Saccharimeter

A saccharimeter is a polarimeter calibrated for measuring sugar concentration through optical rotation. A sample rotates the plane of polarization, and the instrument determines the angular change under specified optical conditions.

For a single optically active solute in the appropriate dilute regime,where $\ell$ is the optical path length and $c$ the concentration in units consistent with the stated specific rotation. Calibration, wavelength and temperature matter. Other optically active solutes, changing sugar composition or mutarotation can change the rotation, so a sugar-mixture measurement need not directly equal one compound's concentration.