Everyday experience tells us that light reflected from a perfectly flat mirror will give us the correct image without any deformation. Interestingly, this is not the case when the light field itself is structured in a complex way. Tiny deformations appear. These have now been observed in the laboratory. The results confirm the prediction of this fundamental optical effect made more than a decade ago. They also show how it can be used, for example, as a method for determining material properties.