The laser source determines what a cleaning system can achieve

Average power in watts is the most frequently quoted and at the same time least meaningful figure here. It describes how much energy is delivered per second, but not how that energy arrives on the workpiece. And that is what decides whether a layer of rust is removed, whether a paint layer comes away cleanly and whether the base material remains undamaged in the process.

This article sets out the characteristics of a laser source: which figures actually say something about the result, where data sheets from different manufacturers are not comparable, and which properties cost or save money in daily operation.

Why the laser source is the decisive assembly

A cleaning system consists essentially of four assemblies: the laser source, the beam delivery with scanner and optics, the cooling and the control system. Of these four, the source accounts for the largest share of the purchase price – and it sets the physical upper limit of what the machine can achieve.

Scanner, optics and software can improve a process but cannot generate energy the source does not deliver. If the pulse energy is not sufficient to loosen a layer of scale, no other scan pattern will help.

The reverse also holds: a capable source in a poorly designed system likewise falls short of its potential. Both statements are correct – but only one of the two assemblies cannot be changed afterwards.

The question of which laser source is fitted is therefore not a matter of detail when buying a cleaning system, but the central technical decision.

Pulse energy: the quantity behind material removal

In pulsed laser cleaning the energy is not delivered evenly but in very short pulses. What matters is the energy of a single pulse, stated in millijoules (mJ).

The physical relationship is direct: contamination and base material have different thresholds at which they absorb energy and vaporise. If the energy density of a pulse lies above the threshold of the rust or paint layer but below that of the metal underneath, the layer is removed and the component remains untouched. This window is the actual core of the process.

Average power says nothing about this. A source with 200 watts and high pulse energy can loosen a thick layer that a source with 500 watts and low pulse energy fails to remove – because its individual pulses never reach the threshold and the energy goes into the component as heat instead.

Pulse energy is the single most important figure in the data sheet of a cleaning source. It is not always stated there.

What low pulse energy achieves on the component

At the lower end – in the order of a few millijoules – the process is particularly gentle. Typical tasks:

• injection moulds and tooling where dimensional accuracy and surface quality must be preserved
• delicate components from engine and equipment manufacturing
• thin sheet metal that would distort under heat input
• restoration and heritage conservation, where the substrate is irreplaceable

Material is removed layer by layer here and can be controlled through the number of passes. That costs time but gives control: after each pass the operator sees how far the process has progressed and can stop at any point.

For sensitive materials this is precisely the reason to work with a laser at all. Mechanical processes remove material with every pass, including from the base body.

What high pulse energy is needed for

At the upper end stands area performance. Thick layers of rust, old industrial paints, fire residues or mill scale need considerably more energy per pulse to be loosened at all.

If the pulse energy remains too low here, a typical picture emerges: the surface becomes warm and discolours, but the layer does not come away. The process then not only takes longer – it does not work.

Manufacturers of pulsed fibre lasers for cleaning state single pulse energies of more than 30 mJ for their stronger series, at average powers reaching into the several hundred watt range. These classes contain the systems with which large-area derusting, paint removal and scale removal become economical.

The range is the actual buying argument

A business that only cleans moulds does not need 30 mJ. A business that only derusts structural steel does not need fine gradation at the lower end. Most businesses, however, have both – and then what matters is how far the range of a series extends.

Pulse duration and repetition rate belong with it

Pulse energy alone does not yet describe the process fully. Two further quantities belong with it:

• The pulse duration – measured in nanoseconds – determines how quickly the energy is introduced. Short pulses produce high peak power with low heat input; longer pulses spread the same energy over more time and heat the component more strongly.
• The repetition rate – in kilohertz – indicates how many pulses are delivered per second. Together with the feed rate it determines how densely the pulses lie on the surface.

The three quantities are connected: average power is pulse energy times repetition rate. Raising the frequency lowers the energy per pulse at the same power. This is exactly where many process trials fail – the frequency is turned up to work faster, and material removal stops because the individual pulses fall below the threshold.

A reliable process window therefore only emerges when all three values are set and documented together.

Q-switch or MOPA: two designs for two purposes

Pulsed fibre lasers come in two widespread designs, and they are built for different tasks.

Q-switch sources generate the pulse via a Q-switch in the resonator. The pulse duration is largely fixed and the frequency adjustable only within limits. In return, these sources reach high single pulse energies – exactly what is needed to remove layers. Most cleaning systems work with this design.

MOPA sources (Master Oscillator Power Amplifier) generate the pulse in a seed laser and then amplify it. This allows pulse duration and frequency to be set independently of one another. This design is the strength of manufacturers such as JPT and the prerequisite for applications such as colour marking on stainless steel or fine marking on plastics.

For surface cleaning this flexibility is rarely the decisive factor – there, energy per pulse is what counts. Anyone needing both should define the application before the design, not the other way round.

Efficiency shows up in the electricity bill

The efficiency of a laser source describes what proportion of the electrical power drawn emerges again as laser light. The remainder becomes heat and has to be carried away.

Modern fibre lasers reach values in the region of 30 to 35 per cent, depending on series and manufacturer. That sounds like a small difference, but in continuous operation it has a twofold effect:

1. Directly through the electricity consumption of the source.
2. Indirectly through cooling – every watt not converted into light has to be carried away by the chiller, which costs additional energy and loads the cooling components.

On a system running several hours a day this adds up over the service life. For a machine in occasional use, by contrast, efficiency is a secondary criterion – there, purchase price and availability decide.

Anyone comparing the value should note what it refers to: the source alone or the complete system including cooling and control. Both figures are in circulation, and they differ considerably.

Back reflection with copper, brass and aluminium

Bare non-ferrous metals reflect a considerable part of the laser energy directed at them. If this reflected light travels back into the fibre, it can damage or destroy the source.

This is not a theoretical risk: it is one of the most frequent causes of failure in fibre lasers in practice, and repairs to the source are expensive.

Manufacturers counter this with multi-stage protection mechanisms – optical isolators in the beam path, sensors monitoring the returning power, and a control system that shuts down when a limit is exceeded. How far this protection reaches differs considerably between series.

For businesses working with copper, brass, bronze or bare aluminium, back reflection protection is therefore not a side issue but a question to put to the supplier that should be answered before purchase – with a specific figure, not with the word “fitted”.

Physical design and weight determine handling

Two sources with identical optical data can differ in size and weight. That affects not only transport but the work itself.

Compact modules allow lighter hand-held machines, smaller housings and mobile systems that can be used on a construction site or inside a ship's hull. Larger modules tie the system to a fixed location or require a corresponding trolley.

In practice this often decides whether a machine is used daily or stands in the corner. A hand-held gun that becomes too heavy after twenty minutes changes the work result regardless of any optical figure.

When specifying a system, the question of weight and dimensions therefore belongs in the same place as the question of power – not at the end of the list.

Why fibre lasers need little maintenance

The design of a fibre laser source is the reason for its robustness. The active medium is a doped glass fibre; the pump diodes couple directly into that fibre. A free-space resonator with aligned mirrors, as required by older laser types, is not present.

This has immediate consequences:

• There are no mirrors that can go out of alignment, become contaminated or need readjusting.
• Vibration during transport does not alter the beam alignment.
• Dust and workshop conditions do not affect the resonator because it is sealed.
• There are no gases and no consumables in the beam generator.

Manufacturers state pump diode service lives in the order of 100,000 operating hours. That is a calculated value under rated conditions, not a warranty – but it describes the order of magnitude correctly: the source is usually not the assembly that fails first.

Maintenance effort arises at the periphery instead: the protective glass on the hand-held gun, the extraction filters, the cooling circuit. These items belong in every operating cost calculation; the source itself usually does not.

Which laser source Beamlux fits

Beamlux uses pulsed fibre lasers from Maxphotonics in its systems. The manufacturer, based in Shenzhen, was founded in 2004, develops and produces fibre lasers and their optical core components in-house, and according to the industry reports for 2024 ranks among the leading suppliers in the Chinese market – measured by revenue and units shipped.

Three points, which relate to the preceding sections, were decisive:

1. The range of available pulse energies covers both gentle work on sensitive components and area removal of thick layers. This makes it possible to build a portfolio without needing a different supplier for every class of application.
2. The compact physical design of the modules allows hand-held machines and mobile systems at an acceptable weight.
3. The integrated back reflection protection covers the processing of copper, brass and aluminium – materials that appear regularly in enquiries.

All Beamlux systems are designed for the European market and CE marked. The declaration of conformity and the details of the laser class are supplied with every machine.

What goes wrong when reading data sheets

Four points regularly lead to false conclusions when comparing:

Comparing watts with watts. Average power is not meaningful without pulse energy and pulse duration. Two machines with the same wattage can solve different tasks.

Reading peak values as continuous values. Data sheets frequently state maximum values that are only reached at a particular frequency. At other settings the pulse energy is lower.

Mixing system figures with source figures. Efficiency, dimensions and weight may refer to the laser source or to the complete machine. Without that distinction the numbers are not comparable.

Stating area performance without the material. Values in square metres per hour always apply to a particular layer on a particular substrate. Transferred to a different component they are worthless.

The reliable answer to all of this is the same step: a test on your own workpiece, with documented parameters and measured time.

Conclusion

The laser source sets the limits of a cleaning system. Four characteristics describe it sensibly: pulse energy, pulse duration, repetition rate and efficiency – supplemented by back reflection protection and physical design, which decide failure risk and handling in daily operation.

Average power in watts is the figure that is advertised most prominently and says the least. Anyone comparing quotations should therefore ask for the pulse energy – and for the frequency at which it is reached.

Beamlux fits fibre laser sources from Maxphotonics and selects the series according to the application. Which combination suits a particular component cannot seriously be derived from a data sheet, however, but only established on the workpiece itself.

Sources

• Maxphotonics – product documentation on pulsed fibre lasers — figures on single pulse energy, pulse duration, repetition rate and power classes of the MFP series and the cleaning sources.
• Fraunhofer ILT – publications on laser cleaning and laser ablation — process fundamentals on selective removal via energy density thresholds and on process design.
• Cross-manufacturer market overviews of fibre laser sources — classification of the Q-switch and MOPA designs and of the power and efficiency classes of available sources.

Related content