A jet engine turbine blade lives in an environment hotter than the melting point of the metal it is made from. It survives because it breathes. Hundreds of microscopic holes across its surface bleed cool air outward, forming a thin protective film that holds the combustion gases off the metal. Drilling those holes without wrecking the blade is one of the quiet problems that decides whether an engine runs for years or fails in flight. The blade is a single crystal of nickel superalloy, grown as one continuous lattice so there are no grain boundaries for cracks to run along. Inside it is hollow, threaded with cooling passages. A laser drilling through the outer wall faces two enemies: - The recast layer. Fast, energetic pulses melt the metal and blast it clear, but molten material resolidifies around the hole as a brittle, cracked skin that seeds fatigue failure. - The back wall. Punch straight through the outer wall and the beam carries on to strike the opposite internal surface, goug...