Troubleshooting Handheld Laser Welding Head Issues: Lens Damage

In handheld laser welding operations, the laser welding head plays a critical role in ensuring stable power output and consistent welding quality. However, one of the most common issues operators encounter is lens damage, which can lead to weakened laser output and even visible sparks at the copper nozzle. Understanding the causes, identifying the symptoms, and applying proper maintenance are essential to restoring performance and preventing future failures.

Problem Description

Typical symptoms include:

The laser output is initially strong but gradually weakens, eventually becoming too weak to melt the filler wire.

Sparks appear at the copper nozzle during welding.

Video showing lens damage in handheld laser welding machine

Possible Causes

In most cases, the issue is caused by damage to one or more optical lenses inside the welding head. These lenses include the protective lens, focusing lens, collimating lens, and reflective lens.

Detailed analysis:

Any single damaged lens—or a combination—can cause weak output or unstable light.

Begin troubleshooting by replacing the protective lens first, then inspect the focusing and collimating lenses, followed by the reflective mirror.

If sparks appear near the copper nozzle, the issue may be focal point misalignment, which should be checked and corrected.

Additionally, inspect the laser fiber head for contamination or physical damage.

Understanding Lens Damage Types

Mechanical Interference or Beam Misalignment

Improper red-light alignment or unstable motor movement may cause abnormal oscillation.

The sealing ring often burns together with the lens when this happens.

Convex Lens Surface Damage

Usually caused by contamination during lens replacement or poor protection during operation.

Appears as black dot-shaped burn marks on the lens surface.

Flat Lens Surface Damage

Results from laser scattering or reflection, where reflected light focuses onto the lens and burns the coating.

Appears as white burn spots. The same phenomenon can occur on convex lenses.

Protective Lens Damage

Often due to spatter from the molten pool or contamination during replacement.

Gaussian Beam Focus Issue

When the laser beam is too concentrated, a white spot appears suddenly in the center of the beam path, damaging any lens in its focus.

Troubleshooting & Repair

Solution:

Replace all damaged lenses immediately. Refer to the equipment’s assembly and structure manual for proper replacement procedures and optical path alignment steps.

How to Prevent Future Damage

Lens damage is one of the most frequent maintenance issues in handheld laser welding. To reduce replacement frequency and improve welding stability, follow these preventive measures:

Use original manufacturer lenses to ensure coating quality and optical precision.

Prevent contamination when replacing lenses — always wear gloves and operate in a clean environment.

Avoid vertical welding whenever possible, especially when welding high-reflectivity materials like aluminum or copper.

Replace damaged lenses promptly to prevent further optical path degradation.

Ensure proper grounding of the machine to reduce electrical interference that may affect laser output stability.

Summary

Lens health is directly linked to the welding machine’s performance. A well-maintained optical system ensures:

Stable and consistent laser output

Clean and smooth weld seams

Extended equipment lifespan

ZS Laser reminds all users: regular inspection, proper operation, and timely maintenance are key to keeping your handheld laser welding machine performing at its best.