Cornu depolarizer Depolarizer (optics)

cornu depolarizer

the cornu depolarizer 1 of earliest designs, named after inventor marie alfred cornu. consists of pair of 45° prisms of quartz crystal, optically contacted form cuboid. fast axes 90° apart , 45° sides of depolarizer (see figure). ray entering prism passes through 2 wave plates. thickness of these wave plates , therefore retardance varies across beam. phase shift given by

δ
(
y
)
=



2
π

λ


[

n

2


−

n

1


]
(
2
y
−
a
)
.


{\displaystyle \delta (y)={\frac {2\pi }{\lambda }}[n_{2}-n_{1}](2y-a).}

for input beam of uniform polarization output polarization periodic in



y


{\displaystyle y}

. phase shift dependent on wavelength due dispersion.

the use of 2 prisms means output coaxial input. @ interface between prisms refraction take place, refractive indices exchanged. there therefore separation of components of output beam.

this device not commonly used today, similar designs commercially available.