(Including quarter wave plates, full wave plates etc)





The retardation calibration plates are used in the calibration of any instruments which measure the degree of
birefringence, or retardation, of transparent products which may be made of plastics or glass etc.

The instruments in question may be strain viewers employing methods to accurately measure birefringence such as the Freidel, Tardy or Senarmont techniques or automatic instruments designed to measure the degree of retardation in compact discs or CD Roms.

As these calibration plates are manufactured in our own laboratory we can match them to any light source or supply them in any range of retardation in nanometres. They can also be produced in any format to facilitate their use in a particular design of strain viewer. For instance, when intended to be used for the inspection of CD disks or CD Roms they are made in 120mm dia discs and can be transparent for single pass measurements or have one surface metalized for a double pass.

We shall be pleased to advise and quote for suitable calibration plates upon receipt of the retardation ranges required and the type of strain viewer, or instrument, in use. In the case of strain viewers the size of the field of view is usually sufficient along with details of the light source employed. If you inform us of the products which are examined in your strain viewer we can then recommend the retardation ranges which are most suitable for its calibration purposes.

        It is only when it is desired to express retardation in degrees of rotation of a strain viewer's analyser filter that knowledge of the light source is required. Retardation when measured in nanometres is,of course, independent of the wavelength of light used.

Quarter Wave and Full Wave Plates.

In addition to Retardation Calibration Plates, Quarter wave and full wave plates can be manufactured to match any particular wavelength requirements. Polarising filters can also be supplied.

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