Taira, Y. TUD02 electron radiation target beam-diagnostic diagnostics 2015 2015-12 Non-invasive beam diagnostics using a diffraction radiation (DR) has been developed at several electron accelerator facilities. Generation process of DR is similar to that of transition radiation (TR). TR is emitted when a charged particle passes through the boundary between two media with different dielectric constants. On the other hand, DR is emitted when it passes through in the vicinity of a boundary between two media. In the generation process of DR, the charged particle doesn't intersect the medium but its electric field intersects the medium. An aperture, a slit, and an edge are used for DR target. Optical wavelength of DR is usually used for beam diagnostics. One can evaluate energy, a transverse beam size, and a divergence of an electron beam by measuring a spatial distribution of DR. Moreover, coherent diffraction radiation with the wavelength of less than millimeter range is used for a bunch length measurement. In this conference, a theoretical background of DR and experimental results carried out at several facilities will be presented.