  We report observations of coherent optical transition radiation
interferometry (COTRI) patterns generated by microbunched ~200-MeV electrons as
they emerge from a laser-plasma accelerator. The divergence of the microbunched
portion of electrons, deduced by comparison to an analytical COTRI model, is
~6x smaller than the ~3 mrad ensemble beam divergence, while the radius of the
microbunched beam, obtained from COTR images on the same shot, is < 3 microns.
The combined results show that the microbunched distribution has estimated
transverse normalized emittance ~0.5 mm mrad.
