The Sample Alignment panel allows a user to align a sample so that Bragg's Law is satisfied. The user inputs the crystal lattice and the reciprocal lattice and iteratively redefines Θ and 2Θ angles.
Components of the Sample Alignment Panel
Setting Up the Orientation Lattice
a, b, c
The user specifies vectors a, b, c that approximate spacings of the crystal lattice of the sample. Default values are 2π.
alpha, beta, gamma
The user specifies angles between vectors of the orientation lattice. By default these angles are set to 90 degrees.
h1, k1, l1 and h2, k2, l2
The user enters two non-colinear reciprocal lattice vectors that define the scattering plane.
Apply/Reset
The user must to press Apply in order for changes to take effect. Pressing Reset button will re-set parameters to previous values.
Move Devices
Device
The user can move Ei and A3 devices.
Current Position
Positions of Ei and A3 are displayed after each iteration.
Target Position
The user can input new position for Ei and/or A3.
Jog Step
The user can move Ei and A3 step-by-step in each direction.
Align Sample at Lattice Reflections
h, k, l
The user is required to specify the lattice reflection. In order to define the scattering plane, at least two reflections have to be found.
Drive A4
The user may choose to drive motor A4 (sample 2Θ angle) to specified lattice reflection.
Drive Q (A3/A4)
Alternatively, the user can change values of motors A3 and A4 together by driving vector Q.
Calculated Angular Alignment Position
Current sample position as given by values of 2Θ (or motor A4) and Θ (or motor A3) are displayed.