Optics: measuring and testing – Sample – specimen – or standard holder or support – Fluid containers
Reexamination Certificate
1998-10-22
2001-07-24
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Sample, specimen, or standard holder or support
Fluid containers
C356S244000
Reexamination Certificate
active
06266139
ABSTRACT:
The invention relates to a capillary tube holder according to the type defined in more detail in the preamble of claim
1
.
Capillary tube holders of the generic type which are used, for example, for microHPLC (micro high performance liquid chromatography) and for CE/CZE (capillary electrophoresis/capillary zone electrophoresis) are known from practice.
In this case, a capillary tube, which usually consists of silica, has a transparent window burned free on it after which the window is cleaned, whereupon the capillary tube is pushed into a recess in the capillary tube holder and adjusted in the capillary tube holder such that the transparent window comes to be situated in the region of two light channels arranged situated opposite one another axially with respect to the capillary tube in the capillary tube holder, it being possible to determine the exact position of the capillary tube and/or the window described in the capillary tube holder by means of the evaluation device such as, for example, a spectrometer.
During the measuring operation with the known capillary tube holders, light beams are led through the input light channel to the transparent window in the capillary tube, there flowing through said capillary tube a medium, in particular a liquid, on which measurements or determinations are to be undertaken.
A suitable optical system for focusing the light beams is provided in the input light channel, the focused light beams passing through the capillary tube or the window in the capillary tube and the medium flowing through the capillary tube, whereupon the light beams are fed through the light output channel to a detector or a spectrometer or another suitable evaluation device.
FR 2 643 147 A1 describes a measuring system having optical components which effect an expansion of light in all directions. An optically imaging element provides transillumination, it being possible to detect only relatively large units. Capillary tube measurements are not possible thereby.
It is also disadvantageous in known capillary tube holders that overall only an insufficient quantity of the light fed through the input light channel passes through the capillary tube, with the result that it is also possible to feed only an insufficient quantity of light to the evaluation device. The reason for this is that the capillary tube has, for example, an inside diameter of only 75 &mgr;m, that is to say the useful quantity of light which can be led through the capillary tube can be distributed only over this cross-sectional surface.
Furthermore, a relatively large proportion of the light fed through the input light channel is led in an unused fashion over the outer wall of the capillary tube to the output light channel, that is to say the light fed does not pass through the medium flowing through the capillary tube, and on the one hand this entails impairment of the measurement result in the evaluation device, and on the other hand it causes a reduction in the sensitivity of the evaluation device, for example a detector or a spectrometer, connected downstream of the capillary tube holder, since the useful component of the light received by the evaluation device, or of the light contributing to the absorption, is too small. Thus, to a substantial extent, the light is not used for absorption of the flow of medium in the capillary tube, but passes through the side wall of the capillary tube in a partially unused fashion.
Since, as already mentioned, this fact has a disadvantageous effect on the sensitivity of the measuring arrangement, the disadvantages described lead to a substantial impairment of the measurement results.
It is therefore the object of the present invention to provide a capillary tube holder which eliminates the described disadvantages of the prior art, in particular in the case of which a larger proportion of the light fed through the input light channel passes through the medium flowing through the capillary tube.
This object is achieved according to the invention by the features mentioned in the characterizing part of claim
1
.
As a result of the use of optical conductors with individual fibers, a larger proportion of the light fed to the capillary tube holder is supplied overall to the capillary tube, and thus also to the medium flowing through the capillary tube.
The optical conductors, with the individual fibers, which are used are positioned in this case directly in front of the capillary tube, so that the capillary tube acts as an optical system and deflects the light beam or the light beams, which is/are fed through the input light channel, to such an extent that approximately 90% of the light beams are led through the medium and to the output light channel, that is to say 90% of the light beams participate in the absorption. There is no need in this case for optical imaging, the capillary tube itself, instead, being used for this purpose. Thus, by contrast with the prior art the useful component of the light fed is substantially higher for the capillary tube holder according to the invention.
A slight gap, which is caused, for example, by manufacturing tolerances of the capillary tube, always remains between the respective optical conductor and the capillary tube. Otherwise, the optical conductors are, however, brought as tightly as possible up to the capillary tube.
Since, as fiber bundles, the individual fibers furthermore have in each case a diameter which is at least approximately as large as the inside diameter of the capillary tube, just so much light is fed through each individual fiber that said light is not largely led through the wall of the capillary tube and that, on the other hand, too much light is not unnecessarily fed to the capillary tube.
According to the invention, on the capillary tubes [sic] the incoming light bundle composed of a plurality of individual fibers is either split up in the longitudinal direction or laid around radially in a semicircle, it also being possible to combine the two, that is to say longitudinal and radial directions. In the same way, the outgoing, that is to say the output beams and the receiving optical conductors are arranged in a corresponding way to this.
In a development of the invention, it is possible to provide in this regard that at their ends facing the recess, the optical conductors in each case have a cross section-transforming element for transforming the cross-sectional surface of the optical conductors, that is to say the cross section-transforming elements are a component of the optical conductors.
These cross section-transforming elements can be used to transform the, for example, round cross sections of the optical fibers or of the fiber bundles in the input light channel and the output light channel into other suitable cross sections or cross-sectional shapes, which are described at another juncture.
Cross section-transforming elements of extremely varied design are already known from practice for other applications. The aim is to use the cross section-transforming elements, which are packed as tightly as possible, to achieve the highest possible light power on very small surfaces, and this can be achieved, for example, by virtue of the fact that in the region where the light channels open into the recess a plurality of individual fibers of the optical conductors are arranged parallel to the longitudinal axis of the recess, and therefore along a straight line, that is to say the totality of the individual fibers, which normally has a round cross-sectional surface, is dismantled or transformed into a multiplicity of smaller individual cross sections.
In the arrangement of the optical conductors described, the useful cross-sectional surface of the optical conductors can be optimally adapted to the cross-sectional surface of the capillary tube in a straight line for which a plurality of individual optical fibers with a correspondingly smaller cross-sectional surface lead light beams through the capillary tube.
However, it is also possible as an alternative for a plurality of individual fibers of the o
Font Frank G.
Lockwood, Alex, Fitzgibbon & Cummings
Ratiff Reginald A.
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