You will normally know what screen angles and frequencies that you want to use. A Kodak service representative will use this information to output a test to confirm that a particular combination of angles and frequencies will produce an image without noticeable patterns.
Patterns can occur as a result of the microscopic debris trails left when the mask is ablated. The debris trails are not visible to the naked eye, but can interact with certain angles or frequencies and produce visible patterns. The trails left by a particular imaging head are referred to as its head signature. Head signatures change, depending on the imaging method (thermal or laser diode), and can also vary on individual devices, due to differing numbers of diodes or beams, power settings, resolution, focus, drum speed, or head intensities. For this reason, it is impossible to qualify any particular set of angles or frequencies for a particular device. Kodak service representatives must treat each device as an individual case, and confirm that specific angle and frequency combinations work for that device.
Prerequisites
Do not try to determine screen sets until the Kodak service representative has confirmed that the device is working to optimum specifications. It is particularly important that the debris removal system is optimized.
You should use gradients that output in all four colors, for testing screen set combinations. Gradients will show whether there are any specific tone areas that cause problems.
Service representatives should begin by outputting tests at the specific line frequencies and angles that you have requested. The exposed black mask should then be inspected to see whether there are any visible patterns when put on a light table and viewed in transmission. In most cases, the screen set combinations will look good, and the service representative can continue to help you to configure your output process templates with the selected screen sets.