So far our approach in carrying out the M2 test has been the clean room equivalent of zooming in on a destination with Google Earth... We started out with Africa filling the screen & this week we're hoping to close in on the small Northern Cape town of Sutherland by bringing in the Faro Arm. This will allow us to refer directly to the CAD & optical models, enabling us to steer all the components much closer to where they need to be.
At this stage we're simply "jumping" the Faro from its high perch on the NRS simulator to a lower base that's within reach of the M2 test gear. The Faro software performs the coordinate transformation after a specific set of points has been measured from the two base positions.
Having taken the leap, we could establish & adjust the tip/tilt & despace of the null lens by measuring a plane on its retaining ring, while the decentre was determined by measuring a circle on the cell's outer diameter.
Similarly, we could adjust the interferometer using the Faro to measure the position of the point source focus.