Our new pulsed positron microbeam is not only a microprobe for the local analysis of defect characteristics but also a microscope providing a complete lifetime image of defect distributions at micron resolution. Both aspects are discussed with examples from recent applications to basic problems of materials research. For fundamental reasons an image of defects at nanometer resolution by the present generation of microbeams is impossible. Therefore, a more advanced dual microbeam system will be proposed, where the defects are stained with positrons. Then a scanned electron beam with nanometer spot size is sensitive to the stained defects. (C) 2002 Elsevier Science B.V. All rights reserved.