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Laser Beams Deflected Off of Nothing but Air for First Time Ever in Breakthrough Patent Pending Process - The Debrief (thedebrief.org)
submitted 2 years ago by [M, B] to c/technology@lemmy.world
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Laser Beams Deflected Off of Nothing but Air for First Time Ever in Breakthrough Patent Pending Process - The Debrief::An international team of scientists report that they have successfully used acoustics to deflect laser beams in an engineering first.

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[–] 47 points 2 years ago (1 child)

In an ultrasonic frequency we can’t hear. But your pets and any nearby bats or rodents etc may be upset by it..

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  • [–] 61 points 2 years ago (2 children)

    Can't hear but still cause damage?

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  • [–] 70 points 2 years ago (1 child)

    I didn’t know the answer to this so I looked it up - yes. Over 120 Db can cause damage even if it’s ultrasonic and you can’t hear it. Apparently at 155Db the heat created by the sound wave can be dangerous as well.

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  • [–] 40 points 2 years ago* (5 children)

    Just a small note, it's written dB, small "d", big "B".

    "B" is the unit symbol for bel and "d" is the symbol for the SI prefix deci, a tenth.

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  • [–] 1 point 2 years ago (1 child)

    In that case can we use just B. MB, etc.

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  • [–] 3 points 2 years ago

    Oh yes, sure you can, 140 dB is 0.000014 MB. The confusing thing is just that the non-SI unit byte also uses the symbol "B" and uses the SI prefix "M" quite often.

    Sometimes when I calculate optical power levels I actually use B in between. For example:

    How much signal is 88 optical channels at 1.6 dBm of power each?

    0 dBm = 1 mW by definition

    1.6 dB = 0.16 B = log10 ( x ) --> x = 10 ^ 0.16 = 1.45

    So 1.6 dBm is 1.45 * 1 mW = 1.45 mW

    Then 88 channels is 88 * 1.45 mW = 127.60 mW = 127.60 * 1 mW

    log10(127.60) = 2.11 B = 21.1 dB

    So 127.20 mW is 21.1 dBm, just below the output specification of our amplifier, good, nothing should melt.

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  • [–] 18 points 2 years ago* (1 child)

    Yes. Industrial grade ultrasonic sensors are harmful to your health. They can be used, for example, to measure the water level in a tank. If you need to enter a place like that, you should physically disconnect the sensor first. You might not hear much of the noise, but you may feel it in your teeth or some other places.

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