The Aspect Aerosol Size and Shape Analyser is manufactured by UK company BIRAL. It is the only commercially available aerosol characterisation system that simultaneously measures the shape of an airborne particle in real time, as well as its size and total particle concentration.
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Many particle characterisation instruments measure only particle size and base their measurements on the assumption that the particles are perfect spheres. Both natural and man-made particles have a very wide variety of shapes and this can be a powerful parameter in classifying them. The Aspect particle analyser uses Biral’s ASAS technology to simultaneously measure the size and shape of single particles at a high output rate. |
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·Aerosol research
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| ·Climate change research, cloud formation studies |
| ·Environmental monitoring, pollution concentrations |
| ·Source apportionment |
| ·Pharmaceuticals, particle formulation, particle morphology |
| ·Biodetection, monitoring of bioaerosol levels |
| ·Powder processes, particle discrimination |
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A key feature of the Aspect is its high sensitivity which enables subtle changes in aerosol population to be detected. This is particularly useful for:
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| Identifying subtle differences between aerosol or powder samples. Even when particle populations have continuous size and shape distributions, Aspect has the sensitivity to spot very small changes in size and shape characteristics. |
| Discriminating particle types within aerosol or powder mixtures. Aspect can discriminate discrete particle classes within a mixture by characterising particle shape. As a result, separate size or shape distributions can be generated and the ratio of particle species can be calculated. |
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| ASAS Technology is at the core of Aspect operation. Developed jointly with the University of Hertfordshire and Dstl Porton Down in the UK, ASAS is an optoelectronic technology using elastic scattering of laser light to determine particle size, shape and concentration. Scattered light is detected by four photomultiplier tubes (PMTs), three of which provide information on shape in terms of the light scattering profile which defines the particle asymmetry factor Af. A spherical particle is by definition symmetrical about all axes passing through its centre and is assigned an Af of zero. An infinitely long fibre is assigned an Af of 100. All four PMTs contribute information on the particle size. |
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