The limitation of spatial resolution of orientation imaging via electron backscattered diffraction analysis in the scanning electron microscope makes it difficult to investigate the microstructure of nanocrystalline materials. The use of the recently developed transmission electron microscope based technique, known as ASTAR™, offers the possibility of reliable orientation mapping with a spatial resolution of 5 nm. In ASTAR™, a nanoprobe electron beam is scanned over the specimen and spot diffraction patterns are collected. Electron beam is precessed to reduce dynamical effects and improve pattern quality. Using template matching, the diffraction patterns are indexed automatically. ASTAR™ is also capable of identifying phases, with similar composition but different structures which is not possible with spectroscopic techniques. We present several examples of applications of ASTAR™ in investigating microstructure and microtexture of polycrystalline materials.