Optics: measuring and testing – By shade or color – With color transmitting filter
Patent
1994-12-21
1996-09-17
Evans, F. L.
Optics: measuring and testing
By shade or color
With color transmitting filter
2504581, 2504611, G01N 2164
Patent
active
055574157
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention concerns a novel apparatus and method for inducing and detecting fluorescence. The apparatus is particularly useful for measuring fluorescence emitted from turbid or highly turbid fluid media, such as, e,g., fluorescence emitted from living cells in a fermentation tank or in a mixed culture in a water purification plant. Thus, the apparatus is most valuable for performing the fluorescence determinations in the method disclosed in WO90/10083 published 7 Sep. 1990, which relates to a method for controlling and/or optimising a process in which an aqueous system comprising biodegradable material, such as waste water or sewage, is subjected to biological treatment using mixed cultures of microorganisms.
U.S. Pat. No. 4,577,110 discloses an apparatus for inducing fluorescence in, and measuring fluorescence emitted from, a biological medium. The apparatus is adapted to launch, from a continuous light source, a beam of exciting light through a ring-shaped detector. The apparatus is designed so that the field of illumination of the exciting light is substantially contained within the field of view of the detector measuring the emitted fluorescence.
EP 0.047.094 discloses an apparatus for inducing and detecting fluorescence in a medium. The pulsed exciting light and the fluorescence emitted from the medium are guided to and from the measured medium by means of optical fibres.
In highly turbid media, light is not able to travel more than a few mm or even only fractions of a mm before it becomes very considerably attenuated. Therefore, fluorescence measurements in such media present severe problems, and there is a considerable demand for fluorescence measuring equipment which is able to perform measurements with a high sensitivity and over a broad dynamic range.
The present invention relates to an apparatus of a novel type which is particularly adapted for performing the inherently very difficult fluorescence measurements in highly turbid media, but which will also be advantageous for applications in less turbid or non-turbid media.
SUMMARY OF THE INVENTION
In one aspect, the invention relates to an apparatus for inducing and detecting fluorescence in a fluid medium containing at least one fluorophore, the apparatus comprising: fluorophores in the fluid medium, excited by the exciting light, at least light having a wavelength corresponding to the wavelength of the fluorescence and having a sensor face adapted to be exposed to the fluid medium, emitter, and to transmit the received exciting light into the fluid medium through the sensor face, to receive, through the sensor face, fluorescence emitted by excited fluorosphores in the fluid medium, and to transmit at least part of the received fluorescence to the light detector, the sensor face, and the relative positioning of the light emitter, the optical detector, and the sensor face being such that the detector is able to receive light transmitted from at least a portion of that part of the sensor face which receives light from the light emitter.
In another aspect, the invention relates to a method for inducing and detecting fluorescence in a fluid medium containing at least one fluorophore, the method comprising: internally reflecting wall parts at least capable of reflecting light having a wavelength corresponding to the wavelength of the fluorescence and through a sensor face thereof into the fluid medium, at least part of the light being of a wavelength capable of exciting the fluorophores so as to induce the emission of fluorescence, fluorophores in the fluid medium, and transmitting at least part of the received fluorescence through the sensor body to a light detector adapted to detect the fluorescence emitted by the fluorophores excited by the exciting light, fluorescence received through a part of the sensor face from which light from the light emitter is emitted to the fluid medium.
The fluid medium will normally be a liquid, but it may also be a mixture of a liquid and a gas, or it may be a gas with, e.g.
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Hansen Jan
Nielsen Hans O.
Evans F. L.
Faxekalk A/S
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