The machine in question is a 3D Systems Viper high resolution unit. I used a long exposure on a tripod to capture the actual laser beam tracing the part; the laser is a diode pumped solid state Nd:YVO4 100mW laser. For those of you unfamiliar with how SLA process works, it works like this:

1) A computer solid model is sliced into thin slices, between 0.002″ to 0.003″ thick. All the newer machines are 0.003″ or better in Z-resolution.

2) A laser then traces the cross section in a vat of photopolymer. Okay, by photo-polymer, I mean, a vat of very expensive goo – where the laser touches the goo, the goo turns into plastic. How expensive? I’ve heard that when it first came onto the market, resins were about $5000 – $6000 per gallon. They have since came down in price, but suffice to say it’s a very expensive proposition.

3) After each layer is formed, the platform in the tank drops by a build layer thickness and the goo flows over the part, readying the next layer to be drawn.

4) At the end of the build the platform gets raised again and the goo drains off the part, leaving you with a solid object.

These are very expensive machines – starting price of one of these is in the quarter-million dollar range, and the laser only lasts so many hours before it has to be replaced. Needless to say, unless you’re keeping the machine *very* busy, just the depreciation would eat you alive.