Recording slight defects or textural differences in the microstructure of an object until now has either not been possible or only with a great deal of effort. The resolution of industrial cameras is generally limited to 50 megapixels (MP). Higher resolutions can usually only be reached at the expense of pixel size and that normally goes hand in hand with lower light sensitivity.

What's more, when it comes to quickly recording and analyzing large surfaces at high resolution, imaging methods for inspecting surfaces soon reach their limits. It is often necessary to scan the desired measurement field, which only causes further problems. For example, the camera or the object must be traversed with precision, and it becomes necessary to carry out time-consuming calculations when combining the individual images (stitching), since acquisition characteristics such as perspective and lighting differ across the measurement field.

Higher resolution at large measuring field thanks to pixel shifting 

With TexCam, Fraunhofer IPM offers a flexible, robot-assisted (depending on use) inspection system that solves these problems: A highresolution camera increases the resolution of an overall image recording up to ninefold by rapidly and precisely shifting the image sensor.

The recording is done in a sequence with up to nine individual images which are then combined. For each of these individual images, the image sensor is shifted laterally in 1/3 pixel steps in both directions within a matter of milliseconds by means of an integrated nano stage. Traversing the camera or the object externally is not required, and computationally intensive stitching of individual images is no longer necessary. Equally, the perspective and lighting remain unchanged during each of the individual recordings. That’s how TexCam can either reach extremely high resolutions with comparably large measurement fields (e.g., 5 µm / pixel at 100 mm × 80 mm) or very large measurement fields at high resolution (50 µm / pixel at 1 m × 0.8 m).

Rapid microstructure and surface analysis

The TexCam inspection system enables rapid microstructure or surface analysis on the flat surfaces of almost any structure or material. That could be the recognition of microcracks in metal materials or defects in woven textiles, for example. TexCam is also suitable for the inspection of photolithography plates used for the production of electrical components, or for the inspection of entire printed circuit boards (PCBs). Even inclusions in natural materials such as wood or cork can be detected thanks to the high resolution. In practice, TexCam analyzes all materials in which potential surface defects are noticeable due to a change in its microstructure

One inspection system, a multitude of possibilities

The system’s flexible design is easily adapted, making the inspection of different objects possible. The robot-assisted handling facilitates a simple and precise recording of the object. Both optics and lighting can be adjusted thanks to the modular structure, to best highlight individual textures and defects. The software, which is customized for each use, provides an automated image recording and allows for evaluation on the basis of typical texture analysis algorithms and high-efficiency AI methods (in particular deep learning).