Coherent transition radiation-based diagnosis of electron beam pulse shape

The bunch shapes of an electron beams is increasingly difficult to measure, as the time-scales of interest are now sub-picosecond. We discuss here the use of coherent transition radiation CTR for such measurements. Two types of measurements are presented: the deduction of macroscopic (0.3 psec resolution) pulse profile using interferometry, and the examination of microbunch (50 fsec) structure from an FEL-bunched beam using spectral characteristics of the CTR. For the macrobunch measurement we discuss the problem of missing low frequency radiation and one solution for extracting meaningful data with this problem present. For microbunch CTR, we examing initial spectrally--resolved measurements, and some interesting deviations in the CTR spectrum from the standard theoretical predictions