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In this article we will look at how a UV marker differs from a fiber optic marker, how a UV marker works and how to choose one.

What is the difference between a UV marker and a fiber optic marker?

The main difference is the wavelength, for example, fiber-optic machines have a wavelength of 1064 nm and UV machines have a wavelength of 355 nm. The wavelength affects the performance of the laser and which materials the laser can work well on.

The UV marker can be used on almost all metals and plastics, various types of glass, precious stones, wood, stone and ceramics and many other materials.

A fiber laser is mainly specialised in processing metals and plastics and does not “see” glass or paper. And not all metals and plastics can be processed; for example, highly reflective metals such as copper are beyond its capabilities. And some plastics simply char or foam when processed with a fiber laser.

How the UV laser marker works

In terms of physics, the principle of operation is quite complex. To simplify it as much as possible, the pump diode generates radiation with a wavelength of 808 nm, which then passes through a series of crystals and reflectors that convert this wavelength first to 1064, then to 532 and finally to 355 nm.

Much more important is how the principle of operation affects the result and what features and capabilities these machines have, besides being able to process almost any material.

The beam diameter of a UV marker is approximately three times smaller than that of a conventional fiber laser.

The shorter wavelength gives a smaller laser beam diameter, which means more detailed images and, most importantly, a much smaller heat affected area with a higher power density. This means that materials will not overheat, deform, burn or crack. The UV marker changes the properties of the material without destroying it – this is the marking, it is also possible to make ablation of various materials and oxidation of metals. The latter makes it possible to apply coloured images to metals.

Due to its relatively low power, the UV laser marker is suitable for marking, not engraving.

How to choose a UV laser marker?

UV
TT
Laser power 3/5/10 W
Laser source JPT
Work area 200 x 200 mm
Marker type Table type
More

At the current stage of the laser industry, quality UV markers are usually significantly more expensive than fiber-optic or CO2 laser markers.

For production tasks involving simple laser marking of metals, plastics or non-metallic materials, many will find it more sensible and cost effective to purchase the appropriate fiber-optic or CO2 marker.

Read more about choosing a metal laser marker in our article: «Laser Marking Machine for Metal».

Laser UV markers are used for specific applications: most often in the jewellery and microtechnology industries and for processing particularly complex and delicate materials: diamonds and sapphires, optical lens glass, some types of plastic, precious and highly reflective metals – copper, silver, gold.

Let’s look at the basic parameters for selecting a laser marker: emitter, lens, scanner, controller and software.

Emitter for UV laser markers

We supply the Wattsan UV TT marker with a JPT SEAL 355 3, 5 or 10 W emitter. We have chosen these as they are the most reliable and high quality. We can also install more expensive air cooled JPT emitters at the customer’s request.

The JPT emitter allows stable output power to be maintained, has interference protection and a fully sealed, dustproof, moisture-proof and self-cleaning design.

Let’s move on to the main parameters. If necessary, you can compare the following values with other UV laser sources.

  • The average power can be 3 or 5 watts depending on the emitter model.
  • The frequency range of 20 to 150 kHz allows marking to be carried out with high speed and efficiency and to be adapted to different materials and applications.
  • Power stability of the laser system: RMS ≤ 3%, indicating the range of laser power values in the system.
  • Pulse-to-pulse energy stability shows how precisely the energy of each laser pulse is repeated. This indicator also does not exceed 3%.
  • Pulse duration <15 ns provides high resolution, minimises thermal effects on the material, allows processing of thin and delicate materials and increases marking accuracy.
  • The beam quality M² ≤ 1.2 expresses the ability of the laser beam to maintain a Gaussian shape. A value of M² = 1 corresponds to a perfectly Gaussian, theoretically perfect, beam. The closer the M² value is to 1, the closer the beam shape is to the ideal beam shape.
  • Beam circularity >90%, a high degree of similarity to a perfect circle, ensures a uniform distribution of energy and intensity, which contributes to a consistent and precise result.
  • Beam diameter (1/e^2): 0.55 ± 0.15 mm. The laser beam diameter measured by the standard (1/e^2) defines the distance from the centre of the laser beam to the point where its intensity decreases by 1/e^2 of the maximum, i.e. by about 13.5%. In other words, it reflects the maximum diameter while maintaining a high radiation power without significant loss.

Do not confuse the laser beam diameter measured at 1/e^2 with the minimum focused beam diameter, which for an ultraviolet laser is theoretically closer to 0.000355 mm, but in practice can range from 0.012 to 0.047 mm, depending on the focal length and other lens characteristics.

Beam Divergence Angle <2 mrad, i.e. approximately 0.114592° at a distance of 1 metre from the source.

UV laser marker lenses

The UV laser marker can be equipped with lenses with different working fields: 75×75, 110×110, 200×200, and 300×300 mm. The smaller the working field, the greater the effect on the material as the focal point is smaller.

For example:

  • The 75×75 lens is well suited for micromachining;
  • The 200x200mm lens covers a wider area but has a larger laser beam diameter, making it more versatile;
  • The 300×300 mm lens produces a wide beam and a large spot, but also a larger possible engraving area.

It’s always best to have a few different lenses for different types of work.

Laser UV laser marker scanner

The original scanner gives you the ability to operate at 7000 mm/s without interruption, overheating, errors or malfunctions. The Wattsan UV TT laser marker scanner has the following features.

  • Linearity: 99.9% measures how closely the mirror movement matches the input control signal. In this case, a change in the control signal will result in a predictable change in mirror position.
  • Response time (setting time): ≤0.4 ms (0.0004 s) indicates how quickly the galvanoscanner responds after receiving a control signal.
  • Resolution: 12 µrad (≈ 0.00069°) indicates the minimum angle by which the galvo-scanner is able to change the position of the laser beam.
  • A microradian (µrad) is a unit of measurement that is equal to one millionth of a radian.
  • Repeatability: 8 µrad (≈0.00046°) indicates the numerically expressed ability of the device to reproduce the positioning result with multiple repetitive operations.
  • The long term drift over 8 hours shows how much the characteristics change during this operating time. The deviation is max. 0.5 mrad, i.e. ≈0.029°.
  • A scale drift of <40PPM/℃ provides an estimate, in parts per million, of how much the processing scale changes when the temperature changes by one degree Celsius. For example, if PPM/℃ is 40, this means that the performance of the galvo scanner will change by 40 ppm, or 0.004%, when the temperature changes by one degree Celsius – a negligible figure.

UV laser marker control board

The BJ JCZ laser marker control board is the key component that controls, coordinates and adjusts all the parameters of the laser system. The control system determines the positioning accuracy of the Wattsan UV TT, which is 0.003 mm. The control board also synchronises the UV laser marker with other devices, such as the rotary unit.

We only supply Wattsan laser markers with original control boards.

Software and PC requirements

The Wattsan UV TT is supplied with the EZCad 2 software installation package, which allows you to create and edit various graphic elements and assign processing parameters. EZCad 2 supports the creation of QR codes, barcodes and serial numbers and has the ability to synchronise with Excel.

EZCad has low system requirements, so any modern computer will do.

What products and materials can the UV laser marker process?

The ultraviolet (UV) marker can handle delicate and difficult-to-machine materials such as gemstones, microchip substrates, flexible circuit boards, resin and ceramic substrates, create circuit outlines and mark circuit boards, optical glass or highly reflective metals without causing structural damage or deformation to the material.

The UV laser is also suitable for the following materials: wood, stone, ceramics, textiles and leather.

Conclusions

The UV laser marker is ideal for precision marking, micro-machining, colour marking on metals and processing delicate materials.

The Wattsan UV TT laser marker creates a minimal heat affected area and has high accuracy and speed. The Wattsan factory not only provides a mandatory warranty on this equipment, but also helps with commissioning and training for new and existing customers. And all existing customers receive a free lifetime information service.

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