Abstract
White Light Interferometry (WLI) is widely used for rapid and accurate topographic measurements of surfaces. By creating three dimensional images with lateral sizes from several millimeters to some tens of micrometers, both large and small samples can be studied. The introduction of a separate laser interferometer in the scanning unit was meant to increase the accuracy of the depth scale from 1 % to about one hundredth of this value. This would mean that WLI could be used for accurate measurements of the vertical dimensions of millimeter sized components, and not only to quantify their surface roughness.
In order to investigate the capabilities of the Wyko NT9800 white light interferometer and to check its accuracy for large step measurements, we built our own step standard and measured the step height independently by a white light interferometer with a reference laser interferometer set up in the lab. A thorough investigation of possible sources of error for the lab measurements was carried out. We further investigated the stability of the step standard over time and checked the reproducibility of the NT9800 measurements. Our results indicate that the accuracy of the NT9800 is about 0.05 %.
In order to investigate the capabilities of the Wyko NT9800 white light interferometer and to check its accuracy for large step measurements, we built our own step standard and measured the step height independently by a white light interferometer with a reference laser interferometer set up in the lab. A thorough investigation of possible sources of error for the lab measurements was carried out. We further investigated the stability of the step standard over time and checked the reproducibility of the NT9800 measurements. Our results indicate that the accuracy of the NT9800 is about 0.05 %.
