Technology to see through the dazzling flame watermarking with blue light developed and expected to advance fire research

A research group at the National Institute of Standards and Technology (NIST) · Fire Research Division succeeded in visually observing a sample wrapped in a violent flame by using blue light and a filter.

NIST Unblinded Me with Science: New Application of Blue Light Sees Through Fire | NIST
https://www.nist.gov/news-events/news/2018/07/nist-unblinded-me-science-new-application-blue-light-sees-through-fire

Wildfire naturally occurs in the United States, especially in the west coast, like a year due to the dry climate. A large wildfire occurred in Los Angeles, California in December 2017, and many damage was reported. For that reason, fire research is actively conducted in the United States.

The scene where the forest fires approaching the expressway taken in Los Angeles is too shocking - GIGAZINE

For fire research it is necessary to observe "how fire spreads and burns things". However, due to soot, smoke, strong light emitted by the flame, and heat gradient generated by hot air, there were things that it was difficult to observe by visible light. Until now I used a fire of gas that does not emit soot or smoke in the test, but even if I tried to bring the camera close to grasp the brightness and the refraction of the light somehow, Due to the possibility of being broken, it was not possible to obtain detailed visual data in real time from large test flames

Glass and steelmakers, who process materials at temperatures as high as 1000 degrees Celsius or so, have traditionally measured the properties of materials that have been heated so that it glows red with the use of blue light lasers. NIST's research team applied this idea and thought that by utilizing blue light, we could visually grasp material samples burning in fire research.

The research team placed a target to be observed behind a gas flame, "Shoot with ordinary camera shining with only white light", "Shoot with blue light only and shoot with ordinary camera" "Shine blue light Three patterns of shooting with camera attached with optical filter were tested. As a result, with the method using blue light and optical filter, we succeeded in taking extremely detailed images by decreasing the influence of flame light by 1/10000.

In addition, NIST photographs samples of ignited timber under white light and blue light, and is published in the following movie. The left side of the following movie shot with the usual white light shooting, the right is shooting through the optical filter hitting blue light.



In shooting under white light, the flame can not see the surface of the timber due to disturbance. On the other hand, when shooting under blue light, you can observe which part of the wood is carbonizing.

With this technology, it will be possible to observe how the house burns, for example in a fire, in real time, so further progress in fire research is expected. NIST is also developing a system to measure volumetric changes and movements of three-dimensional objects deformed and dissolved by flames even when covered with soot and smoke by laser.