Method and apparatus for evaluating one or more materials in accordance
with size of particles. The method includes evaluating a spectrum of
light reflected from a first group of particles; evaluating a spectrum of
light reflected from a second group of particle; comparing results of
said evaluating of said first group with results of said evaluating of
said second group; and providing an indication of a state of said
material when said comparing produces a predetermined comparison result.
Distance between a first light conductor for conducting light to the
particles and a second light conductor for conducting light from said
particles for said evaluations may be varied. Monitoring of a process for
changes in particle size as a function of time or to determine various
physical and/or chemical characteristics of the particles or a mixture
containing same, including homogeneity, may be achieved.