Holograms, lasers used to identify free-flowing aerosol particles

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According to a new study published in Nature’s Scientific Reports it is possible to use holograms and lasers to keep an eye on the free-flowing air particles in atmosphere thereby enabling climate change and biological weapons watchdogs to better monitor the atmosphere.

The method involves taking holographic images of particles as they float through the air using two overlapping lasers: one red and one green. The green laser is the traditional method that can be used to measure the light deflection; by providing the red laser, they also get a 3-D image that can subjectively account for a variety of particle shapes.

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Matthew Berg, associate professor of physics at Kansas State University, explains that their method gives them two properties of the particles – shape and size – and that’s what they want to get. Berg is working to put the laser setup on an unmanned aircraft to measure free-flowing aerosol particles in the atmosphere. Removing the particles from their natural environment can change the particle form, Berg said. For example, if the particles are frozen in the atmosphere and scientists collect them to bring them back to the ground to study, the particles could melt and change their shapes and sizes.

“If we think about climate science, they want to know the size and shape of particles floating in the atmosphere,” Berg said. “This information can help climate scientists account for how much sunlight those particles scatter back into space or absorb — and if they absorb, by how much will it heat up the surrounding atmosphere.”

Referring to a problem that is worked backward from results to cause, Berg said before this study, the inverse problem with aerosol particles was largely educated guesswork based on mathematical calculations. Researchers could not objectively define free-floating aerosol particles because merely capturing a particle and looking at it under a microscope could change its physical shape or size. Now, they can bounce light waves off the particle and measure the deflection.