 01/98-108

  9. Analysis - normalized matrix, maximum, integrated profiles DBS 01/98-109

  10. Analysis - normalized, barycentre, personal, length DBS 01/98-110

  11. Analysis - normalized, barycentre, gaussian fit DBS 01/98-111

  12. Analysis - normalized, barycentre, gaussian fit, real beam DBS 01/98-112

  13. Analysis - normalized, 3-D DBS 01/98-113

  14. Conclusion - Next developments. • Last version of the laser beam analysis program with Matlab 5. User friendly. • Adaptation from Windows 3.1 to Windows 95, and finally from Matlab 4 to Matlab 5  It runs better ( display speed, printing, saving,... ). • Still a little bit slow. • Good results for the analysis ( widths, fits,… ). Reliable if correct calibration ! • Possible to add other specific functions : • different fits • remote control for the aperture • Next version with VME technology... DBS 01/98-114

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