Subsurface Laser Engraving, the Ultimate Glass Decoration Technique

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Principle and History

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 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.

Optical glass is a type of glass which is made in a very precise way. Any artefacts in the glass would influence the optical quality. For the 3D laser engraving process it is very important that the quality of the used optical glass is uniform throughout the whole block to avoid mistakes.

So the next time that you see somewhere written “3D crystal” you know it is actually not crystal but (optical) glass.

Applications

The most well-known application is for making corporate gifts. A glass block or any other form with an internal design of a company logo and text is a long-lasting gift which will definitely get a place at the desk of the receiver.

The technology has developed and objects are not limited anymore to a few centimeters by a few centimeters. Massive blocks of 15cm by 15cm can completely be filled up with designs and texts. So it is also an ideal material for glass trophies which are usually bulkier then the smaller blocks which are seen everywhere in the shops.

The general gift ware market is the second market for these products. Images of landmarks, like the Eiffel tower or the Taj Mahal, are popular souvenir items and create a lifelong remembrance of that special holiday.

Personalized gifts is another increasing market for the 3D crystal gifts. With new camera techniques and also just by software, a 3D image of the face/head is made in the wink of an eye. With some additional text it becomes a beautiful anniversary gift, a birthday gift or just a beautiful home decoration.

The technique of 3D crystal laser engraving is continuous evolving and the speeds are ever-increasing. This opened the way for other, larger applications. In offices, glass dividers with an internal laser engraved design find their way. Glass furniture, like table tops, can be decorated with this technique.

More and more popular are signs for commercial purposes. Especially the combination of these signs and LED-light technology are very powerful, because the engraving lights up and the other parts of the glass stay unlit.

Subsurface laser engraving has become in 15 years, from scratch, a powerful glass decoration technique which has found its place in the market and new technical improvements hand in hand with new developments for CAD will make it sure that we will see much more of this technique in the near future.

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