With Flying Triangulation we can measure the 3D topography of an object surface “on the fly”. Fields of application are twofold: On the one hand, measurements of complex or large objects such as sculptures or rooms, which require an excessive repositioning of the sensor. on the other hand, measurements of faces, teeth, or other body parts, where an uncontrolled motion of the object relative to the sensor is unavoidable.

FlyTri enables a motion-robust and freely hand-guided acquisition of objects by combining a simple sensor with complex algorithms. With a measurement uncertainty of 30 µm on a volume of measurement of 20 mm x 15 mm x 15 mm the sensor works at the physical limits. The sensor is scalable, from a measurement of teeth to an acquisition of large rooms.

 
We work on information-theoretically efficient full-field sensors for the inspection of technical surfaces with a depth sensitivity at the nanometer scale. The sensors use spatially and temporally incoherent illumination, are not based on interferometry and have no confocal pinholes.

Structured-Illumination Microscopy (SIM): A sinusoidal grating is projected in the focal plane of the microscope. By local contrast evaluation, SIM delivers the 3D-topography of smooth surfaces with a depth uncertainty of a few nanometers. At rough surfaces, the principally achievable uncertainty is determined by speckle noise and depends on the aperture (as in all triangulation systems).

Microdeflectometry (µPMD): A sinusoidal grating is projected by the micro-objective at a remote distance from the focal plane. The specular (smooth) object is located at the focal plane. A local tilt will cause a local phase shift of the grating mirror image. So this phase shift intrinsically encodes the local slope of the object. This unique feature makes the sensor the proper tool to measure local defects. Height variations in the order of one nanometer can be detected, with simple hardware.

Both sensors exploit the same technology, so they can easily be combined in one single microscope. The low noise, the high angular dynamic range, and the high depth of field allow for microscopic images with a quality similar to SEM images - with the further advantage to display quantitative 3D-data.

 
With phase-measuring deflectometry we are able to measure the slope - and by numerical integration the topography - of reflecting surfaces. We project fringes on a ground glass screen and observe the pattern, using the object as a mirror. Any slope deviations of the object lead to distortions of the fringe pattern observed by the camera.
To calculate the local curvature of aspheric lenses, we measure the slope of the surface and calculate the first derivative. This process is much less noise sensitive than the evaluation from shape data. The image on the right shows the surface astigmatism of a progressive eyeglass lens, measured with PMD. The curvature maps have an accuracy of better than 0.02D calculated on an area of only 3x3mm².
The method is scalable from large objects like painted car bodies or windscreens, over eyeglass lenses and wafers down to microlenses.

 
Observations about scientists life and all that.