![]() Strictly speaking, the laser diffraction equivalent diameter is the diameter of a sphere yielding, on the same detector geometry, the same diffraction pattern as the particle. The blue source is used in liquid dispersion measurements of sub-micron particles. Laser diffraction analysis is based on the observation that the angle of the light diffracted by a particle is inversely proportional to its size. In the case of the blue light source, since we are only interested in scattering from the smallest particles, scattered light is only measured on the side scatter detectors and the back scatter detectors. Light from this source passes through optics and enters the measurement cell at exactly the same angle and position as with the red laser. To improve the resolution of particles in the sub-micron region, the Mastersizer 3000 combines measurements made with the red laser and a powerful solid state blue light source (470nm). Finally light scattered at angles greater than 90 degrees, from the smallest particles, is collected on a series of back scatter detectors. Laser light scattered at wider angles, from smaller particles, is collected on a series of side scatter detectors. This article presents the advantages and drawbacks of each technique, and their comparability among each other. Light scattered at small angles, from the larger particles, is collected on the focal plane detectors. The most common techniques to determine particle size distribution are dynamic image analysis (DIA), static laser light scattering (SLS, also called laser diffraction), dynamic light scattering (DLS) and sieve analysis. Laser light diffracted or scattered by the sample is captured on a series of detectors situated at a range of angles relative to the main laser beam. Particle analyzers with dynamic light scattering are mostly used to examine particles in solution (size range: 1 nm to 6 um). This article describes the benefits and drawbacks of each method, their comparability among each other as well as comprehensive application examples. The beam then passes through the measurement cell where the sample is dispersed. The most widely used methods for establishing particle size distribution are dynamic image analysis (DIA), sieve analysis, and static laser light scattering (SLS, also called laser diffraction). Laser Diffraction and Static Light Scattering Analysis are often used interchangeably, although the term laser diffraction has become established in many industries and laboratories. The laser beam passes through a precision folded optical arrangement that transports the light through 180 degrees. The red laser light is provided by a 633nm HeNe gas laser which was chosen for its excellent long term stability. Humic and fulvic acids were dissolved at relatively low concentrations (15-30 mg L (-1)) in solutions of different temperature, cation and ethanol content, and pH. Let’s take a closer look at how laser diffraction measurements are made in the Mastersizer 3000. Dynamic light scattering (DLS) has been used to monitor changes in aggregate sizes of aqueous humic materials as a function of solution properties.
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