The points are tiny (.1mm) fractures created by a focused laser beam. The conical beam, with a focal length of about 3", shines into the glass without damaging it except at the focal point. At that one point, concentrated energy heats the glass to the cracking point, causing a microfracture.
To draw more points, the laser is pulsed on and off. To make the beam move between points, it's reflected from a mirror that is repositioned between pulses. The mirror is moved by computer-controlled motors, so many points can be drawn with great speed and accuracy. A typical design might use several hundred thousand points, or half a million isn't unusual in a large block, each placed with .001" accuracy.
This can be done with different types of laser, and the results vary -- you've probably seen cheap crystals with fuzzy points, which mean that the laser is either low-frequency or not well focused. I'm currently using a high-frequency laser, which draws points that are barely visible to the naked eye. I'm told it's a Nd:YAG laser, named after its active medium: a yttrium-aluminum-garnet crystal doped with neodymium.
The glass itself must be clear optical crystal, since any ripples or bubbles would block or blur the laser. It's also necessary to draw in layers, moving from rear to front of the glass, so that previous points don't block the laser from drawing new ones.
The glass surface must be dead flat, or refraction will blur and redirect the beam; that's why it's difficult to work with spheres or other curved shapes. They can be burned by immersing the piece in a glass vat of optically matched liquid, but that's a lot of work. Refraction is also an issue in viewing curved glass: in a 60mm sphere only about the central 20mm can be used, because optical magnification makes that area seem to fill the whole sphere. If anything is drawn closer to the surface than that, it will look very distorted.
The origin of laser-damage imaging is shrouded in mystery and lawsuits. Some hold that it was invented in what's now Russia, possibly as a byblow of military laser research. More about that is in this interview. (The interviewee, Dr. Troitski, has been very helpful to me in understanding the uses and constraints of the medium.) Others assert that the laser marking process was created by a British brewery as a method for indelibly marking beer bottles. I couldn't say which is true.
All designs are made entirely of points because the process offers no way to draw continuous lines or surfaces. However, with small enough points it's possible to arrange them into convincing curves, surfaces and volumes.
This isn't a trivial process, since a simple row of points doesn't look like a clean line, nor does a plane of points give a good-looking surface. Spacing is critical: points can't be grouped too closely or the glass can crack, but if they're too far apart the structure will be grainy.
Commercial software exists to solve these problems, but it doesn't address the special requirements of scientific imaging. To get precise control over the medium, I've written my own software for building and conditioning point clouds.
It took many experiments and much recycled glass to get everything working. I began by drawing sculptures in glass, using CAD to generate the initial points, and from there I moved into scientific imaging. Now I'm casting a wide net for interesting data: astronomy, mathematics and molecular biology have yielded some good models, but there's plenty to do!
Know of some interesting 3D data? Suggestions are welcome.
I'd like to use one of your pieces for an award or memento, can you add text to the image?
Yes, please write. I can probably do it,
with a modest setup charge.
I want to buy a laser etching machine, can you advise?
I don't own or sell laser etching machines. One manufacturer
Can you work from a photo or drawing?
I only work in 3D. Laser Crystal Awards can etch photos for you.
Can you etch my car/house/child/sculpture?
Scientific imaging is my specialty. I also don't have a 3D scanner.
I saw a similar glass cube at a sidewalk stand, it cost $6.
Yes, there are many cheap imports, often with very large laser
marks. Mine are US-made with the highest frequency laser
available, and also they are designed by me.
Can you put me in touch with a laser etching facility?
Yes, there are links here.
Can I get just the light stands without glass?