Application of the /spl Omega/scan to the sorting of doubly rotated quartz blanks

The X-ray /spl Omega/-scan method allows the quick (cycle time, e.g., 15 sec.) determination of both rotation angles of doubly rotated, rectangular or round quartz blanks with high precision (a few arcsec.). It was designed originally for AT cut blanks and has been extended to SC (and FC) cuts. However, the principle of the method is applicable to blanks of any orientation. The lattice orientation is determined on an absolute scale. Therefore, any calibration of the instrument is unnecessary. Based on this method, charges of blanks in a certain orientation range (up to several degrees in the rotation angles) can be sorted semiautomatically or automatically, respectively, using the equipment and procedure which is described below.