  China's first quasi-periodic undulator (QPU) has been developed for the Hefei
Light Source (HLS). It uses a magnetic configuration with varied thicknesses of
NdFeB blocks, based on the QPU of European Synchrotron Radiation Facility
(ESRF). Depression of 3rd harmonic radiation is significantly improved over the
ESRF QPU, as deduced from the measured magnetic fields. A method of configuring
shims of different geometries and sizes, based on a symmetric principle to
correct multi-pole field integrals, was demonstrated.
