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AssigneeThe Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland
InventorRobert G. W. Watling
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A dynamic light scattering apparatus (10) comprises a laser (12) optically coupled to a light scattering sample (26) via a first monomode optical fibre (18) and a first lens (22). The lens (22) produces a beam waist (24) in the sample (26), and scattered light is collected by a receive lens (30) and a second monomode optical fibre (34). The second fibre (34) has an end face in the Fourier plane (84) of the receive lens (30, 70), and defines an aperture matched to a single Airy disc (82) of the lens (30, 70). The receive fibre (34) accordingly receives a single spatial mode of light scattered from the sample (26), this mode corresponding to a single plane wave to which many scatterers contribute. The receive fibre (34) also attenuates unwanted spatial modes because of its monomode character. A photodetector (36) detects light transmitted by the receive fibre (34).
A dynamic light scattering apparatus comprising a laser (12) arranged to produce a laser beam (24) in a fluid scattering volume (26), and means (28 to 36) for collecting and detecting light scattered from the scattering volume (26), characterised in that the apparatus (10) also includes means (30, 34) for spatially Fourier transforming light scattered from the scattering volume (26) and for isolating a single spatial mode thereof for detection.
Dependencies are inferred from the claim text.