Complex sentence: Before the advent of the CCD beam profiler, the beam width was estimated using the knife-edge technique: slice a laser beam with a razor and measure the power of the clipped beam as a function of the razor position.
Split into simpler sentences: Before the advent of the CCD beam profiler, the beam width was estimated using the knife-edge technique. The technique is as follows: slice a laser beam with a razor and measure the power of the clipped beam as a function of the razor position.