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posted by chromas on Friday November 15 2019, @03:16PM   Printer-friendly

A new technique for continuously monitoring both the size and optical properties of individual airborne particles could offer a better way to monitor air pollution. It is especially promising for analyzing fine particulate matter measuring less than 2.5 microns (PM2.5), which can reach deep into the lungs and cause health problems.

[...] For the new analysis approach, airborne particles are trapped inside a laser beam by optical forces and propelled forwards by radiation pressure. The trapping force is strong enough to overcome the gravitational force acting on very small particles such as PM2.5 and automatically aligns the particles with a hollow-core photonic crystal fiber. These special fibers feature a central core that is hollow and surrounded by a glass microstructure that confines light inside the fiber.

Once aligned, the laser light propels the particle into the fiber, causing the laser light inside the fiber to scatter and createe a detectable reduction in the fiber transmission. The researchers developed a new signal processing algorithm to retrieve useful information from the particle-scattering data in real-time. After detection, the particle simply ejects from the fiber without degrading the device.

"The transmission signal from the fiber also lets us measure time-of-flight, which is the time the particle takes to travel through the fiber," said Abhinav Sharma, the doctoral student working on this project. "The drop in fiber transmission together with the time-of-flight information allow us to unambiguously calculate the particle size and refractive index. The refractive index can assist in identifying the particle material because this optical property is already known for most common pollutants."

Journal Reference: Abhinav Sharma, Shangran Xie, Richard Zeltner, Philip St.J. Russell. On-the-fly particle metrology in hollow-core photonic crystal fibre. Optics Express, 2019; 27 (24): 34496 DOI: 10.1364/OE.27.034496


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  • (Score: 2) by JoeMerchant on Friday November 15 2019, @09:26PM

    by JoeMerchant (3937) on Friday November 15 2019, @09:26PM (#920806)

    There's a very old philosophical concept 2-3 millennia at least, billions of believers - many actual adherents, it goes something like this (in any one of a thousand languages):

    Do not do to others what you would not want them to do to you.

    With the coming robot revolution and the attendant hordes of idle unemployed, I would think that closer scrutiny of our elected officials' activity would be a worthy use of many people's time. The higher the office, the more detailed the scrutiny, and when a super majority of common voters believe that an elected official has violated the above principle, the penalty should be (in direct violation of that most Christian of themes: turn the other cheek) to visit upon the elected official whatever unpleasantry they have been shown to visit upon their constituency, or they may excuse themselves from office, permanently. We've put up with too much of this [kym-cdn.com] for one reality.

    --
    My karma ran over your dogma.
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