Sample Alignment Panel

Introduction

This panel helps the user to align a sample.

Basic description of functionality

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.

Picture of the Sample Alignment Panel

Components of the Sample Alignment Panel

  1. Setting Up the Orientation Lattice

    Orientation Lattice subpanel of the Sample Alignment Panel
    • 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.

  2. Move Devices

    Move subpanel of the Sample Alignment Panel
    • 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.

  3. Align Sample at Lattice Reflections

    Lattice reflections subpanel of the Sample Alignment Panel
    • 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.