Intertek MSG Laboratory tests for the birefringence of polymers by measurement of the individual components of the refractive indices.

The refractive index components are determined with an accuracy of around +/- 0.0005, so typically the lab is able to determine birefringence to about +/- 0.001. Birefringence analysis is normally conducted at a wavelength of 633nm, but other wavelengths can be used if necessary.

The birefringence method utilises reflectivity measurement, and determines the refractive indices (and hence birefringence) at the surface of the sample. If the composition or orientation of the polymer varies throughout the thickness the laboratory will not pick this up, and the sample should have at least one flat surface on which to make the measurements.

Birefringence testing of plastics by Intertek MSG is competitive, with prompt sample analysis turn-around times from receipt of samples.

Double Refraction is another way to describe Birefringence. Double Refraction is simply the splitting of a light ray into two separate rays when the original light ray passes through certain materials, including polymers and plastics. Minimisation of birefringence is important in processing some polymers for applications such as CD or DVD manufacture.

Measurement of birefringence in polymer films can provide useful information on polymer orientation, which related to physical properties of the films. Intertek MSG helps our clients determine the birefringent properties of a wide range of optical materials materials. Contact Intertek MSG for Birefringence and Double Refraction materials testing and research information.