-- The 41st International Symposium on Combustion, or ISOC 2026, brought together researchers working on combustion fundamentals, chemical kinetics, turbulent flames, low-carbon fuels and advanced optical diagnostics.
As ammonia, hydrogen and other alternative fuels move closer to practical use, combustion research is shifting beyond conventional measurements of temperature and pressure. Researchers increasingly need time-resolved information on flame structures, reaction zones and radical emissions.
A High-speed Camera(UV) extends high-speed imaging into ultraviolet spectral bands associated with weak chemiluminescence. This capability allows researchers to examine reactive species that may not be adequately resolved through visible-light flame imaging alone.
High-speed Camera(UV) for Weak Ultraviolet Combustion Emission
Combustion involves coupled chemical reactions and fluid motion. Excited species such as NO*, OH*, CH* and NH₂* emit radiation at characteristic wavelengths, providing information on reaction-zone structure and chemical evolution.
Ultraviolet combustion imaging remains difficult because radical emission is weak, the available photon flux is limited, and ultraviolet transmission is reduced by atmospheric absorption and optical losses. Higher frame rates also shorten the exposure time available for each image, creating a trade-off between temporal resolution and signal-to-noise ratio.
The Revealer NEO25(UV) High-speed Camera(UV) is designed for weak-light and ultraviolet combustion diagnostics. It uses a back-illuminated CMOS sensor with 20-micrometer pixels and records at a full-frame resolution of 1,280 by 1,024 pixels at up to 25,000 frames per second. Its spectral response extends from about 200 to 1,100 nanometers.
Product data in the source article show that the ultraviolet version maintains substantial sensitivity in the deep-ultraviolet region, with quantum efficiency of about 60% near 250 nanometers. This response supports high-speed detection of weak NO* and OH* emissions.
The NEO25(UV) can be combined with ultraviolet-transmitting lenses, narrowband filters and an image intensifier. The configuration varies with the strength of the target emission. Extremely weak NO* radiation near 228 nanometers requires intensification, while stronger CH* and NH₂* signals can be recorded without an image intensifier under suitable experimental conditions.
Methane-Ammonia Flame Experiment
In a study of radical evolution in low-carbon fuel combustion, researchers used the Revealer NEO25(UV) High-speed Camera(UV) to build a multiband imaging system for methane-ammonia-oxygen flames.
The experiment examined emissions at 228, 310, 430 and 632 nanometers. These wavelengths were used to observe NO*, OH*, CH* and NH₂* signals associated with different regions and processes within the flame.
At 228 nanometers, NO* emission was extremely weak. The system used an image intensifier to amplify the optical signal and recorded the flame at 100 frames per second. The resulting images showed an elongated emission region concentrated along the flame axis.
When the frame rate was increased, the recorded signal declined rapidly. This indicated that the measurement was photon limited rather than constrained by camera readout speed.
At 310 nanometers, OH* emission provided information on the main reaction zone. Without an image intensifier, the High-speed Camera(UV) recorded a recognizable flame profile at 100 frames per second with an exposure of 8,000 microseconds.
With image intensification, the system captured continuous flame structures at 1,000 frames per second. The sequence showed fluctuations along the flame front, reflecting the influence of shear-layer instability and local flow disturbances on the reaction-zone geometry.
At 430 nanometers, the CH* signal was stronger than the emissions recorded at 228 and 310 nanometers. The NEO25(UV) captured stable images at 1,000 frames per second without an image intensifier.
The images resolved flame-front curvature, localized entrainment and changes in the propagating combustion interface. Because the CH* signal appeared closer to the flame boundary, the sequence could support studies of flame-front motion and propagation behavior.
At 632 nanometers, NH₂* emission was substantially stronger and lay within the visible spectral range. The camera recorded high-contrast images at 1,000 frames per second without an image intensifier.
The NH₂* emission occupied a broader region than the OH* and CH* signals in the reported images. This distribution may support analysis of nitrogen-containing intermediate transport and subsequent reactions in ammonia-containing flames.
The image intensity, however, should not be interpreted as absolute species concentration without additional spectroscopic calibration and correction for temperature, pressure, quenching and optical-system response.
From Flame Imaging to Mechanism Analysis
The experiment shows that multiband high-speed imaging can extend combustion diagnostics beyond overall flame luminosity.
At 228 nanometers, the measurement required image intensification because of limited photon availability. At 310 nanometers, intensification increased the achievable temporal resolution from the hundred-frame-per-second range to 1,000 frames per second. At 430 and 632 nanometers, stronger emissions supported 1,000-frame-per-second imaging without intensification under the reported conditions.
These results also show that frame rate alone is not sufficient when selecting a High-speed Camera(UV). Effective ultraviolet combustion imaging depends on the combined performance of the sensor, ultraviolet lens, optical filter, exposure settings and image intensifier.
The Revealer NEO25(UV)-based configuration combines a High-speed Camera(UV) with ultraviolet optics, narrowband filtering and optional image intensification. The system provides a time-resolved method for observing weak radical emissions in methane-ammonia flames.
As research on ammonia, hydrogen and alternative fuels expands, ultraviolet high-speed imaging may help researchers examine where reactive intermediates form, how reaction zones fluctuate and how local flow structures deform the flame front.
Contact Info:
Name: Harrison Shawn
Email: Send Email
Organization: HF Agile Device Co., Ltd.
Website: http://www.revealerhighspeed.com
Release ID: 89199915
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