This adjustable component is intended as a manual focusing device for a lens and nozzle assembly. By turning the notched ring, the tube with the engraved scale lowers or rises at a rate of 1mm per turn. 0.1mm increments are engraved on the outer sleeve. In total there is 20mm of movement, engraved as 10-5-0-5-10 with 1mm lines. A locking knob is provided to secure the focus setting.
The tube does not rotate as it slides: a pin at 90° to the locking knob rides in a slot to prevent rotation. This inturn prevents any beam wander from residual lens centring errors.
Both ends of the focusing unit have the thread to take the thread inserts.