Page 14 - smartWLI technology

extended phase shift interferometry

µm

20
15
10
5
0
-5
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 m

VSI (vertical scanning interferometry)
algorithms are looking for the max. interference pattern in the image stack

the z – resolution is limited to app. 1 nm

PSI (phase shift interferometry)
the phase shift analyses increase the z resolution

the z – resolution is improved to app. 0.1 nm but limited to steps up to app. 250 nm

EPSI (extended phase shift interferometry)
the extended phase shift interferometry combines both algorithms

the improved z – resolution can be used on objects with heights of several µm

Ra = 25 nm