Polymer gels have three dimensional structure which is consist of cross-linked polymers. However, the static inhomogeneities fixed in gel during the gelation process prevent us to observe the structure of gels by scattering method. It is necessary for critical improvement of gel product performance to establish a method of quantitative analysis derived from the internal structure and the mechanical properties of gels. To solve this problem, the scanning microscopic light scattering (SMILS) has been originally developed.
Although the SMILS was very similar to general type of DLS system on the hardware, the SMILS developed enabled us to scan the sample in the vertical direction in micrometer scale, and to measure at many different positions in an inhomogeneous gel. In addition, the ensemble averaged correlation function of density fluctuation can be observed, because the intensity of scattered light depends on the position. In this system, the resulting data provides the statistically-averaged distribution corresponding to the mesh size distribution of gels, which are very important in characterizing physical properties of soft matters.