Review recent optical issues in LEP

We review some optical measurements and correction strategies adopted for the new lattice with 900 phase advance used in LEP during 1992. In particular, we compare three different techniques used to measure beta-beating: a multi-turn orbit measurement in presence of betatron excitation, a method based on the variation of chromaticity due to opposite trims in the strength of two sextupole families and an orbit measurement with two orthogonal kicks. The average vertical beating measured by these three methods (up to 37%, depending on the optical configuration) shows a substantial agreement among them. We also discuss a resonant method of correction for residual dispersion by special orbit bumps. The amplification factors for such bumps range from 200 to more than 700, i.e. a 1 mm orbit bump can give rise to more than 70 cm peak dispersion and these bumps have been routinely used to control beam size and optimize machine performance without any appreciable effect on the closed orbit