Off-Focus Etching of Print Making Plates

Off-Focus etching of print plates allows for thick vector lines without having to resort to a much slower raster etch technique. By controlling the amount the lens is moved out of focus the laser can be used to make precise line thicknesses. These line widths would still be designated in illustrator by a 0.1 pt line but would use a non-standard color to designate the desired line width through off-focus etching. Below are preliminary results from the first round of testing this technique, more information to follow when the plate has been printed. Attached is the file shown in the pictures.

I started by printing a set lines at different line widths using standard raster etch settings. These make a good comparison for looking at the line widths and depths produced by the off-focus technique.

The next step was to print blue vector etch lines and incrementally increase the focus distance between the lens and the material. Each time the lens is moved further away the line gets wider and occasionally the power must be increased to compensate for the spread of the beam. For each line I recorded the off focus amount, the line # as reference, and the power settings.