A METHOD AND A POLARIMETER FOR MEASURING OPTICAL ROTATION OF SUGAR AND OTHER OPTICALLY ACTIVE SOLUTIONS

摘要

The invention relates to a method and a polarimeter to measure optical rotation of a sugar or other optically active solution by producing a monochromatic and collimated light beam, which is split into a measuring beam (11) and into a reference beam (12), directing the measuring beam (11) through the optically active solution (1) and by making reference beam (12) to pass the solution cell, directing the original light beam first through a fixed polarizer (5) and then directing each split beam through an analyzer (6), which is rotated at constant speed hence producing a cosine squared waveform for each beam, measuring the phase difference between the cross-polarization positions of the analyzer (6) for the measuring beam (11) and for the reference beam (12) thus allowing for measuring the absolute angle of optical rotation. According to the invention constant triggering pulses are generated by using the steep rising/falling parts of the periodical waves to generate pulses to start and to stop counting procedure on a crystal oscillator counter, and that a first time delay between the consecutive triggering pulses is measured for the measuring (11) and the reference beams (12) and a second time delay for the full half period of one beam, wherein the said phase difference is counted from the said first and second time delays.