Electron radiography using a table-top laser-cluster plasma accelerator

We explore the use of a laser-based electron gun for applications in transmission electron radiography and microscopy at electron energies up to 2 MeV. This new approach holds the promise to overcome some limitations of existing conventional electron guns at high beam energies especially for ultrafast applications. Our laser-electron gun is based on titanium-sapphire, ultrashort pulse lasers to drive electron acceleration in a plasma. The focused laser pulse travels in a tailored Ar gas target and accelerates electrons to MeV energy in less than a millimetre. As a first application, we use this electron beam to perform contact transmission electron radiography of cm-scale thin and thick samples. We obtain transmission electron radiography of organic and inorganic dense objects over a field of view more than 50 mm wide. The images are well exposed and show details of both thick and thin samples. The spatial resolution for the current geometrical configuration was found to be approximately 60 µm and was limited by geometrical effects combined with the intrinsic detector resolution and diffusion in the sample. (Some figures may appear in colour only in the online journal)