Phase-sensitive compressed ultrafast photography (pCUP) can take video not just of transparent objects but also of more ephemeral things like shockwaves and possibly even of the signals that travel through neurons. The new imaging system combines a high-speed photography system with phase-contrast microscopy that was designed to allow better imaging of objects that are mostly transparent such as cells, which are mostly water.
Phase-contrast microscopy works by taking advantage of the way that light waves slow down and speed up as they enter different materials; for example, if a beam of light passes through a piece of glass, it will slow down as it enters the glass and then speed up again as it exits. Those changes in speed alter the timing of the waves. With the use of some optical tricks, it is possible to distinguish light that passed through the glass from light that did not and the glass, though transparent, becomes much easier to see.
The fast-imaging portion of the system consists of lossless encoding compressed ultrafast technology (LLE-CUP). Unlike most other ultrafast video-imaging technologies that take a series of images in succession while repeating the events, the LLE-CUP system takes a single shot, capturing all the motion that occurs during the time that shot takes to complete. Since it is much quicker to take a single shot than multiple shots, LLE-CUP is capable of capturing motion, such as the movement of light itself, that is far too fast to be imaged by more typical camera technology. Capabilities of pCUP were demonstrated by imaging the spread of a shockwave through water and of a laser pulse traveling through a piece of crystalline material.