DE202006007621U1 - Compact built spectral measurement equipment e.g. for ATR interferometric high resolution spectral determination of oil types, has measuring substance in direct contact with ATR element or separated by radiation-transparent partition - Google Patents

Abstract

The instrument has the passage of a measuring radiation taking place via an ATR element. A measuring substance is in direct contact with the ATR element or separated by a radiation-transparent partition. From the ATR element, measuring radiation is supplied directly or over optical elements to a compact interferometer. The interference length is necessary for the increase of the spectral resolving power taking place via multiple reflection of the beam within the compact interferometer. The measuring radiation has a continuous wavelength from the ultraviolet to the thermal infrared range.

Description

1. Designation of the object

at the subject matter of the utility model is a respect to the State of the art extremely compact built device, with its help, oil species, and other liquids, their metabolites and other ingredients, by application of a ATR interferometric measurement method spectral High Resolution can be determined.

2. Description of the device

2.1 Classification of the device purpose

The Purpose of the novel measuring system is the immediate, qualitative and quantitative, virtually time-lag-free, highly specific Identification of natural and synthetic fluids, as well the determination of the chemical and physical composition, the ingredients and the concentration by measuring spectral Signatures. The method of measurement used belongs to the category the so-called active methods, which are characterized that this measured object, So the liquid, With radiation of a certain property expression applied directly or indirectly is and with the DUT interacts. From the resulting changes the beam properties can the characteristic parameters of the DUT are derived.

at The subject of the invention is a device in which the measuring device brought into contact with the substances and ingredients to be detected becomes. Under certain conditions, the measured value determination can also take place through a partition wall. In this application, neither the measuring method still the basic structure of the measuring instrument can be changed.

in the The present case is the application of the measuring method and the use of the device for natural and synthetically produced oils explained. in principle can this measuring method and the device in an analogous way also for other liquids be applied.

2.2 State of the art

The here treated novel determination system combines the basic Operating principles of an ATR element (ATR = Attenuated Total Reflection, attenuated Total reflection) with the method of Fourier interferometry. By a suitable technical design of the interferometer this compact design of the overall device achieved.

Around the disadvantages - in particular the high power losses - too Avoid this when reflected by radiation at or during transmission of radiation through the test object result in the present device, the measuring radiation using an ATR element with the DUT interacted. Characterized by the characteristic for the ATR element Total reflection occurs while no energy loss during the passage of Radiation through the test object on. It will only be based on the excitation of the substance molecules wavelength and substance-specific components (in the evanescent field of radiation) absorbed. From the thus partially or completely absorbed wavelength shares can on the type of liquid (ie, for example, the oils and oil mixtures), their composition, their ingredients and their concentration getting closed.

By Using an ATR element is the radiation with the DUT intense in touch comes comes, there is no attenuation of the radiation intensity and consequently, the provision of a powerful measurement signal ensured.

One Significant advantage of this Meßstrahlführung by an ATR element is that, even with heavy background absorption the measuring radiation (eg due to ingredients or contamination of the oil substance) to no reduction or falsification of the measuring signal comes. This means that interfering components from the test sample before implementation the measurement - how common with other beam spectroscopic measurements - do not need to be removed. Lie high soot levels before, then the otherwise required dilution of measured substance, for example with fresh oil, for Reduction in concentration also not necessary. Basically you can use it the oil samples immediately and directly for the analysis can be used without any preparations of the Sample substance must be made.

By The use of the ATR element can be the spectroscopic Properties about the entire wavelength range across or in a section of it. This will be but not at the same time for the characterization of the measuring substance and the contents required high spectral resolution of individual spectral energy bands reached.

To increase the spectral resolution over the entire wavelength range or a portion thereof, the radiation emerging from the ATR element in a novel device is based on the functioning a Michelson interferometer used.

In its conventional execution this interference generator consists of a beam splitter and two Reflection mirrors, of which the radiation sensor opposite Mirror is transversely movable. By this arrangement and the movement of a mirror result in periodic interference patterns, from which using a Fourier analysis, the energy shares by the individual wavelength be determined.

The spectral resolution is thereby by the (double) path length the radiation between the beam splitter and the movable mirror affected. This law requires to achieve a high spectral resolution greater movement lengths of movable mirror and leads with it to considerable lengths of the interference generator.

in the In this case, a technical design of the interferometer for Achieving high spectral resolution used by multiple deflection and partial decoupling of the beam path structurally very compact is and with their help those with the usual interpretations reached highest spectral resolutions In comparable sizes still exceeded become.

By Combination of the ATR element with the compact interferometer becomes a largely trouble-free high-resolution Measurement of spectral signatures of oils and their metabolites and other ingredients without special preparation of the sample allows. This proves the measuring method as particularly suitable for a direct use on machines during operation. The simple one Construction makes the measuring apparatus also insensitive to mechanical vibrations as well as temperature and pressure variations.

2.3 Performance of the device and the procedure

(shown by the example of measurements on oils)

Determination of the type of oil and the oil mixture

• – Getriebe (auch bei Windkraftanlagen),
• – Kolbenmotoren und Strömungsmaschinen,
• – Transformatoren,
• – Hydraulische Anlagen.
• – Fahrzeug- und Motorprüfstände
• – Kühlschmierstoffe.

Basically, the novel method and device is suitable for the identification of all types of oil and oil mixtures. The spectral ranges listed below are selected very generally with regard to their use and they relate preferably to technically used synthetic oils. These include, among other uses, oils for

• - gearboxes (including wind turbines),
• - piston engines and turbomachines,
• - transformers,
• - Hydraulic systems.
• - Vehicle and engine test stands
• - Coolants.

For identification and differentiation between different types of oil and oil brands are measurements over larger spectral ranges and a comparison of the measured with previously determined experimentally Spectral signature needed.

The listed below Spectral ranges and the achievable high spectral resolution allow the Identification of additives and decomposition products of the oil. Especially can be the causes of an oil degradation and for derive the presence of foreign substances.

determination of decay products

oxidation

• Occurs mainly in connection with combustion processes and High temperature stresses. Caused by high temperatures and / or high pressures in the presence of oxygen.
• Product Classes: Ketones, Esters, Aldehydes, Carbonates, Carboxylic Acids and Further;
• Effects: oil takes high acid value on, promotion corrosion of metals, increase in oil viscosity;
• Spectral range: 1800 cm ^-1 to 1670 cm ^-1 ;
• Possible Additional rating: Oxidation level of the oil, quantified by TAN value (TAN = Total Acid Number);

Nitrifzierung

• Occurs mainly in connection with combustion processes and High temperature loads. Caused by high temperatures and / or high pressures in the presence of oxygen and nitrogen;
• Product classes: NO, NO ₂ , N ₂ O ₄ and others;
• Impact: increase the viscosity (Oil thickening) Increase in acidity, Acceptance of firnis-, varnish-like Constitution;
• Spectral range: 1650 cm ^-1 to 1600 cm ^-1 ;

Sulphatisierung

• Caused by sulfur compounds in crude oil or in Additives in lubricating oils;
• Product classes: SO ₂ , SO ₃ and others;
• Effects: By reaction with water formation of organic and inorganic acids, such as. B. H ₂ SO ₄ ;
• Spectral ranges: 1180 cm ^-1 to 1120 cm ^-1 ;

additives

additives

• Additives serve to improve the oil properties.
• Material classes: Thinner, aliphatic substances, eg. Octane, aromatic compounds;
• Product classes: due to chemical transformation, the chemical compounds change the additives and thus the properties of the oil;
• Spectral ranges: Measurements over wide spectral ranges from approximately 650 cm ^-1 to 950 cm ^-1 required for comparison purposes for the determination of the change over time of the additive constituents and of the additive degradation;

Example glycol

• Spectral ranges: about 3000 cm ^-1 to 3200 cm ^-1 and 1070 cm ^-1 to 1080 cm ^-1 and 1025 cm ^-1 to 1045 cm ^-1 and 870 cm ^-1 to 890 cm ^-1 ; the glycol content is rated positive / negative;

foreign substances

water

• Origin through condensation, cooling line leakage (hairline cracks, defective head gasket), water is light in certain conditions in oil soluble and acts dispersively;
• Effects: Reduction of the lubricating and cooling properties of the oil;
• Spectral ranges: Water causes strong absorption of near infrared radiation. The presence of absorption bands of water indicates the reduction of oil-specific properties; broadband absorption bands of about 3000 cm ^-1 to 3800 cm ^-1 and 1600 cm ^-1 to 1700 cm ^-1 ;

soot

• Made at high temperatures, low oxygen combustion; Review of the Engine adjustment required;
• Impact: change the viscosity. Rußschlammbildung;
• Spectral ranges: detectable by scattering phenomena of the infrared radiation, no actual absorption of the radiation; Measurement over a wide wavelength range; with increasing wavenumber of radiation, scattering effect increases; Spectral ranges:> 4000 cm ^-1 ; from about 2000 cm ^-1 to about 2500 cm ^-1 ;

fuel

Increased fuel value requires review of Carburettor and injection system;

Determination of the condition natural oils

With Help this novel device can also the conditions natural oils become. So z. B. olive oil under the influence of heat and sunlight metabolites of high toxicity. Training and the presence of these metabolites can be determined by measuring the spectral Absorption in the ultraviolet wavelength range of the electromagnetic Spectrum can be determined.

3. Structure of the device

• – einer oder mehreren Strahlenquellen;
• – einer optischen Komponente zur Zerlegung der Gesamtstrahlung in diskrete Spektralbereiche;
• – einer optischen Komponente zur Erzeugung einer Wechselwirkung mit der zu vermessenden Substanz;
• – einer optischen Komponente zur Erhöhung der spektralen Auflösung;
• – einem oder mehreren Strahlungssensoren;
• – Komponenten zur Pulsung und zur Polarisierung der Strahlung.

The device ( 1 ) consists of the following units:

• - one or more sources of radiation;
• An optical component for decomposing the total radiation into discrete spectral ranges;
• - An optical component for generating an interaction with the substance to be measured;
• An optical component for increasing the spectral resolution;
• - one or more radiation sensors;
• - Components for pulsation and polarization of the radiation.

• – elektronischen Komponenten zur Aufbereitung und Auswertung der erfaßten Strahlungsinformationen;
• – Komponenten zur Steuerung und Überwachung der Gerätefunktionen und zur Durchführung der Meß-, Aufbereitungs- und Auswerteprozesse;

In addition, the device is made

• - Electronic components for processing and evaluation of the detected radiation information;
• - components for controlling and monitoring the device functions and for carrying out the measurement, preparation and evaluation processes;

3.1 The radiation sources

to fulfillment the measuring task it is necessary to use radiation over the entire wavelength range of about 0.25 microns (ultraviolet) to about 12 microns (thermal Infrared) without gaps to apply. In addition, it is necessary that the radiation density over the entire used wavelength range with enough high energy provided becomes.

When Radiation source for the ultraviolet and visible regions of the electromagnetic spectrum be z. As diodes, for generating the radiation in the infrared range of about 0.76 μm to about 12 microns become so-called black body emitters used.

3.2 Selective use the optical elements

Because of the different ways of the radiation interaction with the materials of the optical components, different elements are each selectively used, sometimes bypassing unnecessary optical com components.

3.3 Connection of radiation source to the prism

Along The propagation direction of the radiation is determined by means of optical Elements a concentration of the radiation density and an adaptation the radiation cross section for the purpose of introduction into the dispersion element performed.

3.4 The dispersion element

With Help of a dispersion element (eg a dispersion prism) a division of the radiation is made in their spectral components for the purpose of selectively using individual limited spectral components from the total spectrum of radiation.

3.5 connection from the dispersion element to the deflection mirror

On the path from the dispersion prism to the deflection mirror becomes a limited Spectral component with the help of an aperture for forwarding to a Deflection mirror selected and the other spectral components hidden. On the way from the aperture optionally up to the deflecting mirror is a beam shaping with Help made an optical element. This beam shaping can also after forwarding over the mirror in the direction of the ATR element.

3.6 deflecting mirror

Of the Deflection mirror serves to deflect a selective spectral component towards the entrance area of the ATR element. Between deflecting mirror and ATR prism can one be introduced optical element for beam shaping.

3.7 Jet Pulser

With The help of a jet pulse generator is the beam continuity temporarily for one interrupted for a certain period of time. The duration of the interruption and the period of unhindered beam propagation is variable determinable.

3.8 pre-polaristor

In front Entry of the beam into the ATR element is this either in a randomly polarized expression leave a specific polarization mode imprinted on it.

3.9 ATR prism and sample contact

With Help of an ATR element occurs the radiation with the measuring substance in interaction. For this purpose, the sample material is either directly in contact with or from the prism one for the measuring radiation transparent material deposited. The admission of the test sample can either one-sided or two-sided along the ATR element respectively.

The not after interaction with the test sample Absorbed radiation components occur at the entrance surface opposite End of the ATR element off.

3.10 Post-polarizer

To Leaving the ATR element, the jet enters a device a, which happen only beam components with a certain polarization expression leaves.

3.11 compact interferometer

construction and operation of this unit will be described under 4..

3.12 Radiation measurement by sensor elements

To Exit of the radiation from said Kompaktinterferometer and after passage or without passage through the associated peripheral optical Elements, the radiation is one or more sensor elements supplied and their intensity detected by wavelength.

The Type of sensor elements used is determined by the wavelength of the Radiation and other radiation parameters such as polarization and pulsation certainly. As a suitable sensor element has at least for the infrared range the use of thermopile elements proved.

4. Description of the compact interferometer.

The compact interferometer ( 2 ) consists of several tube-like nested movable cylinders 1 , wherein a closure surface 2 firmly fixed and the opposite end surface 3 is transversely movable.

The one from an external beam splitter 10 deflected beam is through an opening 6 on the fixed cylinder side 2 initiated. Inside the cylinder there are several reflection mirrors 4 . 5 , arranged such that the incoming beam 7 by one on the movable end wall 3 attached reflection mirror 5 on a likewise on the movable end wall 3 attached mirror 5 directed and from this towards one opposite, at the fixed end wall 2 attached mirror 4 is forwarded.

On the fixed end wall 2 there is another mirror 4 , which deflects the beam perpendicular to the previous orientation until the beam on another mounted on the fixed end wall mirror 4 meets and from there in turn towards the movable end wall 3 is forwarded.

This direction reversal of the beam by reflection mirrors on the fixed or the movable end wall is repeated several times. The last change in direction of the beam at the movable end wall by means of a mirror oriented perpendicular to the beam propagation direction 8th serves to return the beam via the same mirror system to the jet entry opening 6 reflect back. The beam finally passes through this opening in the direction of the beam splitter 10 out again. The jet entering and exiting the cylinder is to be guided in such a way that appropriate interference phenomena occur to increase the spectral resolution.

Because of the multiple change of direction of the Beam between the two end walls will be a Weglängenvergrößerung between Beam entrance and beam exit reached, which over the path lengths at conventionally designed interference units of equal length.

By This technical design results in the same length significant increase the interference length and the spectral resolution, the so far over the resolution at (conventional) single reflection and the required greater moving length of the mirror and thus construction length of the interferometer.

The through the inlet 6 Exiting light beam passes through the external beam splitter 10 for further use.

A Variant of this configuration is the beam or beam components not through the inlet alone, but through other openings to exit (and enter) from the fixed wall. These rays can be transmitted through a beam splitter with other shares of the original or already changed by interference Beam interact and thus additional interference phenomena form. By this arrangement, different interference ranges of the total amount of interference forms extracted and one fed further use become.

The essential novelty of this interpretation of an interferometer in the multiple reflection of the steel inside the cylinder, the Beam exit at the location of the beam entrance or from other openings and the further use of the beam for generating further interference forms, that in a compact design of the unit over that with conventional Single reflection reaches a much higher spectral resolution becomes.

5. Possible measuring modes

• a) es wird gleichzeitig der gesamte für die Messung erforderlichen Spektralbereich zur Erreichung einer Wechselwirkung mit dem Meßobjekt verwendet;
• b) es wird jeweils nur ein begrenzter schmalbandiger Spektralbereich für die Messung verwendet, jedoch durch kontinuierliche Verschiebung des Frequenzbandes der gesamte erforderliche Spektralbereich vollständig abgedeckt;

The measurements can be done in two different modes:

• a) at the same time the entire spectral range required for the measurement is used to achieve an interaction with the DUT;
• b) only a limited narrowband spectral range is used for the measurement, but completely covered by continuous shifting of the frequency band of the entire required spectral range;

at Both modes can the measuring beam continuous or pulsed and in a certain polarization mode or randomly polarized.

At the Mode b) one uses to select the required spectral section a dispersive optical element, e.g. B. a dispersion prism. In mode a), this dispersion prism is out of the beam path decoupled.

6. Interpretation of the device

Of the substantial advantage of this device consists in the quasi loss of energy and largely trouble-free Determination of the absorption spectrum of the substance to be measured and simultaneous Achieving a significantly high spectral resolution at greatest compactness the device construction.

Because of the small volume of the device This device is suitable as a mobile measuring system for accommodation in a container the size of one Briefcase. In a related Application is an oil sample removed from an operating system and introduced into the measuring apparatus. Already after a period of one minute, the result of the measurement is with regard to the type of oil, the oil mixture, the ingredients and their concentration available. Special preparations and preparations the test sample and additional studies wet chemical Art are not required.

The application of this measuring method also allows a continuous determination of the oil condition, when the beam path is brought into interaction with the oil of a plant. Thus, it is possible to change the state of each used Oil without interrupting the operation.

Next the components for the spectroscopic determination of the oil condition can be additional Facilities to the device append, with their help also the viscosity, the temperature and the density of the oil can be determined.

Claims (20)

Compact spectral measuring device for the ATR interferometric high-resolution spectral determination of oils and other liquids, their metabolites and other ingredients, characterized in that the passage of the measuring radiation is carried out by an ATR element, wherein the measuring substance with directly the ATR element in contact can stand or is separated from this by a radiation-transparent partition wall; Spectral measuring device according to claim 1, and characterized in that emerging from the ATR element measuring radiation directly or via optical elements is fed to a compact interferometer, being the one to increase the spectral resolution required Interference length through Multiple reflection of the measuring beam takes place within the compact interferometer; Spectral measuring device according to claim 1 and 2, and characterized in that the measuring radiation used the wavelength ranges from the ultraviolet to the thermal infrared range continuously covers; Spectral measuring device according to claim 1 and 2 and 3, and characterized in that the measuring radiation is different wavelength generated by different radiation sources and by the same or different conducting optical elements; Spectral measuring device according to claim 1 and 2 and 3 and 4, and characterized in that the measuring radiation on the route from the radiation source to a dispersion element is concentrated by optical elements so that they have an increased power density per unit area having; Spectral measuring device according to claim 1 and 2 and 3 and 4 and 5, and characterized in that the measuring beam on the route from the radiation source to a dispersion element is geometrically shaped by optical elements in such a way that it is holistic is introduced into the dispersion element; Spectral measuring device according to claim 1 and 2 and 3 and 4 and 5 and 6, and characterized in that the beam at a wavelength-dependent angle is introduced into the dispersion element so that it depends on the wavelength Minimum exit angle disperse decomposed into its spectral components, from exits the dispersion element; Spectral measuring device according to claim 1 and 2 and 3 and 4 and 5 and 6 and 7, and characterized that the measuring beam after exiting the dispersion element on a reflector mirror impinges and from this to a subsequent optical element is forwarded; Spectral measuring device according to claim 1 and 2 and 3 and 4 and 5 and 6 and 7 and 8, and characterized in that the measuring beam bypassing the dispersion element without first being submitted to his spectral components are directed directly to the reflection mirror and forwarded by this to a subsequent optical element becomes; Spectral measuring device after one or more of the preceding claims, and characterized that the Reflection mirror is mounted pivotally such that the reflected measuring radiation on an aperture and another optical element is directed so that either with previous use of the dispersion element only a subset the wavelengths from the entire wavelength range the measuring radiation through the aperture passes in the direction of the subsequent optical element, or if the dispersion element bypasses the measuring radiation in its entirety Wavelength scope through the aperture in the direction of the subsequent optical element passes and forwarded; Spectral measuring device after one or more of the preceding claims, and characterized that the measuring radiation by an element for beam interruption during a certain period of time in terms of attenuated his performance or completely at its continuation is prevented or completely continue unhindered can; Spectral measuring device after one or more of the preceding claims, and characterized that the measuring radiation after leaving the element for beam interruption by a polarizer passes through, wherein the radiation can be randomly polarized or imprinting one or more polarization modes on it; Spectral measuring device after one or more of the preceding claims, and characterized that the measuring radiation subsequently enters the ATR element, there with the measuring substance directly or interacts indirectly and after passing through the ATR element exits the ATR element; Spectral measuring device after one or more of the preceding claims, and characterized that the measuring beam passes through a polarizing element, all polarization modes or only one or more selected polarization modes selectively forwarded and the other polarization modes at the Forwarding are prevented; Spectral measuring device after one or more of the preceding claims, and characterized that the measuring radiation After passing through a beam splitter on a fixed Mirror directed and from this again in the direction of the beam splitter is forwarded, wherein a proportion of the measuring radiation in the Kompaktinterferometer introduced and after leaving this in the direction of the beam splitter is forwarded; Spectral measuring device after one or more of the preceding claims, and characterized that the in the compact interferometer introduced beam cascade to a reflection mirror passed and from this also cascade to inlet opening thus redirected that will happen through the mutual influence of opposing ones Directions propagating beams result in interference textures that with the help of a periodicity analysis to increase the spectral resolution of the measuring radiation be used; Spectral measuring device after one or more of the preceding claims, and characterized in that the interfering Radiation after passage or reflection at the beam splitter in the direction of a radiation sensor is forwarded; Spectral measuring device after one or more of the preceding claims, and characterized that the Radiation dependent on their wavelengths Beam characteristic with the help of wavelength and polarization specific reacting Sensors detected becomes; Spectral measuring device after one or more of the preceding claims, and characterized that this measuring signal a treatment to reduce the signal interference and increase the Is subjected to signal unambiguity; Spectral measuring device after one or more of the preceding claims, and characterized that the Evaluation and presentation of signal evaluation in digital form he follows.