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Laser absorption

D

DIY

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If I shown my 445nm 1000mW laser through 5 different typey of liqiud, water, corn syrup, cokecola, (I havent decided), and coffee. and then they hit my LPM. Would the liquid be absorbing the heat or the power? And how does it? Is it based upon the thickness of the liquid or the color of the liquid? Or is there some kind of molecular thing happening?

Thanks,
DIY

P.S. I have looked on google went to the library looked at old science magazines, everything, but i have not found this anywhere.
 
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millirad

millirad

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It will depend on the power, frequency of the laser and whether or not the liquid fluoresces to some extent. Also the density of the liquid, it's refractive index and "how much"/length of liquid it's passing through. In general to give you an idea, a laser won't travel very far through murky pond water and therefore is being absorbed by the particles in the water. In a "clear" liquid many lasers would pass through with very little absorption, but that is "in general". If it was a UV laser and the liquid is fluorescent, the beam is absorbed and re-emits at a lower wavelength(inside of the liquid) with a loss of input beam power exiting the vessel.
 
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Bionic-Badger

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The liquids act as filters, causing attenuation of some of the wavelengths as the light passes through. Where does the energy go? Heat, scattering, fluorescing, etc.
 
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ok i eddited the post to say the power and frequency. How do you both know this, is there a book or site, that you have learn all this or do I just have to wait and let it come in my education.
 
Bluefan

Bluefan

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We have the situation of shining a 1W laser through a certain liquid. Liquids can have many interesting properties, but in case of the laser we are looking at the absorbtion and what happens afterwards.

This absorbtion is dependent on the wavelength, if you look through a red wine you will see red light, but green and shorter wavelength like cyan and blue will be strongly attenuated. A single wine drop doesn't absorb all green or blue light, some still leaks through. But in a glass of wine there is a much longer distance the light travels through the wine, and each length it travels it loses a certain percent of it's power. Or you could say that each time it travels through a certain amount of wine half the power is lost.

Where does this light go? It can be converted to heat, warming up your wine. Another option is emission of radiation. If the same light sort of bounces off the fluid to all directions without leaving any energy behind, this si called elastic scattering. This is for example why milk is white (not exactly but good enough).

If you have some fluorescent dyes, they seem to light up. So if you have such a property in your fluid, the incoming light will be absorbed and converted to another color light, having a langer wavelength. In this process a part energy is absorbed in the fluid, this will be heat, the other part is the lower energy light. This is called inelastic scattering, although it has probably more names like fluorescence.
Under certain conditions with certain media you can even make a laser out of this.

I hope I make sense :)

EDIT: And in case the input power and absorbtion isn't nicely linearly related you're looking at non-linear optics, very complicated :)
 
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Bluefan said:
We have the situation of shining a 1W laser through a certain liquid. Liquids can have many interesting properties, but in case of the laser we are looking at the absorbtion and what happens afterwards.

This absorbtion is dependent on the wavelength, if you look through a red wine you will see red light, but green and shorter wavelength like cyan and blue will be strongly attenuated. A single wine drop doesn't absorb all green or blue light, some still leaks through. But in a glass of wine there is a much longer distance the light travels through the wine, and each length it travels it loses a certain percent of it's power. Or you could say that each time it travels through a certain amount of wine half the power is lost.

Where does this light go? It can be converted to heat, warming up your wine. Another option is emission of radiation. If the same light sort of bounces off the fluid to all directions without leaving any energy behind, this si called elastic scattering. This is for example why milk is white (not exactly but good enough).

If you have some fluorescent dyes, they seem to light up. So if you have such a property in your fluid, the incoming light will be absorbed and converted to another color light, having a langer wavelength. In this process a part energy is absorbed in the fluid, this will be heat, the other part is the lower energy light. This is called inelastic scattering, although it has probably more names like fluorescence.
Under certain conditions with certain media you can even make a laser out of this.

I hope I make sense :)

EDIT: And in case the input power and absorbtion isn't nicely linearly related you're looking at non-linear optics, very complicated :)
Click to expand...

Thanks, It makes perfect sense. And all the ones before it.
 
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