HREM alignment aided by a real-time diffractometer using a liquid-crystal panel

By using a high-resolution liquid-crystal panel, a high-performance real-time diffractometer is realized. With this diffractometer, a high-precision astigmatism correction can be carried out easily even by a novice operator. A coma-free alignment procedure proposed by Zemlin [Ultramicroscopy 4 (1979) 241] is re-examined in order to take into account the three-fold astigmatism. The accuracy of the coma-free alignment using the real-time diffractometer is similar to that obtained by computer diffractogram analysis.