A polarimeter and polarimetry method are disclosed of the type in which light polarization rotating properties of a sample are measured by interposing the sample in the path of a light beam having base plane polarization in a plane of known orientation; along the beam path, compensating or nulling the rotation introduced by the sample, and determining the optical rotational properties of the sample based on the amount of compensation introduced to the light beam. In accordance with one aspect of the present invention, the light beam is subjected to plural compensations along its path the compensations being of at least two different types. Preferably, one of the types of compensation is mechanical, introduced through a device in which polarization rotation is adjusted mechanically, and the second type of compensation is provided through a device in which polarization rotation is controlled electrically. In accordance with another aspect of the invention, a first polarization rotation compensation is performed with the sample in the beam path, the sample is removed, and compensation is restored by performing a second polarization rotation compensation, the second compensation being used to determine the polarization rotation introduced by the sample.
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