Waveplates (retardation plates or phase shifters) are made from materials which exhibit birefringence. The
velocities of the extraordinary and ordinary rays through the birefringent
materials vary inversely with their refractive indices.
The difference in velocities gives rise to a phase difference
when the two beams recombine. In the case of an incident
linearly polarized beam this is given by a=2pi*d(ne-no)/l (a-phase difference; d-thickness of waveplate; ne,no-refractive
indices of extraordinary and ordinary rays respectively;
l-wavelength). At any specific wavelength the phase difference
is governed by the thickness of the retarder.
Thermal Expansion Coefficient:7.5x10-6/K
The thickness of a half waveplate is such
that the phase difference is l/2-wavelength (true-zero order)
or some multiple of l/2-wavelength (multiple order).
A linearly polarized beam incident on a half
waveplate emerges as a linearly polarized beam
but rotates such that its angle to the optical axis is twice
that of the incident beam. Therefore, half waveplates can
be used as continuously adjustable polarization rotators.
Half waveplates are used in rotating the plane of polarization,
electro-optic modulation and as a variable ratio beamsplitter
when used in conjunction with a polarization cube.
The thickness of the quarter waveplate is
such that the phase difference is l/4 wavelength (true-zero
order) or some multiple of l/4 wavelength (multiple order).
If the angle q (between the electric field
vector of the incident linearly polarized beam and the retarder principal plane) of the quarter waveplate
is 45, the emergent beam is circularly polarized. When a
quarter waveplate is double passed, i.e. by mirror reflection,
it acts as a half waveplate and rotates the plane of polarization
to a certain angle. Quarter waveplates are used in creating
circular polarization from linear or linear polarization
from circular, ellipsometry, optical pumping, suppressing
unwanted reflection and optical isolation.
Order Information: Part No.+Retardance+Wavlength
Sample: WPL1101+ l