Graduate How to calculate the temperature change of a laser-irradiated material

[jgk5141]

TL;DR

How to calculate the temperature change of a laser-irradiated material when the absorption, laser pulse energy, spot size, wavelength, pulse width, and frequency are known?

I am looking to approximately calculate the temperature change of a sample that was exposed to a laser pulse. Experimentally, we know the optical absorption, reflection, and transmission, as well as the source parameters for our laser system. I realize that I will have to make approximations about the thermal relaxation times, optical absorption mechanisms, and the fact that the absorbed energy is completely converted to thermal energy. I am simply trying to understand absolute thermal maximums from the sample from the laser exposure.

 

[Baluncore]

Draw a diagram that shows the flow of energy from the laser to all the thermal and chemical products.

 

[Chestermiller]

Are you really referring to a pulse, or are you referring to a laser beam that is suddenly turned on and then allowed to continue irradiating the sample?

 

[jgk5141]

Are you really referring to a pulse, or are you referring to a laser beam that is suddenly turned on and then allowed to continue irradiating the sample?

Yes, I am really referring to a pulse. The laser pulse width is ~6ns from the experiment.

 

[Twigg]

With a 6ns pulse width, you will be dumping a ludicrous amount of peak power into the target sample. Depending on the absorbance, you may see ablation of the target. To calculate the temperature change of the target (as per the original post), you will need to factor in the latent heat due to ablation.

Overall, the advice from @Baluncore in post #2 still applies.

 

[jgk5141]

With a 6ns pulse width, you will be dumping a ludicrous amount of peak power into the target sample. Depending on the absorbance, you may see ablation of the target. To calculate the temperature change of the target (as per the original post), you will need to factor in the latent heat due to ablation.

Overall, the advice from @Baluncore in post #2 still applies.

This makes sense. Could you point me in the direction to get started with this?

 

[Twigg]

As in post #2, start by drawing a diagram that shows the flow into your sample from the laser, as well as the flow of power out of your system due to ablation and any other losses (conduction, etc.).