2. Optical metrology

We will now take a closer look at the main methods used in optical metrology. Rather than catalog them, we will group them according to the underlying optical concept. In this way, we hope to highlight the profound unity and permanence of the methods from which they derive, beyond the rapid evolution of technological advances. A remarkable example is provided by the development of the laser. For more than thirty years, we have been witnessing a flowering of devices in which this source is the fundamental element. For most of them, however, the laser has merely made measurement easier, the method itself having been known for a very long time.

We'll confine ourselves to sporadic allusions, as this is not our purpose, but the union of optics and electronics is growing ever closer, to the point where some have seen fit to rename the old science of Huyghens and Fresnel...