Fibers in composites, paper, or biological tissues are often hidden from view, but their orientation determines the strength and properties of the material. Previously, to see fiber directions, you had to take many images at different angles and assemble a three-dimensional picture, like slicing a loaf of bread into thin pieces. For thin samples, this approach doesn't work: you can't slice what isn't thick enough.

The new method works differently. An X-ray beam passes through the sample, and a special mask creates a pattern that changes depending on the tilt of the fibers. From these changes, the model reconstructs the orientation of multiple fibers at each point — up to two per pixel. It's like being able to tell from a shadow on the wall how several pencils in a cup are turned.

Tests on computer simulations and real experiments showed that the method reliably determines fiber angles. For materials science, this means rapid analysis of thin composites, films, and tissues without complex tomography. One image instead of dozens, and the picture is clear.