Patent ID: 7394545

Claim:
A method for measuring concentration of opaque particles in a fluid, comprising the steps of: a. providing an optical lens system comprising a translation stage, said translation stage having three axes of movement; b. introducing a sample of said fluid onto said stage, said particles in said fluid having a range of size with diameter less than about 20 microns; c. selecting a laser light source that produces a laser light beam with a wavelength effective to transmit through said fluid, but not said particles; d. focusing said laser light beam into said sample with a beam waist of said light beam based on the size of said particles; e. directing said light beam along a plurality of path lengths across a predetermined area of said sample; f. detecting light transmitted through said sample along each said path length; g. quantifying the intensity of said transmitted light; and h. correlating said quantified transmitted light to a concentration of said particles in said sample.