Lumpkin, A.H. Berg, W. Dooling, J.C. Murokh, A.Y. Musumeci, P. Rule, D.W. Sun, Y. Wootton, K.P. JACoW Publishing Geneva, Switzerland 2673-5350 978-3-95450-230-1 10.18429/JACoW-IBIC2021-TUPP19 English 244-248 electron bunching laser diagnostics experiment Contribution to a conference proceedings 2021 2021-10 https://doi.org/10.18429/JACoW-IBIC2021-TUPP19 https://jacow.org/ibic2021/papers/tupp19.pdf One of the advantages of relativistic electron beams with microbunching at UV to visible wavelengths is the potential to generate coherent optical transition radiation (COTR) at a metal foil for diagnostics purposes. A significant microbunching fraction of at least 10% is expected for the case of a seed laser at 257.5 nm copropagating with a 343-MeV electron beam through a modulator undulator (3.2 cm period) at the Linac Extension Area (LEA) at Argonne National Laboratory. Diagnostic plans have been made for the COTR based-characterization of the microbunched beam size (~100 microns), divergence (sub-mrad), microbunching fraction, spectrum, and bunch length (sub-ps), as well as coalignment of the laser pulse and electron beam as previously described**. For that case, COTR enhancements over OTR of more than seven million were calculated, and we expect a similar enhancement of coherent optical diffraction radiation (CODR). Thus, we propose the modification of the microbunching diagnostics station to support initial (CODR) experiments with beam transit through an aperture in a metal screen or near a metal edge at the second screen position of the interferometer. We would explore whether the coherence function for CODR provides a complementary beam size monitor and whether COTR and CODR interferences from the two interferometer screens provide divergence and pointing information.