An endoscope (which contains a surgical light and small camera) is placed through the tube, allowing the surgeon to view the annulus, disc, and epidural space on a video monitor.

The surgeon typicallys two small openings in your skin. An arthroscope is placed through one opening. This device is a camera attached to a thin tube. It shows live images on a monitor.

It is proved that this system can also be used to monitor the property of the cathode in the assembled tube by measuring a grid controlled travelling-wave tube.