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3D Roughness Metrology

Working Group 5.14

Developements in interference microscopy

Determination of the aperture correction
The distance between the different stripes of light interferences correlates to the hight differences in the surface. The hight difference between two stripes is equal to the half of the wavelength of the used light. But on closer inspection it is necessary to determen and use an korrection factor to calculate the hight profile of the surface. This correction factor includes the aperture correction of the objective.

Interference microscopy with not required aperture correction
With an modfied Michelson interferometer head is possible to avoid aperture corrections.

Standard procedures for calibration of interference miroscopes
To compliance quality assurances some important metrological characteristics of interference microscopes has to bee refeeded. For user help the PTB in cooperation with representatives of industrie, manufacturers and institudes of VDI created standard procedures to calibrate interference microscopes.

  • description rules to refeed uncertain calculations.
  • foundation for comparability between different interference microspoes and other surface measurering methodes
  • presents acceptance conditiones and performance between producer and consumer.

Two wavelenth interference microscope
To meas deeper grooves above 10 µm up to 100 µm an exactly knowledge of the wavelength of the used light is necessary. A resolution of this problem is am interference microscope witch uses two different wavelengt at once. Such an microscope is in developement by PTB.