The Duet3D Laser Filament Monitor uses a IR laser optical motion detector to detect filament movement. The detected movement is transmitted to the Duet 2 Wifi, Ethernet or Maestro which uses the indicated movement to determine if the filament has run out, jammed or been ground away in the extruder. It is available for 1.75mm diameter filament only.
The monitor PCB comes with two Molex KK-style 3 way plugs and pins, along with ~60mm of Capricorn XS Ultra Low Friction PTFE tubing to act as the filament guide. The 3D-printed enclosure and M3 mounting bolts are not included. Please see the documentation for more information: Documentation for the Duet3D Laser Filament Monitor.
Warning: The Laser Filament Monitor is a Class 1 Laser device: Under normal conditions, the laser beam is always below the IEC/EN 60825-1:2014 maximum permitted output level of 716uW according to the manufacturer of the optical sensor; nevertheless we advise against looking into the beam when the filament monitor is powered. You should most definitely not look at the sensor through magnification when it is operating. The laser beam is invisible infra red, therefore your eye blink reflex will not protect you!