WO2014000811A1

WO2014000811A1 - Method for measuring the propagation direction of a beam and method for measuring the energy distribution in a beam

Info

Publication number: WO2014000811A1
Application number: PCT/EP2012/062690
Authority: WO
Inventors: Thomas Engel
Original assignee: Carl Zeiss Industrielle Messtechnik Gmbh
Priority date: 2012-06-29
Filing date: 2012-06-29
Publication date: 2014-01-03

Abstract

The present invention relates to a method (70) for determining a propagation direction (68) of a beam, in particular of an x-ray beam (12) by means of a sensor system (51) and to a method (90) for determining an energy distribution within a beam (12) by means of the sensor system (51). The radiation penetrates two optical transducers (14, 14') that are arranged one behind the other, whereby the optical transducers emit light. This light is imaged onto optical sensors (18, 18') by imaging systems (22, 22'), the optical sensors recording the images of the two optical transducers (14, 14'). The two images are then evaluated together.

Description

METHOD FOR MEASURING THE SPREADING DIRECTION OF A BEAM BUNCH METHOD FOR MEASURING THE ENERGY DISTRIBUTION IN

A BEAM BUNDLE

According to a first aspect, the present invention relates to a method for determining a propagation direction of a radiation, comprising the step of providing a sensor system with a first sensor device, wherein the first sensor device comprises a first optical sensor for detecting light in a first wavelength range, and a first optical transducer which emits light in the first wavelength range depending on the radiation incident on the optical transducer and at least one second sensor means, the second sensor means comprising a second optical sensor for detecting light in a second wavelength range, and a second optical sensor Transducer has, depending on the incident on the second optical converter radiation light in the second Emitted wavelength range, wherein the first optical transducer of the first sensor device and the second optical converter of the at least one second sensor device with respect to an incident direction of the radiation are arranged one behind the other,

[0002] According to a second aspect, the present invention relates to a method for determining an energy distribution within a radiation, comprising the step of providing a sensor system with a first sensor device, wherein the first sensor device comprises a first optical sensor for detecting light in a first wavelength range, and a first optical converter which emits light in the first wavelength range depending on the radiation incident on the first optical transducer, and at least one second sensor device, wherein the second sensor means comprises a second optical sensor for detecting light in a second wavelength range, and second optical converter which emits light in the second wavelength range as a function of the radiation incident on the second optical converter, wherein the optical converter of the first sensor device and the optical converter of the at least one zw Siten sensor device with respect to an incident direction of the radiation are arranged one behind the other.

Measuring systems that use X-radiation, γ-radiation or particle radiation to inspect an object are well known in the art. In addition to applications in the medical field, applications in microscopes or for checking workpieces are also known. In particular, measurement systems operating in X-ray quality used in quality assurance make it possible to examine a manufactured workpiece according to material defects which can not be detected by a visual inspection. An example of such measuring devices is the applicant's series marketed under the name "Metrotom®".

In systems for quality control can be used directly for example. For y-sensitive detectors or sensor units. However, these are usually very expensive and relatively limited in their dynamics. As a rule, such sensor systems have an effective bit data depth of only about 8 to 10 bits. In addition, there are approaches by means of an optical transducer, for example. A scintillator, usual, ie for sensitive light in a visible spectral range of 380 nm to 780 nm, optical sensors to make usable. For example, the scintillator can emit light in a visible spectral range or in the ultraviolet or infrared spectral range depending on the radiation irradiated thereon, which then from an optical sensor, eg a PMT (photomultiplier), a photodiode, an avalanche diode or a CCD or CMOS camera can be detected. Such optical sensors are widely used and relatively cheap. However, a problem in this case is that such optical sensors, if they are exposed to high-energy radiation, for example, .gamma. Radiation or X-radiation, are exposed to strong aging effects. The lifetime of the sensors is then very low.

For example, document US 2006/0192129 A1 shows a microscope operating with X-ray radiation. In the linear structure shown there, the CCD camera is inevitably exposed by the X-ray strong aging effects. It should be noted that high energy radiation, such as γ-radiation and very short wavelength X-ray, has a refractive index of about 1 in almost all materials. In the case of a transmission, therefore, virtually no beam deflection occurs, so that a linear structure proposed in this publication inevitably leads to the CCD camera being constantly exposed to X-rays.

It has therefore been proposed variously to arrange the optical sensor in an area in which it is not directly exposed to high-energy radiation. For this purpose, it has been proposed to redirect the light emitted by the optical converter through plane mirror so as to enable a secure arrangement of the optical sensor. Examples of such arrangements can be found in the publications DE 10 2008 007 595 A1, WO 97/20231 A1 and DE 10 2009 033 304 A1.

The arrangements proposed there, however, absolutely require reflective optical elements in addition to the imaging optics per se, in order to avoid the wanted to effect beam deflection. Furthermore, these additional reflective optical elements are likewise located in the direct beam path of the high-energy radiation, for example the X-ray radiation. In addition, the quality of such a sensor system depends very much on the quality of such a reflective element, since there errors directly affect the image captured by the optical sensor.

In the prior art, for example, the document DE 10 2005 033 533 A1 possibilities are proposed, for example. Make a spectrally resolved analysis of the radiation. By means of the proposed arrangements, however, it is regularly difficult to direct the light through beam splits to a plurality of optical sensors by means of complex mirror arrangements in order to thus provide new possibilities of evaluation.

Furthermore, the proposed arrangements are limited in terms of the evaluation options of the measurement results. Special analyzes such as X-rays are not possible.

It is therefore an object of the present invention to provide improved methods for detecting and evaluating radiation, in particular X-ray radiation.

According to a first aspect of the invention, a method for determining a propagation direction of a radiation is proposed with the following steps:

Providing a sensor system having a first sensor device, wherein the first sensor device has a first optical sensor for detecting light in a first wavelength range, and a first optical converter which emits light in the first wavelength range depending on the radiation incident on the first optical converter, and at least one second sensor device. wherein the second sensor device has a second optical sensor for detecting light in a second wavelength range, and a second optical transducer which emits light in the second wavelength range depending on the radiation incident on the second optical transducer, wherein the first optical transducer of the at least one difference vector between a first location of the optical transducer of the first sensor device and a second location of the optical converter of the at least one second sensor device is known, the first sensor device and the second optical converter of the at least one second sensor device being arranged with respect to an incident direction of the radiation

Detecting a first image of the first optical transducer of the first sensor device by means of the first optical sensor of the first sensor device,

Detecting a second image of the second optical converter of the at least one second sensor device by means of the second optical sensor of the at least one second sensor device,

Determining a correlation result by correlating the first image and the second image, and

Determining the propagation direction of the radiation from the difference vector and the correlation result.

In this way, it becomes possible to detect a propagation direction or propagation direction of the radiation. By knowing at least the difference vector between the location of the optical transducer of the first sensor device and the location of the optical transducer of the second sensor device, by image correlation an offset of corresponding image components on the way from the optical transducer of the first sensor device to the optical transducer of the second sensorein - direction in a plane perpendicular to the difference vector. By vector addition of the difference vector with the offset determined by the image correlation, one then obtains a three-dimensional vector indicating the direction of propagation of the radiation from the first optical transducer to the second optical transducer. In particular, in this way, assuming that the radiation propagates from a radiation source isotropically and almost rectilinearly without diffraction and refraction phenomena, a backprojection of the images acquired by means of the optical sensors onto a checked workpiece becomes possible.

According to a second aspect of the invention, there is provided a method of determining an energy distribution within a radiation comprising the steps of:

Providing a sensor system having a first sensor device, wherein the first sensor device has an optical sensor for detecting light in a first wavelength range, and a first optical converter which emits light in the first wavelength range depending on the radiation incident on the first optical converter, and at least one second sensor device, wherein the second sensor device has a second optical sensor for detecting light in a second wavelength range, and a second optical converter which emits light in the second wavelength range depending on the radiation incident on the second optical converter, wherein the first optical converters of the first sensor device and the second optical converter of the at least one second sensor device with respect to an incident direction of the radiation are arranged one behind the other, wherein a portion of the first optical converter of the first Sensor device is known up to the respective optical converter of the at least one second sensor device filtered out radiation, Detecting a first image of the first optical transducer of the first sensor device by means of the first optical sensor of the first sensor device,

Detecting a second image of the second optical converter of at least one second sensor device by means of the second optical sensor of the one of the at least one second sensor device,

Determining a difference image from the first image and the second image, and

Determining an energy of the portion of the radiation filtered out from the first optical converter of the first sensor device to the optical converter of the at least one second sensor device by means of the differential image.

As already stated above, radiation penetration inevitably occurs during the penetration of the optical converter, ie a soft or long-wave component of the radiation is filtered out. In addition, additional filter elements can be arranged in the beam path of the radiation in order to specifically influence the filtered-out portion. At the same time, owing to the knowledge of the optical transducers of the first sensor device and the at least one second sensor device, the images detected by the respective optical sensors can be used to infer the energy emitted by the optical transducer in the form of light and, moreover, to that incident on the optical transducer Energy of radiation can be drawn. Due to the planar extension of the optical transducer even two-dimensionally spatially resolved. It is thus possible to determine a difference in the energy of the radiation between the impact on the first optical transducer and the second optical transducer by comparing corresponding portions of a first image and a second image. Furthermore, it is known what proportion of the radiation, ie which wavelength range in the penetration of the first Optical filter and a possible filter was filtered out, so attributable to this energy or wavelength range energy component can be determined. In the step of determining the difference image, it is necessary, in particular via correlation and / or scaling of the images, to take into account the propagation of the radiation, in particular the X-ray radiation, between the two detectors. For example, scaling would be the simplest case - as the radiation from the X-ray source propagates in a straight line - to assume a steady widening of the beam from the source to the transducer in the detector. Thus, the images scale like the distances of the transducer from the radiation source or X-ray source. By scattering effects in the measurement object, it is also possible to produce components in the image which can be determined with this distance of the optical transducer to the measurement object, for example a mean distance of the measurement object - as an approximation of which its axis of rotation can be used - to an optical transducer, and then via the correlation can be evaluated.

In particular, by the cascading, i. arranging a plurality of optical transducers of the sensor devices in succession in an incident direction of the radiation, it is thus possible to successively filter certain areas of the radiation and to determine the energy fractions attributable to them.

The term "radiation" is understood in the present case any type of electromagnetic radiation or particle radiation. In particular, the "radiation" is X-radiation or γ-radiation. X-radiation can be understood to mean electromagnetic radiation in a wavelength range from about 10 pm to about 50 nm. Under γ-rays electromagnetic waves can be understood in a wavelength range of less than 10 pm. The particle beams may be α radiation, β radiation or neutron radiation. Furthermore, the "radiation" can also be radiation in the ultraviolet range, for example in a range from 50 nm to about 200 nm. The "radiation" is thus high-energy radiation.

An "optical converter" is understood to mean a component which, when irradiated by "radiation", emits electromagnetic radiation in a certain wavelength range, in particular of light in a wavelength range from about 380 nm to about 780 nm, is excited. An example of such an optical converter is a scintillator. In particular, the first wavelength range of the first optical converter and the second wavelength range of the second optical converter are identical.

By "light" is thus understood electromagnetic radiation in a wavelength range visible to humans from about 380 nm to about 780 nm. In addition, it is also possible that the optical transducer emits electromagnetic radiation in the ultraviolet range from about 200 nm to about 380 nm or emits in a near infrared range from 780 nm to about 2500 nm. The wavelength range in which the optical transducer emits the light is the "first wavelength range", the optical sensor is sensitive to this first wavelength range and can thus detect the light emitted by the optical transducer.

By "imaging optics" is meant at least one optical element which images the light emitted by the optical transducer onto the optical sensor. The imaging optics thus has a focusing effect. This allows the plane of the optical transducer, referred to as the "object plane", to be imaged onto a plane of the sensor elements of the optical sensor, referred to as the "image plane". A plane mirror which has no focusing effect is thus not the first optical element to which the light emitted by the optical converter hits. In the further course of the beam path, at least one reflecting mirror may be provided in principle, for example, in order to fold the beam path and / or keep it compact. However, this is not involved in an imaging property of the imaging optics.

By "directly" applying to the imaging optics, it is understood in the present case that the light emitted by the optical converter directly hits the imaging optics without influencing by further optical elements. For example, no further elements for influencing the beam path are provided between the imaging optics and the optical converter in the beam path of the light. In particular, no plane mirrors are provided for the reflection of the light. The "direction of incidence" is understood to mean the main direction in which the radiation is incident on the optical transducer of the first sensor device and the optical transducer of the second sensor device. Typically, an optical transducer will have a substantially disc-like geometry. In this case, the optical transducer has a relatively large front and rear surface and, moreover, a relatively small thickness with respect to the dimensions of the surface of the front and rear surfaces. The "direction of incidence" is then perpendicular to the front and back surfaces of the optical transducer.

In this way, as stated above, it is possible to record the radiation at two different locations. In this way, new methods for evaluating the radiation are made possible, in particular, a propagation direction of the radiation can be determined in this way, or energy information about specific portions of the radiation can be obtained.

The object mentioned is thus completely solved.

In one embodiment of the method according to the first aspect of the invention can be provided that the first location and the second location are known, and in a further step, a rear projection of at least the first image along the particular propagation direction is carried out on a workpiece, the was penetrated by the radiation.

In known locations of the first optical converter and the second optical converter are basically two known location information. From the image correlation, furthermore, the offset of the correlated image components from the first optical converter to the second optical converter can be determined. As already stated above, in this way a three-dimensional propagation vector of the radiation can be determined. In this way, it is particularly possible to recalculate a specific pixel or pixel of an image to a specific location or area of the workpiece in the direction of transmission. In this way, for example, errors, for example. An undesirable cavity in the workpiece, not only captured in the image, but immediately the position of the error are determined.

In a further embodiment of the method according to the first aspect of the invention, in a further step, an absorption coefficient or the optical density (absorbance) of the workpiece with knowledge of a radiation source emitting radiation can be determined based on at least the first image.

By means of the methods provided, not only is there a propagation vector of the radiation and thus the possibility of backprojection, but also, based on knowledge of the optical transducers, energy information about the radiation. With knowledge of the radiation source, i. the original energy state of the radiation, therefore, it can be deduced which part of energy was absorbed in the penetration of the workpiece. It allows, in effect, a spatially resolved determination of the absorption coefficient or the absorbency of the workpiece. Also from the absorption capacity can then be deduced under certain circumstances errors in the workpiece. In particular, for example, a very low absorbency in an environment of otherwise very high absorbency may indicate a void in the workpiece.

In a further embodiment of the proposed method according to the invention can be provided that, in order to determine a spectrally and locally resolved absorption capacity of a workpiece, the method is carried out according to the fourth aspect of the invention and the method is carried out according to the fifth aspect of the invention wherein the step of determining the difference image is performed for respective correlated image portions of the first image and the second image.

The combination of the two proposed methods can be made not only in the back projection of certain pixels on the workpiece, but also determine the energy information separately for certain spectral ranges. In this respect, it is also possible, with knowledge of a correspondingly spectrally resolved information about determine the radiation source, a corresponding spectrally resolved absorption coefficient of the workpiece.

In this respect, devices and methods are provided by the present invention, which allow novel evaluation options of radiation. This is possible in particular by a so-called "multi-shell evaluation" of the radiation, since according to the invention an evaluation of the radiation at different distances from the radiation source or a workpiece penetrated by the radiation is possible.

This is ultimately possible by the juxtaposition of inventively proposed sensor devices in a cascading manner to form a sensor system according to the invention.

Basically, it is possible in the specified method to then apply an evaluation analogous to the evaluation of layer images from a data set of a measurement in the different image planes. For example, it is possible to determine a propagation direction due to the rectilinear propagation of the radiation, in particular the X-ray radiation, for example using algorithms of the so-called "Phase Retrieval" method. In the present case, the desired information would have to be obtained from the propagation of the radiation in the extrafocal region-that is, at divergent diverging beams - to be determined.

The individual sensor devices can be calibrated to each other in their sensitivity. This can be done by, for example, taking images without a measurement object and, due to the geometrical conditions, ie essentially the distance between the optical transducers and the beam divergence of the x-ray beam then a correction factor for the entire image or - to compensate for errors of the camera - pixel-wise irradiates , About the projection of geometric structures by means of X-rays or optical radiation (short-wave light that possibly responds to the fluorescence with or even directly this excitation light itself from the camera system of the respective sensor devices is recorded) then geometric distortions of the individual sensor directions can be added to each other. For calibration, the traversing axes of the measuring system can then be measured, for example, in a translation parallel to the plane of the optical transducers at different geometrical distances the same object, so as to determine the beam divergence directly. Furthermore, the rotation axis required anyway for a tomography or also an optionally available stroke axis can be used. Of course, the changes to the calibration can also be made manually, but it is also a fully automatic calibration conceivable.

It may further be provided to further develop at least one of the sensor devices such that an extending through the optical converter, in particular the light emitting object plane of the imaging optics and extending through the optical sensor image plane of the imaging optics intersect, the light directly meets the imaging optics.

It is thus proposed to let the light emitted by the optical converter directly strike the imaging optics and to focus on the optical sensor. Accordingly, an object plane extending through the optical converter is at an angle to one another on the image plane extending through the optical sensor or parallel to the sensor elements of the optical sensor. The object plane and the image plane intersect. The optical sensor can thus be arranged behind the shielding device in a secured area. The imaging optics is accordingly designed such that, although the image plane and the object plane are not parallel to one another, a sharp imaging of the object plane on the image plane takes place. This makes it possible in particular to dispense with reflecting mirrors within the beam path of the radiation.

Furthermore, it is thus made possible that the area which has become free due to the omission of any reflecting mirrors makes possible an uninfluenced further propagation of the radiation, in particular of X-ray radiation. The only influence on the radiation thus occurs in the transmission of the optical converter. However, the design of the optical converter can be carried out with knowledge of the th materials are made such that the influence of the radiation by the optical converter is known. In particular, a radiation hardening caused by the optical transducer, ie filtering soft or long-wave radiation components, may be known in advance. In this way one is able to know the properties of the radiation after penetration of the optical transducer of the sensor device. Since there is no further influencing of the radiation in the free space behind the optical converter, it is possible to determine additional information about this radiation at a further location once it has penetrated the optical converter of the sensor device. This enables new methods of detection and evaluation of the radiation.

A measuring system for testing a workpiece is proposed, which has a radiation source emitting radiation, in particular wherein the radiation penetrates the workpiece, and further comprising a sensor system with at least two sensor devices.

According to one embodiment of the sensor device according to the first aspect of the invention can be provided that the imaging optics is configured such that the imaging optics sharply images the object plane to the image plane.

In this way, the radiation can be detected with high accuracy. The sharp imaging of the light emitted by the optical transducer onto the image plane or the sensor plane of the optical sensor allows the best evaluation of the light emitted by the optical transducer.

In a further embodiment of the sensor device can be provided that the imaging optics consists of the at least one optical element, and wherein each optical element of the imaging optics from a group consisting of a refractive optical element, a diffractive optical element and a holographic optical element is selected. In this way, a particularly simple and space-saving designed imaging optics can be provided. Any type of mirrors are not part of the imaging optics in this embodiment.

In a further embodiment of the sensor device can be provided that an extending through the optical converter, in particular the light emitting object plane of the imaging optics and extending through the optical sensor image plane of the imaging optics intersect, in particular wherein the at least one optical element is a refractive is optical element or diffractive optical element or holographic optical element, and wherein the optical transducer, the imaging optics and the optical sensor are arranged in compliance with the Scheimpflug- condition relative to each other.

This development makes it possible to arrange the optical sensor in a safe area behind the shield in front of the radiation, in particular the X-ray radiation. In this case, the image plane extending through the sensor surface of the optical sensor and an object plane of the imaging optical system passing through the optical converter intersect in a cutting axis. The imaging optics is now to be arranged in this embodiment so that the Scheimpflug condition is met. In this case, the sharp imaging of the object plane on the image plane can be ensured. The Scheimpflug condition or the Scheimpflug rule states that, for a sharp optical image, the image plane, the focal plane or object plane and the objective plane must intersect in a common straight line.

In this case, an image with maximum sharpness is formed. The lens plane is the main plane of the lens. In the present case, therefore, the main plane of the imaging optics. In the construction of the imaging optics from only a single refractive optical element, the main plane of the optical element is at the same time the main plane of the imaging optics or of the objective. In a construction of the imaging optics of a plurality of optical elements, the imaging optics or the lens will have, for example, two main planes, an object-side main plane and an image-side main plane. The Scheimpflug condition is then exactly that the focal plane or object plane with the object-side main plane at the same distance from the optical axis of the lens intersects as the image plane with the image-side main plane of the lens or the imaging optics, wherein both intersecting lines are parallel to each other. Both degrees of cutting are also located on the same side of the optical axis of the imaging optics. The intersection line could also coincide, which means that the individual elements in the imaging optics are also tilted towards each other.

With this specification, an imaging optics can thus be designed for the average person skilled in the art, which images the light emitted by the optical converter sharply onto the optical sensor. In particular, the entire area of the optical transducer, i. the object plane, sharply imaged on the image plane. With such a design imaging optics eliminates any need to reflect mirrors, etc. in a beam path of the radiation, in particular the X-rays, to arrange to redirect the light suitable for the optical sensor. Thus, by means of simple and inexpensive producible refractive optical elements, a suitable imaging optics can be provided.

In a further embodiment it can be provided that the at least one optical element is a diffractive optical element. In yet another embodiment it can be provided that the at least one optical element is a holographic optical element.

Also with a suitably designed diffractive optical element or a suitably designed holographic optical element which is irradiated by the light emitted by the optical converter, the object can be solved to focus the light on the optical sensor or the image plane. Such a solution may be advantageous, in particular since a diffractive optical element or a holographic optical element generally has a lower weight and smaller dimensions than, for example, an imaging optic formed from refractive optical elements. In a further embodiment of the sensor device according to the first aspect of the invention can be provided that the at least one optical element and the optical transducer are arranged directly adjacent to each other.

The term "immediately adjacent to each other" is understood to mean that the optical transducer and the optical element abut each other.

In particular, it can be provided that the optical converter and the optical element have no air gap between them.

Even if the at least one optical element were penetrated by the radiation in this case, such a construction could possibly be preferable due to its compactness. Further, a design of a diffractive optical element or a holographic optical element may be simpler provided that it is immediately adjacent to the optical transducer.

Provided in a further embodiment of the sensor device, that the sensor device further comprises a socket device, which carries both the optical transducer and the at least one optical element.

In this case, the optical converter and the at least one optical element are thus held together in a housing part or a housing section which forms the mounting device.

Hereby, a design of a diffractive optical element or a holographic optical element can be simplified again by fixing the relative positioning of the diffractive optical element or the holographic optical element and the optical transducer by means of the socket device. It can also be provided that the at least one diffractive optical element or the at least one holographic optical element is integrated into the optical converter. By "integrated" is meant a one-piece, non-destructive separable connection. In a further embodiment it can be provided that the imaging optics has more than one optical element, wherein the imaging optics has a first optical element, which is a diffractive optical element or a holographic optical element, and at least one second optical element and wherein the first optical element is disposed immediately adjacent to the optical transducer.

Thus, a combination of a refractive optical element with a diffractive or holographic optical element is conceivable. In this way, a design of the diffractive optical element or of a holographic optical element may possibly be simplified, since a deflection to be effected by the diffractive optical element or the holographic optical element can be kept smaller and is additionally assisted by the refractive optical element. The at least one second optical element can furthermore be formed from a plurality of refractive optical elements as refractive optics, which is part of the imaging optics. In this case it can be provided that the above-mentioned Scheimpflug condition is maintained such that it, in particular only, for the refractive optical elements formed refractive part of the optics with his or her main axes, the image plane in the optical sensor and an object plane is complied with. The object plane in this case run through the diffractive or holographic optical element or, as usual, through the optical converter.

In a further embodiment of the sensor device can be provided that an extending through the optical converter, the light-emitting object plane of the imaging optics and extending through the optical sensor image plane of the imaging optics at an angle of more than 10 °, but in particular less cut as 60 °. In particular, the angle may be greater than 20 °, in particular greater than 30 °, in particular greater than 45 °. In this way it is ensured that a suitable large tilt between the object plane and the image plane or the optical transducer and the optical sensor is made, which allows to arrange the optical sensor in a safe area behind the shielding device. Furthermore, a geometric distortion, in particular a keystone distortion, is kept low. In a further embodiment of the sensor device can be provided that the optical transducer is a scintillator.

A scintillator is a body that is excited by the passage of high-energy photons or high-energy radiation or charged particles or particle radiation and the excitation energy in the form of light, usually in the visible spectral range, but also, for example, in the ultraviolet range, gives up again. The emitted light can then be deflected by the imaging optics and detected by the optical sensor. By measuring the amount of light, e.g. By means of a photomultiplier or a photodiode, it is possible to deduce directly the energy emitted by the radiation to the scintillator.

In a further embodiment of the sensor device can be provided that the optical sensor is a CCD (charge-coupled device) camera or a CMOS (complementary metal oxide semiconductor) camera. Already mentioned at the outset, the optical sensor can also be any type of photomultiplier, photodiode, avalanche diode or multiple numbers or a two-dimensional array structure thereof. In particular, it may be provided to use so-called Lin-Log CMOS sensors. These have a linear response in a first region and a logarithmic response in a second region. In particular, a linear response may be implemented for low illuminance and a logarithm response for high illuminance. In this way, the sensitivity of the entire device and the resolution of energy differences can be increased.

In a further embodiment of the sensor device it can be provided that the radiation is an electromagnetic radiation, in particular an X-ray radiation or a γ-radiation, or a particle radiation.

With such a type of radiation quality controls of a workpiece are usually performed. Furthermore, these types of radiation are particularly suitable for use with conventional scintillators. In a further embodiment of the sensor device it is provided that the shielding device, the imaging optics and the optical sensor are arranged such that the shielding device shields both the optical sensor and the imaging optics. In particular, the shielding device can also serve as a carrier device for elements of the sensor device.

In this way, the imaging optics can be arranged in a safe area by not directly exposed to the radiation.

In a further refinement of the sensor device, provision may be made for a structure to be applied to the optical signal converter, which enables scaling and / or distortion correction of the image onto the optical sensor. For example, the structure may be a uniform grid. The structure may also be exposed to the optical transducer.

In this way, it is very easy to make a scaling and / or distortion correction in the evaluation of the image detected by means of the optical sensor. Changes in the imaging system that affect the scaling can also be recognized immediately and taken into account in the evaluation.

It can be provided that a surface of the optical transducer is roughened to make the structure visible in the image detected by the optical sensor. In particular, this surface can be one of the surfaces facing the optical sensor or one of the surfaces of the optical converter incident on the optical transducer.

In one embodiment of the sensor device, the optical transducer may be e.g. be formed by a face plate.

Such a face plate is easy to replace by a customer or user. An optical transducer would then represent a wearing part, that can be exchanged easily and inexpensively. In particular, no special service personnel with specialist knowledge are required for this exchange.

In order to be able to produce sharp images on the image plane of the optical sensor, the optical converter should have a not too large thickness. By "thickness" is meant a longitudinal extent of the optical transducer in the direction of the incident radiation. However, depending on the material used for the optical transducer and its quantum efficiency, the optical converter may not be too thin to generate sufficiently many photons per radiating energy. In particular, the optical transducer may have a thickness in a range of about 0.1 mm to about 10 mm.

In one embodiment, it may be provided that, if, for example, an optical converter with the above incoming thickness should not be stable enough, a carrier surface or substrate is provided for supporting the optical converter. A material of this carrier should have a small effective mass number, e.g. be made of a lightweight construction material or porous material, such as, for example, from magnesium. In this case, structures can be introduced into the support, which allow a thickness calibration of the dose for linearity correction of the optical sensor.

A linearity correction of the optical sensor is performed in order to correct any nonlinearities of the readout and amplifier circuits of the optical sensor or a non-linear behavior of the optical sensors at long exposure times. Furthermore, the optical transducer itself can exhibit nonlinear behavior based on the time-limited regeneration capability of the fluorescence transitions, also referred to as "depletion." This behavior can also be corrected.

In one embodiment of the sensor device can be provided that the sensor device comprises an auxiliary light source that emits light in a known spectrum and known energy or power. In an embodiment, it can be provided that the auxiliary light source is arranged such that it covers the optical Transducer illuminated. In a further embodiment it can be provided that the auxiliary light source is arranged such that it directly or directly illuminates the optical sensor.

In one embodiment of the sensor system it can be provided that at least one filter for filtering a portion of the radiation is arranged between the optical transducer of the first sensor device and the optical transducer of the at least one second sensor device.

In this way, a proportion of the radiation filtered out between the first optical converter and the second optical converter can be adjusted precisely.

In particular, it can be provided in the case of a sensor device or a sensor system that the filter and the optical converter are attached directly to one another. In particular, the filter and the optical converter may be constructed as one unit.

A filter can be provided, for example, in the form of an absorbent coating, as a film, or as a disk of suitable material. Even a suitable choice of the material of the optical transducer can already bring about a desired filter effect.

It is understood that the features mentioned above and those yet to be explained not only in the particular combination given, but also in other combinations or alone, without departing from the scope of the present invention.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show it:

1 shows an embodiment of a sensor device, 2 shows an embodiment of a measuring system,

3 shows a further embodiment of a sensor device,

4 shows an embodiment of a sensor system,

Fig. 5 shows an embodiment of a method according to the invention for

Determining a propagation direction of a radiation, and

Fig. 6 shows an embodiment of a method according to the invention

Determining an energy distribution of a radiation.

1 shows an embodiment of a sensor device 10. The sensor device 10 serves to detect a radiation 12. The radiation 12 may in principle be electromagnetic radiation or else particle radiation or particle radiation. In particular, the radiation 12 may be X-radiation. In the following, the embodiments of the invention will be explained using the example of X-ray radiation.

In order to make the radiation 12 more detectable, an optical converter 14 is provided. The optical transducer 14 is excited by the energy of the radiation 12 to emit light 16. The light 16 may be light in a visible wavelength range. However, it may also be provided, depending on the choice of the optical transducer 14, that light is emitted on an ultraviolet or infrared spectrum.

In particular, the optical transducer 14 may be a scintillator. In principle, various materials, both organic and inorganic materials, are known, with which a scintillator can be provided. The scintillator 14 has approximately the shape of a disk. In the coordinate system shown in FIG. 1, the optical transducer 14 has an areal extent in an XY plane, for example in the form of a rectangle. In addition, points the optical transducer 14 has a certain thickness D extending in the Z direction. This thickness D extends approximately in the direction in which the radiation 12 penetrates the optical transducer 14. The usual thickness D for the optical transducer 14 is 0.1 to 10 mm. On the one hand, depending on the material of the optical transducer 14, it is not too thin to be chosen so that the optical transducer 14 can emit a sufficient amount of photons in the form of the light 16; on the other hand, it should not be too thick to allow the optical transducer 14 to emit has sharp contours emitted by the optical transducer 14 in the form of light 16 representation.

The light 16 emitted by the optical converter 14 is then detected by an optical sensor 18. The optical sensor 18 is chosen such that it is sensitive to the wavelength range in which the light 16 is emitted. In particular, the optical sensor 18 may be capable of detecting, in the manner of a photomultiplier, the number of photons impinging on the optical sensor 18.

With this basic structure by means of optical transducer 14 and optical sensor 18 is ultimately able to with an optical sensor 18, which is sensitive to light in a conventional, usually visible to the human eye wavelength spectrum, a high-energy radiation 12th , For example, to detect an X-ray radiation.

In order to image the light emitted by the optical converter 14 onto the optical sensor 18, an imaging optical system 20 is provided. The imaging optics 20 are capable of focusing the light 16 onto the optical sensor 18. This is made possible without the aid of merely reflective elements, such as plane mirrors, in a beam path of the light 16 between the optical converter 14 and the imaging optics 20. The light 16, which is emitted by the optical converter 14, thus falls directly onto the imaging optics 20. The imaging optics 20 has at least one optical element 22, with which the light 16 is then focused onto the optical sensor 18. In the simple exemplary embodiment shown in FIG. 1, the imaging optical unit 20 has an optical element 22, which is shown in the form of a lens in the form of a refractive optical element. However, this representation is chosen merely for illustrative purposes. About that In addition, it is of course possible that the imaging optics 20 has more than one optical element 22, in particular more than one refractive optical element 22. Furthermore, as will be explained below, the imaging optics 20 can also be formed with at least one optical element 22 , which is a diffractive or a holographic optical element.

Furthermore, the sensor device 10 has a shielding device 24. The shielding device 24 serves to shield the optical sensor 18 from the radiation 12. The arrangement and dimensioning of the shielding device 24 in FIG. 1 is merely an example. By means of the shielding device 24, any damaging influence of the radiation 12, in particular the occurrence of aging effects, on the optical sensor 18 is avoided.

In the case of radiation 12, which is, for example, an X-radiation, it can be assumed that it propagates isotropically substantially straightforwardly through every type of matter. For such X-ray radiation, all materials essentially have a refractive index of 1, so that substantially no beam deflection occurs. In this respect, the radiation 12 continues straight after transmission through the optical converter 14.

Therefore, the optical sensor 18 is to be located outside a region where the radiation 12 would enter when propagated rectilinearly. Only there can the optical sensor 18 be shielded by means of the shielding device 24 in such a way that at the same time the optical sensor 18 has the possibility of detecting the light 16 emitted by the optical converter 14. The light 16 emitted by the optical converter 14 is essentially a two-dimensional image that allows a conclusion about the spatial distribution and the spatial energy distribution of the radiation 12 in the XY plane. Accordingly, the imaging optics 20 must be able to image the light 16 emitted in an XY plane sharply on the optical sensor 18, which is arranged substantially in an XZ plane in the representation selected in FIG. As a rule, the optical sensor 18 has a two-dimensional sensor array. This would extend in the representation selected in FIG. 1 in the XZ plane and is referred to as sensor plane 26. Accordingly, an image plane into which the imaging optics 20 must sharply image the light 16 emitted by the optical converter 14 extends parallel to the sensor plane 26. The image plane is identified by the reference numeral 28. An object plane 30 of the imaging optics 20 then extends in the view shown in Fig. 1 in the X-Y plane parallel to the optical transducer 14 therethrough. Depending on the thickness D of the optical transducer 14, the object plane 30 may extend, for example, exactly through a center D / 2 of the optical transducer 14.

The imaging optics 20 is now configured and arranged such that the object plane 30 is imaged sharply onto the image plane 28.

In an embodiment in which the at least one optical element 22 is a refractive optical element, a sharp image of the object plane 30 can be made on the image plane 28 by the optical transducer 14, the optical sensor 18 and the imaging optics 20 and in the illustrated view, the at least one optical element 22 are arranged such that the Scheimpflug condition is met. In the simplified example illustrated in FIG. 1, the imaging optical unit 20 has a refractive optical element 22. A main plane of the optical element 22 is designated by the reference numeral 34. The Scheimpflug condition is only met exactly when the object plane 30, the image plane 28 and the main plane 34 intersect in a section axis 32.

In this way, it becomes possible, by means of the imaging optics 20, to image the object plane 30 sharply onto the image plane 28, although they are inclined relative to one another. This makes it possible to completely dispense with optical elements, in particular the mirror deflecting light through reflection, in a beam path of the radiation 12. A region "behind" the optical converter 14, indicated schematically by the reference numeral 33, can thus remain free. This allows a further propagation of the radiation 12 after transmission through the optical transducer 14, which is unaffected or can be influenced in a targeted manner. This makes a capture and Evaluation of the radiation 12 at a plurality of locations and at different distances from an example, by means of the radiation 12 transilluminated object or the radiation 12 emitting source possible.

FIG. 2 shows an embodiment of a measuring system 43 in which the sensor device 10 can be used.

In the measuring system 43, the optical transducer 14 is arranged such that it is arranged substantially perpendicular to an incident direction 36 of the radiation 12. One of the radiation 12 facing incident surface 38 of the optical transducer 14 is thus substantially perpendicular to the direction of incidence 36 of the radiation 12. The radiation 12 is emitted by a radiation source 40. In principle, it can be provided that the radiation source 40 and the sensor device 10 are arranged in a stationary manner. However, it can also be provided that the radiation source 40 and the sensor device 10 are movable in such a way that they move absolutely but not relative to one another. In this way it is possible, for example, not to move the radiation source 40 and the sensor device 10 relative to one another, but relative to a workpiece 42 which is to be measured or checked by means of the measuring system 43. In this way, it is possible, for example, to check 42 areas of the workpiece 42 in succession for large-volume workpieces.

Accordingly, the workpiece 42 is disposed between the radiation source 40 and the optical transducer 14 of the sensor device 10. In this area, a workpiece holder (not shown) may be arranged to clamp the workpiece 42, for example. Such a workpiece holder can for example also be designed such that the workpiece 42 can be rotated or moved transversely. For example, it can be provided that the workpiece 42 is arranged on a turntable.

In this way, it becomes possible to check the workpiece 42 by means of the radiation 12. The workpiece 42 is penetrated by the radiation 12 and then incident on the optical transducer 14 parallel to the direction of incidence 36. The light 16 emitted by the optical transducer 14 is imaged by the imaging optics 20 on the optical sensor 18. In this way it is possible to detect and evaluate a spatial distribution and intensity after the transmission through the workpiece 42. In this way, for example, one is able to detect voids or inclusions that can not be detected in a material of the workpiece 42 by a purely visual inspection. The recognition of such errors is usually based on the fact that inclusions or cavities cause a lower or different absorption of the radiation 12 than the surrounding material. This ultimately also causes a different emission of light 16 in the corresponding spatial areas. These irregularities are then detected by means of the optical sensor 18.

In the illustrated embodiment in FIG. 2, the shielding device 24 is designed and arranged such that it shields both the optical sensor 18 and the imaging optics 20 from the radiation 12. In this way it is possible to protect the imaging optics 20 from damaging influences of the radiation 12.

The measuring system 43 can furthermore have a data processing device 14 and a user interface 16. By means of the data processing device 1 14, for example, the measured values detected by means of the optical sensor 18 can be read out, evaluated and output. For this purpose, the user interface 1 16 may have a suitable display device. Furthermore, the user interface 16 may include a suitable input unit that allows a user to control the measurement system 43.

Also in this way it is possible that the space 33 "behind" the optical transducer 14, that is on the incident direction 36 of the radiation 12 opposite side of the optical transducer 14, remains free. An influence on the radiation 12 or the light 16 in the space 33 thus remains off. A radiation 12 that is uninfluenced in the space 33 can be evaluated in this way at further locations or at different distances from the radiation source 40 or the workpiece 42. This will be explained in more detail below. FIG. 3 shows a further embodiment of a sensor device.

In this embodiment as well, the shielding device 24 is initially designed and arranged such that it protects the optical sensor 18 and also the optical element 22, in particular the refractive optical element 22, from being influenced by the radiation 12.

In the embodiment shown in FIG. 3, the imaging optics 20 also have a further optical element 46, 46 'beyond the optical element 22. The optical element 46, 46 'may, for example, be a diffractive optical element 46 or a holographic optical element 46'.

It can be provided that the diffractive optical element 46 or the holographic optical element 46 'is arranged directly adjacent to the optical transducer 14. In this way it may be possible for the light 16 emitted by the optical converter 14 to already have an effect in the direction caused by a diffraction effect deliberately caused by the diffractive optical element 46 or by the interference or diffraction pattern deposited on the holographic element 46 ' of the optical sensor 18 to deflect. The beam deflections to be effected by the other optical elements of the imaging optics 20 can be reduced in this way. In principle, it is even possible that the diffractive optical element 46 or the holographic optical element 46 'are provided in isolation and already effect the necessary focusing of the object plane 30 on the image plane 28. In this case, the imaging optics 20 are thus provided only from a diffractive optical element 46 or only from a holographic optical element 46 '.

The image plane 28 and the object plane 30 enclose an angle 44 between them. In the illustrated embodiment, the angle 44 is about 90 °. In principle, however, it can be provided that the angle 44 also assumes a different value. In particular, it can be provided that the angle 44 is more than 10 °, in particular more than 20 °, in particular more than 30 °, in particular more than 45 °. For example, by selecting the angle 44 of approximately 75 °, the refraction of the light 16 to be effected by the imaging optics 20 in order to image it sharply from the object plane 30 onto the image plane 28 can be reduced. At the same time, such an angle 44 may still be sufficient to be able to shield the optical sensor 18 by means of the shielding device 24. Accordingly, an angle 45 included by the major axis 34 of the imaging optics 20 and the image plane 28 may be selected correspondingly with a different value. In particular, the angle 45 may be less than 45 °, in particular less than 30 °, in particular less than 15 °.

FIG. 4 shows an embodiment of a sensor system 51. The sensor system 51 may be part of the measuring system 43.

The sensor system 51 has more than one sensor device 10, as shown for example in the embodiments in FIGS. 1 and 3. Accordingly, in the embodiment illustrated in FIG. 1, the sensor system 51 has a total of three sensor devices 10, 48 and 50. The first sensor device is identified by the reference numeral 10, the second sensor device by the reference numeral 48 and the third sensor device by the reference numeral 50.

Identical elements of the sensor devices 10, 48, 50 are marked with corresponding reference numerals and will not be explained again.

As can be seen, the optical transducers 14, 14 ', 14 "are arranged in a cascade one behind the other with respect to the main incident direction 36. In this way, it becomes possible to transmit the radiation 12 at different distances or at different locations Radiation source 40 and the workpiece 42. As will be explained in more detail below, this allows completely new possibilities of evaluation. It can be provided that the sensor system 51 has at least one filter element which is arranged between two optical transducers 14, 14 'or 14', 14 ". In the embodiment shown in FIG The first filter element 52 is disposed between the optical transducer 14 and the optical transducer 14 'A second filter element 54 is exemplarily disposed between the optical transducer 14' and the optical transducer 14 ''. The filter elements 52, 54 also extend flat in the XY plane. The filter elements 52, 54 selectively filter a certain portion of the radiation 12. This may, for example, be a specific wavelength range, if the radiation 12 is an electromagnetic radiation, for example an X-radiation.

By the excitation of the radiation 12, as already explained above, for example, the optical transducer 14 is excited to emit light. This light emitted in the XY plane by the optical transducer 14 is referred to as the "first image" 56. It is imaged on the optical sensor 18 via the imaging optics 20. Accordingly, a second image 58 generated by the optical transducer 14 'is imaged onto the optical sensor 18'. At the same time, a third image 60 "emitted by the optical transducer 14" is imaged onto the optical sensor 18 ". The optical sensors 18, 18 ', 18 "can all be connected to the data processing device 1 14' (not shown in this figure), so that the information transmitted by means of the images 56, 58, 60 can be read out and evaluated.

As will be explained below, the evaluation of the images 56, 58, 60 of the radiation 12 generated at different distances from the workpiece 42 makes it possible to provide improved evaluation options for the radiation 12. As will be explained in more detail below, it is possible, for example, to determine corresponding image components, for example an image component 62 of the first image 56, an image component 64 of the second image and an image component 66 of the third image 60, by means of an image correlation method. Assuming that the radiation 12 propagates isotropically, the "piercing point" of the radiation 12 can thus be determined, so to speak, through the object planes 30, 30 'and 30 ", the optical converter 14 at a first location 106 being the optical converter 14 'at a second location 108 and the optical transducer 14 "is positioned at a third location 110. The locations 106, 108 and 110 are known, which are determined by the structural design of the sensor system 51. In this respect, a difference vector 112 is also between the first location 106 and the second Location 108 and a difference vector 1 12 'between the second location 108 and the third location 110. The optical transducers 14, 14' and 14 "are aligned parallel to each other, that is, the object planes 30, 30 'and 30" are parallel to one another Thus, for example, an image correlation of the first image 56 and the second image 58 may determine an offset of the radiation 12 in the XY plane from the first image 56 to the second image 58. Further, since the difference vector 12 is known , it is possible in this way to determine a three-dimensional vector indicating a propagation direction 68 of the radiation 12.

Furthermore, it may then be provided, for example, to determine the corresponding image components 64, 66 between the second optical converter 14 'and the third optical converter 14 ", and a propagation direction of the radiation 12 between the optical converter 14' and the optical converter 14 "to determine. Since the image components 62, 64, 66 correspond to one another, a redundant determination of the propagation direction 68 can be carried out in this way, for example. Likewise, it is possible to work directly with the first image 56 and the third image 60 and determine a direction of propagation between the optical transducer 14 and the optical transducer 14 ".

The number of individual sensor devices 10, 48, 50 in the sensor system 51 is merely an example. Of course, it is possible that further sensor devices are arranged in the sensor system 51. The optical transducers 14 can each be arranged in the described form in cascade fashion one behind the other with respect to the direction of incidence 36 of the radiation 12. In this respect, two, three, four, five, six etc. sensor devices can also be arranged one behind the other. Likewise, it is then possible not only to make image correlations between images of adjoining sensor devices, but also, for example, to correlate directly between a second image 58 and a fifth image (not shown). Any combinations are possible here. Furthermore, by means of the sensor system 51, for example, information about the energy of a specific portion of the radiation 12 can be obtained. In principle, it is to be assumed that it is known from which material the optical transducers 14, 14 'and 14 "are provided, and because of this it is also known in which context the emission of photons generated by the optical sensor 18, 18', 18 ", with which the energy emitted by the radiation 12 is transferred to the corresponding optical transducer 14, 14 ', 14" A certain number of photons detected by means of, for example, the optical sensor 18 on a specific pixel of the first image 56 are let to Energy or irradiance of the radiation 12 when passing through the optical converter 14 close at this particular pixel.

When the radiation 12 passes through the optical transducer 14 or the optical transducer 14 ', 14 ", a certain radiation hardening inevitably occurs." Hardening "is to be understood as meaning that the" soft ", ie long-wave, radiation components are filtered out of the radiation 12. It can be assumed that this effect of "radiation hardening" is known for a particular optical transducer 14 depending on its particular material and its dimensions, in particular its thickness D.

If, for example, the energy in the images 56 and 58 is now determined, the first image 56 not only shows how the energy distribution of the radiation 12 is in the first image 56, but also the energy distribution within the image Radiation 12 from the image 58 can be determined, which hits the optical converter 14 '. Since a radiation hardening or filtering of the radiation value has already occurred in the optical converter 14, a corresponding evaluation of the second image 58 for an energy distribution will yield different results than that of the first image 56. From these differences in the energy distribution in the images 58, 56 and the knowledge about the portion of the radiation 12 filtered out during the transmission by the optical converter 14, it is thus possible to make a statement about its energy and energy distribution for precisely this filtered-out portion of the radiation 12. In particular, this makes it possible to filter out specific portions of the radiation 12 specifically by means of the filter elements 52, 54 between two optical transducers 14, 14 'or 14', 14 "and to determine the effects on the energy distribution in the images 58 and Thus, a statement about energy distributions of certain radiation components can be made on the basis of this difference analysis.

Finally, due to the assumption of isotropic propagation of the radiation 12 along the propagation direction 68 without refractive effects, it is possible to project a particular point of an image 56, 58, 60 back onto the workpiece 42 knowing the direction of propagation 68. Thus, it can be determined exactly along which path an image component, for example an image component 62, 64, 66, has generated radiation through the workpiece 42. By knowing the radiation 12 originally emitted by the radiation source 40 and the energy distribution in the images 56, 58, 60, it is thus possible to make a statement as to which portions of the radiation 12 were absorbed by the workpiece 42. In particular, it is also possible to make a statement for certain radiation components. In this respect, it is possible, for example, to specifically indicate the local absorption coefficient of the workpiece 42 for a specific region of a workpiece 42.

FIG. 5 schematically shows a schematic flow diagram for determining a propagation direction 68 of a radiation 12 and denoted by the reference numeral 70.

The method begins with step 72. In a step 74, first of all a sensor system 51 is to be provided which has at least two sensor devices 10. Furthermore, at least the difference vector 1 12 between the first location 106 of the optical converter 14 of the first sensor device 10 and the second location 108 of the optical converter 14 of the at least one further second sensor device 48 or 50 is known. In a step 76, the first image 56 of the optical transducer 14 of the first sensor device 10 is then detected by means of the optical sensor 18 of the first sensor device 10.

In a step 78, the second image 58 of the optical converter 14 'of the at least one second sensor device 48, 50 is detected by means of the optical sensor 18' or 18 "of the at least one second sensor device 48, 50.

The steps 76 and 78 can basically be carried out consecutively. However, it is also possible that steps 76 and 78 are performed substantially simultaneously or simultaneously.

In a step 80, a correlation result is then determined by correlating the first image 56 and the second image 58, 60. Such image correlation methods have already been proposed in the prior art. These image correlation methods make it possible to determine the mutually corresponding image portions 62, 64, 66 in the images 56, 58, 60.

In a step 82, the propagation direction 68 of the radiation 12 is then determined from the at least one difference vector 1 12, 1 12 'and the correlation result determined in step 80.

The method may then end in step 84.

Furthermore, it is further possible that in a further step 86, provided that the first location 106 and the second location 108 are known, a back projection of at least the first image 56 along the determined propagation direction 68 onto the workpiece 42 he follows. In this way, a path on which the radiation 12 has passed through the workpiece 42 can be determined.

Moreover, in a further step 88, it is then possible for an absorption coefficient of the workpiece 42 to be detected with knowledge of the radiation 12 emitted. radiating source 40 is determined based on at least the first image 56. Since the energy distribution of the radiation 12 can be determined in the first image 56 and, furthermore, the path of the radiation 12 through the workpiece 42 can be determined by the proposed rear projection, it is then possible for this passage through the workpiece 42 to show the absorption capacity under consideration of the energy distribution in the first image 56 compared to the values of the radiation 12 originally emitted by the radiation source 40.

Finally, the method can then end in a step 84 again.

FIG. 6 further schematically illustrates a method with which an energy distribution within the radiation 12 can be determined.

This method begins in a step 92. In a step 94, the sensor system 51 is provided, wherein the sensor system 51 has at least two sensor devices 10 or 48, 50. A portion of the radiation filtered out by the optical transducer 14 of the first sensor device 10 as far as the respective optical transducer 14 'or 14 "of the at least one second sensor device 48, 50 is known, wherein the radiation can be detected both by an inevitably occurring radiation hardening in an optical radiation However, it can also be provided that an additional filter element 52 or 54 is provided, with which a certain portion of the radiation 12 is specifically filtered out.

In a step 96, the first image 56 of the optical transducer 14 of the first sensor device 10 is then detected by means of the optical sensor 18 of the first sensor device 10.

In a step 98, the second image 58 or 60 of the optical transducer 14 'or 14 "of the at least one second sensor device 48, 50 is detected by means of the optical sensor 18', 18" of the at least one second sensor device 48, 50 , Consequently, both the second sensor device 48 and the third sensor device 50 can be understood by the "at least one second sensor device". Accordingly, both the second image 58 and the third image 60 can be understood by the "second image".

In a step 100, a difference image is then determined from the first image 56 and the second image 58 or 60, in particular, for example, rescaled via a correlation. Thus, differences in energy distribution between the first image 56 and the second image 58, 60 can be determined.

In a step 102, it is thus possible to determine energy of the proportion of the radiation 12 filtered out from the optical converter 14 of the first sensor device 10 to the optical converter 14 "of the at least one second sensor device 48, 50 by means of the differential image is performed in a step 102. The method then ends in a step 104.

By combining the methods 70 and 90, it is possible to determine the absorption capacity of the workpiece 42, which is resolved according to radiation components or spectrally as well as spatially. In this case, the method 70 and the method 90 can be carried out, the step 100 of determining the reference image being carried out for correlating image portions 62, 64, 66 of the first image 56 and of the second images 58 and 60, respectively.

Claims

Method (70) for determining a propagation direction (68) of a radiation (12), comprising the following steps:

Providing (74) a sensor system (51) with a first sensor device (10), the first sensor device (10) having a first optical sensor (18) for detecting light (16) in a first wavelength range, and a first optical converter ( 14) which emits light (16) in the first wavelength range as a function of the radiation (12) incident on the first optical transducer (14) and at least one second sensor device (48, 50), the second sensor device (48, 50 ) comprises a second optical sensor (18 ', 18 ") for detecting light (16) in a second wavelength range, and a second optical transducer (14', 14") which depends on the second optical transducer (14 '). , 14 ") incident light (12) emits light (16) in the second wavelength range, the optical transducer (14) of the first sensor device (10) and the optical transducer (14 ', 14") of the at least one second sensor device (48 , 50) with respect to an incident direction (36) of the radiation (12) are arranged one behind the other, wherein at least one difference vector (1 12, 1 12 ') between a first location (106) of the first optical transducer (14) of the first sensor device (10) and a second Location (108) of the second optical converter (14) of the at least one second sensor device (48, 50) is known,

Detecting (76) a first image (56) of the first optical transducer (14) of the first sensor device (10) by means of the first optical sensor (18) of the first sensor device (10),

Detecting (78) a second image (58, 60) of the second optical converter (14 ', 14 ") of one of the at least one second sensor device (48, 50) by means of the second optical sensor (18 ', 18 ") of the at least one second sensor device (48, 50),

- determining (80) a correlation result by correlating the first image (56) and the second image (58, 60), and

- Determining (82) the propagation direction (68) of the radiation (12) from the at least one difference vector (1 12, 1 12 ') and the correlation result.

2. Method according to claim 1, characterized in that the first location (106) and the second location (108) are known, and in a further step (86) a backprojection of at least the first image (56) along the determined propagation direction (68 ) on a workpiece (42) which has been penetrated by the radiation (12).

3. The method according to claim 1, characterized in that in a further step (88) an absorption capacity of the workpiece (42) with knowledge of the radiation (12) emitting radiation source (40) is determined based on at least the first image (56).

4. Method (90) for determining an energy distribution within a radiation (12), comprising the following steps:

- providing (94) a sensor system (51) with a first sensor device (10), wherein the first sensor device (10) comprises a first optical sensor (18) for detecting light (16) in a first wavelength range, and a first optical transducer ( 14) which emits light (16) in the first wavelength range as a function of the radiation (12) incident on the optical transducer (14), and at least one second sensor device (48, 50), wherein the second sensor device (48, 50) a second optical sensor (18 ', 18 ") for detecting light (16) in a second wavelength range, and a second optical transducer (14 ', 14 ") emitting light (16) in the second wavelength range depending on the radiation (12) incident on the second optical transducer (14', 14"), the first optical transducer (14) of the first Sensor means (10) and the second optical transducer (14 ', 14 ") of the at least one second sensor means (48, 50) with respect to an incident direction (36) of the radiation (12) are arranged one behind the other, wherein a portion of the first optical transducer (14) of the first sensor device (10) up to the respective second optical transducer (14 ', 14 ") of the at least one second sensor device (48, 50) filtered out radiation (12) is known,

Detecting (96) a first image (56) of the first optical transducer (14) of the first sensor device (10) by means of the first optical sensor (18) of the first sensor device (10),

Detecting (98) a second image (58, 60) of the second optical transducer (14 ', 14 ") of the at least one second sensor device (48, 50) by means of the second optical sensor (18', 18") of the at least one second optical sensor Sensor device (48, 50),

- determining (100) a difference image from the first image (56) and the second image (58, 60), and

Determining (102) an energy of the portion of the radiation (12, 12) filtered out from the first optical transducer (14) of the first sensor device (10) to the optical transducer (14 ', 14 ") of the at least one second sensor device (48, 50) ) by means of the difference image.

A method for determining a spectrally and locally resolved absorbance of a workpiece (42), wherein the method (70) of claim 1 is performed, and wherein the method (90) of claim 4 is performed, wherein the step (100) of determining of the difference image for each correlating image portions (62, 64, 66) of the first image (56) and the second image (58, 60).

6. The method according to any one of claims 1 to 5, characterized in that each sensor device (10, 48, 50) of the sensor system (51) further comprises an imaging optics (20) for imaging of the respective optical transducer (14, 14 ', 14 ") emitted light (16) on the respective optical sensor (18, 18 ', 18"), wherein the imaging optics (20) at least one optical element (22, 46), and a shielding means (24) for shielding the optical sensor (18, 18 ', 18 ") of the radiation (12).