Dichroic Sheet Polarizers

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For low power applications, dichroic sheet polarizers are an inexpensive alternative to crystal prism polarizers. They are made from a sheet of polyvinyl alcohol that has been stretched in one direction and stained with polymeric iodine. This results in light polarized parallel to this direction being absorbed more strongly than orthogonally polarized light.

We supply a range of dichroic polarizers covering different spectral intervals. When selecting the polarizer for your application, the variation of both transmittance and extinction with wavelength should be carefully considered. Since dichroic polarizers are designed for use principally with white light sources, they are not suitable for high power laser beams. A maximum safe working limit is 3W/cm² (equal to 11mW in a 0.7mm diameter HeNe gas laser beam).

Dichroic sheet polarizers are specified by principal transmittance and extinction ratio. The principal transmittance (designated Trans in the plots below) is the transmission of the polarizer to the preferred plane of polarization and includes Fresnel reflection losses at the two external plastic-air interfaces. The extinction ratio (designated Ext) is this transmission divided by the trans-mittance of the orthogonal blocked polarization.

DP22 Sheet Polarizer	DP32 Sheet Polarizer
DP38 Sheet Polarizer	DPIR Sheet Polarizer

Mounts

Dichroic sheet polarizers are supplied unmounted as free components unless mounting in a black anodised aluminium ring is specified at the time of ordering. To specify mounted polarizers, simply add suffix:

Specifications