3-D carving??

[Ken Garlock]

HI. I was at the local flea market today, and noticed that several vendors were selling what they called 3-D carvings in crystal. I examined a couple items and the carving was inside the block of of whatever. I would guess that it was Lucite or Plexiglas, but seemed heavy for a block about 1.5" square and 2" long. There was no apparent seam where two sections had been joined after the carving. It reminded me of the carving our shop teacher did in Plexiglas with a Dremel-like tool and a sharpened nail.... The difference was that it was in the center of the block, and was of extreme detail. The images were truly 3 dimensional, and white like you see in cut glass. It was obviously computer generated, IMO.

So my question to all you Laser experts is how do they do it?

[Aaron Koehl]

Ken,

The 3D Crystal "carving" is done with lasers, yes, but not your average laser engraver. Basically, the 3D projection is made by melting the material at precise depths.

Like surgical lasers, a cut is only made at the focal length of the laser, with the surface of the material left untouched. The crystal itself or the laser is moved on each of 3 axes to create a 3D rendering inside of the crystal.

They also use these types of lasers to zap and break apart kidney stones without damaging the layers of skin between the laser and the stone.

I was looking into these (crystal engraving lasers, not kidney stones) a few months ago, but the lasers used are much more expensive.

(Well, here was hoping!)

[Ken Garlock]

Hi Aaron

Thanks for the info. The engraving detail is just too much to believe at first glance. I was a little puzzled since laser light by nature is non-diverging beam without a need for a focal point. From what you say, if read correctly, they focus the parallel light beam into a single point to cause the material to "char" within the crystal material.

I knew that the doctors were using sound waves to break kidney stone several years back. It only seems like a natural follow-on that they would have a laser probe to smash the stones. I think I would want to be deep under while they had that probe working

Thanks....

[Aaron Koehl]

Indeed- each point inside the crystal is .1 mm in diameter. I also found out that special
care has to be taken in the design of the graphic so as not to have areas that are too
clustered, otherwise the crystal would break. (which makes sense)

It was my initial hope that 3 of the 6 planes in the cube could be engraved with a 2D
projection, showing a 3D hologram when viewed at the right angle. Turns out it
really is 3D- I guess I couldn't be that lucky.