Low order dual wavelength waveplates

Waveplates are made from materials that exhibit birefringence. The velocities of extraordinary and ordinary rays through the birefringent material vary inversely with their refractive indices.                    Differences in velocity give rise to a phase difference when two beams recombine. At any specific wavelength, this difference is governed by the thickness of the retarder (waveplate).

Dual-wavelength low-order waveplates are made from high-quality crystalline quartz and are available at quarter-wave, half-wave, and full-wave retardance.

• One possible example is a waveplate designed for use in a dual-wavelength set-up at 800nm and 400nm. This operates as a λ/2 plate at 800nm and a λ/4 plate at 400nm.                                 This means that a 45° rotation of the waveplate induces a 90° rotation of the electrical vector at 800nm and does not change the state of polarization at 400nm.
• Another possible configuration is a λ/2 plate at 800nm and a λ/4 plate at 400nm. In this case, the waveplate rotates the electrical vector by 90° at 800nm and provides a circular polarization at 400nm.

These are just two possible configurations of many available. All the low order dual wavelength waveplates are mounted in a Ø25.4mm black anodized aluminum ring and feature a clear aperture of    18mm. Controls polarization for dual-wavelength sources.