X-ray studies of materials in extreme conditions of pressure call for focusing optics able to deliver very clean micron-size focal spots of high energy X-rays with added stringent requirements of flexibility to accommodate different experimental geometries and fast focal spot size adjustment. These requirements are fully met by multi-electrode modular piezoelectric bimorph mirrors (PBMs) in Kirkpatrick-Baez configurations, and these optical systems have already been successfully used for several years at high brilliance 3rd generation synchrotron radiation facilities such as the ESRF and SPring-8. The optical characterization and in-situ X-ray performance of the first pair of modular PBMs installed at the Advanced Photon Source at
Argonne national laboratory is reported here. Metrology tests show that the mirrors are able to approximate an arbitrary surface described by a 9th order polynomial in shape with only 100 Å rms shape error over their full optical surface. Full adaptive zonal control allows wave front correction, delivers optimum focal spot profiles (as small as 8.5 (H) x 5.0 (V) μm2 FWHM at a focal distance of 1 m) and fully achieves the creep-free short and long term stability and repeatability required by the experimental program.