Determination of blank orientation by using reflection spectroscopy

X-ray technique is normally used for the determination of the orientation of blanks of crystals. An attempt is made to develop another technique, the infrared reflection spectroscopy, in order to determine some of the characteristic angles of a cut. The reflection spectra of anisotropic crystals can be measured in the 1500-400 cm/sup -1/ range using or polarized or unpolarized beam. The measurements of the reflectance at specific and selected wavenumbers lead to the /spl theta/ and /spl psi/ angle values (IEEE convention). A multivariate calibration can be used for the interpretation of the reflection spectra and to get these angle values. As this calibration shows the "outliers" or irregular samples, it can allow to face of an automatic control for large series of blanks. An application of this method is made for /spl alpha/-quartz AT-cuts. The results obtained by using this technique are compared with those given by X-ray diffraction.