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Interferometric flatness calibration

We offer flatness calibrations of optical plane surfaces of a diameter of up to 300 mm using a traceable Fizeau interferometer. The flatness deviation should be smaller than 5 µm. Due to the measuring principle which uses a wavelength-shifting laser diode, plane-parallel plates can also be measured. The expanded measurement uncertainty (k = 2) amounts to 11 nm. The lateral resolution is determined according to the size of the surface to be measured. While doing this, the surface is imaged on a camera with 1000 × 1000 pixels.

Figure: Interferometer setup for flatness measurements


Heiko Reinsch
Phone: +49 531 592-4219
E-Mail: heiko.reinsch(at)ptb.de

Dr.-Ing. Gerd Ehret

Phone: +49 531 592-4220
E-Mail: gerd.ehret(at)ptb.de