snell

typhon.physics.snell(n1, n2, theta1)

Calculates the angle of the transmitted wave, according to Snell’s law.

Snell’s law for the case when both n1 and n2 have no imaginary part is found in all physics handbooks.

The expression for complex n2 is taken from “An introduction to atmospheric radiation” by K.N. Liou (Sec. 5.4.1.3).

No expression that allows n1 to be complex has been found.

If theta2 is found to be complex, it is returned as NaN. This can happen when n1 > n2, and corresponds to a total reflection and there is no transmitted part.

The refractive index and the dielectric constant, epsilon, are releated as

\[n = \sqrt{\epsilon}\]

Parameters:

• n1 (float or ndarray) – Refractive index for medium of incoming radiation.

• n2 (float or ndarray) – Refractive index for reflecting medium.

• theta1 (float) – Angle between surface normal and incoming radiation [degree].

Returns:

Angle for transmitted part [degree].

Return type:

float or ndarray