As part of the "HoloMotion" project, a demonstrator for optical gear measurement was developed for use in production
Fraunhofer IPM has found two significant findings following the completion of the “HoloMotion” project. The measuring technique solution provider claims to have enhanced the 3D measurement method of digital multiwavelength holography, which was already established. Allegedly, Fraunhofer IPM found enhancements in two directions, the first being that components in motion can now be measured with high precision, and the second being an improvement in optical gear measurement using digital holography.
Key information:
- Fraunhofer IPM made two significant findings following the completion of the "HoloMotion" project.
- According to the project's researchers, the "HoloMotion" project found that components in motion can now be measured and that improvements can be made in optical gear measurement when using digital holography.
- The measuring technique solution provider believes the findings from the project will help further develop its HoloTop sensor.
The German Federal Ministry of Education and Research (BMBF) funded the joint “Dynamic holographic measurement method for detecting metallic freeform surfaces (HoloMotion)” project. During the six (approximate) years the project ran, researchers from Fraunhofer IPM demonstrated that digital holographic measurements could be made on moving test components. This allowed the researchers to exploit the advantages of interferometry on moving surfaces, for the very first time. Additionally, gear measurement was chosen as a sample application for the new method. This is due to the measurement being very challenging for interferometric measurements because of the high inclination angles and low component tolerances.
As the project progressed, researchers were able to demonstrate that digital holographic measurements were possible even at velocities above 10 mm/s. The researchers found two decisive contrasting factors:
- Movements perpendicular to the optical axis are not critical and will still allow for precise interferometric measurements.
- Whereas axial movements, meaning movements in the direction that the method measures most accurately, are critical.
These measurements are sensitive, with very small movements of half a wavelength making them impossible. To make up for these disturbances, the researchers started investigating the fundamental relationships and limitations, as this allowed the team to develop successful solution strategies. The result of this strategy led to a patented compensation approach which can make up for axial relative motions of more than one wavelength per each exposure time.
With help from FRENCO GmbH and ZF Friedrichshafen AG, the project spawned a demonstrator system for optical gear measurement. The system was developed and tested, with a close proximity to production in mind. Following the assistance of the two previously mentioned companies, researchers were able to prove that the digital holographic measurement of gears was possible in industrial environments. Additionally, the new system (in an optical process) displayed a proven advantage over other tactile gear measurements, as the new method could perform two-dimensional flank measurements every second.
As a result of the “HoloMotion” project, Fraunhofer IPM has been able to extend the capabilities of its HoloTop sensor for 100% inline inspection of precision components. The measuring technique solution provider believes it can now extend the HoloTop’s capabilities to measure moving objects. This could lead to the advancement of interferometric measurement techniques, both generally and in optical gear measurement techniques.