High resolution and dynamic range characterisation of beam imaging systems

All imaging techniques require the use of optical components to transfer light from a source to a sensor. The impact of the transfer optics on the image resolution is often not well understood. To improve this situation, the point spread function (PSF) of the optical system needs to be measured; this requires a good point source and sufficient dynamic range to fully characterize the PSF distribution. For this purpose we have created an intense optical point source, using a high quality laser and special focusing optics. The PSFs of various optical systems, developed for high resolution electron beam imaging, were measured using this source and compared to Zemax simulations. These systems incorporate a digital micromirror array, which was used to produce very high (>105) dynamic range images. The goal is to systematically understand and mitigate any ill effects due aberrations, diffraction, and misalignments of all the components of the imaging system. Presented here are the results of our measurements and simulations.