PROCESS DATA ANALYZER

The PROCESS-DATA-ANALYZER (PDA) is a software tool for visualizing signals related to your scan system. It was developed to support you in the setup, analysis and optimization of your beam deflection unit because these tasks can be complex and time-consuming. The same applies to process analysis in the event of errors or when debugging control programs and API program codes. One of the main difficulties with these tasks is the lack of visualization of the adjustments. To find out how changes have affected the system, experiments in the laboratory must be carried out and then evaluated. This slows down optimization or troubleshooting and also leads to rising cost. 

To circumvent this, the PDA records all relevant control signals from the SP-ICE-3 card and the feedback signals from the connected deflection unit. In addition, the signals from external sensors connected to the SP-ICE-3 card can be recorded and analyzed. Thanks to both temporal and spatial mapping of the data, the PDA functions as a "digital oscilloscope". Its graphical user interface offers many options for visualizing and analyzing the data in a targeted manner. 

For example, the spatial representation in field coordinates enables signal curves to be assigned to a precise location in the scan field, so that, for instance, anomalies in the sensor signal can be directly correlated with a error pattern in the process. 

The programmable interface (API) also allows data recording to be automated and the integrated streaming server also offers the option of transferring large amounts of data to corresponding storage media for quality assurance during the ongoing process. The PROCESS-DATA-ANALYZER helps you to set up your laser machining processes more quickly, make better use of the performance of your deflection units and draw more precise conclusions from process parameters to the quality of the result. After all, to see is to understand. 

The PDA uses the SP-ICE-3 control card and picks up data of the signals that are provided to control the deflection unit and laser source. Status information of the deflection unit or digital signals, which are transmitted to the control card, can be used in the PDA, too. In addition, data from external sensors connected to the SP-ICE-3 via AD converter boards can be made available for use in the PDA.

The control card temporarily stores all this data in the trace buffer server, where it is tagged with a time stamp. The PDA's Graphical User Interface (GUI) and Software Development Kit (SDK) access this data and can ensure that the different data sets are clearly matched to each other. The PDA GUI is used to visualize and evaluate the data. For automatic data acquisition and storage on an external data storage device, the PDA SDK and the streaming server are used.

To enable convenient analysis of the process data and status information of the deflection unit, the PDA GUI prepares the data for graphical display. The temporal signal curves and the spatial positions (field domain) can be displayed side by side, whereby a position can also be assigned to each point in time by linking the time cursor with the position cursor. In order to better interpret the position data, it is recalculated from the scanner coordinates into field coordinates using inverse field correction.

While the PDA GUI is intensively used to analyze the deflection unit, laser, and sensor data when setting up a laser process and helps to optimize it, continuous optimization is usually not necessary in series production. Here, it becomes important to maintain the defined process windows and thus ensure the quality of production. To do this, defined process parameters are logged during the process and can then be used for quality control and monitoring. 

For such an automated data acquisition, the PDA’s programming interface (API) with an optional streaming server was developed. Like the PDA GUI, it uses the trace buffer of the SP-ICE-3 control card to synchronize the data and scan positions. However, instead of visualizing them in the GUI, they can be continuously saved to a local or external storage medium where they are available for later use. The basic license provides you with commands for configuring the signals and trigger settings. It also allows local saving of data in the PDA file format or exporting the recorded data after each process cycle. For large, continuous data volumes, the streaming server is advisable for transferring the data to appropriate storage media to avoid memory overflow (requires appropriate license).

Verification of the actual focus re-adjustment of 3d beam deflection units by monitoring the position of the z-axis 

In applications with a pre-focusing system such as the AXIALSCAN or the AXIALSCAN FIBER, focus readjustment can be critical for the process result. By comparing the target and actual position of the focus axis, the maximum deviation at the critical points can be measured and evaluated in the PDA display. This ensures that the process remains stable within the desired process window.

In this case, the actual position of the z-axis should not deviate from the target position by more than one Rayleigh length:

Speed-dependent power correction by using virtual signals

For the analysis, it can often be helpful to visualize signals that are not directly measurable but can be calculated live from the raw signals. A typical example is the scanning speed, which is a derivative of the change in position over time. This makes it possible to check functions of the control card that, for example, regulate the laser power or pulse frequency depending on the actual scanning speed: 

• At a polygon point, the scan speed is slowed down and accelerated again due to the commanded polygon delay.
• When using the "Speed-dependent power correction" option, the control card adjusts the commanded power according to the actual scanning speed. This can be visualized and monitored via the PDA.
• When using the "Equidistant laser pulses" option, the control card readjusts the commanded pulse frequency according to the actual scanning speed.
   

Load tests by recording the current consumption or temperature sensor data of the galvo motors during demanding processes

In some applications, such as laser cleaning or solar wafer processing, the deflection units or their galvo motors are often pushed to their load limit or even beyond. This can negatively impact the reproducibility of the processing result or, in the worst case, damage the deflection unit. 

To ensure that the performance of the deflection unit is fully utilized without overloading the galvo motors, it can be helpful to analyze the current consumption. For example, the average current consumption (RMS Current) can be recorded for the continuous load:

This data reveals which movement affects the load on the motors and how. This knowledge can then be used to modify the process parameters in order to achieve a high-performance and reliable laser process. 
 

Visualization of sensor data for process analysis 

An important aspect of the PDA is the spatially resolved display of data for process analysis and monitoring. This is because data can typically only be used for analysis when it is linked to positions on the component or in the image field. However, this is not limited to laser or scan head data. External sensors can also be used for this purpose. Classic pyrometers, special photodiodes or welding sensors are particularly suitable, as long as they provide analog signals for the measurement data. 

In the PDA application, this sensor data can be easily combined with the position values. By defining the color ranges for the XY diagrams, heat maps and defect maps of sensor data can be easily created and also arranged next to each other for direct comparison. This can provide valuable assistance in quickly setting up stable processes.

In-process quality control

Sensor data can also be saved for quality control purposes during production processes. This means that a data set can be attached to each component, which can be used for analysis in case of doubt. The PDA software does not directly assess/evaluate the data; This has to be carried out by the user.