Achromatic Waveplate Achromatic waveplate is made from two different substrate materials such as crystal quartz and magnesium fluoride. For the single material,waveplateâ??s working wavelength is very limited because of the dispersion of the material. But Achromatic Waveplate uses two different kinds of materials,with the different dispersion, such waveplate is not sensitive to the wavelength change. Dual Wavelength Waveplate Dual wavelength waveplate is a special type of multiple waveplate that provides a specific retardance at two different wavelengths, itâ??s particularly useful when used in conjunction with other polarization sensitive components to separate coaxial laser beams of different wavelength. It is widely used to improve conversion efficiency in solid double frequency laser device. Polarization Rotator Due to the rotation activity of natural quartz crystal, it also can be used as polarization rotators so that the plane of input linearly polarized beam will be rotated at special angle which is determined by the thickness of quartz crystal.