I Gold's absorbance of blue light

  • Thread starter Martwilk
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Summary
How many watts of <500nm light can 1 square centimeter of gold foil absorb? Is there a limit?
I have a LED light, which has a strong spectral peak around 470nm, and a broad emission spectrum in the deep red and infrared. I want to block most of the blue peak, and gold will absorb around 62% of this blue light. Will a polished gold foil surface of 1 cm2 be able to absorb 1 watt of this light?
And out of curiosity; is there a limit to this? Will it be able to absorb 100 watts of this light? Thanks!
 
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At some point the foil will overheat. Apart from that: No.
 

marcusl

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Won’t most of the light be reflected?
 
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I'm surprised but apparently not:

 

fluidistic

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It depends on the thickness of the gold foil. If you have a thin film of gold (say a few nm thick), it will appear green (by transmission). For silver, this would be more blue. When the thickness is macroscopic one loses almost entirely the transmission, of course.

Will a polished gold foil surface of 1 cm2 be able to absorb 1 watt of this light?
.
If you polish the surface, you will increase its reflectance, thereby reducing light absorption. What's more, the "1 W" that you quote, entirely depends on the power of the source, or the incident light's power. It certainly is possible, given a strong enough light source, but I guess the light source is not something tweakable?
 

DrDu

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While gold is most absorbing in the blue to green, a thin foil will also be most transparent in this region. In the reddish part of the spectrum, almost all of the light will be reflected.
 

Henryk

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Summary: How many watts of <500nm light can 1 square centimeter of gold foil absorb? Is there a limit?

I want to block most of the blue peak, and gold will absorb around 62% of this blue light.
And what do you want to do with the remaining light?
It seems to me that you want to filter out blue light and transmit the rest. Using gold isn't a good idea; it will absorb blue light but reflect longer wavelengths, i.e. red, orange, green.
There are other options available: color glasses which have a specific transmission curves, for more accurate filtering there multilayered filters. They are specifically designed to provide rejection of some light while transmitting another.
 

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