![]() The blue source is used in liquid dispersion measurements of sub-micron particles. 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. ![]() Light scattered at small angles, from the larger particles, is collected on the focal plane detectors. ISO 13320 consists of the following parts, under the general title Particle size analysis Laser diffraction methods : Part 1: General principles Part 2: Validation of inversion procedures Annexes A to E of this part of ISO 13320 are for information only. 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. A particle-sizing method based on laser diffraction suffers from several major pitfalls, namely: (1) the method is based on false assumptions (2) the. sizing methods, Subcommittee SC 4, Sizing by methods other than sieving. The beam then passes through the measurement cell where the sample is dispersed. 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. Let’s take a closer look at how laser diffraction measurements are made in the Mastersizer 3000. ![]()
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