  Though new affordable high power laser technologies make possible many
processing applications in science and industry, depth control remains a
serious technical challenge. Here we show that inline coherent imaging, with
line rates up to 312 kHz and microsecond-duration capture times, is capable of
directly measuring laser penetration depth in a process as violent as kW-class
keyhole welding. We exploit ICI's high speed, high dynamic range and robustness
to interference from other optical sources to achieve fully automatic, adaptive
control of laser welding as well as ablation, achieving micron-scale sculpting
in vastly different heterogeneous biological materials.
