Enhancement of Scattering Efficiency and Development of Optical   Magnetometer Using Quantum Measurement Set Up
  Quantum measurement principle is employed to detect water quality and presence of nano-colloids. The setup uses spatially low coherent light source, for which the outcome of measurement is dependent on the presence of a reflecting surface and a linear polarizer. The introduction of a reflecting surface induces enhanced side scattering. The enhancement has specific patterns for pure water, ions and nanoparticles and can be employed to detect refractive index of liquids at high sensitivity. The differential enhancement can be used as an optical magnetometer that sensitively senses magnetic moments of colloidal magnetic nanoparticles at concentration untenable by other measurement techniques. 
Sufi O Raja and Anjan K Dasgupta
physics.optics physics.ins-det quant-ph