Optics: measuring and testing – Sample – specimen – or standard holder or support – Fluid containers
Patent
1999-04-22
2000-10-24
Font, Frank G.
Optics: measuring and testing
Sample, specimen, or standard holder or support
Fluid containers
356440, G01N 110
Patent
active
061375713
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an instrument for monitoring characteristics of a liquid, such as water.
It is known to use optical techniques for physical and chemical analysis of liquids, including monitoring the quality of water. Typically, a beam of light is shone into a sample of the liquid and transmitted or scattered components of the light are detected and analysed. Such systems may utilise a variety of effects to measure a particular characteristic of the liquid, including measuring absorption, scattering, refractive index, and polarisation properties.
Whatever the analysis technique used, transmitting light in to and out of the liquid sample poses practical problems. In conventional systems the light typically enters and exits the sample via transparent windows which are in direct contact with the liquid. It is therefore important for the efficient and reliable operation of such systems that the windows are kept free from damage, fouling and condensation. Whilst not being particularly problematical in a laboratory environment, degradation of the optical quality of such windows is a fundamental problem encountered with practical industrial measurement systems. Known provisions for the protection or cleaning of windows in such systems are often only partially effective and introduce problems of complexity and unreliability.
It is an object of the present invention to obviate or mitigate the above problems.
According to the present invention there is provided an instrument for monitoring the characteristics of a liquid, comprising a source of radiation which is transmissible through the liquid, means for directing a beam of the radiation from the source through a sample of the liquid, and means for detecting radiation emerging from the liquid, the detector being responsive to components of the emerging radiation which are affected by variations in the characteristics of the liquid, wherein he source and detector are arranged such that the radiation is transmitted through at least one free surface of the liquid which is supported at least in part by surface tension of the liquid.
The present invention also provides a method for monitoring the characteristics of a liquid, comprising directing a beam of radiation through a sample of the liquid and detecting components of the emerging radiation which are affected by variations in the characteristics of the liquid, wherein the radiation is transmitted through at least one free surface of the liquid which is supported at least in part by surface tension of the liquid.
The at least one free surface of the liquid is preferably defined by a meniscus formed at an aperture through which radiation may be transmitted.
In one embodiment of the invention, the aperture is defined by a container which contains at least part of the sample of the liquid. Means may be provided for applying differential pressure between opposite sides of the aperture to provide support for the free surface.
The aperture may be defined in the base of the container and the beam of radiation directed up through it. Alternatively, the aperture may, for instance, be defined in a side wall of the container and the beam of radiation directed substantially horizontally there through.
The container may be a pipe through which the liquid is flowing.
In one embodiment of the invention in which the aperture is defined in a base of a container, means are provided for forming an unsupported thread of the liquid above said container, and the radiation is directed into the thread and guided to the container along the length of the thread by total internal reflection.
In an alternative embodiment of the invention, a drop of the liquid sample is retained by surface tension outside the aperture, and the radiation is directed transversely into the drop.
Rather than being defined by a container containing liquid, the aperture could be defined by a bore such that the meniscus prevents liquid from flowing into the bore. This arrangement is particularly suited for instrument adapted to be immersed in the liqu
REFERENCES:
patent: 4413504 (1983-11-01), Voigtman et al.
patent: 4477186 (1984-10-01), Carlson
patent: 4488814 (1984-12-01), Johnson
patent: 4919899 (1990-04-01), Herrmann et al.
patent: 4943735 (1990-07-01), Nishikawa
patent: 5030010 (1991-07-01), Birkle
patent: 5194915 (1993-03-01), Gilby
patent: 5290705 (1994-03-01), Davis
Font Frank G.
Lauchman Layla
United Utilities PLC
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