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An introduction to laser marking

laser marking

As its name implies, laser marking involves the use of a focused continuous-wave, pulsed, or ultrashort-pulsed beam of light that interacts with the surface of a material to alter its appearance and properties. The process can be used to create precise, high-quality, high-contrast and permanent marks that are easy to read or scan, on virtually any surface. 

The first laser marker was developed in 1965 for drilling holes in diamond manufacturing dies, with the use of the technology growing rapidly thereafter. CO2 lasers were first used for marking in 1967, with the technology reaching maturity in the mid-1970s through a commercial, modern laser system.

Laser marking systems are today used in the automotive, aerospace, pharmaceutical, retail and medical device industries, among others. 

Laser marking is quick to carry-out; the fastest commercial laser markers can now process tens of thousands of parts per hour. In addition, in comparison with other marking technologies, such as inkjet printing, marks made with lasers are often more robust, repeatable, and cheaper to produce. Furthermore, the process does not require the use of any consumables such as ink or paper, making it more environmentally friendly than conventional marking technologies.

Types of laser marking

There are a wide range of laser-marking techniques available, the choice of which will depend on the material to be marked and the quality of marking required.

Each of the below methods can be applied to create, for example: lettering on awards, trophies and jewellery; symbols and maps on signage; and serial numbers, barcodes or data matrix codes on parts used in the automotive, aerospace, electronics and medical device industries – where traceability is becoming increasingly important.

Laser engraving

Laser engraving involves using a beam to remove material from the surfaces of components. During the process, the material the component is made from will absorb heat from the laser until it vaporises, creating marks in the form of depressions. The material will also react with air, causing a colour change to black that will make the mark more distinct. 

As no consumables are needed to carry-out laser engraving, it is generally more cost-effective than other engraving methods that rely on, for example, drill bits, which need replacing as they wear out. Furthermore, laser engraving is highly versatile; it can be carried out on a wide range of materials, including metals such as steels, aluminium, and copper, as well as certain plastics and ceramics. The depressions created by laser engraving make the resulting marks highly tactile while also being very durable. 


Lasers can be used to engrave a wide variety of metals and non-metals with durable, permanent marks. (Image: Shutterstock/Zyabich)

However, laser engraving can be energy intensive when materials such as stainless steel are to be engraved. In addition, the integrity of the surface of the material can become compromised after engraving, which in some cases can hasten the corrosion of parts used in harsh environments. 

Laser etching

Laser etching involves using a fibre laser to create a raised mark on the surface of a material by delivering large amounts of energy to a small, localised area. Consequently, the surface of the material melts and expands, and its colour changes to black, grey or white depending on the parameters used.

Much like laser engraving, laser etching is a versatile process and is suitable for marking a wide range of metals including aluminium, steels, zinc, lead and magnesium, as well as non-metals such as paper, wood and plastics. 

Compared to laser engraving, laser etching is a faster process that consumes less energy. This is because more energy is required to vaporise material (as is done in laser engraving) than to simply melt material (as is the case in laser etching). However, while laser engraving doesn’t have the upper hand in terms of speed and energy consumption, its marks are notably more durable than those of laser etching. This is because the depressions made with engraving have a better protection against abrasion than the elevated marks formed with etching.

Laser etching elevation can reach up to 80µm, whereas engraved marks can often be up to 500µm deep. 

Laser etching regains the upper hand however when it comes to creating high-contrast marks. This is because it can be used to create white, black and grey marks, whereas laser engraving can only be used to create black marks.

Laser annealing 

Laser annealing involves the surface of a metal being slowly heated with a beam. This creates a mark 20-30µm below the surface as the metal begins to oxidise internally. The thickness and thereby colour of the internal oxide layer is determined by the highest temperature reached at the surface of the metal during heating. This temperature is controlled by the intensity of the laser, the speed at which the beam sweeps the surface, and the line spacing between consecutive passes of the beam. Marks created by laser annealing can be made in a variety of colours, are abrasion-proof, and do not affect the corrosion resistance of the part (as is the case with engraving). This makes the process highly suitable for marking materials used in harsh environments, such as ferrous metals and titanium.


Lasers can be used to mark metallic surfaces in high-resolution and in a wide range of colours. (Image: AIDAM)

Carbon migration

Through carbon migration, the base material is heated with a laser beam, causing it to chemically bond with carbon molecules at or near its surface. This creates a dark, smooth, permanent mark, making it suitable for use on medical devices where any surface roughness might harbour contaminants and/or microbes, and the process is fast compared with annealing. Carbon migration can be used to apply marks to metals, paper, wood, leather and packaging materials. Marks produced using carbon migration will not be easily visible on dark-coloured components, however.


Foaming is suitable for producing light-coloured marks on dark-coloured plastics, and sometimes stainless steel. Through the process, the surface of a material is heated with a laser so that it melts and creates bubbles that become trapped during cooling. The resulting markings are raised around 20-40μm high and can be relatively wide. Light then reflects off the raised marks, making them appear bright on dark plastics.

Lasers used for marking

While the earliest laser marking systems relied on COlasers, there are now a variety of technologies available.

CO2 lasers

CO2 laser markers often take the form of sealed-tube systems with galvo-steered light beams. With their relatively long wavelength of 9-11µm, they are best-suited to marking non-metallic surfaces – e.g. materials such as papers, leather, wood and some plastics. High-power CO2 lasers can be expensive to maintain, however, and are less energy-efficient than their modern fibre laser counterparts.

Fibre lasers

Fibre lasers feature a gain medium of silica glass fibre doped with a rare-earth element, and can produce infrared wavelengths of light of between 780nm and 2,200nm. Fibre lasers are suitable for the production of high-contrast markings through metal annealing, etching and engraving. They have an extremely small focal diameter that increases laser intensity by up to one hundred times compared with CO2 systems, making them good options for the permanent marking of serial numbers, barcodes and data matrices They are capable of marking a range of materials, however are generally optimised for metal marking. Fibre lasers are smaller, more energy efficient and require less maintenance than CO2 lasers. They can, however, be significantly more expensive than CO2 lasers to purchase.

Nd:YAG/Nd:YVO4 lasers 

Similar to fibre lasers, Nd:YAG/Nd:YVO4 lasers are compact, energy-efficient, and emit around the 1,064nm wavelength. They offer excellent beam quality, depth of focus and high peak powers, and are suited to fine marking (annealing, etching and engraving) heat-sensitive materials in applications where high consistency is required. They can be used to mark metals including steels, iron, aluminium, brass, copper, gold, silver, nickel, titanium and platinum, as well as non-metals such as glass, plastic, paper, plexiglass and ceramic.

Ultraviolet lasers

Ultraviolet (UV) lasers have a wavelength of 355nm, far shorter than either fibre or CO2 lasers. This wavelength is achieved by passing a standard wavelength laser at 1,064nm (infrared) through a nonlinear crystal, reducing it to 532nm (green), this is then passed again through another crystal, which brings the wavelength down even further to the final 355nm (UV).

This short wavelength makes them well-suited to ‘cold marking’ – delivering high-energy photons that break the chemical bonds of a material to produce a mark while avoiding any thermal damage on the inner layers and surrounding areas of the target. For this reason they are not suitable for engraving. UV lasers can be used however to create highly precise marks on virtually any delicate material: glass, teflon, diamond, ceramics, silicone, plastics, precious metals, even fruit. UV lasers are also very energy efficient and require little maintenance. They can however be more expensive than COand fibre lasers.

Green lasers

The 532nm wavelength of light created by a green laser can be used to mark a wide range of plastics, reflective materials, and materials that are sensitive to heat. Precious metals such as gold, silver and copper can be marked easily using a green laser and they are often a good choice for marking printed circuit boards, electrical components, computer chips, foils, magnetic cards, and sensitive electronics. Transparent or translucent materials, or those of colours that cannot be marked using a traditional 1,064nm wavelength fibre laser, can often be marked with a green laser.

Growing applications of laser marking


Owing to the growing use of ceramics in the manufacture of printed circuit boards (PCBs), laser marking systems are increasingly being employed as alternatives to ink-based printing. Many laser system manufacturers have developed machines that exploit sources particularly suited to the marking of ceramics, such as UV lasers as well as traditional CO2 lasers, in order to serve this growing market.

Fruit and vegetables

Distributors of fruit and vegetables are looking to reduce the number of stickers and the amounts of packaging that they use to brand and protect their products. Organic products are required by law to be recognisable as such by consumers, meaning that many supermarkets need to package and/or sticker the organic products they sell. 


Ginger, avocados, mangoes and sweet potatoes are commonly marked using laser technology (Image: LaserFood)

Eosta, a European distributor of organic fruit and vegetables, claims to have saved fifty million pieces of plastic packaging thanks to its use of laser marking technology. The process it uses involves the removal of a trivial amount of pigment from the outer layer of the skin or peel of a vegetable or fruit. The method not only saves plastic and paper, but also large amounts of energy and emissions; a laser mark requires a mere fraction of the energy required for a sticker. According to EcoMark, a European provider of food-marking systems, throughput rates of around 50,000 vegetables or pieces of fruit per hour are achievable using laser technology.


By marking individual products with unique data matrix codes, it is possible to easily identify the company that made it, its lifespan and its batch number in a quick, easy and non-invasive manner. Such codes are used for quality assurance purposes; consumers and users can check where a product comes from simply by scanning the mark with their smartphones. This is especially useful in the manufacture of medical devices and components for the automotive/aerospace industries, for instance, where an easily accessible record of such details could be vital in the event that something goes wrong. 


Parts in the aerospace and automotive industries, such as this tyre, are increasingly being laser-marked with data matrix codes for traceability purposes. (Image: 4JET Technologies)

The ability to trace a product, learn when it fails, or find out when it reaches the end of its lifetime, enables manufacturers to be proactive about replacement and recycling. 

Due to their precision, lasers can produce detailed codes down to 200μm in size, small enough that they cannot be easily seen, but can still be scanned if a person knows their location. At such sizes, data matrices can be used for anti-counterfeiting purposes, making it easy to confirm the authenticity of a high-quality good in a non-invasive way. 

Glasses, polymers and thin metal foils can be difficult to mark with such codes, however, as can curved surfaces. To solve this latter problem, laser-marking system manufacturer Laserax offers CO2 and fibre lasers equipped with focusing optics that adjust automatically for the curvature of an object. 


Medical devices such as these scissors (left), kidney dishes (middle) and syringes (right) can be laser-marked with anti-corrosive traceability codes and other key information. (Images: Foba & NKT Photonics)

Manufacturers also often require extremely high throughput. This is a problem, as each mark must be adapted for the individual product to which it is applied, but the rate of marking must be high. To address this, another laser marking system manufacturer, QiOVA, has developed its VULQ1 technology that does not rely on one beam operating on a sequential basis (as is the case for traditional marking systems), but instead uses hundreds of beams to create a stamp-like effect, producing a whole data matrix code in an instant. The technology can, for instance, be used to mark polyvinyl chloride (PVC) medical parts with 570μm-wide data matrix codes at a rate of 77,000 parts per hour. Other materials the system can mark include aluminium coated with high-density polyethylene (HDPE), soda-lime and borosilicate glasses, pure gold and epoxies.

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Lead Image: Shutterstock/Surasak_Photo

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