Capturing fast movements with clarity has always been a challenge in the world of imaging. But researchers from the Institut national de la recherche scientifique (INRS) in Canada, alongside collaborators from Concordia University and Meta Platforms Inc., have developed a revolutionary camera that could change the game. This camera offers a much more affordable solution to achieve ultrafast imaging for various applications such as real-time monitoring of drug delivery and high-speed lidar systems for autonomous driving.
The new camera, known as diffraction-gated real-time ultrahigh-speed mapping (DRUM) camera, aims to match the imaging speed and spatial resolution of commercial high-speed cameras but at a fraction of the cost. While ultrafast cameras currently on the market can start at close to $100,000, the DRUM camera can achieve similar results using off-the-shelf components that are estimated to cost less than a tenth of the price.
In a paper titled “Diffraction-gated real-time ultrahigh-speed mapping photography,” published in Optica, the researchers showcase the capabilities of their DRUM camera. It boasts the ability to capture dynamic events in a single exposure at an impressive rate of 4.8 million frames per second. This remarkable achievement is demonstrated through imaging the fast dynamics of femtosecond laser pulses interacting with liquid and laser ablation in biological samples.
Jinyang Liang, one of the researchers involved in the development of the DRUM camera, speaks of its potential impact on various fields. He highlights the advancements it could bring to biomedicine and automation-enabling technologies such as lidar, which would benefit from faster imaging for more accurate sensing of hazards. Furthermore, Liang notes that the concept of DRUM photography is versatile and can be applied to any CCD and CMOS cameras without compromising other advantages such as high sensitivity.
While there have been significant advancements in ultrafast imaging, current methods remain expensive, complex, and limited in their performance. Trade-offs between the number of frames captured, light throughput, and temporal resolution hinder progress in this field. Addressing these challenges, the researchers developed a groundbreaking time-gating method known as time-varying optical diffraction.
Traditionally, cameras use gates to control the lighting hitting the sensor. For instance, in a traditional camera, the shutter acts as a gate that opens and closes once. Time-gating involves opening and closing the gate in quick succession multiple times before the sensor reads out the image. This technique captures a short high-speed movie of a scene.
Liang’s insight into the space-time duality of light led to the realization that he could achieve time gating using light diffraction. By rapidly changing the tilt angle of periodic facets on a diffraction grating, multiple replicas of the incident light can be generated, each traveling in different directions. This approach allows for sweeping through different spatial positions to gate out frames at various time points. These frames can then be assembled to create an ultrafast movie.
To transform this idea into a working camera, the researchers harnessed the power of a digital micromirror device (DMD). DMDs are commonly found in projectors and can produce the diffraction gate required for the DRUM camera without the need for mechanical movement. This makes the system cost-efficient and stable, as DMDs are mass-produced and readily available.
The team successfully created a DRUM camera with a sequence depth of seven frames, meaning it captures seven frames in each short movie. After characterizing the camera’s spatial and temporal resolutions, they tested its capabilities by recording laser interactions with distilled water. The resulting time-lapse images showcased the evolution of a plasma channel and the development of a bubble in response to a pulsed laser. The measured bubble radii aligned with predictions based on cavitation theory. The camera also captured the bubble dynamics of a carbonated drink and transient interactions between an ultrashort laser pulse and a single-layer onion cell sample.
DRUM photography holds promise not only in biomedicine and automation but also in nano-surgeries and laser-based cleaning applications. The researchers are committed to advancing the capabilities of DRUM photography. Their future efforts include increasing the imaging speed and sequence depth, exploring the capture of color information, and expanding its application to areas such as lidar.
The development of the DRUM camera marks a significant milestone in the field of ultrafast imaging. It offers a low-cost solution that rivals the performance of expensive ultrafast cameras. With its potential applications ranging from biomedicine to lidar systems, the future looks bright for high-speed imaging. As the researchers continue to innovate and improve, we can expect even greater advancements in this groundbreaking technology.