The practical application of the invention will be described more specifically in the following, in connection with a gas-adapted arrangement or a gas meter for being able to determine the existence of gas by means of this gas meter, said gas at that time occuriπg in the form of relatively high concentrations of gas or gas mixtures in a sample of gas adapted for evaluation and being enclosed in or passing through a measuring cell

Such gas-adapted arrangement is then to exhibit an emitting or transmitting means, adapted for electromagnetic radiation, and having a cavity serving as a mβasur- ing cell for a sample of gas and Intended to be able to define an optical measuring distance applicable to the measuring itself, a detecting or sensing means or detector of said electromagnetic radiation passing through said optica! measuring distance from said transmitting means, and a unit performing spectral analysis and being connected in any case to said sensing means or detector.

to-etectricaliy sensitive to the electromagnetic radiation which is intended to fat! within

as to determine in this unit the relative intensity of radiation of the spectra? element. In this technical field the transmitting means and sensing means or detector In- dieated and utilized here are known in the prior art as well as units performing spectral analyses and thereto connected display units or similar presenting the results, and therefore these means, units and display units will not be the object of the more specific in this appl

Methods, arrangements and structures related to the technical field and character mentioned above are known earlier in a plurality of different embodiments.

As a first example of the technical background and the technical field to which the invention refers may be mentioned an arrangement adapted for spectra! analysis of a sample of a gas and/or a gas mixture with a transmitting means adapted for electromagnetic radiation, a space, such as a delimited space in the form of a cavity, serving as a measuring ceil and intended to be able to define an optical measuring distance, a sensing or detecting means for said electromagnetic radiation passing said optical mea- suring distance from said transmitting means, and at least one, to said sensing means related one or more opto-electric detectors with associated light-receiving and/or light-

sample of gas.

Said means, sensing the electromagnetic radiation, is opto-electrically adapt- ediy sensitive to the electromagnetic radiation, which is intended to fail within the spectral field whose chosen wavelength components or spectral elements are to become objects of an analysis in said unit performing the spectral analysis for determining in thi unit the relative radiation intensity of the spectral elements) for relevant and chosen

Reference Is here made to United States Patent Publication US-A-5 009 493,

German Patent Publication DE-A1-4 110 853, United States Patent Publication US-A-5 268 782 and United States Patent Publication US-A-4 029 521.

As a more specific first example of the arrangement analysing the sample of gas indicated here, reference is made to the contents of the published International Patent Application No. PCT/SE99/00145 (WO 99/41 592-A1), comprising a method for producing a detector related to a gas sensor and a detector thus produced.

As a second, more specific example of the arrangement indicated here, reference is made to the published International Patent Application having Publication No. As a third specific example of the arrangement indicated here, reference is made to the contents of the published International Patent Application having Publication No. WO 98/09152 A1.

Furthermore, reference is made to the contents of the International Patent Ap- plication having Publication No. WO 01/81 901 Al

With regard to the peculiarities related to the present invention it may be mentioned that it is also known that the relative intensity of radiation of a spectral element(s) for relevant wavelength sections is low in lesser and very small concentrations of gas

In known units for spectral analyses normally a minimum (high) concentration oi gas is required on the one hand for determining the relevant gas and on the other hand

It is known to supply, at right angles to a bandpass filter, electromagnetic or optica! radiation having a large wave range and to create in the filter prerequisites for let- ting through a selected narrow wave range to an opto-electric detector so as to have in this detector, with its light-receiving and light-sensitive portion, such as a chip, and a unit connected thereto for performing spectrai analysis, the intensity and/or relative intensity of the narrow wave range evaluated,

Generally, in gas test analyses over a spectral analysis of chosen wave range, it Is known that different criteria provide different measuring results with varying accu-

Thus it is earlier known: a. that a chosen furnished high power to the transmitting means normally increases the accuracy of the measuring result, b. while utilizing pulse technology the transmitting means can be activated periodically in order to create prerequisites for permitting the chip of the detector to cool off between activating pulses, c. with an increasing measuring distance through a sample of gas, between the transmitting means and the chip of the detector, to increase the exactness of the measuring result, applicable in low concentrations, d. that different gases in a sample of gas provide different signifk spectra at different frequencies and/or frequency sections, e. that different gases in a sample of gas provide a plurality of signific tion spectra, at different frequencies and/or frequency sections, mospheric pressure, increase the accuracy of the result of the measuring, g. that more and more sophisticated measuring units can be made to provide a more

distance. measuring distance assigned and utilized at that time, it is known in the prior art that very short measuring distances can have the disadvantage and expose of the foilowiπg drawbacks: from the transmitting means to a chip of the detec- iround light and/or background noise and heat, which

j. to reduce the heating of the detector and its chip, by leading generated heal into

k. to reduce the effect of conditions, to the greatest possible extent, us detection so as to clarify the influence of the transmitter in the

I, to create prerequisites for subtracting noise from a detected signal In the detector and its chip to the greatest possibie extent, m. to create good mechanical prerequisites for effective cooiing of the detector and

m. to create prerequisites for additionally reducing the influence of radiated heat to the detector, such as by leading heat over the sample of gas, in the cavity of the

Considering the significant features related to the present invention the following prior art publications are to be mentioned.

The European Patent Publication EP- 1 859 390-A1 is related to a microchip testing device (10), having an absorbance measuring chamber (25) for measuring ab- sorbances, a transmitted light receiving unit (15) for receiving light, which has been emitted from the light source (13) and have been transmitted through the absorbance measuring chamber (25), an aperture, which extends in a straight line in the direction of an optical axis of the absorbance measuring chamber with an entry opening for the Sight emitted by the iight source on one end and a light exit opening on an opposite end, measuring chamber, an splitter, which is located in the optica between the light exit opening of the aperture and the absorbance measuring and which transmits a first part of the incident light and reflects another part of it, and reflected light receiving part, for receiving the light which has been reflected by the

The arrangement thus described is adapted to test a liquid, and especially ev-

Patent Publication WO 2004/048 929-A2 is describing a high throughput sere-

is shown and described a device and a method for a rapid spectrum assay of

Multiple wavelengths scan with Fouriee analysis is here combined with large numbers of sample wells boated within infrared light compatible solid materials.

Very large scate measurement devices and systems for their use are fabicated b

Figure 1 is showing that light from a light source (105) passes through a beam splitter (110) and is reflected by interferometer mirrors (115) into spectra! filter (120).

Light from spectral filter (120) is focused via focusing and beam steering optics (125) into a bottom of a sample holder (130). 0 The light than interacts with each sample in one or more passes and is than re- an infrared ca~

., I] ₅ source o red radiations, 2), a device to modulate the radiation, 3), a sample holder, 4} _s an infrared detector, and S) a computer to collect, process, and present the spectral data.

Patent Publication EP-O 557 855-A1 is disclosing a system for collecting weakly scattering optical signals (100) and employs a laser (102), which illuminates an unknown gas (107), contained by or within a long hollow chamber (105) having a highly reflecting coating (106 or 111). The illuminating electromagnetic radiation (103) from the laser is directed along the entire length (L) of the chamber and collides with the vibrating molecules of the unknown gas within the containment tube.

The collisions causes the emission of shifted electromagnetic radiation (112) that is separated from the incident light and than is collected through one of the aper- The scattered photons are than guided to a collection optics assembly (118)

Patent Publication US-2006/119 851 -A 1 discloses a method and a device for measuring a concentration of a preselected gas in a gas sample.

The device comprises a "Harriotf-type muitϊpass eel! {10} having a center axis (74) and a housing (80A, 80B) surrounding and spaced from the axel to provide a tubu-

The gas sample is pumped through the sample cavi via apertures (154, 158) provided in opposed ends of the axle. supported at opposed ends of

A iight source, e.g. a laser or LED, is provided for emitting a light beam into the sample cavity via an entry aperture (30) in the first mirror, the light beam having a wave length, at which the preselected gas strongly absorbs,

The beam is reflected between the mirrors for a number of times before exiting the cell via an exit aperture (48) in the second mirror and impinging on a detector (52). The device further comprises a reference detector /32} for rninitoring the \n~ tentensity of the uπattenuated light beam and a detector for detecting the intensity of light transmitted through the second mirror after a single pass through the ceil.

If the circumstance is considered, that the technical considerations which a per- son skilled in the relevant art of technology must carry out in order to offer a solution to one or more given technical problems are on the one hand initially a neccessary understanding of the meaures and/or the sequence of measures which are to be carried out and on the other hand a necessary choice of the one or more means, which are required , the following technical problems should in consideration of this be relevant in pro- ducing and forming the present subject of invention,

Considering the standpoint of earlier technology, as it has been described above, it should therefore be seen as a technical problem to be able to understand the significance of, the advantages related to and/or the technical measures and considerations which will be required to offer, in an arrangement adapted for spectral analysis, a simple and cost-effective way of having the intensity of electromagnetic radiations or light radiations analyzed, for analyzing a sampte of a gas and/or a gas mixture, such as a sampte having a relatively high concentration of gas, within a delimited space or cavity related to the measuring cell and its measuring distance. There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for creating the prerequisites which are necessary for in reality being able to achieve high measuring accuracy, primarily by reducing the length of the measuring distance and reducing the overall size of the measuring eel! with regard to its casing, such as one or more of the conditions disclosed under sections "i" to "n" above.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for creating prerequisites for reducing the effect of indirect radiation heat, emana-

There is a technicai problem in being able to understand advantages related to and/or the technical measures and considerations that will be required for letting the length of said measuring distance, between the transmitting means and the sensing means or detector, be selected to be very short, such as less than 15 millimeters, and having a narrow slit or aperture for passing light rays for passing gen- erated light rays over the transmitting means be adapted such as to pass solely, or at any rate mainly, the light rays that are directed straight from the transmitting means and

There is a technical problem in being abie to understand the significance of, the advantages related to and/or the technical measures and considerations that will be re- quired for letting the length of the measuring distance be chosen to solely between 1 and 8 millimeters, such as around 2 - 4 millimeters.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting said slit or aperture be adapted so narrow and/or limited that a light ge~ Derating portion, associated with the transmitting means, will be abie to project towards a light-receiving or light-sensitive portion, such as a chip, associated with the sensing

There is a technical problem in being abie to understand the significance of, the advantages related to and/or the technical measures and considerations that will be re- lid sfit ion such, that it will ca- use the Hght-generating portion, such as a pinhoh projected against the light-receiving and light-sensitive portion or area.

There is a technical problem in being able to advantages related to and/or the technical measures and considerations that will be required for letting said sensing means, or in connection posed adjacently to or close to one or more optical fil significance of, the that will be re- quired for letting said optical filter be subdivided Into so as by means of these to permit passage of mutually separated wave elements and that to said receiving means this fight

is a technical problem in being able to understand the significance of, the s related to and/or the technical measures and quired letting the transmitting means and the sensing means, be oriented in a right angle or at least an essentially right angle to the casing of the measuring cell and cavity, There is a technical problem in being able to under; advantages related to and/or the technical measures and re~ quired for letting said slit or aperture be fashioned as fwo with a first being adaptei portion being adapted for

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be retransmitting means and the sensing casing cell and the cavity in a right or at any essentially right angle. There is a technical problem in being able to understand the significance of, the advantages refated to and/or th quired for letting said slit or aperture tion of the cavity oriented, relatedly to the direction of the light rays, adjacently to or closely to but at a small distance from said sensing means and an optical filter related to this sensing means.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting said sample of gas in said cavity or measuring cell consist of a flowing gas, with said gas being adapted to pass, by said disc and/or wall portion, adjacently to filter is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting said cavity or measuring cell and its surrounding wall portions in the measuring cell be processed and/or consist of a light-absorbing surface layer.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting the cavity of the measuring cell be restricted by a solidly reiated but easily removable wall portion or a cover, There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting the wall portion or the cover of the measuring cell be adapted to cooperate with the remainder of the measuring cell by means of a gasket, such as an elastic Oaring or the like. There is a technical problem in being abie to understand the significance of, the advantages related to and/or the technical measures and considerations that wiii be required for letting the wall portion or cover have the form of a gas-penetrable filter for diffusion of the sample of gas intended for the measuring sequence.

advantages related to and/or the technical measures and considerations that will be π quired for letting the waif portion or cover exhibit an inlet port or an outlet port for said

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be re~ quired for letting the sample of gas be adapted to be supplied and removed at an overpressure, for increasing the concentration rate.

There is a technicai problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be re- »n ot light π _, towards the sensing means for individual light-receiving portions. being abte to understand the significance of, measures and considerations that will be re- quired for having a performed measuring modified with an externa! partia! system adap ted for compressing the measuring gas modified so as t

There is a technical problem in being able to understand the significance of, sehnica! measures and considerations that will be quired for being abte to and letting the amplification factor be limited in the absorptio calculations so as to thereby be able to limit the influence of a noise factor.

Jem in beiπq abie t< sideratioπs that will be rent and/or a zero-point error. There is a technicai problem in being able to understand the significance of, the

quired for building on an arrangement, with a transmitting means adapted for electromagnetic radiation, a space in the form of a cavity surrounding and enclosing the sample of gas and sen/ing as a measuring cell with its measuring path and being intended to be able to define an optical measuring distance through the sample of gas; a sensing means in the form of a detector for said electromagnetic radiation, which passes through said optical measuring distance from said transmitting means; and at least one unit performing the spectral analysis and being connected to said sensing means, wherein said means sensing the electromagnetic radiation is adaptedly opto-etectrically sensitive to the electromagnetic radiation, which is intended to fall within (the wavelength compo-

of an analysis ϊn the unit performing unit, the (relative) radiation intensity elernent(s) and to present the on a display unit or screen or in it is

'length, of closely adjacent lyi electromagnetic light bundle iigh concentrations of gas.

There is a technical problem stand the significance of, the n measures quired for, with the prerequisites given above, measuring the mutual relationship of signal intensities with regard to each other and solely for specific and closely related wave-

in besπ to understand the significance of, the ica ^' >s and considerations that will be re~

:mg a VSf! pted to a measuring technology within fie

in a high concen- tration of gas and of a short measuring distance, such as around 3 millimeters.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting a small number of wavelength-specific measuring points or spectral e~

ldentifk

There is a technics in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be re- quired for utilizing electror bandpass filters for being able to create measuring signals at fixed predeterm gths In accordance with the principles of a πon- dispersive infrared technolo ive InfraRed or "NDIR ^D -technique). in being able to understand the significance of, the advantages related to and/or quired for letting said sample of gas in said measuring chamber be subjected to an

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for having a delivered result, depending on one or more wavelengths during ab~

ted correction circuit, for an influence of the chosen overpressure and a chosen gas or mixture of gases, for delivering a signal corresponding to the concentration of the relevant gas or gas mixture at atmospheric pressure.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting the overpressure chosen beforehand be capable of being generated by There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting the mechanical means comprise a piston-cylinder arrangement, whose piston is displaceabfy disposed between associated turning points in a cylinder unit.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for having said electromagnetic radiation be adapted to pass a specifically adapted optical bandpass filter, places between said transmit means.

There is a technical problem in being able t< advantages related to and/or the technical measures and considerations that will be required for letting such bandpass filter be structured or constructed such as to be capable of offering in the transmission a wavelength dependent on the angle of incidence of the electromagnetic radiation, with a large wave range generated and transmitted in said transmitting means.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be re~

gles of incidence or similar, be adapted to separate a first chosen spectral elements) and/or a first wavelength component from a second chosen spectral eiement and/or a

diation.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting said unit be adapted to be able to electrically detect via opto-electric detectors an occuring radiation intensity applicable to more than one wavelength component and/or more than one spectral element.

There is a technical problem in being able to understand the significance of, the advantages related to and/or the technical measures and considerations that will be required for letting the optical (electromagnetic) bandpass filter be adapted to be able to deflect an Incident and emitted optical or electromagnetic radiation to at least two different optical and predetermined outfalling or outgoing angies, each one applicable to a narrow wavelength component(s) and/or spectral element(s). There is a technical problem in being s advantages related to and/or the technical me* ing or outgo ing the existence of an opto-electric detector, associated wavelength components) or its associated spectra! eiement(s) in its associ- unit performing the spectra! analysis.

There is a technical problem in being able to understand the significance of, the es related to and/or the technical measures and considerations that will be re-

bandpass filter. lem in advantages related to and/or the technical considerations that will be re- concentration, such as of carbon di- ύ-

of introduction and is based on an arrangement adapted for a spectral analysis of gas concentrations having a means, adapted for transmitting electromagnetic radiation in accordance with the preamble of ciaim 1.

In addition to the mentioned transmitting means the arrangement utilized here i for gas test analysing also to indicate a space, such as in the form of a cavity, serving as a measuring cell Intended for the sample of gas and being intended to be able to de fine an optical measuring distance, a sensing means or detector of said efectroma_ radiation passing said optical measuring distance from said transmitting means, and a unit performing spectrai analysis and being connected at any rate to said sensing me-

to be sensitive of the electromagnetic radiation, which is intended to fall in the spectral range whose chosen wavelength cornponent(s) and/or spectral element(s) i.a. over an optical filter, which is to be the subject of analysis in the unit performing the spectrai a- nalysis, so as within this unit being able to determine the relative intensity of radiation o the wavelength components) or the spectral element(s) in relation to a relatively high

In order to be able to solve one or more of the technical problems mentioned above the present invention more specifically indicates that the thus known technology

means or detector, be chosen to be short, such as to less than 15 millimeters, a narrow slit or aperture for passing light rays, is medium, and is adapted such, that it lets through solely or at any rate mainly, ht rays which are directly directed from the trans-

As proposed embodiments falling within the frame of the present inventive con- is indicated that the length of the measuring distance in reality should be chosen to between 1 and 6 millimeters, such as around 2 - 4 millimeters.

Said slit or aperture is then to be adapted so narrow or restricted that a light ge- portion, associated with the transmitting means, will be able to project against s -receiving or light-sensitive portion or area allotted to the sensing means, such as a

Said slit or aperture is then to be allotted a limited dimension that causes the

Said optical filter is adapted adjacent to said sensing means or in connection

Said optical filter can be subdivided into two parts for permitting, by means thereof, mutually different wavelength components or spectral elements to pass, with said receiving means and these light-receiving or light-sensitive parts being shaped as to two

adapted to a second wave-length component, Mountings for the transmitting means and the sensing means should be, with regard to the casing of the measuring cell and the cavity, oriented at a right angle or at least an essentially right angle.

Said slit or aperture is fashioned in a disc or a wall portion oriented, related in the direction of the light rays, adjacent to but a small distance from said sensing means and an optical filter, related to this sensing means.

ceil are processed and/or consist of a layer absorbing light rays.

The cavity of said measuring cell is but easily rernovabte, wall portion or a cover. The wall portion or the cover of the measuring cell is adapted to cooperate with the measuring cell in general over a gasket, such as an elastic "Q"-ring.

The wall portion or cover Is allotted the form of a gas-permeable filter, for creating prerequisites for a diffusion of the sample of gas or gas mixture, The wall portion or cover exhibits an inie port! and/or an outlet port for said sample of gas in the cavity.

The sample of gas is adapted to be able to be supplied under a predetermined

A first portion of light rays is directed directly from the transmitting means and towards the sensing means, and a second portion of light rays is directed reflected towards the sensing means for indivuda! light-receiving portions.

Furthermore, it is indicated that said gas in the mentioned measuring chamber can be subjected to an overpressure chosen in advance and wherein a delivered result depending on one or more wavelengths being absorbed in the measuring chamber, is compensated for over a correction circuit relevant for the chosen overpressure with re-

As proposed embodiments falling within the framework of the present invention if is additionally indicated that the overpressure is to be adapted and chosen in response to the capability of absorption existing at the chosen overpressure for a chosen gas and/or gas mixture.

The correction circuit cooperates with a correction unit having an abililty of absorption/pressure relation for a circuit determining a chosen gas or gas mixture.

The overpressure chosen beforehand may be generated by a mechanical means, with said means being comprised of an arrangement of piston and cylinder, said piston being movabfy disposed between associated turning points and alternatively having the mechanical means comprise a magnetic body, oriented in the measuring cell, said body being capable of carrying out an oscillating motion by a surrounding electric circuit,

In accordance with the present invention it is further indicated that said transrnit- ted electromagnetic radiation, between said transmitting means and said sensing me-

lister, with said bandpass ti wavelength dependent of the angle of incidence in the transmission of the electroma netic radiation generated by said transmitting means. This ter is then to wavelengths waveleπqth or a or a first chosen th or a narrow area or

:ιc radiau ay means of one or more opto-electrica! detectors, inq inten- sities of radiation from one or from more than one such spectral element

radiation be deflected in at least two predetermined outfalling or outgoing angles of the

adapted to receive one and the same electromagnetic radiation, within which radiation in any case two different wavelength components or spectral elements fall.

As said optica! bandpass filter may to advantage be chosen a filter, active on the basis of optical interference. existence of and the concentration of carbon dioxide (CO ₂ ), such as in air or exha ation air, are included.

A light ray (in the form of a narrow electromagneti lected portion of light rays may to advantage be adapted t angle towards an opto-electric detector from a transmitting means

iich primarily

■pecific significative characteristics that hereby prerequisites have been created for an arrangement adapted for spectral analysis having a transmitting means adapted for electromagnetic radiation, a space, and a sensing means or detector of said electromagnetic radiation from said transmitt- ting means, and a unit performing the spectral analysis at any rate connected to said sensing means, wherein the mentioned means (or detector) sensing the electromagnetic radiation is to be adaptedly sensitive to the filter-passing electromagnetic radiation which is intended to fall within the spectral field whose chosen wavelength components) or spectral element(s) are over an optical filter to become objects of an analysis in the unit performing the spectral analysis for determining in this unit, by various calculations, the relative radiation intensity of the spectra! elemeπt(s) for high concentrations of gas, indicating that the length of said measuring distance between the transmitting and the sensing means or detector is to be chosen to be short, such as to less 15 millimeters.

A narrow slit or aperture ight rays in the via the transmitting means U such, that it lets through solely mainly the light rays which transmitting means the sensing means or _*

and 6 millimeters, such as around 2 - 4 millimeters.

The subject matter, primarily must be considered to be characterizing of present invention, is disc characterizing portion of the following claim 1.

S ig the ssgmf lated to the present invention, will now be described more specifically as an example with reference to the accompanying drawings, in which;

Figure 1 shows the principle of measuring gas at high gas concentrations while utilizing a NDIR-technology with a light transmitting means, a space adapted for a gas test, such as a cavity in a measuring cell, a light sensing means or detector and a light calculating unit, adapted to performing a spectral analysis and its associated display unit or the like, as well as a correction circuit, compensating for the absorption capability in dependency of prevailing pressure. Figure 2 shows in an enlarged scale the means transmitting light rays and the means for sensing light rays or detector with a measuring distance "L" therebetween and in a first embodiment

Figure 3 illustrates in this respect a second embodiment. Figure 4 illustrates a third embodiment with directly acting light rays and indi- rectly or reflected acting light rays.

with openings for the transmitting means' and the sensing means' mountings.

Figure 6 shows Figure 5 in a lateral view, with a wall portion or a cover with an inlet port and an outlet port for a gas-perrneabie filter, Fϊg ^y re 7 shows Figure 5 in another lateral view of the measuring cell, and Figure 8 shows the measuring cell, according to Figures 5 to 7, in two different perspective views, one corresponding to the illustration in Figure 5 the other disclosing an enlarged under section of said measuring cell.

in the following of a presently proposed embodiment which exhibits the significative characteristics related to the invention and which is clarified by the Figures, shown in the accompanying drawings, we have chosen terms and specific terminology with the purpose of thereby primarily clarifying the basic concept of the invention.

However, in this connection it should be noted that the terms chosen here are not to be seen as limiting solely to the terms utilized and chosen here and it should be understood that each term chosen in this manner is to be interpretered such, that in ad- dition it will be capable of comprising ail technical equivalents which function in the same manner or essentially the same manner so as to thereby result in achieving the same or essentially the same purpose and/or technical effect.

Thus, with reference to the accompanying drawings, the basic prerequisites for the present invention are shown schematically and in detail, with the significative pecu- liarities or features associated with the invention being concretized by the embodiments Dposed and more specifically described in the following. Thus, Figure 1 schematically shows the principle of an arrangement "A" adap-

netic radiation "S" with a large wave range and a delimited space 11 , in the form of a cavity, serving as a measuring cell 1 adapted for a sample "G' ^] of gas and intended to be able to define an optical measuring distance, designated "L" (See Figure 2).

Furthermore, a iight sensing means 12 or detector (3b) of said eiectromagnetic radiation "S", passing said optical measuring distance "L" from said light transmitting means 10 and a unit 13 performing the spectral analysis connected over a lead 121 to at least said sensing means 12 and therein included opto-eiectric detectors are illus-

Aiso, the means 12 sensing the electromagnetic radiation "S" should be mentioned, and the thereto belonging detector and/or detectors 3b should be adapted to be sensitive to the electromagnetic radiations, which are intended to fall within the spectral field whose chosen wavelength comρonent(s) or spectra! element(s) are to become objects of analysis within the unit 13 performing the spectra! analysis so as to primarily having calculated and determining the relative intensity of radiation of a chosen spectra! element in this unit 13. Said transmitted electromagnetic radiation "S", between said transmitting means 10 and said sensing means 12 is adapted to pass towards and to selectively pass through a bandpass filter, such as an optical bandpass filter 14 (See Figure 2),

Such bandpass filter 14:3 is, according to Figure 4, structured and/or designed so as to offer a wavelength dependent of the angle of incidence in the transmission of the electromagnetic radiation ⁿ Sa1" and "Sa2" ^! generated by said transmitting means 10.

This bandpass filter 14:3 in Figure 4 is adapted to separate, with a chosen angle of incidence, a first chosen spectral element 4a from a second chosen spectra! element 4b, and two opto-e!ectrϊc detectors 3b and 3b ¹ are both connected to said unit 13, which is adapted with modules for detecting an occuriπg radiation intensity for more than one such spectral element.

The unit 13 performing the spectral analysis exhibits a transmitter module 13a

a centra! unit 13b, and a number of signal receiving modules 13c, 13d and 13e, serving

Over a circuit 13g signals emanating from electromagnetic radiation "Sa" can be compared to a received selective electromagnetic radiation "Sb" (4a, 4b) in unit 13 over

The evaluated and calculated result in the central unit 13b can then be transferred to a display unit 15, as a graph 15a or similar over a circuit 13k. More specifically, Figure 1 illustrates an application in an absorption cuvette, in which cuvette the sample "G" of gas, which with the assistance of the electromagnetic radiation "Sa", or considered as a bundle of radiation, is to be analyzed, with the radiation "S" resp. "Sa" being transmitted by an emitter unit 10 and being received by optc™ electric detectors, such as a detector 3b. This emitter unit 10 can then consist of a source of radiation and a collimator coordinating rays of light with the purpose of gathering, as effectively as possible, the emitted radiation "Sa" with its bundle of radiation and directing the same through the length of the absorption cuvette towards the detector 12 or 3b.

Emitter unit 10 can here have the form of a glowing wire in a glass bulb fiiled with gas or evacuated of gas, i.e. an incandescent lamp, or a heated resistor on a ceramic substrate or on a thin membrane produced by silicon techπoiogy and microme- chaπics or a light-emitting diode, having a well defined emission spectrum.

In accordance with the instructions of the invention the emitter unit 10 is to transmit an emission "S" and "Sa" of bundles of radiation, which at feast must comprise all of the wavelengths whose intensities are to be detected opto-electrically in their detector 3b or in individual detectors 3b, 3b ¹ and be evaluated in unit 13.

The absorption cuvette can then be designed in different ways depending on the chosen application, chosen measuring accuracy, the manner in which the measur- ing gas or sample "G" of gas can be expected to be collected, via overpressure, etc.

In certain applications the space 11 of the absorption cuvette 1 can concurrently be permitted to be the mechanical body on which the emitter unit 10 and the receiver 12

The detector 3b of the receiver unit or means 12 is adapted to create the opto- electric wavelength-dependent electrical signals, which later are to become the object o a calculating analysis in the unit 13 performing the spectral analysis,

Such units 13 are well known in this technical field and are therefore not descri-

Said unit 13 is intended to calculate the result, which discloses a relevant con- centration of gas and/or a gas and/or a gas mixture.

It is important that the opto-eiectric detector 3b has the ability of generating some kind or some form of electric signals, whose size and shape are to be dependent of and correspond to the intensity of radiation 4a passing through an opening or aperture

By means of not shown electric connections these electric signals are transferred to the two measuring iegs 3d and 3e of the receiver unit or means 12, from where i subsequent amplifier stage (not shown) in unit 13 and/or other electronics/computer processing refines the measuring signal to a final result, which may be evaluated, for example visible as a graph 15a ^' on display unit 15a. If measuring of gas is to occur according to NDIR-technoiogy the wavelength ft the filter transmission 4a is chosen to coincide with an absorption wavelength, which is characteristic of the matter whose concentration of gas is to be measured.

Short-time variations in the inwardly radiated intensity from the electromagnetic radiation "S" or the light clusters or rays "Sa", which run the risk of distorting a careful evaluation of the measuring signals on lead 121 , can be neutralized and regulated away entirely if one of the measuring channels is used as an intensity reference over a signal neutrai wavelength.

With reference to Figure 6, more specifically an arrangement "M" for compress- ing the sample "G" of gas and for increasing the value of the evaluating concentration of gas to values that may be more carefully evaluated is illustrated.

The invention is to be exemplified with high values of gas concentration either occuring naturally or in a gas compressed form.

Correction circuit 13g is only schematically indicated but cooperates with a cor- rection unit 13h, with a circuit determining capability of absorption/pressure for each gas or gas mixture and wherein the relationship of the absorption capacity to the chosen pressure can be illustrated in a "Pa"-graph (Pressure-Correction-Graph).

Thus, correction circuit 13g is adapted to reduce an evaluated fictive gas concentration with a stored or evaluated value. The overpressure (Pa) chosen beforehand may be generated by a mechanical

iir of which is dispiaceably positioned between associated turning points.

The mechanical means can consist of a magnetic body oriented in measuring cell 11 or related to the measuring cell, with said body being capable of being given an oscillating motion by a surrounding electric circuit (not shown).

The frequency of a chosen change of overpressure via means can be chosen to between 1 and 50 HeFtZ ₃ such as around 25 - 35 Hertz.

The measuring chamber 11 can be adapted to a volume of 0,5 to 3,0 cubic cen- timeters, such as around 0,8 - 1 ,2 cubic centimeters.

The increase of pressure Is dependent on an expected concentration of gas and should in the norma! case be chosen to between 1 :2 and 1 :10, such as around 1 :4 to 1 :6.

The correction circuit 13g is adapted to produce a reduced value of the gas con- centration to the display unit 15 related to the atmospheric pressure.

Thus, there is a number of possible solutions of the arrangement "A" and variations thereof which on the one hand can generate the necessary angles of incidence of the receiver unit 12 and on the other hand can assign other means for generating different pressures and different correction circuits 13g so as thereby to offer solutions of the arrangement "A" associated with the invention.

With a specific description of the present invention as it may be seen in Figure 1 measuring of high concentrations of gas will be particularly accentuated.

Thus, Figure 2 (enlarged view) illustrates that the length "L" of said measuring distance between the transmitting means 10 and the sensing means 12 or the detector 3b has been chosen to be short, such as to less than 15 millimeters.

A narrow slit or aperture 15a, letting through generated light rays via the transmitting means 10, is adapted such, that it will let through solely or at least mainly the light rays "Sa", which are directed straight from the transmitting means 10 and towards the sensing means 12 or its detectors 3b, 3b'.

The length of the measuring distance is in reality to be chosen to be as short as possible, such as to between 1 and 6 millimeters, such as around 2 - 4 millimeters.

The embodiment shows a length of approximately 3 millimeters.

Said slit or aperture 15a in a disc 15 is adapted to be so narrow and/or limited that a light generating portion 10a, "Sb", associated with the transmitting means 1O ₁ will be able to be projected towards a light receiving or light sensitive portion 12a, 3b associated with a sensing means 12, such as a sensing chip 3b, 3b',

Furthermore, said slit or aperture 15a in a disc 15 is to be allotted such a limited dimension that makes the light generating portion 10a "Sb", such as a pinhole camera, able to be projected towards the light-receiving portion 12a, 3b.

Figures 2, 3 and 4, respectively, now illustrate that to said sensing means 12 or in connection with said sensing means 12 said optical filter is disposed, which is designated the reference numeral 14 in Figure 2, 14:1 and 14:2 in Figure 3 and 14:3 in Figure 4. Said optical filter 14 can thus be subdivided into two partial portions 14:1 and

14:2 so as by means of these to permit mutually separated wavelength components or spectral elements 4a ^! and 4b ^s (In Figure 3) to pass, and than to said receiving means 12, the light-receiving or light-sensitive portion 12a thereof is formed as two portions

and a second portion adapted to a second wave-length component.

Mounting bases or recesses 110, 112 (In Figure 5} belonging to the transmittϊπc means 10 (or receiving means 12) are oriented to a casing 1 of the measuring cell 11 and the cavity at a right angle or under all circumstances an essentially right angle, ■igure 5 has the purpose of ^"" Said slit or aperture 15a is formed in a d oriented, related to the direction of the light rays to but at a small distance D said sensing means. g cell 11 consists of a flowϊn gas, wherein the sample of gas is adapted to pass along said disc 15 and said optica! filter 14.

More specifically it is indie M 1 or measuring cell 1 and its surrounding waii portions in the measuring processed and/or consist of a light-

However, the cavity of the measuring cell is limited by a sily removable wall portion or a cover 18.

The wall portion or cover 16 of the measuring cell 1 is adapted to cooperate with the remainder of the measuring cell via a gasket, such as an elastic O"-ring 17. The wall portion or cover 18 can be allotted the form of supporting a gas-pe- netrable filter 18 for diffusion of the sample of gas.

The wall portion or cover 16 exhibits an inlet port 16a and/or an outlet port 16b for said sample "G" of gas within cavity 11.

Thus, Figure 4 illustrates that a first portion of light rays "Sa 1" is directed straight from the transmitting means 10 and towards the sensing means 3b ^! and that a sec- ond portion of light rays "Sa2" is directed reflectiπgly in a mirror surface 19 towards the sensing means 3b for each individual light-receiving portion.

With reference to Figure 8 certain parts and details of the arrangement are shown and illustrated in a 3-dimeπsional design.

Thus, this invention intends to be able to offer an evaluation of high concentra- tions of a gas included in a mixture comprising one or more gases.

With regard to CO ₂ -gas it has turned out to be possible to detect and determine a concentration of 5% and higher, such as 6 - 30%, in measuring exhaust gases.

For methane gas an evalution of a gas concentration between 0 - 4 volume percentage is proposed, in a LEL system (Lower Explosive Limit) this is mentioned as be- tween 0 and 100%. Thus, this is relevant to a gas burners.

If the embodiment described above is considered it should be noted that the embodiment of Figure 2 very well can be supplemented with two or more parallel bundles of light, each one associated with its slit or aperture, with individual optical filters Although the embodiments illustrate a small separation between disc 15 or the wall portion it lies within the scope of the invention to glue an optical filter to the detector and to glue a cover to this detector, having a slit or an aperture 15a adjacent to the light-

However, Figures 5 to 8, respectively, illustrate that a wall portion 15 of the cavity 11 is provided with a slit or an aperture 15a and that the detector with the optical filter is Introduced as a unit, so as to engage or to be positioned at a small distance from the slit or aperture 15a.

In Figure 6 the cover 16 can be replaced by a diffusion filter (19) for letting a surrounding gas diffuse into the cavity of measuring cell 1.

Here, the cover 16 is easily removable and easily positionabie such as a slanting wall portion of the measuring eel! 1.

The invention is of course not limited to the embodiment disclosed above as an example, and it can be subjected to modifications within the frame of the inventive con- cept, which is illustrated in the following claims,

It should be particularly noted that each ϋiustrated unit and/or circuit can be combined with each other illustrated unit and/or circuit within the scope of being able to