DE102005033533A1 - Method and device for examining a test object by means of invasive radiation - Google Patents

Abstract

The invention relates to a method and an arrangement for examining a measurement object (1) that has been manufactured industrially and / or by hand. The measurement object (1) has a plurality of different materials, at least two different materials. Expected material properties of at least two different materials of the measurement object (1) are determined. The expected material properties are used when designing and / or setting a measuring arrangement, the measuring arrangement having at least one radiation source (2) for generating invasive radiation and a radiation-sensitive sensor device (3) for detecting radiation after an interaction of the invasive radiation with the measuring object and wherein the measuring arrangement is designed and / or adjusted, taking into account the expected properties, so that different interactions of the invasive radiation with at least two different materials of the measuring object (1) can be detected by the sensor devices (3). The different interactions exist due to the spectrally different material properties of the different materials. A result of the different interactions of the invasive radiation is detected by means of the sensor device (3).

Description

The The invention relates to a method and an arrangement for examination of a measurement object, the measurement object being exposed to invasive radiation is, in particular X-radiation.

The use of invasive radiation to inspect workpieces is known. In computed tomography (CT), for example, the workpiece is placed on a turntable and irradiated by rotating the turntable in different rotational positions from different directions of X-radiation. The attenuated by extinction in the material of the workpiece radiation is spatially and temporally resolved detected by a sensor device. The tomographic back projection is used to calculate a spatially three-dimensional model of the workpiece. For each volume range, the model contains the material properties for the extinction of the X-ray radiation. An example of the CT will be in DE 39 24 066 A1 described.

CT is also used in the field of medical technology, for detection and treatment of pathological conditions. CT apparatus for medical technology However, they are not or only conditionally for the investigation of industrial or crafted items. Especially are those done in medicine Investigations very time consuming.

comparable Effort can not in economic terms at a routine examination operated by manufacturing products.

Out DE 103 52 645 A1 For example, there is known a system comprising a radiation source, a radiation detector and a computer operatively coupled to the radiation source and the radiation detector. The computer is configured to acquire CT exploration data from the radiation detector having a first X-ray spectrum and to obtain CT exploration data from the radiation detector having a second X-ray spectrum different from the first X-ray spectrum. A base material decomposition and a Compton and photoelectric decomposition are performed on several measurements with different mean X-ray energies. This should allow for improved accuracy and characterization.

Though It seems possible with such a system to be accurate increase and additional Gain information. However, this does not overcome the problem that the effort of the measurement, especially the time required, for a routine examination of manufacturing products is too high.

It is an object of the present invention, a method and a Arrangement for examining a test object by means of invasive radiation specify, so a routine examination of manufacturing products with reasonable effort is possible.

According to one Thought of the present invention exist industrially and / or crafted items often consist of several different ones Materials, each in separate volume areas of the Object are located. It is now possible by application of Previous knowledge and / or expectations the measurement and / or evaluation of the Make measurements so that the effort for the investigation is clear is reduced. It benefits the concept that usually a variety of items is produced, with each one of the objects one Specification (in particular CAD design or planning data) should correspond. The measurement and / or evaluation can therefore be carried out again and again in the same way.

• – es werden erwartete Materialeigenschaften von zumindest zwei verschiedenen Materialien des Messobjekts festgestellt,
• – die erwarteten Materialeigenschaften werden bei einer Auslegung und/oder Einstellung einer Messanordnung verwendet, wobei die Messanordnung zumindest eine Strahlungsquelle zur Erzeugung invasiver Strahlung und eine strahlungsempfindliche Sensoreinrichtung zur Detektion von Strahlung nach einer Wechselwirkung der invasiven Strahlung mit dem Messobjekt aufweist und wobei die Messanordnung unter Berücksichtigung der erwarteten Eigenschaften so ausgelegt und/oder eingestellt wird, dass unterschiedliche Wechselwirkungen der invasiven Strahlung mit zumindest zwei verschiedenen Materialien des Messobjekts von den Sensoreinrichtungen detektiert werden können, wobei die unterschiedlichen Wechselwirkungen aufgrund spektral unterschiedlicher Materialeigenschaften der verschiedenen Materialien bestehen,
• – das Messobjekt wird der invasiven Strahlung ausgesetzt und
• – ein Ergebnis der unterschiedlichen Wechselwirkungen der invasiven Strahlung wird mittels der Sensoreinrichtung detektiert.

A method is proposed for investigating an industrially and / or artificially produced measurement object, wherein the measurement object has a plurality of different materials, at least two different materials. The method comprises the following steps:

• Expected material properties of at least two different materials of the test object are determined,
• The expected material properties are used in a design and / or setting of a measuring arrangement, wherein the measuring arrangement has at least one radiation source for generating invasive radiation and a radiation-sensitive sensor device for detecting radiation after an interaction of the invasive radiation with the measurement object and wherein the measuring arrangement takes into account the expected properties are designed and / or adjusted such that different interactions of the invasive radiation with at least two different materials of the measurement object can be detected by the sensor devices, the different interactions being due to spectrally different material properties of the different materials,
• - The test object is exposed to invasive radiation and
• A result of the different interactions of the invasive radiation is detected by means of the sensor device.

general The procedure can also be formulated for any non-medical Investigations are used. For example, can be natural, but not live measurement objects are examined.

ever Depending on the type and / or arrangement of the sensor device may have different Results of the interactions are detected. For example, can when using X-rays invasive radiation merely attenuates the X-rays as they pass through be detected by the materials of the test object. alternative or additionally can the scattering of the X-ray quanta (Compton effect) and / or secondary effects (eg, luminescence and / or the photoelectric effect) become. Consequently, ever according to the type of interactions underlying the detection result the respectively required material properties determined (z. B. from reference works and / or determined by experiments), for example, the absorption coefficient, the extinction coefficient and / or the differential cross section, and indeed all material properties preferably in dependence the wavelength invasive radiation.

alternatives to X-rays As invasive radiation are in particular electromagnetic radiation other wavelengths (eg in the visible or infrared or ultraviolet wavelength range) or particle radiation.

Under In particular, one or more of the design of the measuring arrangement understood the following actions: The geometry of the measuring arrangement is adjusted (eg, the location and / or orientation of the sensor device is changed); components the measuring arrangement (such as a sensor device or a radiation source) are replaced, added, removed or structurally altered.

Under Setting the measuring arrangement is understood in particular that an operating mode of components of the measuring arrangement is set. Z. B. is the electrical voltage of an electron optics of an X-ray tube and / or set the direction of an electron beam and / or become sensitivities the sensor device for set the detection of the result of the interaction.

Also An evaluation device may be part of the measuring arrangement. In In this case, the design and / or adjustment of the measuring arrangement additionally or exclusively be done by that the evaluation device is prepared. On an example of this will be even later received. It is particularly preferred that at least one threshold or limit for the evaluation of a measurement signal of the sensor device is set.

The Adjustment and / or interpretation of the measuring arrangement is preferably carried out automatically taking into account the material properties.

In As a rule, the interactions of invasive radiation with different materials of the test object differently. In the However, practice often happens before that the invasive radiation used for the investigation becomes, a more or less continuous radiation spectrum forms. The invasive radiation is thus a mixture of radiation different wavelengths. This applies to different types of invasive radiation used in the invention can be used z. For example electromagnetic radiation, longitudinal waves (for example pressure waves like ultrasound) and particle radiation (eg positron or electron radiation). Will only be the sum of the interaction effects for the entire Spectrum detected, there are many different materials, in sum, a similar one Have effect and therefore not or not sure distinguished by the detection can be.

Of the Invention is now based on the idea to interpret the measuring system so and / or to adjust that the differences between the materials present in all materials Interactions with invasive radiation can be reliably detected can. To do this, the spectral (i.e., the invasive radiation related wavelength or energy-dependent) Material properties of the materials involved with the invasive Radiation taken into account. The spectrally different behavior of different materials can be used in different ways for safe detection Differentiation of materials can be used. Basically it is possible different spectra of invasive radiation simultaneously (z. B. from different directions) or successively on the measurement object radiation, invasive radiation of different individual wavelengths (resp. narrow energy ranges of z. B. less than 1 keV width) and / or irradiate invasive radiation of different kinds. In each Case offers the possibility to design and / or adjust the measuring system so that the different Interactions with the different materials are detected can and from this it can be determined which materials are present and in particular where the respective materials are arranged in the measurement object are.

One An essential advantage of the invention is that the measurement effort by the appropriate design and / or by adjustment of the measuring arrangement reduced both in terms of time and in terms of equipment can be. This is a crucial advantage for a cost effective and time effective Examination of industrially or artificially manufactured objects. For example can be a relatively large proportion of the produced pieces a series production or can even all the pieces the series production with the inventive method on production errors to be examined. For example, the measurement setup is the measurement objects examined by invasive radiation, for this purpose in the production line integrated or can the to be examined pieces are separated from the production line and fed to the measuring arrangement.

From the term invasive radiation includes radiation of any kind, which penetrates into the test object and / or penetrates the test object. Except electromagnetic Radiation - like z. B. X-rays - can also Particle radiation (eg electron radiation or positron radiation) be used. Also can electromagnetic radiation in others Wavelength ranges (in the visible or infrared wavelength range) may be used. Also can such as B. in magnetic resonance (MR) technology or in the excitation of energy states by electromagnetic radiation (eg luminescence) Secondary effects for the investigation be used. Even with the X-ray can secondary or scattered radiation be detected.

Except the Material properties can also be a target geometry of the DUT taken into account in the design and / or adjustment of the measuring arrangement become. For example, you can choose from the location of the material areas From the different materials conclusions about the optimal location of a Pull sensor device or a plurality of sensor devices. The desired geometry, for example, from CAD (Computer Aided Design) planning data of the measurement object. The desired geometry preferably comprises also the specification, which parts of the DUT from which Material are made. In particular, have modern CAD systems a data interface, which is the further processing of a three-dimensional Model of the respective workpiece or DUT by digital data processing (CAM, Computer Aided Modeling). In a preferred embodiment of an arrangement according to the invention the arrangement is connected to such an interface or at least designed, connected to such an interface to become. Alternatively or in addition the CAD system is part of the arrangement, i. at least the ones for the calculation the expected detection results are required facilities Part of the CAD system. The CAD system can also perform other tasks fulfill, evaluate the measured detection results.

Further can in one of the CAD system over the interface provided model of the workpiece the Material properties may be included and z. For each spectral value, respectively by a color associated with a particular material or the corresponding color value to be coded. Such models can an image display device are shown.

According to one Another idea of the present invention is the energy or wavelength disbanded detected radiation impinging on the sensor device, for one Comparison with an expected detection result used. Especially can each individually, for different materials of the DUT and / or selected energy ranges of the radiation spectrum, expected detection results and measurement results be compared. It is possible to make the comparison and / or after a reconstruction (of spatial, three-dimensional Image data from the detection signals).

The Design is hereby for taken, without single or all of the following or before described features of the invention disclosed, d. H. can take care of itself, without one or more of the features being part of a process be or correspond to the function of an arrangement.

• – das Messobjekt invasiver Strahlung ausgesetzt wird,
• – eine Wechselwirkung der invasiven Strahlung mit dem Messobjekt mittels einer strahlungsempfindlichen, spektral auflösenden Sensoreinrichtung (und vorzugsweise auch örtlich auflösenden Sensoreinrichtung) detektiert wird,
• – ein erwartetes Detektionsergebnis der Sensoreinrichtung unter Verwendung einer Sollgeometrie des Messobjekts und unter Verwendung von Materialeigenschaften berechnet wird und/oder ein erwartetes Detektionsergebnis durch Vermessung zumindest eines Meisterteils ermittelt wird und
• – das erwartete Detektionsergebnis mit einem tatsächlichen Detektionsergebnis der Sensoreinrichtung verglichen wird.

In particular, a method for examining a DUT is proposed, wherein

• The subject is exposed to invasive radiation,
• An interaction of the invasive radiation with the measurement object is detected by means of a radiation-sensitive, spectrally resolving sensor device (and preferably also locally resolving sensor device),
• An expected detection result of the sensor device is calculated using a desired geometry of the measurement object and using material properties and / or an expected detection result is determined by measuring at least one master part, and
• - The expected detection result is compared with an actual detection result of the sensor device.

For further embodiments, reference is made directly and analogously to a further patent application, which relates to an invention of the same inventor as in this patent message goes back. This patent application was filed on 6 July 2005 at the German Patent and Trademark Office by the same Applicant and is entitled "Method and Arrangement for Examination of a Test Object by Invasive Radiation".

at The material properties are in particular the spectral Absorption coefficients of the materials of the test object. In addition, the Material properties also include how the radiation in the material scattered and / or how secondary effects (see above) have an effect. The material properties can for example, in a separate measurement on a block from the relevant material and / or taken from the literature become. The collected data on the spectral characteristics The different materials can also be stored in a database stored in conjunction with the measuring system and / or the CAD system. It is particularly advantageous if the data in a planning system are available for Vorrausberechnung the expected measurement signals and cheaper Way to a priori planning the for the respective measurement most appropriate measurement setting are used. The most suitable measurement setting can then be achieved by optimizing the relevant measurement parameters, such as Measuring time, energy resolution, energy of invasive radiation, signal quality in the image, etc.

Preferably becomes the detection result obtained from the measurement of the measurement object checked for errors by comparison with an expected detection result. at the error check In particular, it is determined whether the measured detection result within given by the expected detection results Tolerances is. The error evaluation can be localized to a coordinate system of the DUT and / or related to a Coordinate system of the sensor device are performed. For example, become one or several dimensions (eg thickness, width and / or diameter at least parts of the workpiece) determined and determined whether the respective tolerance is respected is.

at The sensor device can also be a sensor device act with a plurality of spaced apart part sensors, wherein the part sensors each again a spatially resolved measurement allow the incident radiation.

at A preferred type of examination of the measurement object is (like in CT) uses electromagnetic radiation that penetrates the object under test and on the opposite Side of the radiation source detected by a spatially resolving sensor device becomes. Advantage of this arrangement is its simplicity over arrangements, evaluate the reflected radiation or secondary effects.

Z. B. has at least one of the part sensors or not distributed locally arranged sensor device on a plurality of local areas, wherein in the individual local Fields incident radiation converted into an independent measurement signal can be. In the part sensors or in a non-spatially distributed arranged sensor device may be, for example, a matrix from radiation-sensitive semiconductor elements. Come here both row matrices with only one row semiconductor elements as also semiconductor matrices with sensor elements in several lines and Columns in question.

Especially can automatically digitizes the sensor signals of the sensor device be, so the actual Detection result is available in digitized form. Due to digitization, the cost of an evaluation is special low, especially when generated by the sensor device Measuring signals have a different amplitude, depending on the wavelength or Energy of the particles or radiation quanta impinging on a sensor element.

Under an amplitude of a signal of a sensor device or a Detector will be any size on one (in particular one-dimensional) scale according to which the Signal is quantifiable. The scale can z. B. a scale with positive and negative value ranges can be a continuous Scale or be a scale with only discrete values (e.g. When counting pulses become).

The wavelength or energy of the radiation impinging on the sensor device, is in turn dependent from the radiation source and a result of the interaction with the material or materials of the test object. Further determined The response of the detector also determines the signal With. For different measuring applications can therefore be advantageous to use different types of detectors. Therefore, thresholds can be for the Evaluation of the digitized or analog measuring signals defined become. Is the amplitude and thus the energy over (or below) a threshold or in one between two limits lying area, can be closed, for example, that a particular material was involved in the interaction. This especially applies if the spectrum (or the wavelengths) of the irradiated invasive radiation so on a particular material It is agreed that the interaction with this material (compared to others Materials of the test object) are detected particularly clearly can.

It is not required, the energy or wavelength of the to determine exactly the radiation incident on the sensor device. As a result, considerable effort in the evaluation of the measurement results be avoided. Also can in terms of energy resolution More inaccurate or less sensitive sensor elements are used. This can reduce costs.

In addition, can Of course a count or statistical evaluation of the sensor element or the (especially spatially resolved) of the sensor device detected in the respective energy range Quantum or particle done. Also, the result of the evaluation Ultimately, it will not be determined until a reconstruction (eg tomographic backprojection) has, being for the reconstruction uses a plurality of two-dimensional images, correspond to the different irradiation directions of the measurement object. Due to the use of thresholds or limits can the image information of the two-dimensional images consist in that a pixel or location in the coordinate system of the two-dimensional Picture the number and the energy range of the place in the place (eg from the associated sensor element) received quanta or particles assigned. This can be considered a rasterized or categorized energy resolution be referred to in the detection of radiation.

Preferred dimensions becomes the measurement object from different directions and / or in different Rotational positions (and especially temporal succession) of the invasive Exposed to radiation and in each case a detection result is detected, i.e. become the results of the interaction with the measurement object respectively detected. In particular, when the radiation of the test object With the invasive radiation can be achieved so that everyone Volume range of the DUT from different directions is irradiated.

Basically, different Procedures are applied to the information about the to obtain spectral behavior of the interaction. These procedures can also be combined.

• a) speziell auf die Kombination der Materialien des jeweiligen Messobjekts ausgelegte Spektren der invasiven Strahlung auf das Messobjekt einzustrahlen,
• b) unterschiedliche Spektren oder Strahlung verschiedener Wellenlängen zeitlich nacheinander auf das Messobjekt einzustrahlen und zeitaufgelöst zu messen
• c) eine Mehrzahl von Sensoreinrichtungen mit spektral unterschiedlichen Empfindlichkeiten gleichzeitig, an verschiedenen Orten und/oder zeitlich nacheinander für die Messung der Wechselwirkung zu verwenden und/oder
• d) einen spektral bzw. Energie auflösenden Detektor zu verwenden.

In particular, it is possible

• a) irradiating spectrums of the invasive radiation specially designed for the combination of the materials of the respective measurement object onto the measurement object,
• b) to irradiate different spectra or radiation of different wavelengths successively in time to the measurement object and to measure them in a time-resolved manner
• c) to use a plurality of sensor devices with spectrally different sensitivities at the same time, at different locations and / or in succession for the measurement of the interaction and / or
• d) to use a spectral or energy dissolving detector.

The different spectra or the radiation of different wavelengths (point b) can be achieved in particular by an electric Accelerating voltage of an electron gun of an x-ray tube is changed a spectrum emitted by a radiation source and / or a Spectrum, which is the result of interactions, spectrally filtered be, for. B. with sheets, and / or different radiation sources be used. With the different radiation sources can these are X-ray sources with different anode material and / or with different Material of an exit window of the radiation source (optionally a additional Can have coating) act.

When Sensor devices with spectrally different sensitivities (Point c) can z. B. different scintillator materials with suitable photo detectors (For example, semiconductor diodes or spatial Arrangements with semiconductor diodes, such as CCD cameras, CMOS semiconductor diodes, Avalanche diodes) be used.

at the distinction of the wavelengths or the energy of the incident on the sensor device photons or particles (point d) can in particular an evaluation device be used, the time-resolved (i.e., repetitive or continuous over time) amplitudes (especially pulse heights) the measuring signals (in particular measuring signals of the individual sensor elements, each a particular location or area of the sensor device are assigned) evaluates. This can be done in different ways respectively.

In particular, a pulse-height discriminator can be used, which, for example, only detects the presence of a valid signal or event (for example, only outputs an output signal or allows the input signal to pass) when a certain pulse height has been reached or exceeded. More generally, the pulse heights correspond to an amplitude of the signal and an energy of a detected radiation quantum or particle. Alternatively or additionally, the pulse height discriminator can determine the falling below a certain pulse height or determine that the pulse height is in a certain pulse height range. In particular, such a measuring arrangement can be operated so that repeated with different settings or interpretations the measuring arrangement is measured. Alternatively, the measurement signals can be evaluated by different evaluation paths, each with one or more pulse height discriminators, so that in particular each measurement signal can be analyzed several times.

alternative can at least a so-called multi-channel (multi-channel) analyzer used by, for example, AMPTEK Inc., Bedford, Massachusetts, USA is offered, for example, under the type designation XR 100. Such analyzers directly determine the distribution of Energy or wavelength from the respective measured signal in each case for a specific location or Area of the sensor device. For example, with X-rays in this way analyzes the measurement signal with an energy resolution of 200 eV possible. Advantageously, the energy spectra thus obtained become special evaluated on the expected material properties evaluated. For example, you can Shares in the energy spectrum therefore assigned to certain materials become. this makes possible even without backprojection determine what materials contribute to what percentage in weakening one X-ray beam involved were (eg 20 cm radiation path through material 1 and 5 cm radiation path through material 2 from the radiation source to a certain one Sensor element). As a result, the effort for the reconstruction of a Three-dimensional model of the test object can be significantly reduced.

The Design with the multi-channel analyzer (English: Multi-channel analyzer, MCA) and the Embodiment with the evaluation of pulse heights are similar in principle. Both embodiments allow it, the energy distribution with regard to the materials to be detected evaluate. In the multi-channel analyzer, the information about the Energy distribution according to the number of channels used, however remain. In pulse height discrimination however, after the application of the threshold (s), only still the information exists, whether the respective threshold falls below or exceeded has been. Of course can also be the original one Pulse height information stored separately, in parallel with different thresholds be evaluated and / or several times with different thresholds be evaluated. The choice of the threshold or thresholds takes place preferably in dependence from the expected material properties.

At the Multi-channel analyzer can each have one channel or more adjacent channels (the is called the detect events in the corresponding energy range) assigned to a specific material. This corresponds to the Set a threshold for the pulse height information.

The Number and the respective energy sensitivity range of the channels of the multichannel analyzer can considering the expected material properties of the measuring object are selected. In particular, the measurement time can thereby be optimized. Farther This can achieve a high signal-to-noise ratio. The Energy sensitivity ranges of the channels should not be too narrow, ideally so that with as possible few channels each in the workpiece existing material can be detected (eg, each channel exactly a material of the workpiece is assigned), but no finer energy dissolution takes place. Besides, they are the channels preferably chosen so that the dynamic range of the detector in the energy range of the channel for each Picture or over a series of pictures optimally exploited.

It is possible, too, that you have multiple channels assigns to a single material or a plurality of materials, which is optionally summarized after recording the measurement signals, around the signal-to-noise ratio to optimize or so the usable dynamic range for the signal acquisition and evaluation. These different channels can energetically (in the spectrum of the radiation) be adjacent to each other, or in separate energy areas (through at least one other channel) lie.

general formulated, the present invention includes an embodiment, in which the interaction of invasive radiation with at least one of the materials of the measurement object an energy range or Wavelength range the detected radiation is assigned and wherein by evaluation a measuring signal of the sensor device in this energy range or wavelength range the presence of the associated material is determined. Preferably Such an assignment is made for each of the materials of the Measured object to be detected. In particular, can out a plurality of images of the measurement object taken with the sensor device were determined, then the positions of the assigned material (in particular reconstructed).

In this case, the assignment of the at least one material to the energy range can be carried out in the design and / or adjustment of the measuring arrangement. Alternatively or additionally, however, it is also possible (for example in the embodiment with the multi-channel analyzer) to carry out the assignment only during the evaluation of the measurement signals. However, this requires a beyond the required energy ranges for the detection of the materials beyond, finer energy resolution in the detection of the radiation, which is the result of Wechselwir kung with the exhibition object.

One Photon (eg an X-ray photon) generated dependent from its energy in the sensor device z. B. a signal pulse, whose height or area (i.e., the number of electrons released in the sensor), a measure of the energy represents the photon. The threshold values or the channels of the multi-channel analyzer can then serve for each of these signal pulses to make an arrangement, whether the pulse below or above a threshold or inside or outside of a given energy range. Due to the energy-resolved detection can be so extra Information can be obtained when evaluating the measurement results the quality the statements increased. You also gain the opportunity Materials based on the effect on the energy spectrum of the measuring radiation to characterize and not just indirectly via the gray values, the one Detector signal directly or after rear projection assigned to the voxel become. When two materials integrally have a comparable filtering effect for the Show radiation, a separation of materials was previously difficult possible or in some cases not possible at all. Here then the spectrally resolved measurement and the a priori Information about the object to be measured helps to design appropriate and sufficiently selective ones To find measurement conditions to perform a targeted analysis can.

When alternative or additional Possibility can at least one detector can be used in the measurement, the Radiation detected that is not (essentially) straight through the measuring object has passed through. The one obtained from the detector Signal can then be used to correct integral (via the emitted spectrum integrated) fluctuations in the power of the radiation and / or for correcting spectral shifts in the emission characteristic the radiation source can be used. Spectral shifts can z. B. arise when the target in an X-ray source moved unevenly or change its temperature, because this immediately changes the density of the material and hence the effect on the invasive radiation.

Instead of such a detector can also be an energy range of another Sensor devices (in particular one for the detection of rectilinear sensor device used by the radiation passing through the measurement object, z. B. a channel of the multi-channel analyzer) are evaluated, wherein Signals in this energy range are not specific to a material of the measurement object. This energy range can then be used for the signal correction can be. It is preferably ensured that interactions of the test object with the invasive radiation is not (or only negligible small extent) to the measuring signal in this energy range.

• 1. Es kann das Integral über die innerhalb des gesamten Detektionsintervalls des Detektors oder des oder der für die Korrektur genutzten Energiebereiche(s) der Sensoreinrichtung emittierte Leistung gebildet werden, und über einen Dreisatz I_M_korr = I_ist/I_ref·I_M korrigiert werden. Hier bedeuten: I_M: Messsignal, I_ref: Referenzsignal, I_ist: aktueller Wert des Referenzsignals in der Messung, I_M_korr: korrigierter Messwert.
• 2. Korrektur der Messwerte in jedem Energiebereich getrennt, wobei die Formel nach 1. für jeden Energiebereich getrennt angewendet wird, um hier spektrale Einflüsse auszuschließen.

The correction can be carried out in both cases (separate detector or not) in different ways:

• 1. The integral can be formed over the power emitted within the entire detection interval of the detector or of the energy range (s) of the sensor device used for the correction, and corrected by a rule of three I_M_korr = I_act / I_ref * I_M. Here: I_M: measuring signal, I_ref: reference signal, I_ist: current value of the reference signal in the measurement, I_M_korr: corrected measured value.
• 2. Correction of the measured values separated in each energy range, whereby the formula according to 1. is applied separately for each energy range in order to exclude spectral influences here.

Thereby the measurement signal can be corrected, in particular before a back projection takes place. In principle, however, the correction can also during the rear projection or take place afterwards.

Especially can on the radiation path from the radiation source to the measurement object and / or on the radiation path from the measurement object to the sensor device at least one filter can be arranged, the radiation of certain wavelength or certain wavelength ranges removed or attenuated from the spectrum of radiation. As already described, this way the spectrum of from the sensor device detected radiation to the expected Materials are tuned that share radiation only or mostly interact with a first material and that parts of the radiation only or predominantly interact with a second material. This makes it possible to perform only a single measurement, with the materials in the Measurement result but appear separately, as if only one measurement object would have been measured with one of the materials.

After the measurement and the optional pre-evaluation of the measurement signals as described above (eg pulse height discriminator and / or multichannel analyzer), an evaluation can now be carried out. In particular, the measurement signals generated by the sensor device can be directly evaluated in an energy-dependent manner, in particular before a reconstruction (3D model calculation of the measurement object). Alternatively or additionally, a reconstruction can be carried out from different energy spectra or energy ranges which are obtained from the measurement signals (for example for the partial spectra which are selectively matched to a particular material and which are obtained as described above, see the US Pat following paragraph). In addition, further evaluation steps after reconstruction with z. B. follow procedures known per se. Alternatively or additionally, a comparison of the evaluation results (before and / or after the reconstruction) with expected evaluation results is possible.

at Using the above filters can, taking advantage of a priori information about which materials are present in the DUT, the corresponding ones Filter for the measurement and / or data evaluation are chosen so that the evaluation for each the materials can be carried out separately. To this Way can through Reconstruction of three-dimensional models of the arrangements and local Areas are obtained, each containing a specific material of the DUT is present. These three-dimensional models can then be restored be combined with each other. Alternatively, during a reconstruction of a three - dimensional model the information about the energy of the Sensor device struck quantum or particles are carried and the reconstructed three - dimensional model can be the information about the energy resolution contain. For example, can for every voxel of the model the spectral information will be present. Especially for the case of materials over a total spectral range the same absorption for invasive radiation have enabled this, the materials certainly distinguish from each other, though they have different absorption properties in subregions of the spectrum to have. Also inexperienced Viewers of the result can make such a distinction.

A another possibility the spectrally resolved To use information is by comparing the results from different wavelength ranges or to correct energy artefacts that are otherwise commonplace in particular at the x-ray CT occur. This is based on the knowledge that, for example the effect of the so-called beam hardening is dependent on the wavelength. For example, it can be exploited by using higher energy Radiation usually has less interaction with the materials of the test object shows and in particular the scattering of the radiation in this spectral range (except in the forward direction) having lower cross sections.

• – eine Feststellungseinrichtung zum Feststellen von erwarteten Materialeigenschaften oder eine Datenschnittstelle zum Empfangen von Daten, die Informationen über die erwarteten Materialeigenschaften aufweisen,
• – eine Auslegungs- und/oder Einstellungseinrichtung zur Auslegung und/oder Einstellung einer Messanordnung, wobei die Messanordnung zumindest eine Strahlungsquelle (2) zur Erzeugung invasiver Strahlung und eine strahlungsempfindliche Sensoreinrichtung (3) zur Detektion von Strahlung nach einer Wechselwirkung der invasiven Strahlung mit dem Messobjekt aufweist und wobei die Auslegungs- und/oder Einstellungseinrichtung so ausgestaltet ist, dass die Messanordnung unter Berücksichtigung der erwarteten Eigenschaften so ausgelegt und/oder eingestellt wird, dass unterschiedliche Wechselwirkungen der invasiven Strahlung mit zumindest zwei verschiedenen Materialien des Messobjekts (1) von den Sensoreinrichtungen detektiert werden können, wobei die unterschiedlichen Wechselwirkungen auf Grund spektral unterschiedlicher Materialeigenschaften der verschiedenen Materialien bestehen, und
• – die Messanordnung.

In addition, an arrangement is proposed for examining a measuring object which has been produced industrially and / or by hand, (more generally: for non-medical examinations of any measuring objects, ie non-living objects), the arrangement comprising:

• A determination device for determining expected material properties or a data interface for receiving data having information about the expected material properties,
• A design and / or adjustment device for the design and / or adjustment of a measurement arrangement, wherein the measurement arrangement comprises at least one radiation source ( 2 ) for generating invasive radiation and a radiation-sensitive sensor device ( 3 ) for detecting radiation after an interaction of the invasive radiation with the measurement object and wherein the design and / or adjustment device is designed so that the measurement arrangement is designed and / or adjusted taking into account the expected properties that different interactions of the invasive radiation with at least two different materials of the test object ( 1 ) can be detected by the sensor devices, wherein the different interactions due to spectrally different material properties of different materials, and
• - the measuring arrangement.

Further belongs to the scope of the invention, a computer program, the at expiration a computer or computer network at least those parts the method according to the invention in one of its embodiments carries out the interpretation and / or Concerning the setting of the measuring system. In particular, from the Computer program automatically from the target geometry and the material properties of the object to be measured, which wavelengths or spectra of the invasive radiation best used in the investigation and / or as the Sensor device is set. For example, the computer program Thresholds for calculate the evaluation of the signals of the sensor device, wherein on reaching, falling below or exceeding the respective, a material associated threshold is found that the signal is a signal of interaction with the signal assigned material acts.

Farther belongs to the scope of the invention, a computer program with program code means to the method defined in the previous paragraph in a to carry out its designs, if the program is running on a computer or computer network. In particular, you can the program code means stored on a computer readable medium be.

In addition, the scope of the invention, a volume on which a data structure is stored, which after loading into a working and / or main memory of a computer or computer network, the method in one of his can perform designs.

Also belongs to the scope of the invention, a computer program product with on one machine-readable carrier stored program code means to the method in one of his To carry out configurations if the program is running on a computer or computer network.

there Under a computer program product, the program is considered tradable Product understood. It can basically be in any form so for example on paper or a computer-readable disk and can in particular over a data transmission network be distributed.

The Invention will now be described with reference to the drawing based on embodiments described. However, the invention is not limited to the embodiments limited. Individual features of the following description or any combinations of it can combined with the previously described embodiments of the invention become. The individual figures of the drawing show:

1 a geometry of a measuring arrangement with an X-ray source, a measurement object and a two-dimensionally spatially resolving sensor device;

2 an arrangement for evaluating measuring signals, in particular measuring signals of the sensor device according to 1 ;

3 local areas of a target with different materials traversed by invasive radiation; and

4 a radiation spectrum of invasive radiation.

The schematic in 1 illustrated measuring arrangement has a measuring object 1 on, between an X-ray source 2 and a sensor device 3 is arranged. The X-ray source 2 is, for example, an X-ray tube with an electron gun for generating X-ray radiation. During operation, the X-radiation emanates from the X-ray source, starting from a nearly punctiform focal spot 2 out. The focal spot lies at the origin of the Cartesian coordinate system, which in 1 represented by three axes. More arrows from the origin towards the sensor device 3 indicate that from the radiation source 2 outgoing radiation. The arrow with the dotted line does not strike the target 1 ,

The sensor device 3 has a field of five by eight detector arrays, each represented by squares (distorted due to the perspective representation). Individual one of the detector fields, which can each provide separate detection signals are denoted by the reference numeral 4 designated. In practice, sensor devices with substantially more detector arrays can be used.

As not shown in detail, the measurement object 1 to be rotated about a vertical axis of rotation, thus that of the radiation source 2 outgoing radiation from different directions and the object to be measured 1 can cross. Preferably, the distance between the measurement object 1 and the sensor device 3 in practice much larger than shown in order not to detect the effects of secondary effects such as luminescence and Compton scattering or only to a small extent.

Between radiation source 2 and measuring object 1 is a filter 5 arranged, which can be adjusted or replaced depending on a desired setting or design of the measuring system. It is also possible, at least one other filter in the beam path between the radiation source 2 and the measurement object 1 and / or between the measurement object 1 and the sensor device 3 to arrange. Depending on the material properties of the materials of the DUT 1 the filter (s) are selected and / or adjusted. Representative of the possibility of designing or adjusting the filter or filters is an adjustment 7 shown with the filter 5 is connected and z. As the strength of absorption of radiation through the filter 5 in a certain wavelength range can adjust.

An evaluation device 6 is with the sensor device 3 connected. The evaluation device 6 is designed by the individual sensor elements 4 each measurement signal generated spectrally resolved.

2 schematically shows a preferred way of evaluation of the sensor device 3 generated measuring signals. The measuring signals become a pulse height discriminator 10 the evaluation device 6 fed. The pulse height discriminator 10 represents for each of the individual, from the sensor elements 4 detected measurement signals in which of several defined amplitude ranges, the amplitude supplied by the measurement signal (here: pulse height) is. This achieves a division of the measurement signals into several different energy ranges.

The information thus obtained is processed by an image processor 11 processed into two-dimensional images, wherein the coordinate system of the images of the coordinate system of the sensor device 3 equivalent. By a reconstruction device 12 is reconstructed from the two-dimensional images, a three-dimensional model of the measurement object, the two-dimensional images of different rotational positions z. B. the measurement object, ie different directions of the radiation correspond. The result of the reconstruction may be from a comparator 13 with expected values (in particular with values of the geometry and with material properties of the materials of the test object arranged in the respective areas).

Based on 3 and 4 Now, an embodiment will be described for how the presence of certain materials in a measurement object can be determined in a simple manner.

3 schematically shows the beam path in the irradiation of a measurement object with invasive radiation, for two arbitrarily selected areas (volumes of small cross-section) of the measurement object. Unlike in 3 As shown, the radiation will typically diverge on its way from the radiation source to the sensor device.

In the upper part of 3 It is shown that the radiation incident from the left passes through three different materials A, B, C of the measurement object on its way through the measurement object, exits the measurement object on the right and onto a sensor element 4a which detects substantially only the radiation incident from the direction of the associated area. In any case, this is based on the assumption that the scattered radiation from other areas is negligibly small.

In the lower part of 3 It is shown that the radiation incident from the left on its way through another area of the measurement object successively traverses only the materials A and C and the radiation attenuated by extinction in the area to a second sensor element 4b which essentially detects only radiation from the direction of the associated area.

The wavelength spectrum or energy spectrum of the invasive radiation that traverses the areas is in 4 shown. Plotted on the vertical axis is the intensity in the radiation. The energy E of the radiation quanta is plotted on the horizontal axis.

The Materials A, B, C have the following absorption properties for the invasive Radiation: Material A absorbs in the energy range I with a high absorption coefficient (strong absorption) and absorbed in the wavelength ranges II and III with low absorption coefficient (weak absorption). Material B has a weak in energy ranges I and III Absorption and has a strong absorption in the energy range II on. Material C has a weak in energy ranges I and II Absorption and has a strong absorption in the energy range III on.

Therefore, the materials can be easily distinguished by energy-resolved detection of the radiation transmitted through the measurement object. In this case, it is preferably only possible to determine what proportion of the sensor elements using threshold values 4 detected in radiation in which the energy ranges I, II, III is incident.

sensor element 4a In all three energy ranges, a radiation weakened approximately with the same absorption coefficient will be detected, since the radiation paths through all three materials are approximately the same length. In contrast, sensor element 4b In the energy range I (after evaluation of the signals) notice a particularly strong absorption, in the energy range III a much weaker absorption and energy II a very low absorption, since the radiation path through the material A is long, the path through the material C is relatively short and the material B does not exist along the way.

By Simplified evaluation procedures can therefore be the local Areas where the individual materials are present can be detected. in particular can evaluated images taken by the sensor device which correspond to different transmission directions.

The Setting the measuring system in this case is preferably the thresholds for determine the determination of the energy ranges accordingly. alternative or additionally For example, by filtering the radiation a radiation spectrum only be generated in one of the materials involved is strongly absorbed. In a subsequent second measurement, a Radiation spectrum used only in another the materials involved is strongly absorbed, etc ..

Claims (14)

Method for investigating an industrially and / or handcrafted test object ( 1 ), wherein the measurement object ( 1 ) has a plurality of different materials, at least two different materials, and wherein the method comprises the following steps: expected material properties of at least two different materials of the test object ( 1 ), the expected material properties are used in a design and / or setting of a measuring arrangement, wherein the measuring arrangement comprises at least one radiation source ( 2 ) for generating invasive radiation and a radiation-sensitive sensor device ( 3 ) for detecting radiation after an interaction of the invasive radiation with the measurement object and wherein the measurement arrangement is designed and / or adjusted taking into account the expected properties such that different interactions of the invasive radiation with at least two different materials of the measurement object ( 1 ) can be detected by the sensor devices, wherein the different interactions on the basis of spectrally different material properties of the different materials, '- the measuring object ( 1 ) is exposed to the invasive radiation and - a result of the different interactions of the invasive radiation by means of the sensor device ( 3 ) detected. Method according to the preceding claim, wherein the sensor device ( 3 ) incident radiation, which is a result of the interactions, is detected spectrally resolved. Method according to one of the preceding claims, wherein the design and / or adjustment of the measuring arrangement comprises the step that the invasive radiation is tuned to the material properties of the materials of the test object ( 1 ) is spectrally filtered. Method according to one of the preceding claims, wherein the design and / or adjustment of the measuring arrangement comprises the step that different spectra or radiation of different wavelengths successively on the measuring object ( 1 ) and in each case the results of the interactions are measured. Method according to one of the preceding claims, wherein a plurality of sensor devices with spectrally different Sensitivities for a detection of the results of the interactions simultaneously, used in different places and / or in succession becomes. Method according to one of the preceding claims, wherein the interaction of the invasive radiation with at least one of the materials of the measurement object is assigned to an energy range or wavelength range of the detected radiation and wherein by evaluating a measurement signal of the sensor device ( 3 ) in this energy range or wavelength range, a presence of the assigned material is determined. Method according to the preceding claim, wherein the assignment of the at least one material to the energy range in the design and / or setting of the measuring arrangement ( 2 . 3 ) is carried out. Method according to one of the preceding claims, wherein at least one threshold value and / or a limit value is defined and wherein it is determined whether an amplitude of a measurement signal of the sensor device ( 3 ), which is a measure of a wavelength or energy of the sensor device ( 3 ) or to a local area of the sensor device ( 3 ) is above, on, below or below the threshold and / or threshold. A method according to the preceding claim, wherein it is determined whether the amplitude is in an amplitude range, which is defined by a lower and an upper limit. Method according to one of the two preceding claims, wherein from a result of determining if the amplitude is over, up or below the threshold and / or limit, it is closed is that a particular material involved in the interaction was. Method according to one of the three preceding claims, wherein as a result or intermediate result of an evaluation of measuring signals of the sensor device ( 3 ) Information is determined for a radiation image, wherein in the radiation image pixels or locations in a coordinate system of the radiation image are assigned a number or frequency of quanta or particles and a spectral range or energy range, the quanta or particles, their wavelength or energy in the range is located at a location of the sensor device assigned to the respective pixel or location ( 3 ). Method according to one of the preceding claims, wherein the measurement object ( 1 ) is exposed from different directions and / or in different rotational positions of the invasive radiation and in each case a detection result is determined and wherein each of the detection results is compared with an expected detection result. Method according to the preceding claim, wherein, deviations of the actual detection results from the expected detection results, the location of an error in the measurement object ( 1 ) is determined. Arrangement for examining a test object ( 1 ) which has been produced industrially and / or by hand, the arrangement comprising: - a determination device for determining expected material properties or a data interface for receiving data having information about the expected material properties, - a design and / or adjustment device ( 7 ) for the design and / or adjustment of a measuring arrangement, wherein the measuring arrangement comprises at least one radiation source ( 2 ) for generating invasive radiation and a radiation-sensitive sensor device ( 3 ) for detecting radiation after an interaction of the invasive radiation with the measurement object and wherein the design and / or adjustment device ( 7 ) is designed such that the measurement arrangement is designed and / or adjusted taking into account the expected properties such that different interactions of the invasive radiation with at least two different materials of the measurement object ( 1 ) can be detected by the sensor devices, wherein the different interactions due to spectrally different material properties of the different materials, and - the measuring arrangement.