If you want to incorporate protruding three-dimensional features into a flat sheet of glass, the typical way of doing so involves heating that glass up and placing it in a mold. Those molds are costly to manufacture, however, plus the casting process isn't a quick one. That's why Germany's Fraunhofer Institute for Mechanics of Materials has developed a laser-based alternative technique that promises to be cheaper and faster.
The process begins with the unaltered glass sheet being placed face-down over an open space in an oven – that oven has been preheated to just below the melting point of glass.
Once the glass reaches that temperature, a laser beam guided by moving mirrors is used to selectively further heat the parts of it that are intended to protrude. This causes the glass in those areas to soften to a thick-honey-like consistency.
Because the glass sheet is unsupported underneath (except around the edges), gravity causes those softened bits to start sagging down. Once they've reached the desired shape, the laser is switched off, allowing the glass to cool and harden in its new form.
The whole process, from placing the glass in the oven to its being cooled down completely, takes about half an hour. That said, depending on the complexity of the design, the glass only needs to be in the oven and exposed to the laser for a few minutes – it's set to cool outside of the oven. This means that many pieces of glass could be moved through in a relatively short time.
The scientists are now studying how the process works with various varieties of glass, and are experimenting with the types of shapes that can be produced.