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Wave plates are made from materials which exhibit birefringence. The velocities of the extraordinary and ordinary ray through the briefringent material varies inversely with their refractive indices.This difference in velocities gives rise to a phase difference when the two beams recombine. At any specific wavelength the phase difference is govermed by the thickness of the retarder-waveplate.
Half Wave plates.(see its Schematic diagram)
A linearly polarized beam incident on a half wave crystal quartz waveplate emerges as a linsarly polarized beam but rotated 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 to rotate the plane of polarization, electro-optic modulation and as a variable ratio beamsplitter when used in conjunction with a polarization cube.
Quarter Wave plates.(see its Schematic diagram)
If the angle 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 waveplates and rotates the plane of polarization to a certain angle. Quarter waveplate are used in creating circular polarization from linear polarization from circular,ellipsometry, optical Epumping, suppressing unwanted reflection and optical isolation. Zero Order waveplates are generally preferred since they are least sensitive to variations in wavelength, angle of incidence and temperatute. Air-spaced crystal quartz waveplates are also available. Its performance is as good as cemented zero-order waveplate. Additionally, the air-spaced construction enables it is suitable for the high power laser application. The damage threshold is more than 500 Mw/cm2.
Our waveplates are classified into multi-order, low-order, zero-order, true zero-order wave plates and achromatic wave plates and dual wavelength wave plates by the thickness or order of the phase retardation. We uses laser-grade crystal quartz to produce them. In order to making them suitable for high power applications,all of our waveplates and waveplate assemblies are adhesive free.
To suit different applications, air spaced, glued or optically contacted Zero order compensated phase retardation plates are available.
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