Retardation plates offer the possibility to adjust the polarization of a laser beam specifically without beam deflection. Birefringent materials, such as crystalline quartz, are used for this purpose. Due to the refractive index difference of the crystal axes, the s- and p-polarized portion of the light are retarded to different extents.
By using λ/4 plates, linear polarized light can be converted into circularly polarized light. By using λ/2 plates, circularly polarized light can be converted into linearly polarized light or the polarization direction can be rotated by a selectable angle.
The retardation can be adjusted via high-precision fabrication of the material thickness and thus the desired polarization effect can be realized.
Typical substrate material: quartz crystal Wavelength range: approx. 200 nm to 3 µm Maximum possible diameter: 40 mm Material thicknesses from approx. 100 µm can be produced.
The two polished surfaces are extremely plane-parallel and are anti-reflective for the respective functional wavelength.