Figure 1
The incident radiation (thick line) is reflected by the first crystal C1 and subsequently with a larger Bragg angle by the second crystal C2. By rotating the two crystals in a coupled motion around the incident beam (dashed line), the vertical angle of the incident beam on the sample (S) changes. The detector (D) follows the reflected beam from the sample at the polar angle π − φ upon rotating both crystals by the angle φ. |