Roughness Measuring Methods

Developments in the field of interference microscopy

Determination of aperture correction
The spacing between two interference orders does not exactly correspond to a height difference of /2 on the surface. The result of the interference evaluation must rather be multiplied by the aperture correction factor K. more

Aperture correction free interference microskope
Use of a modified Michelson interferential microscope head allows the challenge of aperture correction to be avoided. more

Guideline for the calibration of interference microscopes
To comply with quality assurance measures, important metrological characteristics of interference microscopes must be traced back. As a support for the users, a guideline for the calibration of interference microscopes was elaborated by PTB in cooperation with representatives from industry, manufacturers and institutes in a committee of the VDI (Association of German Engineers).

• It describes rules for traceability and uncertainty calculation
• It provides the base for the comparability of measurements with different interference microscopes and with other surface topography measuring instruments
• It offers acceptance and acceptance terms between suppliers and purchasers
  more

2 wavelengths interference microscope
For large depths of setting gauges in the range between 10 µm and 100 µm, the wavelength of the light used must be known with high accuracy. To solve the problems connected with it, an interferometer was developed which allows depth setting standards to be calibrated in this depth range. more