The choice of optical elements necessary for parallelism measurements depends on the selected measurement method: i.e. 3D or Wollaston. If 3D method is used then the linear optics plus right angle etalon should be used.
In this case the necessary components are:
Parallelism measurements based on the 3D method require optical elements IL1 and RL1 to be aligned along laser beam as shown in the figures above. The element RL1 should be moved. The beam should be directed to the perpendicular axis with the use of the right angle etalon RE3D.
Wollaston parallelism measurements require optical elements WP2 and WRP2 to be aligned along laser beam as shown in the figure 11.3. The element WP2 should be moved first along Axis 1 and then along Axis 2. No right angle prism is necessary for this measurement.