When large scan fields are processed, speed is only one part of the equation. The beam must also cover the field uniformly, while position, spot size and energy distribution remain predictable from the centre to the edge.
MOEWE dual-polygon optics distributes beam deflection across two coordinated polygon stages. This creates additional degrees of freedom for the optical design, control system and calibration. When properly designed, the approach can reduce field-dependent distortions and improve process consistency across the complete scan field.
The challenge: large scan fields are not automatically homogeneous
With a single deflection element, the geometric conditions change with the scan angle. At the edge of the field, the beam follows a different path through the optics than it does at the centre. The angle of incidence, effective spot size, line spacing and energy density can change at the same time.
For industrial applications, this means that a part may be processed differently in the centre and at the edge even though the nominal process parameters are identical. Typical effects include:
- deviating feature dimensions or contours at the field edge,
- different line widths and overlaps,
- variations in energy input,
- higher requirements for calibration and correction models.
How MOEWE dual-polygon optics works
Instead of concentrating the complete deflection on a single polygon stage, the dual-polygon design coordinates two deflection stages. Depending on the system architecture, the two stages handle different components of the beam deflection or work together in a coordinated combination.
The objective is not simply to add more optics. It is to distribute the geometry more effectively: each stage represents a smaller or more controlled part of the overall movement. The resulting field geometry can therefore be modelled more precisely and matched to the application.
Why the scan-field distortion is reduced
- Lower angular load per polygon stage: Distributing the required deflection across two stages can reduce extreme angle changes at each stage. This creates more favourable conditions for the subsequent focusing optics.
- More degrees of freedom for correction: The spot position can be described through the coordinated movement of both stages. Optics, control and calibration can therefore be matched more closely to the actual field geometry.
- More manageable field edges: The most critical deviations often occur where the beam is deflected far from the optical axis. Distributed deflection can reduce this sensitivity and narrow the difference between the field centre and field edge.
- More stable process conditions: A more uniform beam path supports a consistent spot geometry and energy density. This can improve repeatability in marking, microstructuring and selected laser-processing applications.
Single polygon and dual-polygon optics compared
| Criterion | Single polygon | MOEWE dual-polygon optics |
|---|---|---|
| Deflection | The complete movement is assigned to one stage. | Deflection is distributed across two coordinated stages. |
| Field edge | Geometric sensitivities can become more pronounced at the edge. | Additional design and correction options can make the field geometry easier to control. |
| Calibration | Optics and software must compensate for field deviations with fewer degrees of freedom. | Optics, control and calibration can be coordinated around the dual-stage geometry. |
| Process stability | Spot and energy density may vary more across the field. | A more uniform beam path can support homogeneity and repeatability. |
What this means for industrial processes
For applications involving large areas and demanding throughput and uniformity requirements, dual-polygon optics can provide several benefits:
- more consistent feature dimensions across the scan field,
- more uniform energy distribution when the system is properly designed,
- improved repeatability in marking and microstructuring,
- more freedom when coordinating scan strategy, focus and calibration.
The actual benefit always depends on the combination of wavelength, laser power, beam diameter, scan field, focal geometry, polygon speed, control system and material.
Optics alone does not determine the result
Dual-polygon optics does not replace careful system design. Reliable results require the optical properties to work together with the control system and a suitable calibration method. Scan direction, acceleration profiles, pulse parameters and the thermal properties of the material also influence the achievable homogeneity.
The relevant question is therefore not only, “How large is the scan field?” The key question is which spot quality, speed, accuracy and energy distribution the process requires at every position in that field.
Conclusion
MOEWE dual-polygon optics reduces scan-field distortions by distributing beam deflection across two coordinated polygon stages. This creates additional degrees of freedom for geometry, control and calibration. Edge deviations can be managed more effectively, supporting more uniform process conditions across large scan fields.
Frequently asked questions
Does dual-polygon optics eliminate every scan-field distortion?
No. It creates better conditions for controlling the field geometry, but it cannot replace precise design, calibration and process optimisation.
Which applications can benefit from the approach?
It is particularly relevant for large areas that must be processed quickly while maintaining uniformity and repeatability, for example in marking, microstructuring or selected laser-processing applications.
Which data is needed for an evaluation?
Useful information includes wavelength, laser power, beam diameter, target spot size, scan field, processing speed, material and process objective.
Would you like to evaluate your scan field?
MOEWE Optics supports the evaluation of suitable scanner and optical configurations. Share your key process data and we can assess whether dual-polygon optics is a good fit for your application.