Lasers build three-dimensional circuits

Making a three-dimensional circuit is no easy task. At the moment, chip designers build them layer by layer but this is a tedious process and it limits the designs that can be used.
Now Jianrong Qiu, a physicist at the Shanghai Institute of Optics and Fine Mechanics, and colleagues from China and Japan have worked out a way to draw the desired circuit directly into a block of glass. The secret was to add gold oxide to the glass, at a concentration of one part in 10,000. Then they focused short laser pulses on to specific points inside the block, to dislodge individual atoms of gold. When the block was heated to 550C, the gold atoms coalesced into tiny globules.