Abstract: A new application of dynamic light scattering (DLS) is disclosed for the use in accurately and reliably determining the size and/or size distribution of microscopic particles in laminar or turbulent flow. A system of microscopic particles in a fluid medium are forced to be in a laminar, rotational and/or turbulent flow. Then, a coherent light such as laser light is launched into the flowing particles, and the scattered light from the flowing particles is collected, converted into electrical signal, and processed to numerically derive the size/size distribution of the particles in the flow. The technique of DLS has long been used to determine the size/size distribution of the particles in dispersion under static condition. And, it has long been thought that accurate and reliable size determination of the particles in flow is not feasible. Therefore, present invention is the first ever to disclose that the technique of DLS can be used to accurately and reliably measure the size of the particles in flow.

Abstract: A fiber-optic imaging probe is disclosed for use in dynamic light scattering applications. The probe includes two monomode optical fibers and two GRIN lenses to form a pair of identical fiber-lens combinations. Each fiber is positioned off the optical axis of its associated lens. Further, the optical fibers are placed at an image plane of the lenses. The fiber-lens combinations are parallel to and mirror images of each other. The first fiber-lens combination projects a tightly focused spot of light into a scattering volume containing suspended or dispersed microscopic particles, or biological or live tissues. The second fiber-lens combination collects the light which is scattered from the particles in the scattering volume and conveys it to a photo detector and autocorrelator for analysis. The probe minimizes the scattering volume by advantageously using imaging principles of lenses. Further, the probe optimizes sensitivity and spatial coherence.

Abstract: A method and apparatus of determining the size of particles executing Brownian motion is provided. An integrated fiber optic probe, including a length of a gradient index multimode optical fiber fusion spliced to a monomode optical fiber, delivers laser light to a scattering medium such that the light scattered in the backward direction is collected by another integrated fiber optic probe mounted into the same cylindrical housing. The scattered light, after conversion to a series of photoelectron pulses, is processed to determine the mean particle diameter. The temporal coherence of the scattered field from submicroscopic particles illuminated by laser light is a function of both the integration time and the particle diameter. The temporal degree of coherence of the time averaged scattered intensity decreases as the integration time increases. Statistical processing of the scattered photons leads to a new method of particle sizing, which circumvents the need for digital autocorrelation.