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Form and Wavefront Metrology

Working Group 4.21


The Optical Form and Wavefront Metrology Working Group develops forward-looking novel measurement methods to allow essential components of optical imaging systems to be measured by optical methods with as low a measurement uncertainty as possible. Here, work is at present focussed on measurement methods to determine the form of optical functional surfaces such as reflecting or lens surfaces which exhibit a spherical, aspherical or free-form surface.

New developments are achieved in close cooperation with industry and are also realized in the form of novel measuring instruments to allow customer-specific measurements and calibrations to be carried out for research and industry. The current measurement and calibration service comprises, for example, the measurement of the sphericity of optical surfaces, wave aberrations of imaging systems by interferometry, the refractive index of solid and liquid substances, the optical rotation of quartz control plates, as well as the transmission of beam-shape-changing optical components.

The measurement of flat surfaces is dealt with by PTB's Working Group 4.22 (Flatness Metrology) which focusses on Flatness Metrology.

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  • Asphere metrology using the Tilted-Wave Interferometer (TWI)


  • Traceable Multi Sensor method (TMS) for form metrology of curved optical surfaces

Applications for mathematics-based measuring methods in close cooperation with PTB’s Working Group 8.42 which deals with Data Analysis and Measurement Uncertainty

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