Product features LSO Laser welding monitoring system


Lens Shifting Optics (LSO) for Laser Welding monitoring system

Lessmüller Lasertechnik, through LSO in combination with the latest sensor technology, OCT (Optical Coherence Tomography) -Laser welding monitoring system, brings a welding optics to the market that follows the weld seam and automatically compensates for positional tolerances.

The LSO offers:

  • Precise and fast online correction of the weld position by detecting and tracing the weld joint
  • Real-time control of the weld plane (autofocus)
  • Possibility to measure the weld penetration depth (keyhole measurement) by OCT
  • Measurement and evaluation of the finished weld seam
  • Communication via standard fieldbuses (Profinet, Profibus, Ethercat, Devicenet)

The non-contact LSO system enables high-precision seam tracking as well as real-time process monitoring and quality assurance when welding with solid-state lasers.

Laser welding monitoring system show-off

real-time position control (left), gap bridging with LSO (right)

Due to the seamless integration of OCT into the welding optics, the user receives a compact overall system as a black box that can correct autonomously and ensures optimum welding quality.

During the active welding process, the system uses optical coherence tomography (OCT) to ensure precise position determination with the accuracy of 0.05 mm. The position of the weld joint is determined approx. every 10 ms and tracked by lateral lens shift.

When the distance from the component to the LSO changes, the optimum focus position is determined and regulated in real time by the axial lens shift.

Laser welding monitoring system LSO

Quality assurance algorithms proven in the series production process monitor both position control and the welding process as well as the weld seam and report critical weld seams to the higher-level system control.

If required, the LSO (Laser welding monitoring system) can be expanded with Lessmüller’s WELDCHECK system to maximize functionality.

Advantages with LSO

  • Precise welding with solid-state lasers up to 6 kW

  • Compact and lightweight system; easy integration into different motion systems

  • Reduced positioning times thanks to fast adjustable focusing lens for active control of focus position and welding position

  • Fast setup of the TCP (Tool Center Point) with integrated pilot lasers

  • Temperature monitoring of protective glass, focus and collimation lens

  • Intelligent self-diagnosis and optimization (Industry 4.0)

  • Expandable with WELDCHECK (diode-based quality assurance system)

Advantages with OCT

  • Fast and accurate seam tracking with different seam shapes

  • Automatic adjustment of the system to the focus position

  • Real-time measurement of weld penetration depth

  • Flexible adjustment of the scanning area for active seam tracking and quality assessment

  • Online detection and immediate reporting of welding and seam defects

  • Precise process and quality monitoring through online documentation of measurement data and process parameters

Whether integrated into a processing laser or used as a stand-alone, by using the OCT system from Lessmüller Lasertechnik you are making the choice for the most powerful quality assurance for welding processes on the market. – Laser welding monitoring system.

The possibility of using the system for all types of process monitoring, i.e. as a pre-, in-, or post-process, guarantees you the technically best possible welding quality in your manufacturing production according to today’s standards.


The primary task of OCT sensor technology is to avoid incorrect positioning of the processing optics or the laser beam. This can be done before welding by detecting the actual weld seam geometry and making preventive corrections, if necessary, or during welding by continuous, automated readjustment (seam tracking).

Furthermore, the weld penetration depth can be determined and monitored during welding. If defects occur, the ongoing process can be interrupted and defective parts can be prevented from being processed further.

Finally, the OCT from Lessmüller Lasertechnik can even measure the topography of the weld seam and check it for defects, both during and after the welding process.


Since OCT works independently of extraneous or interfering light, detectability and measurability can already be estimated in the planning phase of impact geometries. There is no need to create complex illumination simulations as for camera systems.

By using OCT for keyhole measurement, it is possible to determine whether the welding process is safe, constant and reliable in the essence during the initial welding tests, even before the feasibility studies. Thus, OCT contributes to the improvement and optimization of welding processes.

For the measurement of the POST process, offline tests can also be made parallel to the still ongoing process development.

From the needs analysis of your requirements and the welding tests of your task in our in-house test laboratory – we are happy to advise you. From project planning to implementation and integration of the modules into your plant as well as user training of your employees on site – with us you get everything from one source.
We are your contact partner both before and after successful completion of the project. Our customers know this and appreciate us for it.

All large and well-known OEM manufacturers have been using Lessmüller sensor technology for years. In the field of electromobility, battery manufacturers from China and Korea are among our customers.

Overall, we work with many system integrators: Bergmann & Steffen, Erlas, Felsomat, Thyssen Krupp Engineering, Manz, Comau, Evobeam, Aumann and others.

Ask us for detailed information.



Here our OCT solutions have already proven themselves

OCT has established itself in practically all manufacturing productions as an optimal and comprehensive tool for quality assurance of industrial laser welding processes. Our laser welding monitoring system.

The technology for laser welding monitoring system is trend-setting and is already considered the standard solution par excellence in many industries.

Our OCT solutions have already proven themselves here …

Product Advise

Florian Günther


Product solutions for laser welding monitoring system


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