High Resolution and Dynamic Range Characterisation of Beam Imaging Systems

Any imaging system requires the use of various optical components to transfer the light from the source, e.g. optical radiation generated by a charged particle beam, to the sensor. The impact of the transfer optics on the image resolution is often not well known. To improve this situation, the point spread function (PSF) of the optical system must be measured, preferably, with high dynamic range. For this purpose we have created an intense, small (~ 1 μm) point source using a high quality laser and special focusing optics; and introduced a digital micro-mirror array in the optical system to substantially increase its dynamic range. The PSFs of optical systems that are currently being developed for high resolution, high dynamic range beam imaging using optical transition and diffraction radiation are measured and compared to Zemax simulations. The goal of these studies is to systematically understand and mitigate any ill effects on the PSF due to aberrations, diffraction and misalignment of the components of the imaging system. We present the results of our measurements and simulations.