Raster (Laser) Plotters

Aperature Lists

Vector photo plotters are increasingly being replaced by the raster (laser) photo plotter. This type of plotter emulates the older style machine in a raster (bit-map) fashion.

For both types of plotters, the term "aperture" is used to describe a pad or trace shape; however the term "aperture wheel" used for vector plotters is replaced by "aperture list" for the raster plotter. This implies the greater flexibility that is available to the designer when using the raster plotter.

There are three main advantages using aperture lists with raster plotters:

1. Aperture shapes can be easily generated in software, eliminating the need to design a physical wheel.
2. More apertures can be defined on a list.
3. Allowable aperture sizes are typically (but not always) greater than those imposed by the physical dimensions of the aperture wheel.

Flash and Draw Apertures

No distinction needs to be made between Flash and Draw aperture types since the light source intensity is constant.

Speed Advantage

Raster (laser) plotters operate much faster than vector machines. A complex plot on a vector machine that requires hours may only take ten minutes or less with a raster photo plotter. This speed increase will lower turnaround times, and therefore costs.