The INRS camera captures transient events and is suitable for various scenarios such as high-speed LiDAR systems for autonomous driving

It is reported that the National Institutes of Sciences (INRS) of Canada has developed a camera platform that can achieve cheaper ultra fast imaging through the use of ready-made components, which can be used in various applications. 

This new device aims to address some of the limitations of current high-speed imaging, including parallax errors and potential damage from pulse illumination. The relevant research is published in Optica under the title of "Diffusion gated real-time ultra-high speed mapping photography".

A single lens high-speed surveying camera is a powerful tool for studying rapid dynamics in various applications. However, existing methods are still constrained by factors such as the trade-off between sequence depth and luminous flux, errors caused by parallax, limited imaging dimensions, and potential damage caused by pulse illumination.

Researchers have developed a diffraction gated real-time ultra high speed mapping (DRUM) camera that can capture instantaneous motion at a speed of 4.8 million frames per second with a single exposure. The picture shows researchers studying optical devices. Image source: INRS.

To overcome these limitations, time-varying optical diffraction was explored as a new gating mechanism to achieve ultra-high imaging speeds. Inspired by pulse front tilt gated imaging and optical spatiotemporal duality, researchers have demonstrated the proposed paradigm in the development of diffraction gated real-time ultra high speed mapping (DRUM) cameras. DRUM cameras can capture transient events at a speed of 4.8 million frames per second in a single exposure. Researchers applied it to study liquid breakdown induced by femtosecond laser and laser ablation in biological samples.

DRUM camera. (a) Schematic diagram. (b) Working principle.

This camera adopts a brand new method to achieve high-speed imaging, with imaging speed and spatial resolution similar to commercial high-speed cameras, but using ready-made components, the cost may be less than one tenth of today's ultra high-speed cameras, and the starting price of these expensive cameras is close to $100000.

Performance characteristics of DRUM cameras.
This breakthrough is named Diffraction Gated Real Time Ultra High Speed Mapping Technology (DRUM) camera, and utilizes optical diffraction as the mechanism for controlling camera gating.

Suitable for any CCD or CMOS camera
According to the published paper, INRS has established a platform that uses ready-made digital micro mirror DMD to create gated lighting, effectively achieving real-time gating at the sub microsecond level.

Use a DRUM camera to observe laser induced breakdown in distilled water from the side.

The team used this as the basis for the DRUM camera, which has a sequence depth of 7 frames and captures 7 frames in each short film. After characterizing the spatial and temporal resolution of the system, researchers used it to record the interaction between laser and distilled water, and used laser ablation of onion cells as a biological imaging model.

In the water experiment, DRUM delay images showed the evolution of plasma channels and the development of bubbles in response to pulsed lasers. The images of onion cells reveal the details of laser induced anisotropic damage, which is caused by small-scale rapid changes in the plasma generated on the surface.

Forward looking imaging of cavitation bubble dynamics using DRUM cameras.

Laser ablation imaging of monolayer onion cells using DRUM cameras.

Future research may include improving imaging speed and sequence depth, as well as methods for capturing color information, and applying the same imaging principles to other applications such as LiDAR. The clinical applications of nanosurgery or laser cleaning will also follow closely.

Researchers believe that DRUM cameras will contribute to advances in biomedical and automation technologies, such as LiDAR, where ultra fast imaging can more accurately perceive hazards, and the DRUM camera paradigm is universal. In theory, it can be used with any CCD and CMOS camera without compromising their other advantages.

Researchers have developed a DRUM camera for two-dimensional ultra high speed real-time imaging, with a frame rate of 4.8 Mfps, a time resolution of 0.37 µ s, and a sequence depth of 7 frames. DRUM cameras provide multifunctional ultra high speed imaging and ready-made components. The use of mass-produced digital micro mirror DMD as the core component eliminates the need for mechanical movement during the production of diffraction gratings, making the system cost-effective and stable. The key feature of DRUM cameras is the ability to perform spatial separation and temporal grid on continuous two-dimensional images in the optical domain while meeting the imaging conditions between objects and sensors. By guiding these continuous images to different regions, sensitive mapping measurements can be made on a single ordinary CMOS sensor. The high sensitivity of these sensors, coupled with the use of continuous wave laser beams for detection, allows for ultra fast imaging at lower peak intensities, thereby reducing the chance of light damage to objects.

Related paper links:
https://doi.org/10.1364/OPTICA.495041
https://optics.org/news/14/9/29

Source: Yangtze River Delta Laser Alliance