Monthly Archives: February 2015

Simplify The Control Of Complex Laser Scanning Jobs

Controlling complex laser scanning systems just got a whole lot easier, thanks to the addition of a laser galvanometer interface to our Power PMAC motion controllers.
 
 

The interface dramatically simplifies and improves the controls for laser scanning applications that require a motion system to position the scanning head relative to the work piece. These applications include laser marking, PCB processing, micromachining and medical device manufacturing.

In the past, these applications typically required separate controllers for the scanner and the motion axes. The new interface, which we based on the laser industry’s XY2–100 communication standard, allows a single motion controller running a unified program to govern every aspect of a laser scanning process.

Here’s why this unified approach to laser scanning control matters:

Improved positioning performance. Laser scanners have traditionally relied on stand-alone PC-based controllers to position the galvo mirrors and modulate the laser power. A separate motion controller would take care of positioning the scanning head relative to the work piece.

This dual-controller arrangement can work well in applications with modest performance requirements. Increasingly, however, laser scanning applications required positioning accuracies and speeds that are not easy to satisfy with separate networked controllers for different parts of the process.

From a positioning accuracy standpoint, using two controllers increases the chance that there will be errors at the boundaries of the laser scanner’s field of view as it moves over different parts of a larger work piece. These “stitching errors”  can reduce the system’s overall accuracy.

Faster laser processes. From a speed standpoint, it takes time to execute two programs and pass data back and forth between two controllers. The control system ends up executing its programs sequentially—moving the scanning head, firing the laser, moving the scanning head. The inefficiencies of this stop-and-shoot approach translate directly to added cycle time.

Schematic3_drawing

The combined control system, by contrast, executes only a single motion program that positions the galvo mirrors in the laser scanner and the x-y position of a scanner or workpiece. Our Spectral Decomposition algorithms allow a seamless coordination of the galvo actuator’s high-frequency movements and of the x-y positioning actuators.

In applications that require frequent positioning of the laser scanning head in relation to the work piece, we’ve found that the speed improvements from the unified control system can be significant.

Simplified controller programming. Another benefit to the single-controller architecture is simplified programming. Rather than writing, troubleshooting and maintaining several distinct chunks of controller code, the Power PMAC with XY2–100 interface needs just one program for all the positioning tasks. That same program will also control laser power on-the-fly through PMAC’s PWM outputs.

Detailed technical specifications for the Power PMAC can be found here.
 
 

Power PMAC