Use Microsphere to Measure Refractive Index/Concentration/Temperature in Micro-regions of Inhomogeneous Media

We present a simple easy method which can accurately determine the refractive index (RI)/concentration/ temperature variation in micro-regions of inhomogeneous medium by immersing microspheres in the medium and analyzing their phase-contrast microscopic images. In this paper, the principle of the method and the experiments of using the method for different applications will be described.