total internal reflection | OptoWiki Knowledge Base

Total internal reflection (“TIR”) occurs, when the angle of incidence of a ray propagating from a higher indes medium to a lower index medium exceeds the critical angle.

$sin(\theta_{c}) = \frac{n_2}{n_1}$

[table caption=”Examples for critcal angles” width=”200″ colwidth=”100|100″ colalign=”left|left”]
$n_1$ , $\theta_{c}$
1.3, 50.3°
1.4, 45.6°
1.5, 41.8°
1.6, 37.8°
1.7, 36.0°
1.8,33.7°
1.9, 31.8°
2.0, 30.0°
[/table]

for an interactive example, see refraction