Resolution of Transverse Electron Beam Measurements Using Optical Transition Radiation

Rasmus Ischebeck, Franz-Josef Decker, Mark Hogan, Richard Iverson, Patrick Krejcik, Robert Siemann, Dieter Walz (SLAC, Menlo Park, California), Melissa Lincoln (Stanford University, Stanford, Califormia), Chris Clayton, Chengkun Huang, Wei Lu (UCLA, Los Angeles, California), Suzhi Deng, Erdem Oz (USC, Los Angeles, California)

In the plasma wakefield acceleration experiment E-167, optical transition radiation is used to measure the transverse profile of the electron bunches before and after the plasma acceleration.
The distribution of the electric field from a single electron does not give a point-like distribution on the detector, but has a certain extension. Additionally, the resolution of the imaging system is affected by aberrations. The transverse profile of the bunch is thus convolved with a point spread function (PSF).
Algorithms that deconvolve the image can help to improve the resolution.
Imaged test patterns are used to determine the modulation transfer function of the lens. From this, the PSF can be reconstructed.
The Lucy-Richardson algorithm is used to deconvolute this PSF from test images.