What is this sensor?

Hi, I see this sensor on Sulzer g6200 textile weaving machine.

http://i00.i.aliimg.com/photo/v4/229...tor_sensor.jpg

It controls the warp thread tension. This sensor is called warp let-off sensor. What type of sensor can this be? Is this some kind of proximity sensor?

Thanks.

If it controls tension I would assume it is some type of load cell.
But warp tension ??? Is it mounted on or near a plasma conduit or Jeffries tube?
(Okay I admit I'm a bit of a trekie)

I would agree it appears to be a tensioner control.
Here is an old patent for one that seems to explain the process?
Patent US4546801 - Warp let-off control device for weaving machines - Google Patents
Al.