US Patent 9468991 Method determining hole completion

The present disclosure provides a method for determining a hole completing in laser drilling of a hole in a near wall of an airfoil. The method includes drilling a hole in the near wall of the airfoil using a laser drill. The laser drill may move in a pattern relative to the airfoil. The method also includes determining when the drilling of the hole is complete based on a calculated time duration between successive breakthroughs of a laser from the laser drill through the near wall of the airfoil, or based on a calculated time duration since the latest breakthrough of the laser from the laser drill through the near wall of the airfoil.