Optical transformation techniques using a laser for illumination were investigated to measure sediment concentration in a water sample. An optical Fourier transformation system was set up with a bundle of fiber-optic light-pipes connected to an array of photo detectors for analyzing the transform of samples of known particle size distribution. Two of seven information channels of the fiber-optic bundle were used as a test. Intensity measurements from the test of two known monodisperse samples were used to generate a matrix of weight functions. The matrix was used to transform the measured intensity from a mixture containing two particle sizes which were different from the sizes used to determine the matrix. Results show that the system could not distinguish between 160 and 187 micrometer diameter particle but discriminated well between 276 and 321 micrometer diameter particles. Both size resolution and accuracy are expected to improve as more fiber-optic channels are used. (Author)