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: Brewster angle : Reflection and Transmission Coefficients : Reflection and Transmission Coefficients

Usual solution

In usual we asuume that $\sigma_{12}(k\sin\theta, \omega)=0, {\rm Im}\tilde{n}=0, \mu_1 = \mu_2 =1,
\le...
...sin\theta, \omega) \right]_x = 0,
\left[J_s (k\sin\theta, \omega) \right]_x = 0$, then for p-wave

$\displaystyle (E_p - R_p ) \cos\theta$ $\textstyle =$ $\displaystyle T_p \cos\theta''$ (96)
$\displaystyle n_1 (E_p + R_p )$ $\textstyle =$ $\displaystyle n_2 T_p$ (97)

and for s-wave
$\displaystyle E_s + R_s$ $\textstyle =$ $\displaystyle T_s$ (98)
$\displaystyle n_1 \cos\theta (E_s + R_s )$ $\textstyle =$ $\displaystyle n_2 \cos\theta'' T_s$ (99)

If we define
$\displaystyle r_p$ $\textstyle \equiv$ $\displaystyle \frac{R_p}{E_p}$ (100)
$\displaystyle t_p$ $\textstyle \equiv$ $\displaystyle \frac{T_p}{E_p}$ (101)
$\displaystyle r_s$ $\textstyle \equiv$ $\displaystyle \frac{R_s}{E_s}$ (102)
$\displaystyle t_s$ $\textstyle \equiv$ $\displaystyle \frac{T_s}{E_s}$ (103)


$\displaystyle (1 - r_p ) \cos\theta$ $\textstyle =$ $\displaystyle t_p \cos\theta''$ (104)
$\displaystyle n_1 ( 1 + r_p )$ $\textstyle =$ $\displaystyle n_2 t_p$ (105)

and for s-wave
$\displaystyle 1 + r_s$ $\textstyle =$ $\displaystyle t_s$ (106)
$\displaystyle n_1 \cos\theta (1 - r_s )$ $\textstyle =$ $\displaystyle n_2 \cos\theta'' t_s$ (107)

And we finally get

$\displaystyle r_p$ $\textstyle =$ $\displaystyle \frac{-n_1 \cos\theta'' + n_2\cos\theta}{n_1 \cos\theta'' + n_2 \cos\theta }$ (108)
$\displaystyle t_p$ $\textstyle =$ $\displaystyle \frac{2n_1 \cos\theta }{n_1 \cos\theta'' + n_2 \cos\theta}$ (109)
$\displaystyle r_s$ $\textstyle =$ $\displaystyle \frac{n_1 \cos\theta - n_2 \cos\theta'' }{n_1 \cos\theta + n_2 \cos\theta'' }$ (110)
$\displaystyle t_s$ $\textstyle =$ $\displaystyle \frac{2 n_1 \cos\theta}{n_1 \cos\theta + n_2 \cos\theta'' }$ (111)

The reflectance $R$ is defined as the ratio of the reflected power (or flux) to the incident power

\begin{displaymath}
R = \frac{I' A \cos\theta'}{I A \cos\theta} = \frac{I'}{I} = \frac{n_1 R^2 /(2c\mu_0)}{
n_1 E^2 /(2c\mu_0)} = r^2
\end{displaymath} (112)

The radant flux density $I$ is given by the averaged Poynting vector $ < {\bf E} \times {\bf H} > = \tilde{n} E^2/(2c\mu_0)$ In the same way The transmittance T may be
\begin{displaymath}
T = \frac{I'' A \cos\theta'' }{IA \cos\theta} = \frac{v_t \e...
... E^2 \cos\theta}
= \frac{n_2 \cos\theta'' }{n_1 \cos\theta}t^2
\end{displaymath} (113)

図 4: He-Ne laser from air to water
\includegraphics[width=8cm]{air2water_reftrans.eps} \includegraphics[width=8cm]{air2water_reftrans2.eps}
図 5: He-Ne laser from water to air
\includegraphics[width=8cm]{water2air_reftrans.eps} \includegraphics[width=8cm]{water2air_reftrans2.eps}


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: Brewster angle : Reflection and Transmission Coefficients : Reflection and Transmission Coefficients
Yamamoto Masahiro 平成14年8月30日