  Treatments of the usage of optical diffraction radiation from the
relativistic electrons moving though a conductive slit for the noninvasive
transverse beam size measurement encounter hard limitation of the method
sensitivity for the electron energy larger than 1 GeV. We consider in this
article a possibility of application in a diffraction radiation technique the
artificial phase shift, which can take place when transverse electron position
varies. This allows us to realize the nonivasive measurements of transverse
size of supper-relativistic electron beams with the small emittance.
