Apparatus to measure electrophoretic mobility

An apparatus comprising:

• a long coherence length laser;
• a fiber splitter optically coupled to the long coherence length laser;
• a polarization maintaining acousto-optic modulator optically coupled to a reference arm output of the fiber splitter;
• a sample cell to contain a sample and optically coupled to a sample arm output of the fiber splitter;
• a polarization maintaining combiner optically coupled to an output of the polarization maintaining acousto-optic modulator and to an output of the sample cell;
• a photo detector to detect light outputted from the polarization maintaining combiner;
• a radio frequency source electrically coupled to an input of the polarization maintaining acousto-optic modulator;
• and
• an in-phase quadrature phase demodulator electrically coupled to an output of the photo detector and electrically coupled to an output of the radio frequency source, to output in-phase data and quadrature phase data, to be analyzed for shifts in frequency to measure electrophoretic mobility in the sample.

An apparatus comprising:

• a long coherence length laser;
• a fiber splitter optically coupled to the long coherence length laser;
• a polarization maintaining acousto-optic modulator optically coupled to an output of the fiber splitter;
• a sample cell to contain a sample and optically coupled to an output of the fiber splitter;
• a polarization maintaining combiner optically coupled to an output of the polarization maintaining acousto-optic modulator and to an output of the sample cell;
• a photo detector to detect light outputted from the polarization maintaining combiner;
• a radio frequency source electrically coupled to an input of the polarization maintaining acousto-optic modulator;
• and
• an in-phase quadrature phase demodulator electrically coupled to an output of the photo detector and electrically coupled to an output of the radio frequency source, to output in-phase data and quadrature phase data to be analyzed for shifts in frequency to measure electrophoretic mobility in the sample.