WO2012051637A1

WO2012051637A1 - Spectrometer

Info

Publication number: WO2012051637A1
Application number: PCT/AT2011/000433
Authority: WO
Inventors: Philipp Ertelthaler; Andreas Weingartner
Original assignee: Scan Messtechnik Gesellschaft M.B.H.
Priority date: 2010-10-20
Filing date: 2011-10-20
Publication date: 2012-04-26
Also published as: AT510630B1; AT510630A1

Abstract

The invention relates to a spectrometer (1) for immersion in a fluid (2) and for examining the substances a fluid (2) contains, having a housing (3) with a light source (4) arranged therein and a detector (5) arranged therein, wherein the light from the light source (4) is guided through a transmitting window (7) along a specified path length(Δχ) through the fluid (2) to be examined and through a receiving window (8) to the detector (5). For simply modifying the spectrometer (1) for different path lengths (Δχ), at least one insert with a through-channel for the light beam and with at least one window for arrangement upstream of the transmitting window (7) and/or the receiving window (8) for shortening the path length (Δχ) is provided, each insert is attached to the housing (3) and each insert is provided with a seal on the side that faces the transmitting window (7) or the receiving window (8).

Description

spectrometer

The invention relates to a spectrometer for immersion in a fluid and for examining the ingredients of a fluid having a housing with light source and detector disposed therein, wherein the light of the light source through a transmission window along a predetermined path length through the fluid to be examined and through a receiving window led to the detector.

The spectrometer may include one or more light sources and also one or more detectors. In Spekt oskopie the intensity of the emitted light is reduced by certain ingredients of the fluid to be measured and inferred by the detection of the intensity of the received light with knowledge of the intensity of the emitted light on the concentration of the ingredient. Different ingredients have different absorption properties and have optimal absorption properties at different wavelengths of light. Accordingly, there are certain suitable wavelengths for the detection of certain ingredients. By emitting light with a broader wavelength range, the concentrations of several ingredients in the fluid to be examined can also be carried out at the same time. For example, flash lamps are particularly suitable.

In order to achieve suitable measurement results, the maintenance of certain absorption ranges is appropriate. Depending on the nature of the fluid to be examined and the nature of the substance to be examined, different path lengths, ie those lengths over which the light passes through the fluid to be examined, are required or advantageous for the maintenance of these absorption regions.

Usually, depending on the nature of the to un ^¬ tersuchenden fluid and the ingredients to be measured in a variety of spectrometers with different path lengths

resorted. This means for the user an increased cost but also organizational effort. In the prior art, spectrometers have become known, which have variable path lengths. For example, US 5,168,367 A describes such a spectrometer. However, the construction is relatively complex and error-prone, since the path length must be set correctly by the user and checked by appropriate gauges.

A construction of a spectrometer with several path lengths has become known, for example, from US Pat. No. 6,643,016 B2. This construction is characterized by a relatively complicated construction and consequently by increased costs.

DE 10 2006 046 265 A1 describes a system for the analysis of gases by means of infrared absorption spectroscopy, wherein a plurality of modular gas cells can be arranged behind one another in the light beam of the spectrometer whose path lengths can be of different lengths. The system is used in particular to analyze different gases in different gas cells. The construction is not suitable for immersion in a gaseous or liquid medium.

The object of the present invention is therefore to provide an abovementioned spectrometer in which the path length for adaptation to the fluid to be investigated or the ingredient to be examined can be easily changed. The cost of the spectrometer should be as low as possible and the change in the path length should be possible quickly and easily. Disadvantages of known spectrometers should be avoided or at least reduced.

This object is achieved in that at least one insert is provided with a passage for the light beam and at least one window for arrangement in front of the transmission window and or or the receiving window to shorten the path length, each insert is attached to the housing, and each insert on the the transmission window or receiving window facing side is provided with a seal. The subject invention thus provides at least one use before the transmission window and or receiving window of the spectrometer is arranged and shortened the path length accordingly. Thus, an adaptation of the spectrometer to changing conditions is particularly easy and easy. The user only has to purchase the insert or multiple inserts and not have another spectrometer with changed path length. Of course, the at least one insert reduces the transmission of the light beam, which can be easily corrected by increasing the intensity of the light source accordingly. Assuming a corresponding construction of the spectrometer and the at least one insert, the cost of changing the path length is particularly low and can be carried out particularly quickly. The optical path length shortening insert is simply placed over the transmission window or receiving window of the spectrometer and the passageway sealed by the seal against the fluid. Thus, the light beam in the area between the transmitting or receiving window and the window in use is not affected, which could lead to measurement errors.

Advantageously, an insert is provided in each case before the transmission window and before the reception window for shortening the path length.

If the inserts are identically constructed, the manufacturing costs thereof can be reduced and mis-assembly by the user can be avoided.

In order to prevent corrosion of the insert, in particular in spectrometer probes, which are introduced or immersed in the fluid to be measured, it is advantageous if each insert is formed of stainless steel. In addition, it is advantageous if the inserts have no edges or corners to which impurities could accumulate. For certain applications, it is of course also possible to manufacture the inserts made of other metals or plastic.

In the case of spectrometers, which are immersed in a liquid to be measured and detect the ingredients to be examined "in situ", it is customary to use the transmission window and the reception window in to clean regularly. For this purpose, nozzles are arranged on the spectrometer, which direct a rinsing liquid or purging air on the transmission window and receiving window and thereby remove impurities from the surface. If the optical path length is changed by at least one insert, it is expedient or necessary to change the direction of the rinsing liquid or rinsing air to the transmission window or receiving window to the window in the insert. Expediently, so-called flushing stones with flushing channels for guiding the flushing liquid or flushing air for flushing the transmission window and the reception window are provided for this purpose in the spectrometer. These purging blocks are preferably provided with flushing channels adapted to the inserts used. Depending on the path length of the angle of the flushing channels is changed accordingly to direct the jet of rinsing liquid or purging air exactly to the respective window to be cleaned.

In order to further reduce the assembly effort for changing the path length, the inserts may at best be made in one piece with the purging plug. Thus, it is only necessary for the user to attach a component to the spectrometer or to dismantle.

Advantageously, a set of different inserts and possibly different rinsing stones for different path lengths is provided. For example, bets can be made to achieve

Path lengths of 35, 15, 5, 2, 1 and 0.5 mm may be provided. The largest path length is used for a very clear medium, for example drinking water, and the smallest path length for a visually very dense medium or a medium with a high substance concentration, in order to be able to achieve the required absorption range for the spectrometric measurement.

To avoid incorrect assembly, the various inserts may have a coding. Such coding can be realized in the simplest case by a mere color coding or by numbers on the inserts and possibly purging stones up to electronic coding, for example by RFID (Radio Frequency Identification) transponders, which also the same allow automatic adjustment of the intensity of the light source of the spectrometer.

The present invention will now be explained in more detail with reference to the accompanying drawings.

Show in it

Fig. 1 shows a basic structure of a spectrometer;

2 shows a perspective view of a section of a spectrometric probe with two inserts according to the invention for shortening the path length;

3 shows the embodiment according to FIG. 2 with dismantled inserts, in side view;

4 shows the embodiment of Figure 3 in plan view.

5a to 5e different views of an embodiment of an insert for shortening the path length; and

6a to 6d different views of a replaceable sink.

Fig. 1 shows the basic structure of a spectrometer 1, in particular a spectrometric probe, which is introduced or immersed in the fluid 2 to be examined. Within a housing 3, at least one light source 4 and at least one detector 5 are arranged. The light of the light source 4 is possibly directed via an optical system 6 through a transmitting window 7 in the fluid 2 to be examined and a receiving window 8 and a possible optics 9 to the detector 5. From the difference between the intensity of the light received by the detector 5 and the intensity of the light emitted by the light source 4, it is possible to deduce the concentration of certain ingredients in the fluid 2. The fluid 2 is transilluminated along the path length Δχ from the transmission window 7 to the reception window 8 by the light. In the so-called two-beam measuring method, a reference light beam outside the fluid 2 in the housing 3 is sent from the light source 4 to the detector 5 parallel to the measuring beam between the transmitting window 7 and the receiving window 8 for reference purposes.

For certain fluids 2 and for determining certain Inhaltsstof ^¬ fe different path lengths Δχ are appropriate. While in ^¬ example, with very clear drinking water a very large

Path length Δχ is possible, the path length Δχ for visually very dense media or media with very high concentration of the substance must be much lower in order to achieve optimal measurement results.

2, 3 and 4 show a detail of an embodiment variant of a spectrometer 1 in which the path length Δχ is shortened by two inserts 10. The inserts 10, which are arranged in the illustrated embodiment on both sides, ie both on the side of the transmitting window 7 and on the side of the receiving window 8 of the spectrometer 1, comprise a passage 11 for the light beam and at least one window 12, which in a corresponding housing , preferably made of stainless steel, are arranged. The insert 10 is arranged in front of the transmitting window 7 or receiving window 8 such that the light originating from the transmitting window 7 can pass through the passage 11 of the insert 10 and its window 12 into the fluid 2 to be measured and then through the window 12 and the passageway 11 of the second insert 10 enters the receiving window 8 of the spectrometer 1 and the detector 5. With the help of appropriate fasteners, in particular screws 13, the inserts 10 are attached to the housing 3 of the spectrometer 1. In order to prevent the fluid 2 passes into the passage 11 of the insert 10 and there leads to measurement errors, is preferably on the transmission window 7 or receiving window 8 facing side of the insert 10, a seal 14, for example ^¬ in the form of an O Ringes, arranged. By arranging such inserts 10, the path length Δχ can thus be reduced correspondingly to a smaller path length Δχ '. The assembly of the inserts 10 is particularly quick and easy to carry out. Instead of screws 13, other fastening straps may be used. te be used, which allow, for example, a tool-free assembly and disassembly.

5 a to 5 e show various views of an embodiment of an insert 10. FIG. 5 a shows a perspective view of an embodiment of an insert 10 obliquely from the front on the window 12, FIG. 5 b shows a perspective view of the insert 10 according to FIG. 5a from the back, that is the side with which the insert 10 is placed in front of the transmitting window 7 or receiving window 8 of the spectrometer 1. Fig. 5c shows a view of the insert 10 from the front, i. 5d shows a section through the insert 10 according to FIG. 5c along the section line A-A and FIG. 5e shows a section through the insert 10 according to FIG. 5c along the section line B-B. The insert 10 includes the passageway

11, the window 12 and two holes 15 for receiving the screws 13 (see Fig. 3). The holes 15 are preferably arranged obliquely to ensure optimum attachment of the insert 10 on the housing 3 of the spectrometer 1. The window

12, which consists in particular of sapphire crystal, is pressed or glued in the insert 10. To achieve different path lengths Δχ different inserts 10 may be provided with different dimensions. These can be color-coded, for example, to make the application particularly easy for the user.

The two sides, i. In front of the transmission window 7 and the receiving window 8 of the spectrometer 1, arranged inserts 10 may also be made in one piece (not shown).

In the case of spectrometers 1, which are arranged directly in the fluid 2 to be examined, it is customary to clean the transmission window 7 and the reception window 8 on a regular basis. For a rinsing liquid or purge air is used, which is directed under appropriate pressure on the transmission window 7 and receiving window 8. The rinsing liquid or purging air is guided in rinsing channels 17, which are arranged in corresponding rinsing stones 16 on the housing 3 of the spectrometer 1. Figures 6a to 6d show different views of an embodiment of such Purging plug 16, as it can be arranged in a corresponding recess 18 in the housing 3 of the Spe ktrometers 1 (see Figs. 3 and 4). 6a shows a perspective view of a sink 16 from the side facing the fluid 2 to be examined, FIG. 6b shows a perspective view of the sink 16 according to FIG. 6a from the underside, FIG. 6c shows a view of the sink 16 according to FIG 6a from above, ie from the side facing the fluid 2 to be examined. Finally, FIG. 6d shows a sectional view through the sink 16 according to FIG. 6c along the section line BB. The sink 16, which is also preferably formed of stainless steel, has two holes 19 for receiving fasteners, such as screws (see Fig. 3), on. After in the arrangement of inserts 10 on the spectrometer 1 whose windows 12 and not the original transmission window 7 and receiving window 8 of the spectrometer 1 are to be cleaned, the sink 16 provides a correspondingly changed leadership of the flushing channel 17. Preferably, 10 respective purging blocks 16 are provided to each of the corresponding inserts, which can also be offered in a corresponding set. Of course, the purge stones 16 may also be made in one piece together with the inserts 10 and thus be mounted even faster on the spectrometer 1 and dismantled again.

The embodiments of the inserts 10 or sinks 16 are not limited to the illustrated examples. Important in the design of the inserts 10 for spectrometric probes is to avoid edges or corners where dirt can be arranged as possible.

The present invention provides a simple and inexpensive way to quickly and easily retrofit a spectrometer 1 for measuring various ingredients of fluids 2 or for measurement in different fluids 2. The user does not need a multitude of differently constructed spectrometers 1 for the measurement of different ingredients or in different fluids 2.

Claims

claims:

A spectrometer (1) for immersion in a fluid (2) and for assaying the contents of the fluid (2), comprising a housing (3) having a light source (4) and detector (5) disposed therein, the light of Light source (4) through a transmission window (7) along a predetermined path length (Δχ) through the fluid to be examined (2) and through a receiving window (8) to the detector (5), characterized in that at least one insert (10) is provided with a passage channel (11) for the light beam and at least one window (12) for arrangement in front of the transmission window (7) and / or the reception window (12) for shortening the path length (Δχ), each insert (10) on the housing (3) is fixed, and each insert (10) at the the transmitting window (7) or receiving window (8) facing side is provided with a seal (14).

2. spectrometer (1) according to claim 1, characterized in that in each case an insert (10) in front of the transmitting window (7) and the receiving window (8) for shortening the path length (Δχ) is provided.

3. spectrometer (1) according to claim 2, characterized in that the inserts (10) are constructed identically.

4. spectrometer (1) according to claim 1 or 3, characterized in that the seal (14) is formed by a sealing ring made of elastic ^¬ cal material.

5. spectrometer (1) according to one of claims 1 to 4, characterized in that each insert (10) with at least one screw (13) on the housing (3) is fixed.

6. spectrometer (1) according to one of claims 1 to 5, characterized in that each insert (10) is formed of stainless steel.

7. spectrometer (1) according to one of claims 1 to 6, characterized in that a replaceable purging plug (16) with Rinsing channels (17) for guiding a rinsing liquid for rinsing ..... the transmission window (7) and the receiving window (8) is provided.

8. spectrometer (1) according to claim 7, characterized in that rinsing stones (16) with adapted to the inserts (10) adapted flushing channels (17) are provided.

9. spectrometer (1) according to one of claims 1 to 8, characterized in that the inserts (10) at most with the purge ^¬ stone (16) are made in one piece.

10. spectrometer (1) according to one of claims 1 to 9, characterized in that a set of different inserts (10) and possibly different rinsing stones (16) for different path lengths (Δχ) is provided.

11. spectrometer (1) according to claim 10, characterized in that the different inserts (10) have a coding.