Occasionally the camera for the FSEE external viewer is in a different position. This will cause the viewer and beamspot to be out of picture and/or the image will be stretched. This will cause the measurement of the external beamspot size to be inaccurate.

Below is a screenshot of the external viewer D2597 when the camera has been bumped slightly.

There may already be a Viola setting that is correctly transformed. Do File → Open Setting and load the setting from /files/shared/beamops/FSEE_operation/ViolaSettings. If this does not correct the issue you need to use Transform & Trim.

• Do Option → Transform & Trim. This brings up the following window:

• This displays the full camera image. If the viewer is not fully visible here, the camera must be adjusted in the tunnel.
• Once the full viewer is visible, drag the red “corners” to intersection points. Choose intersection points to create a roughly centered square. The dashed border shows the full image that will be displayed in the main Viola window.
• Count the number of horizontal squares between corners. Each square is 10 mm wide, so for 6 squares you should input 60 mm for the “Width” in the “Fiducials” section. Do the same for vertical as well.
• Click “Apply” and “OK” to return to the main window. It should now look similar to below image

• To check that things are scaled correctly, do Option → Slice View, Draw a rectangle over the fiducial lines, and check that the measured X width and Y width are what you expect.

• If the results are good, do File → Save Setting and save it to /files/shared/beamops/FSEE_operation/ViolaSettings for future operators to load.

Similar considerations apply for the internal viewer D2569. This camera rarely gets moved so it is unlikely that is needs to be re-transformed. You will have to turn the light on and adjust the gain/exposure to 1/0.2 in order to see the viewer. The viewer is at a 45 degree angle to the beam, and the fiducial lines are drawn at 50×50 mm as the beam sees it.