Light is scattered when passing through an optically inhomogeneous medium. PDLC (polymer dispersed liquid crystal) is a medium whose light scattering power is adjustable through applying an electric field. In their natural (uncharged) state, the PDLC droplets align randomly.
The
ordinary refractive index of these liquid crystal
()
does not match that of the polymer (),
and the incident light is thus scattered, resulting
in a translucent state. When an electric field is applied
across the material, the PDLC droplets re-orient so
that the extraordinary refractive index of the liquid
crystal ()
matches that of the polymer. Therefore, the incident
light can pass through, resulting in a transparent
state.
)
does not match that of the polymer (
),
and the incident light is thus scattered, resulting
in a translucent state. When an electric field is applied
across the material, the PDLC droplets re-orient so
that the extraordinary refractive index of the liquid
crystal (
)
matches that of the polymer. Therefore, the incident
light can pass through, resulting in a transparent
state. 
