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I have a plastic container and want to make sure that infrared radiation (specifically, in the 750-850 nanometer range) cannot pass through it. Would wrapping it in aluminum foil do the trick? If not, what household material would be best? The fluence of the radiation is around 22J/cm^2.

Thank you very much!

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    $\begingroup$ You can avoid/reflect incoming infrared radiation, but as the material heats up, it will reirradiate that heat as infrared radiation as well. $\endgroup$
    – user56771
    Commented Nov 4, 2012 at 3:03
  • $\begingroup$ I would be quite surprised if your plastic container didn't already block those wavelengths, but I don't know how to find out for sure. $\endgroup$
    – N. Virgo
    Commented Nov 4, 2012 at 4:40
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    $\begingroup$ Does the container have to allow visible light through? If not then foil would work. If you want a high pass filter, i.e. block wavelengths less than 750nm but allow everything above this wavelength, you'll need to be a bit more cunning. $\endgroup$
    – John Rennie
    Commented Nov 4, 2012 at 9:11

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The chart for the reflectance of aluminum tells us that it should do the job for you. But it will likely block anything else within that spectral range, see the plot! reflectivity aluminum

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  • $\begingroup$ You can avoid/reflect incoming infrared radiation, but as the material heats up, it will reirradiate that heat as infrared radiation as well. $\endgroup$
    – user56771
    Commented Nov 4, 2012 at 3:03
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    $\begingroup$ Not at 750-800nm until it gets very very hot! $\endgroup$
    – Martin Beckett
    Commented Nov 4, 2012 at 18:38
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    $\begingroup$ It is worth noting that even when the reflection is not quite 100%, that doesn't mean light can pass through the aluminum foil. The rest gets absorbed, not transmitted. (Unless the aluminum is under ~50 nanometers thick, for visible and near-IR!) $\endgroup$
    – Steve Byrnes
    Commented Nov 5, 2012 at 1:52
  • $\begingroup$ @SteveB: Good addition! $\endgroup$
    – elcojon
    Commented Nov 5, 2012 at 18:09
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Any electrically conductive material will block IR. The greater the conductivity, the greater the blocking. Aluminum foil will kill all IR, bot high range and low. Most plastics allow IR to pass through. Glass will bock low frequency IR (red hot), but allow the passage of high frequency (white hot) IR. Hence, the heat of the sun will easily pass into a greenhouse, but once this energy is converted into low frequency heat by the objects within that absorb it, then the resulting low frequency heat is trapped. Hence, the Greenhouse Effect.

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  • $\begingroup$ I can't make an answer because of low rep. But a common material is a survival blanket. It is especially designed to block IR. 90% of it. But I don't know at which wavelength. $\endgroup$
    – solsTiCe
    Commented Dec 18, 2020 at 10:13

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