Researchers at MIT have identified an unexpected effect in optical physics that could lead to a faster and more detailed way to image living tissue. Under specific conditions, what normally looks like a scattered and disordered laser signal can reorganize itself into a narrow, highly focused "pencil beam." With this self-formed beam, the team produced 3D images of the human blood-brain barrier at speeds about 25 times faster than the current gold-standard approach, while preserving similar image quality. The method also makes it possible to watch individual cells absorb drugs in real time. This could help scientists evaluate whether treatments for conditions such as Alzheimer's or ALS are actually reaching their intended targets in the brain. "The common belief in the field is that if you crank up the power in this type of laser, the light will inevitably become chaotic. But we proved that this is not the case.…