WHY CONFOCAL AND INTERFEROMETRY?
Interferometry is a well known optical profiling technology. Its advantages are high Z resolution not depending on the magnification used, and thus low magnifications are performing very well. In contrast, confocal has the disadvantage of being sensitive to NA, but has the advantage of having high numerical aperture and thus being able to profile high local slopes. For NA bigger than 0.8, the Z resolution is better than 2 nm, comparable to white light Interferometry and performing at the same level. The main advantage is that high magnification is only possible with EPI/APO microscopy objectives. The Sensofar's PLu series cover the highest measurable surfaces by combining the low magnification interferential objectives (from 2.5X to 50X) and the high magnification confocal objectives (from 10X to 200X).