Camera Offers Single-Shot, Real-Time, Ultrafast Imaging of Transparent Objects

A camera developed at the California Institute of Technology (Caltech) uses picosecond imaging technology to take photographs and videos of transparent objects at speeds of up to 1 trillion frames per second. Called phase-sensitive compressed ultrafast photography (pCUP), this camera technology can also take video of shockwaves and other ephemera.

The new camera combines the contrast of dark field microscopy with the speed and the sequence depth of compressed ultrafast photography (CUP), a high-speed photography system previously developed by professor Lihong Wang and his team. Phase-contrast microscopy allows better imaging of objects like cells, which are mostly transparent. “What we’ve done is to adapt standard phase-contrast microscopy so that it provides very fast imaging, which allows us to image ultrafast phenomena in transparent materials,” Wang said.

The fast-imaging portion of the system consists of lossless encoding compressed ultrafast technology (LLE-CUP), a video imaging technology that in a single shot can capture all the motion that occurs during the time the shot takes to complete. It is much quicker to take a single shot than multiple shots. LLE-CUP is capable of capturing motion, such as light in motion, which is too fast to be imaged by conventional camera technology.

A shockwave created by a laser striking water propagates in slow motion, as captured by a new ultrafast photography technology. Courtesy of Caltech.

To demonstrate the capabilities of their new camera, the researchers imaged the spread of a shockwave through water. They also imaged a laser pulse traveling through a crystal. By capturing images of shockwave propagation and the optical Kerr effect, the team showed that pCUP could image light-speed phase signals in a single shot, with up to 350 frames captured at up to 1 trillion frames per second, and with a 3-mrad noise-equivalent phase sensitivity.

The technology, though still early in its development, could ultimately be used in the fields of physics, biology, and chemistry. “As signals travel through neurons, there is a minute dilation of nerve fibers that we hope to see,” Wang said. “If we have a network of neurons, maybe we can see their communication in real time.”

Because temperature is known to change phase contrast, the new camera system could potentially be used to image how a flame front spreads in a combustion chamber.

The research was published in Science Advances (www.doi.org/10.1126/sciadv.aay6200).