| 摘要 |
PCT No. PCT/GB84/00324 Sec. 371 Date May 14, 1985 Sec. 102(e) Date May 14, 1985 PCT Filed Sep. 24, 1984 PCT Pub. No. WO85/01349 PCT Pub. Date Mar. 28, 1985.A method of and apparatus for setting the orientation of a single crystal which may be a seed crystal, boule, wafer or a growing boule. The crystal is irradiated with a beam of X-rays having a peak of energy at a given wavelength and the orientation of the crystal is adjusted while moving the crystal and the beam about an axis perpendicular to the equatorial plane containing the X-ray beam until a pair of reflexions that are symmetrical with respect to the equatorial plane occur simultaneously at the said wavelength of radiation. When the X-ray beam has a peak of energy at the said wavelength against a back ground of white radiation, symmetrical reflexions can be detected and will flash simultaneously only when one of the crystallographic planes of symmetry is set in a predetermined or determinable orientation relative to a given datum. In contrast to conventional techniques which involve quantitative analysis or measurements of one diffracted beam at a time, the present invention depends only upon detecting simultaneous flashing of symmetrical reflexions above and below the equatorial plane, in order to set the orientation of a crystal with a high degree of accuracy. |
