Optics: measuring and testing – By particle light scattering – With photocell detection
Patent
1998-07-29
2000-02-01
Font, Frank G.
Optics: measuring and testing
By particle light scattering
With photocell detection
356339, G01N 2100
Patent
active
060209615
DESCRIPTION:
BRIEF SUMMARY
The invention relates to the arrangement of various optical and optoelectronic assemblies to form a nephelometric measuring device. Thus, the invention relates to the arrangement of various optical and optoelectronic components and assemblies to form an optical measuring channel for measuring the scattered light of samples. In this context, a nephelometric arrangement is presupposed, i.e., only light scattered by the sample in a certain solid angle is measured.
Conventional nephelometers for liquid samples in cuvettes operate as follows:
The sample is filled into a cuvette and is transilluminated by light of small bandwidth and low divergence. The light scattered by the sample is measured by a detector arranged at a right angle to the transillumination direction.
There is a large number of modifications of this principle:
An example is the objective to reduce the influence of the cuvette on the background signal (DE-OS 29 07 000) or to obtain further data by measuring the scattered light in various solid angle ranges, for example 90.degree. and 35.degree. (DE-OS 29 20 276).
Of special interest are arrangements which are also able to measure samples arranged in the form of a matrix, for instance in so-called microtitration plates or on flat transparent supports, e.g. glass plates. Such a system which transilluminates the sample in a vertical direction and which can be equipped with a mechanical movement means for horizontally positioning the samples is described in DE-OS 35 35 652.
The principle of this arrangement consists in the combination of an illumination device transilluminating the sample and a detector device with a detector and a detector optical system with high which concentrates the scattered light onto a detector in this context, the light directly passing through the sample is absorbed by a central shading element in the central zone of the detector optical system.
This arrangement has the disadvantage that the signal is unsatisfactorily high in the case of measurements in the air and in the case of an empty cuvette and that the overall sensitivity is too low.
From DE-OS 24 09 273, an optical arrangement is known for measuring antigen-antibody reactions in which scattered light emanating from a sample is obtained by means of a detector device. The light originating from an illumination device transilluminates a sample behind which a light trap is arranged for absorbing direct light. Within the detector optical system, a black shutter is arranged on the optical axis of the arrangement for shuttering out scattered light originating from shutters arranged between the illumination device and the sample.
The object is to design this arrangement such that the sensitivity of the measuring system is high and free of background signals and the use of multiple open-top vessels is possible. Thus, it is the object of the invention to be able to measure nephelometrically samples arranged in the form of a matrix in open-top vessels with high sensitivity and free from disturbing background signals.
To achieve this object, the invention proposes a nephelometer for optically detecting the scattered light of an illuminated sample, comprising an illumination device (subsequently also called illuminator) for illuminating a sample. The illumination device further comprises a light source, an exit lens assembly (subsequently also called illuminator optical system) and an exit opening shutter (subsequently also called exit pupil) which are arranged, in this order, on a common optical axis originating in the light source. A detector device is provided to detect the scattered light originating from the sample. This detector device comprises a central shading element by means of which the light directly passing through the sample can be absorbed so that it does not impinge on the detector device and especially not on the detector thereof. The detector device further comprises a detector entrance lens arrangement (subsequently also called detector optical system). Furthermore, the detector device comprises a second sha
REFERENCES:
patent: 4679939 (1987-07-01), Curry et al.
Font Frank G.
Merlin Gesellschaft fuer mikrobiologische Diagnostik mbH
Stafira Michael P.
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