Each focus tool's length is identical to the optimal focal length of its corresponding lens. For instance, a 2" focus tool has the same length as the ideal focal length of a 2" lens. Each tool is also appropriately colour-coded for easy identification.
The correct laser focus setting can be conveniently determined using a focus tool. The laser operator simply hangs the focus tool on the laser head, and proceeds to manually raise the work table until the tip of the tool touches the workpiece's surface.
This method is especially useful if you work with a variety of materials, if the material thickness is unknown (or can not be measured), or if you are processing round or cylindrical objects.