# Photonics - peak temperature / thermal diffusivity

1. Mar 30, 2008

1. The problem statement, all variables and given/known data

Estimate the peak temperature for a 1 ns versus a 1 ms optical pulse with a total energy of 1 J in a 1 cm^2 spot is incident on a sheet of metal. The metal is 20 thou ( 20 thou = 0.5 m). The metal sheet is mounted on a copper block which is held at room temperature. The thermal diffusivity is, D = 0.1 cm^2/s. The absorbtion coefficient at the relevant wavelength (0.37 $$\mu$$m) is $$\alpha$$ = 8000 cm$$^{-1}$$

2. Relevant equations

x bar = (Dt)^1/2
I(x) = Ie^($$^{-\alpha}$$X)
dI/dx = -$$\alpha$$I

3. The attempt at a solution

this is for my general engineering phsycis class, the prof gave us a 4th year photonics assignment, i have no idea how to even approach it..
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution