Device and method for measuring scattering of radiation

摘要

A photometric device for investigating a sample, comprises an array of radiation sources that are spaced apart from one another, and which are operable to generate radiation that differs from that generated by the other radiation sources in the array. The device includes a lens arrangement for focusing the radiation at a region of space where a sample may be located for example by means of a sample holder, and at least one detector for receiving radiation from the region of space. Preferably, a number of detectors are employed that are spaced apart from one another, and especially about an axis of the device, so that one radiation detector can detect radiation transmitted by the sample and the other detectors can detect radiation scattered by it. The radiation sources may be time division multiplexed so that in each time slot the detectors receive radiation originating from each radiation source. In an alternative embodiment, the radiation from the region of space may be transmitted to the sample via a beam homogeniser, for example an optical waveguide in the form of an optical fibre, which may be used to reduce or remove speckle where laser diodes are employed as the radiation sources. The device may be used to determine the particle size distribution of particles in a sample by a method employing Bayesian inference.

主权项

1. A photometric device which comprises:
an array of radiation sources that are spaced apart from one another, and which are operable to generate radiation that differs from that generated by at least one other radiation source in the array, and a lens arrangement for directing radiation from the radiation sources to a region of space, and at least one radiation detector for receiving radiation from the region of space; the device further comprising signal processing means for determining a size distribution of a sample of particles in said region of space on the basis of scattering data of the particles, the signal processing means operable to: (a) determine a scattering vector z for scattering of radiation of a number of different wavelengths and polarisation states by the sample of particles at a number of different scattering angles; and (b) apply Bayesian inference to the scattering vector to determine the posterior probability distribution of the mean over a period of time of the particle size distribution from prior information regarding the likely particle size distribution and the Mie scattering equations for determining the scattering vector z from the size distribution.