Determining optical activity of non-doubly refracting media - passing light through measurement paths of different lengths containing two polarising elements with relative polarisation angle dependent on desired measurement range

摘要

The method of determining the optical activity involves coupling light into a measurement path containing the medium under investigation. The light is polarised at a point in the measurement path and passed to at least one measurement channel and a reference channel. The relative polarisation angle of the polarising elements varies with the desired measurement range. The length of the measurement path is changed at least once to find the change in polarisation state of the light passing through it. The degree of optical activity is derived from a relationship of channel intensities for the different path lengths using a scale factor and the damping channel of one channel. Optical fibres are used to register the measurement signal. USE/ADVANTAGE - For chemical analysis using polarimeter. Method is implemented using miniaturised, low-cost arrangement and eliminates problematic operation under adverse conditions.