10/19/2023 0 Comments Laser diffraction spectroscopyThe "raw" scattered light data is then passed to the calculation algorithm where it will be transformed into a particle size distribution.įor more information about acquiring an instrument, click here. It is based on the constructive interference of monochromatic X-rays and a crystalline sample. X-Ray diffraction analysis (XRD) is a nondestructive technique that provides detailed information about the crystallographic structure, chemical composition, and physical properties of a material 48. Ultra long-life solid-state light sources and detectorsĪcquiring the best possible scattered light data is the basis of any reliable size measurement. 3.7 X-Ray diffraction analysis technique.Tilted measurement cell to reduce stray light noise.Maximum stability and alignment with post-less, cast aluminum mountings.Maintenance-free, dust-free sealed optical bench.Hundreds of refinements to the basic design have been included to improve performance and usability. The LA-960V2 particle size analyzer represents the tenth generation laser diffraction instrument designed by HORIBA. Very high quality lenses, mirrors, and glass measurement cell.80+ photodetectors covering an approximate angular range of 0-170 degrees.Two light sources at different wavelengths.A typical laser diffraction optical system will include: The core technologies are all mature, but as with many things higher quality leads to superior performance. Measurement quality is all about the analyzer itself: quality of components, engineering refinement, and a fundamental design which reflects basic principles. Transform that scattering data into a particle size distribution.Measure scattered light angle and intensity.The basic workflow of a laser diffraction particle size analysis breaks down into two parts: 1: Red wavelength laser diode for larger particles, 2: Blue LED for smaller particles, 3: Low angle detectors for larger particles, 4: Side and back angle detector arrays and smaller particles. All HORIBA laser diffraction analyzers use the Mie scattering solution by default and allow the user to input custom refractive index values.Ī simplified layout of the LA-960 optical bench. The use of a refractive index and the Mie scattering theory directly affects accuracy in this size range. The scattered light is at relatively low intensity and wide angle for these smaller particles. ![]() This means the measurement will not benefit from the use of a refractive index to accurately interpret refracted light.įor particles smaller than 20 microns refracted light becomes increasingly important to calculate an accurate particle size. Particles larger than this size communicate useful size information through diffraction and not refraction. The "certain size" is determined as a multiple of the wavelength of light used for the measurement and typically approximated at 20 microns. The scattered light is at relatively high intensity and low angle for these larger particles. Diffracted and refracted light is useful for this purpose absorbed and reflected light works against this purpose and must be taken into account during measurement and size calculation.įor particles larger than a certain size the vast majority of light is scattered by diffraction. We can obtain information about the size of a particle using the angle and intensity of scattered light. Refraction occurs as light changes angle traveling throught the particle. The powder is measured and then evacuated though the bottom of the system automatically by vacuum.Ĭross-section of the PowderJet cell (left) and a close-up of the PowderJet cell dispersion mechanism (right).Diffraction is also known as "edge diffraction" as that is where it occurs. The now-dispersed powder flows into the measurement zone where the optical glass in the cell is protected from wear by laminar sheets of air generated by the air guidance plates. The dispersion nozzle geometry is designed so that the air is accelerated to supersonic velocity (this is the Jet in PowderJet). There, the sample flows through a venturi nozzle where any agglomerates are dispersed using 360° compressed air and no impaction surfaces which may cause milling. Sample flows along the vibratory feeder before falling into the dispersion chamber. The two figures below show details of the PowderJet dispersion system and measurement cell. This fourth-generation of the PowderJet technology has built upon user feedback and previous versions to become the easiest to use, most powerful dry dispersion accessory available. To accomplish this, HORIBA created several tools such as a feedback control loop, scan filters, and more. ![]() The LA-960V2 PowderJet was designed from the very beginning with the goal of maximizing precision. Thus the PowderJet became just as important to the development team as the choice of laser, detector layout, and circuit design. ![]() When the LA-960V2 project was launched it had the explicit goal of producing not just the most advanced optical system but also sample handlers to take advantage of it.
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