Shape of the Recorded Area in Precession Photographs and Its Application in Orienting Crystals

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Science  17 Jul 1964:
Vol. 145, Issue 3629, pp. 264-265
DOI: 10.1126/science.145.3629.264


The equation of the perimeter of the recorded area of zero-level precession photographs as a function of the orientation error is derived in polar coordinates. The angle between the tangent to the perimeter and the radius vector is also derived. How these relations can be conveniently applied to determining the orientation error of a crystal mounted on the precession instrument is discussed.