Subsurface Laser Engraving, the Ultimate Glass Decoration Technique

Nowadays, everybody has seen these glass products with a 3D image inside. People are always amazed about the looks of the models inside whether it is a car, a sailboat or just a company logo.

In fact the image created in this way looks like a sculpture inside a glass block. This is probably the reason, why this glass decoration technique is so very popular. It is the first technique which makes it possible to create a ‘sculpture’ with the help of a computer (CAD). The first time that the 3D models from inside the computer can be transformed in something real outside the computer!

Subsurface laser engraving or 3D crystal laser engraving, is a style of glass decoration where glass markings (tiny dots) are made inside a glass object without disturbing the surface of the glass object.

How these subsurface laser engraving machines do their job is in fact not so difficult to understand.

Everybody has, mostly in his or her youth, put a shoe string or a piece of paper on fire with the help of a magnifying glass. The sunbeam is focused or bundled by the magnifying glass. In the focal point the bundled energy of the sunbeam is so high that the material and the oxygen in the air react and so the material starts burning. The condition in this case is that the material must be able to burn in air, like paper, wood, dry grass, shoe string, etc.

Instead of sun light it is also possible to focus a laser beam with a lens. If the wavelength of the laser light is well-chosen, the bundled energy in the focal point of the lens can interact with glass. For glass, that wavelength is 1064nm or 532nm. Light and also laser light travel through glass normally without any interaction. Is the energy of the light high enough and has the laser light the right wavelength, then something happens to the glass. While glass is normally transparent, at that focal point that specific laser light makes it locally non-transparent. This area in the glass is then seen as a tiny white dot.

By moving the focal point and laser to different locations and creating dots at these locations, a 3D model can be built.

In fact, the subsurface laser machine makes the model in slices. First the machine makes the dots in one plane at the bottom of the glass cube. Then it moves up a little higher and makes the dots in the next plane, by doing so, on and on, it creates a 3D model.

So the fun part of this technique is that the laser light only can make dots at the focal point and the rest of the glass object through which it travels stays untouched.

Originally the technique was invented in Russia as a spin-off of the Best laser engraver laser program during the Cold War. At first the dots were relatively big and the models were only composed of 50 to 200 points. But since they were the first ever shown at gift ware fairs, everybody was truly amazed.

After the Fraunhofer Institute in Aachen, Germany, the powerhouse for international laser developments, invented in 1997 a new type of laser the technique became really popular. This new laser made very tiny dots and the writing speed was incomparable with the Russian technology. This resulted in models, with say 50,000 dots, which took only 20 seconds to be engraved in a glass block.

The gift ware world had a new tool to make wonderful glass products.

3D Crystal or Glass?

The term 3D crystal laser engraving is widely used instead of subsurface laser engraving.

Although subsurface laser engraving describes exactly what happens, it sounds commercially more interesting to call it 3D crystal laser engraving. The word ‘crystal’ appeals more valuable to people than glass and that is probably the reason for this somewhat confusing name.

Although it is possible to do subsurface laser engraving in crystal and many other transparent materials, the material usually used for this technique is Optical Glass.

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