Work Package 4: Process-integrated Quality Assurance

The global objective of work package 4 “Process integrated quality assurance” is the achievement of a stable replication process for optical components through a comprehensive measurement technology. This facilitates the acceleration of the mold making process and results in a reduction of costs. For this purpose, measurement of all geometric criteria is essential.

The overall objective is to engineer a self calibrating and automated metrology system for form testing of micro parts and the optimization of the data processing along the process chain.
To ensure the reliability along the whole process chain, four measurement principles need to be applied in the metrology system, which constitute the main results of work package 4:  

1. Profilometer

2. Tactile ultra precise coordinate measurement

3. Interferometric form testing

4. Fringe reflection deflectometry

Taylor Hobson Ltd (Leicester, United Kingdom) developed a profilometer which is capable of measuring steep sided, aspherical optics with slope angles up to 80° for optics from 1.2 mm to 50 mm diameter.

Comparison of the two developed probe systems	IBS Precision Engineering bv (Eindhoven, Netherlands) designed and realized an ultra precision tactile probe. In combination with a nanopositioning platform, this miniaturized probe system enables ultra precision coordinate metrology in 3D of a wide range of products.
Form testing interferometer integrated in production machine	Fisba Optik AG (St. Gallen, Switzerland) developed an interferometer for the integration into a production machine. The compensation of external disturbances (e.g. vibrations) by software based methods was a decisive factor for achieving this aim.

Laboratory for Machine Tools and Production Engineering WZL (Aachen, Germany) developed a software tool for the processing of measurement data and the comparison with design data. The target-actual comparison is done via coarse and best-fit alignment by using different surface information like topography, local slope and curvature.
The implemented adaptations of existing and the realization of new measuring systems now enable the measurement of a wide range of optical components. Consequently, corrective values can be directly reported into the production process.

Topography and slope error map of a toric lens