Narrow Line Recovery

The droplet compensation routine essentially "shrinks" the boundaries to be filled so that the droplets do not extend outside the boundary. This algorithm when applied to lines that are very narrow relative to the droplet size can result in lines completely disappearing.

Consider the Gerber data below. The flash diameter = 0.4 mm (400 um) and the line width is 0.1 mm (100 um)

Now suppose we want to print this and our machine's DPI is 2500 and the droplet diameter is 105 um. Will this work?

Not very well.

We'll get something but because we are shrinking by a total of 105 um (52.5 on each edge) there is a strong possibility that part or all of our traces will collapse to zero width.

To resolve that, we added a third parameter to the -coverage: command line option which controls the droplet placement along such traces.

-coverage:0.5,1,1                  Place a droplet along narrow trace in each pixel
-coverage:0.5,1,0.5                Place a droplet along narrow trace every other pixel
-coverage:0.5,1,0.25               Place a droplet along narrow trace every 4 pixels