The LEP synchrotron light monitors

Four monitors are installed in LEP (Large Electron-Positron colliding beam accelerator), two per particle type. Two of the monitors are at dispersion-free locations which permit measurement of the transverse emittance, estimation of the energy spread and detection of various instabilities. The light has its origin in the main bending magnets. The source is imaged onto the detectors by means of catadioptric optics. Two detectors are used, one a charge coupled device (CCD) matrix and the other made up of a fast optoelectronic shutter and wavelength shifter coupled to a CCD matrix. Observations can either be made in the normal TV mode or in digital modes where one or more profiles (burst mode) are stored on the CCD and then digitized. In the burst mode, up to 18 profiles separated by 1 to 256 turns can be acquired. The results are presented either as data mixed with the TV picture or as two or three dimensional plots and projections on a workstation. Results and present performance are presented.<>