148 BELL SYSTEM TECHNICAL JOURNAL 



ting crystal. Hozorth and Haworth^'' made such measurements for 

 variously prepared surfaces of Cjuartz and found that the rocking-cur\-e width 

 at half-maximum was least for etched plates, the smallest width measured 

 being 1.7 seconds. The greatest rocking-cur\-e width measured was 88 

 seconds for which both crystal plates (A and B, Fig. 8) were lapped with 

 lOO-mesh carborundum. Bozorth and Haworth also showed that the 

 rocking-curve width decreased very rapidly in the initial stages of etching 



With this technique we are measuring the angular frequency distribution 

 of the disturbed material that was detected with the intensity-ratio measure- 

 measurements with the single crystal spectrometer. Thus, with the rocking 

 curve, we show the intensity for each angle of incidence separately, but with 

 the single crystal spectrometer we measure the intensity for a relatively wide 

 range of angles of incidence at one measurement, which is the integrated in- 

 tensity under the double cr}'stal spectrometer rocking curve. 



None of this small-angle disturbance is detectable by the Davisson photo- 

 graphic technique because at small angles the reflected rays are too close to 

 those from the main plate and become confused with them on the tilm. Con- 

 versely, none of the material detected by the Davisson photographic tech- 

 nique is detectable by this technique because the intensity of the reflected 

 rays from large-angle disturbance is not great enough to produce a meas- 

 urable current in the ionization chamber. 



Together, these various measurements indicate a relatively large amount 

 of quartz misoriented by less than a minute and a smaller amount of quartz 

 misoriented by larger angles up to three or four degrees. 



The use of a photographic film in place of the ionization chamber in the 

 double crystal spectrometer would presumably permit the precise measure- 

 ment of the smaller amount of material misoriented by more than that now 

 measured with this instrument, as in the Davisson technique with the single 

 crv^stal spectrometer. This has not, to the writer's knowledge, been done. 



4.1 The Traxsmissiox Laue Camera 



In the transmission Laue camera (see Fig. 10) a beam comprising a large 

 range of wave-lengths is passed through a stationary plate. \'arious sets of 

 atomic planes in the cr}-stal, each with a difTerent interplanar spacing, d. 

 making a variety of angles, d, with the incident beam, reflect whatever wave- 

 lengths of radiation in the incident beam satisfy the Bragg equation, ;/X = 

 2d sin d, and the reflected beams are recorded photographically. Figure 11 

 shows films resulting from one-hour exposures. As in the case of the single- 

 crystal spectrometer, the slit-col limated beam comprises non-parallel rays, 



!■< Bozorth, R. M. and Hawoith, F. K., "The Perfection of Quartz and Other Crystals 

 and Its Relation to Surface Treatment." Phys. Rev. 45 (1934) p. 821-826; Bell Telephone 

 System Technical Publications Monograph H-801. 



