Generally speaking, if you want to capture clear images of crazy fast motion, such as molecular interactions or water droplets, you need a super expensive rig. Researchers have developed a system built using projector technology that could significantly reduce costs.
A research team composed of members from Canada's National Institute of Scientific Research (INRS), Concordia University and MetaPlatforms has developed a new camera capable of capturing events in a single exposure at 4.8 million frames per second, with a temporal resolution of 0.37 microseconds and a sequence depth of 7 frames."
Performance-wise, this isn't on par with what Caltech accomplished a few years ago, but the DRUM technology is built using off-the-shelf components and costs a fraction of commercial systems.
"Our camera takes a completely new approach to high-speed imaging," said INRS' Jinyang Liang. "Its imaging speed and spatial resolution are similar to commercial high-speed cameras, but using off-the-shelf components, it may cost less than one-tenth of today's ultra-high-speed cameras, which start at nearly $100,000."
The development centers on a new time-gating method called time-varying optical diffraction. In a regular camera, a shutter-shaped gate controls the amount of light that hits the sensor. Time gating involves rapidly opening and closing a door several times to capture brief high-speed video.
The team proposed a method for temporal gating using light diffraction, which involves "rapidly changing the tilt angle of the periodic facets on the diffraction grating" to produce multiple copies of the incoming light moving in different directions. This effectively gates frames at different points in time to produce very short, ultra-fast time-lapse movies.
"Fortunately, this type of scanning diffraction door can be accomplished in an unconventional way by using digital micromirror devices (DMDs), a common optical element found in projectors," Liang said. "The DMD is mass-produced and requires no mechanical movement to produce the derivative doors, making the system cost-effective and stable."
The Derivative Real-time Ultra-High Speed Mapping (DRUM) camera is capable of capturing seven frames per film. The project's multidisciplinary team tested the device by recording the laser's interaction with distilled water, "showing the evolution of plasma channels and the development of bubbles in response to the pulsed laser."
The DRUM camera also captured the bubble dynamics of carbonated drinks and the interaction between onion cell samples and ultrashort laser pulses. Work is ongoing to further refine the technology, but the researchers see potential applications in biomedicine and autonomous transportation lidar systems.
A paper on the project has been published in the journal Optica.