Electro-optical bunch shape measurements - possible temporal resolution limits

Coherent synchrotron radiation arises when the longitudinal electron bunch length is smaller than the wavelength. In storage rings, substructures on the electron bunches (micro-bunching) can lead to strong ''bursting'' of coherent radiation and investigation of such effects requires a measurement of the electron bunch length with sufficient temporal resolution. In linear accelerators, the bunch lengths themselves can be extremely short. This report considers the main electro-optical techniques for bunch length measurements and discusses systematic limitations of the method. Special emphasis is put on possible ways to increase the temporal resolution.