WO2009121932A2

WO2009121932A2 - Rotating table for spatial, high-resolution computer laminography

Info

Publication number: WO2009121932A2
Application number: PCT/EP2009/053956
Authority: WO
Inventors: Lukas Helfen; Tilo Baumbach; Udo Retzlaff
Original assignee: Forschungszentrum Karlsruhe Gmbh
Priority date: 2008-04-04
Filing date: 2009-04-02
Publication date: 2009-10-08
Also published as: WO2009121932A3

Abstract

The present application relates to a rotating table comprising a rotation platform (4) for laminographic examinations using radiation, wherein the rotation platform (4) comprises a recess (5) disposed around the axis of rotation (10).

Description

Rotation table for spatially high-resolution computer laminography

The present invention relates to a rotary stage and adapted technical realization for laminography, radiography and tomography.

Tomographic methods are based on the scanning of an object from different directions of incidence by means of penetrating, penetrating or penetrating radiation and serve, coupled with suitable reconstruction methods, the non-destructive imaging of cross-sections of the object. In particular, the methods of laminography or tomosynthesis are used predominantly for examining flat and laterally extended objects. These methods, which have been used for many years, allow cross-sectional images of different levels within a sample to be obtained. Et al Two-dimensional, digital images from different directions are evaluated computer-aided and assembled into three-dimensional images with high image contrast.

The three-dimensional information about the external shape and the internal structure of the irradiated object is not directly accessible by means of X-ray projection, since the information of different penetration depths summed up when penetrating the beam and finally only one integral value per pixel is registered on the detector. The problem is to resolve the superposition of spatially separated regions at different depths. This can be achieved by combining many different beam directions and by including corresponding filters and corrections known in the specialist literature. This requires not only a considerable mathematical effort but also a high mechanical repeatability of the measurement conditions. In spite of all the corrections, there are always errors in the image, which are also known as artifacts.

There are several ways to create different beam directions. Usually, two of the three main components (radiation source, object, Detector) here coordinated to each other (eg on coordinated circular paths in the circular laminography) moves and measured their relative position to each other. A large number of the implemented technical solutions (see Avinash et al US 2006/0204076 A1) are based on the fact that the radiation source and the detector are moved and the object to be examined remains in a fixed position. It is easy to understand that almost all tomography systems of medical technology aim at a fixed position of the patient, ie the object.

For material analysis or technical component testing, however, the radiation source and the detector can also be fixed and only the object is moved. In computer tomography (CT), the object is subjected to rotation. The beam falls perpendicular to the axis of rotation, penetrates the object and the incident intensity of the radiation is registered on the detector. The object is rotated step by step around the axis of rotation (aligned perpendicular to the beam axis), resulting in many, mostly several hundred shots of the object from different directions of transmission. In medical technology with fixed object / patient, this corresponds to the execution of two concentric full circles (of source and detector) around the object, with the optical axis rotating and the position of the object to be examined. For objects of rather rotationally symmetric (cylindrical) shape, which can be mounted so that their projection always remains within the field of view of the detector during rotation, CT is mathematically accurate (at least on the optical axis, which is usually perpendicular to the axis of rotation) and good for imaging cross sections or 3D images. However, for objects that have a large lateral extent, but a small thickness, such as flat material samples, electronic boards or even a painting, the tomography is very limited use, since in the radiation directions parallel to the surface, the X-ray transmission tends to zero and thus no reliable Information from these directions can be obtained, which usually creates strong artifacts in the reconstructed image.

Laminography methods avoid such transmission directions in which the long extension of the flat object is parallel to the optical axis. Although the geometries of image acquisition also lead to artifacts in the reconstructed image, they are less pronounced in a wide range of applications than those of CT. Various concepts of laminographic methods with different scanning geometries and corresponding instrumental implementations are known. An instrumentally easy to implement variant is based for example on the translation of the object in a divergent fan beam, which serves to obtain the different transmission directions (Gondrom et al, Nuclear Engineering and Design 190 (1999) pages 141-147). Other instrumentally more complex methods use, for example, synchronized movements of source and detector (see James T. Dobbins IM, Phys. Med. Biol. 48 (2003) R65-R106).

In the case of circular laminography, in contrast to CT, the source and detector no longer make concentric circles around the point to be examined, but the two circles have no common center. Similar to the CT, the optical axis also rotates around the object site to be examined, but runs on a cone surface during the scan (in CT on a circular disk). In the case of the fixed object, the optical axis and the axis of rotation form no angle of 90 °, but a smaller, but precisely known angle. Stevens (Stevens et al., Med. Phys., 28, pp. 1472-1481, 2001) points to the equivalence of the two imaging modes with fixed and mobile optical axes. The definition of the tomographic angle, theta = 90 ° -α (θ = 90 ° -α), is dependent on the angle of inclination alpha of the axis of rotation from the normal with respect to the optical axis, wherein theta corresponds to half the opening angle of the above-described cone shroud. The (axis) pitch angle alpha is typically between 20 and 60 degrees. In the case of tomography, however, the axial tilt angle is exactly 0 degrees. As in the case of CT, in laminography, the object is also rotated either continuously or incrementally about the axis of rotation, with a multiplicity of single, two-dimensional images being read out of the detector. Details of the method and evaluation algorithms are inter alia in Smith in US 2005/0084173 A1 and Jabri et al. US 2004/0008900 A1. By means of laminography, non-destructive examinations of flat material samples, such as printed circuit boards with mounted electronic components, can be carried out (Baker et al., EP 0 355 128 B1 or also Helfen et al., APPLIED PHYSICS LETTERS 86, 071915 - 2005). However, the resolution limits and thus the resulting smallest, meaningfully reconstructable, three-dimensional unit, a voxel, is strongly influenced by the positioning accuracy of the sample. Positioning errors are reflected as artifacts in the reconstructed image that effectively reduce the resolution achieved.

In order to obtain a good spatial resolution, the position of the object relative to the beam direction (optical axis) and to the ideal axis of rotation must be known very precisely. It is therefore important to ensure precise or at least reproducible object positioning for all directions of incidence of the beam, so that the object can be scanned with the highest possible accuracy and thus reconstructed with the highest possible image quality. Because the desired high spatial resolution (for example, resolutions in the sub-micron range), the object under investigation can often be small and light, a test arrangement with fixed beam and detector is advantageous for such investigations.

Stevens et al. Phys. Phys. Vol. 28 (No. 7), June 2001 pages 1472-1481, has studied the influence of the precise mechanical adjustment of the rotation axis on the image quality and its resolution. He started from a fixed x-ray source with a fixed detector. The X-ray source emits diverging beams, so that a corresponding increase in the projection of the X-radiation through the sample results on the detector. The sample lies on a sample table which rotates about an axis inclined to the beam path. He proposes a turntable with an illuminated object platform. It should be noted that an irradiated sample stage additionally weakens the beam and thus acts as an unintentional filter, so that artifacts can arise. In addition, a beam barer sample holder has the disadvantage that it absorbs energy dependent energy (and thus not all energy ranges equally well usable), and in the case of white radiation with a wide energy range changes the energy spectrum. Unavoidable manufacturing or material defects, even with careful production, as well as contamination (eg dust) or wear, can cause defects on and in the sample table. These small defects also lead to unwanted absorption, scattering or diffraction, which then causes further artifacts (eg Cloetens et al., J. Phys. D: Appl. Phys. 29 (1996) pp. 133-146) as a result of the inhomogeneity. In order to obtain evaluable images, Stevens et al. a special evaluation algorithm. He notes that the spatial resolution in the final image depends to a large extent on the resolution limit of the detector used, the size of the X-ray source and the interpolation steps in the reconstruction technique of the image data. Increased accuracy in geometrically positioning the sample is not of paramount importance in typical medical applications. For medical applications, the described instrumentation is certainly the state of the art, but for sub-micron spatial resolution evaluations, geometrical positioning of the object with accuracies of the same order of magnitude as the resolution to be achieved is necessary.

In US 2005/0265517 A1 Gary proposes the use of CRL X-ray lenses (compound refractive lens) to improve the resolution. In many applications, microfocus X-ray tubes are used to make enlarged radiographic images. This method is based on a geometric shadow on a detector. Gary notes that the resolution is limited by the source size of the microfocus X-ray tube, so that the resolution limit is about 5 microns, about the size of the focal spot. He therefore proposes to improve the spatial resolution to use CRL X-ray lenses for focusing the X-ray beam. The disadvantage here is that an additional component is installed and adjusted. In addition, CRLs show a wavelength-dependent focussing behavior, so that preferably monochromatic radiation should be used for this purpose. In X-ray tubes, the photon yield is already limited, so that a further loss of intensity By filtering the radiation leads to extremely long exposure times. In this case, the use of synchrotron radiation may be advantageous since their brilliance is orders of magnitude higher than that of normal x-ray tubes. It is interesting that the resolution in such an arrangement should depend in many areas on the properties of the X-ray lens and the selected magnification and not so much on the source size, so the size of the focal spot. Finally, the position of the object must be well known again.

The high demands on the object positioning is not or only partially possible with currently known and commercially available rotary tables. Traditionally mounted rotary tables with ball, roller or tapered bearings have existed for decades with relatively low aspect ratio and high transmitted light (for example, Euler circles), but their spatial positioning accuracy is significantly worse than a micrometer.

The tomography is usually done only with "compact" turntables, so these massive rotary stages require a beam path that runs outside the table circle, and this eccentric beam passes above or below (at least outside) the rotation bearing, ie the rotating platform and its rotating platform The eccentric beam guidance has the disadvantage of the distance-dependent increased wobbling effect on the eccentricity at the sample location, due to the influence of the axis wobble of the rotation axis on the eccentricity of the scanning movement at the mounting location of the object, which increases linearly with increasing distance the eccentric beam guide in the case of laminography in addition a durchstrahlbaren sample holder which absorbs radiation and has inhomogeneities, possibly a shading or partial absorption with it leads or a parasitic Str euung the beam caused by the object holder.

An alternative, here centric named beam path, passes through the bearing of the rotation platform. Here are usually durchstrahlbare rotary tables which again cause the problem of artifact formation already described. Particularly in high-resolution studies, the susceptibility to artifacts, caused by a "parasitic" phase contrast, which is caused by irradiated areas of the sample holder or of the sample platforms, is greatly increased, which predicts the source size / radiation divergence must be minimized to achieve the resolution, so that a parasitic phase contrast by scattering on the object holder and subsequent propagation of the wave field is accompanied.

An alternative to this are transmitted light rotation circles. This is true for diffractometers, but there they are designed as Euler circles. However, these commercially available Euler circles have a too high aspect ratio for the laminography and offer Achstaumel and the eccentricity insufficient positioning accuracy for the microlaminography. The problem is that on the one hand the transmitted light through the rotary table is not big enough and on the other hand the precision at the sample location is not sufficient.

An object of the invention is to work out a conceptually and technically feasible solution for high-resolution laminography and tomography and similar methods, which basically works without the requirement for a sample holder to be irradiated as well as without eccentric beam path and in their technical realization also a high object positioning accuracy or at least a high reproducibility of the object positioning and, because of the large transmitted light area (aperture), at the same time ensure the transmittability of the object under possible variable axis inclination. In this case, the source and the detector should be able to remain fixed during the measurement, ie it is preferred during the measurement fixed horizontal, vertical or inclined beam path, as in the case of high-resolution measurements, the object to be examined usually lighter (ie provided with less mass and so that it can be precisely positioned with less mechanical effort) is as the radiation source or the detector. It can be used a tilting axis of rotation. The solution according to the invention is intended both the In principle, avoid the requirement for a sample holder to be irradiated and the eccentric beam path for laminography. Such a technically realized solution is not currently known in laminography.

Another object of the invention is to produce a suitable rotary apparatus having a rotary stage with high object positioning accuracy (at least high reproducibility of object position) and low aspect ratio (height to diameter) and large transmitted light area (aperture) for beam applications in which an object can be examined from different angles of incidence and for all angles of rotation (360 degrees) about the axis of rotation. The rotary table is to overcome the disadvantages of the prior art by the aspect ratio and the transmitted light high tomographic angle (ie, low tilt angle of the axis of rotation of the beam normal) under any directions of arrival and without shading or partial absorption or scattering of the transmitted and / or of the Allow sample diffracted / scattered beam.

Another object of the invention is to allow a lateral positioning of the objects with respect to the axis of rotation.

Another object of the invention is to enable lateral scanning of macroscopic objects.

Another object of the invention is the possibility of using the rotary table both for laminography with transmitted light and for conventional computer tomography, ie without the use of Durchl ichtes, but aligned with the axis of rotation perpendicular to the beam direction.

It is noteworthy that the best way to do this is to include contrasting mechanisms (eg, phase contrast) for image acquisition without limitation. Another object of the invention is to allow beam optics in the instrumental setup to increase the spatial resolution or to use additional contrast mechanisms.

The objects according to the invention are achieved by means of a rotation apparatus with a rotation platform for laminographic investigations by means of radiation, the rotation platform having a recess which is arranged around the axis of rotation and on which a rotation support for the objects to be examined can be arranged.

This conceptually describes a technical solution which allows the required accuracies and the transmittability of the sample with a large transmitted-light range. The rotation apparatus with the rotation platform overcomes the disadvantages of the prior art by the aspect ratio and transmitted light for relevant tilt angles of the rotation axis with respect to the incident beam for all rotation angles (360 degrees) of the table without shading or partial absorption / scattering of the radiation of the transmitted and / or the diffracted beam allow. This solution according to the invention can be extended to all beam applications (for example laser and neutron radiation) with comparable requirements for transmitted light, thus also using focused, divergent, convergent or parallel radiation. The sample axis may or may not be tilted, so the setup can be used for both computed tomography and laminography. In addition, it may be advantageous to tilt the optical axis to adjust the tomographic angle, after which it remains fixed during the scan (i.e., during the scan).

The recess arranged around the axis of rotation can have any desired configuration. So it can be a continuous circular (cylindrical) or

act (cone-shaped) opening. Likewise, however, other arbitrary (eg with polygonal / polyedral cross section) forms are possible. So penetrate the X-rays unhindered without suffering absorption, refraction or scattering, the rotation platform.

For the rapid change of the object to be examined, it may be desirable to provide a holder for the objects. Uniform objects can thus be interchanged and scanned in series

The holder for the different objects is used for attachment of the object and with respect to the lateral positioning of the region to be examined of the object respect. the axis of rotation are positioned. It is preferably designed as an X-Y positioning unit with two linearly independent translation directions, which are preferably both aligned perpendicular to the axis of rotation (and i.A. are aligned perpendicular to each other). Translation unit is to be understood as a device for positioning the object to be scanned perpendicular to the axis of rotation. It is important to ensure the lowest possible height, so that the beam path is not shadowed at different tomographic angles by the translation unit. The implemented X-Y positioning unit further enables the possibility of lateral scanning of macroscopic samples. By arranging the X-Y positioning unit, different object areas can be set with the X-Y positioning unit, which rotate around the rotation axis with a high positioning accuracy and are separated from the beams, e.g. X-rays, to be penetrated.

By choosing flat designs in the axial direction of the rotation and the largest possible distances from the axis of the rotary unit results in a low

Aspect ratio. Under aspect ratio is the ratio of the free inner radius of the rotation bearing to the height of the rotation bearing, in both cases including this

Pick-up, optional mechanical reinforcements, and possibly shading attachments, e.g. measured the X-Y positioning unit to understand.

The mechanically adjustable frame of the XY positioning unit can additionally magnetically fixed to the rotation table. Thus, a transilluminable and on the rotation table arbitrarily positionable sample container, which can either be positioned on one on the rotation platform XY positioning and rasterized in position or can be positioned for example via an external positioning robot on the rotation platform. The fixation of the sample holder can be done mechanically or magnetically or in any other way.

According to the invention, radiations emitted by the objects to be examined can also be used. This is for example in the event that radioisotopes are used.

Also, any electromagnetic radiation (e.g., in the terahertz range, infrared, ultraviolet, or visible light, x-ray or gamma radiation) or particle radiation (e.g., neutrons, electrons, ions) may be considered.

This arrangement results in a large aperture and a low aspect ratio. The mechanically adjustable frame of the x-y positioning unit can additionally be magnetically fixed to the rotation platform.

In general, a lateral positioning with respect to the axis of rotation is helpful, if not always the same regions are to be scanned on the objects to be examined. The positioning itself can be achieved by an at least two-dimensional X-Y positioning (X and Y spans a coordinate system perpendicular to the axis of rotation), e. implemented by two crosses (i.a., th e s right to one another) and translation tables. This X-Y positioning unit can

1. be either attached to the rotation platform and rotate with the object 2. or attached to the static (ie non-rotating) part of the rotation table and coupled to the object or its support during positioning 3. or be arranged anywhere in the room and also coupled to the object or its holder during the positioning process

In cases 2 and 3, the object or its holder may be better

Fixation can be attached to the rotation axis on the rotation platform in any manner, e.g. by magnetic force, electrostatic force or by

Vacuum between two contact surfaces. This force may be designed to be switchable, e.g. through an electromagnet, so that the force for positioning

(Overcoming the static friction force) can be minimized by switching off the fixing force. The positioning itself may be slidable (e.g., on a fluid bearing or friction reducing contact surfaces or guides) or rolling (ball or

Roller bearings) on the rotation platform.

The possibility of free lateral object positioning further allows the lateral scanning of the object by means of the radiographic / laminographic / tomographic scanning method. Using computer-aided image analysis, the frames of each scan can then be assembled into a larger image containing the scanned area.

For this purpose, a holder for the objects to be examined can be arranged on the rotation platform, which rotates with the table about the axis of rotation. The aspect ratio of the axle bearings is such that the greatest possible variability of the tomographic angle or axial tilt angle is given with the largest possible radiation cross section for the scan

The object to be examined can be positioned laterally with respect to the axis of rotation, for example by means of an XY positioning unit, which has two linearly independent, preferably mutually perpendicular, translating devices. Thus, a radiographable and on the rotation platform arbitrarily positionable sample holder, which can either be positioned on an attached on the rotation platform xy positioning and scanned in position or just as an external positioning robot can be positioned on the rotation table. The fixation of the sample holder can mechanically or magnetically or in any other way. For example, electromagnetically or by vacuum.

The rotor of the rotation platform or the holder may have an X-Y positioning unit for lateral object positioning with respect to the axis of rotation. The holder may be fixed to the stator by means of a dockable positioning unit on the stator, i. Mounted on the fixed part of the rotation platform or positioned laterally with respect to the axis of rotation by means of a positioning robot and in any manner (e.g., magnetic, electrostatic or vacuum) on the rotor, i. be fixed to the rotation platform of the rotary table. With the holder, different object areas can be set, which can be positioned with respect to the axis of rotation and are penetrated by the radiation, so that object areas are scanned laterally and assembled by means of computer-aided image analysis.

On the whole, the positioning or grid unit and sample holder offer the functionality of positioning and scanning macroscopic areas of the sample with microscopic accuracy. Successively, various object areas are scanned and reassembled using computer-aided image analysis. The tilt angle of the rotation axis of the rotation platform is variably adjusted via a mechanical tilting technique. In this case, the X-ray source and the detector are immovably arranged, allowing a high positioning and repeat accuracy of the measurements. That is, the optical axis of the radiation source to the detector can be oriented at an angle to each other, but need not be arranged to be movable. The radiation is transmitted from a radiation source to a detector unit (detector and, for example, associated optical elements such as monochromators, filters, mirrors, focusing elements such as Fresnel zone plates or KB mirror systems, collimators). For phase contrast laminography different sections between object and detector are adjustable. Different contrast mechanisms (eg absorption, anomalous absorption, phase contrast, diffraction, scattering, Fluorescence) are used.

The high spatial precision of the axis of rotation is realized by the use of one or more fluid bearings (e.g., based on known geometries, e.g., H or dome cross section) in the rotary platform, thereby achieving high positioning accuracies and reproducibility in the range of 1 μm and below. As the fluid gases (such as air, nitrogen or argon) or liquids (such as oils, water, liquid metals or alcohols) come into consideration.

A precise positioning of the sample is not absolutely necessary, as long as their area to be examined remains in the field of view of the detector during the rotation. Rather, attention must be paid to a precise positioning of the rotation and tilt axes and a high accuracy of the axes during rotation. The tilt angle may preferably be adjusted by a parallel kinematic mechanism (e.g., commercial tripods or hexapods) on which the rotary stage is supported. In contrast to the serial kinematics, all actuators in parallel kinematics act directly on the same moving platform. This has the following advantages: lower mass inertia, no moving cables, low center of gravity, no accommodation of guide errors and more compact design.

The tilt angle can also be adjusted by a serial kinematics. In contrast to parallel kinematics, each actuator has its own positioning platform. There is a clear actuator / axis assignment.

In order to measure the angular deviations of the axis of rotation from the ideal, lasers may preferably be installed in the rotation platform. The laser beams generated herewith are preferably not perpendicular to the axis of rotation but are inclined away at an angle greater than 90 °, so that the beams fan out. At a relatively large distance, detectors for the localization of the laser beams are preferably permanently installed, of which one knows the spatial coordinates relative to the origin of the axis of rotation. Thus, an accurate measurement of the tilt axis of the rotation platform is possible during the experiment. moreover the tumbling of the rotation axis can be accurately determined as it rotates. These measurement results can then be taken into account as correction data in the computer evaluation, which in turn improves the achievable resolution.

In the following embodiments, the invention will be explained in more detail with reference to the accompanying drawings.

Fig. 1 a shows the basic structure for tomography. Fig. 1 b shows the basic structure for laminography with a compact

Rotation table and eccentric beam path.

Fig. 2 shows the structure of the rotary apparatus according to the invention together

Achsneigevorrichtung and Objektpositioniereinheit.

Fig. 3 shows integrated lasers in the rotary table for determining the position of the axis of rotation.

Fig. 4 shows the structure of Figure 3 in the plan

FIG. 5 shows embodiments of the rotation platform according to the invention in FIG

Cut along the axis of rotation.

Fig. 5a shows schematically the use of the rotary table with the object positioned outside the rotation bearing, Fig. 5b with the object positioned inside the rotation bearing for expanding the usable area of the laminography angle θ.

In the exemplary embodiments, the beam path in laminographic investigations is explained with reference to FIGS. 1 and 2. From the X-ray source 1, the X-ray beam impinges on the object 2 to be examined via optical elements 20, such as monochromators 1a, filters or focusing optics. The object 2 is fixed on the rotation platform 4 with the axis inclination unit 8 and is rotated stepwise about the rotation axis 10. The angle between the axis of rotation 10 and the beam axis of the X-ray beam 11 is referred to as tomographic angle 15. After the X-rays have penetrated the object 2, hit these are applied to the detector 3. In the example according to FIG. 2, optical elements 21 (eg focusing X-ray optics, analyzers, filters) are arranged between the object 2 and the detector 3. In this case, the intensity of the X-rays arriving at the detector 3 is measured in a two-dimensionally resolved manner. As it passes through the object, it indicates the modality of the local intensity distribution. For example, the detector 3 may consist of many small segments (pixels), so that a two-dimensional image can be recorded digitally with a high spatial resolution. In order to achieve a high spatial resolution in the reconstruction of the images, it must be ensured that the individual volume elements of the object 2 lie as possible on an exact circular path about the axis of rotation 10. In addition to the Verh derder vibration of the measurement setup and the Min in ization of temperature fluctuations in the experimental environment so very high demands are placed on the positioning and repeatability of the mechanical components, in particular on the rotation platform. If this precision is worse than the optical resolution of the system, and if the inaccuracies can not be measured and numerically corrected, blurred and artifacts will result in the reconstructed image.

The rotary platform 4 shown in Fig. 2 has a hole 5 in its center. Through this hole, the X-rays can penetrate the rotation table without suffering additional weakening or distraction. The size of this recess measures 110 mm in diameter in the given embodiment. The total positioning error of the rotary platform 4 at the sample location is between 0 ° and 45 ° for different tilt angles 9 and less than 0.5 micrometers for maximum object masses of 1.5 kg. These requirements require a very accurate storage of the rotation platform. This is achieved by means of air bearing 7. Since at the same time a large area for the transmitted light is desired, a compatible axis-tilting unit 8 must be used. On the one hand, the axle tilting unit 8 must not hinder the beam path, but on the other hand, it must simultaneously meet high accuracy requirements. With the help of a three-armed Construction, both the height of the rotation platform 4 and the tilt angle 9 can be adjusted without the beam path is obstructed. For example, in beam applications with an optical axis inclined only horizontally or at a fixed angle, an object can be examined from many different directions of incidence. An inclination of the axis of rotation 10 between 20 and 45 degrees with respect to the beam axis 11 thus achieves beam cross sections of a maximum of 4 × 4 mm ² , without the occurrence of a stray beam approach. Be i Achsneigungswinkel of 29 to 45 degrees with respect to the beam axis 1 1, even beam cross-sections of a maximum of 15x1 5 mm ² without Strahlabschattung beam guidance through the transmitted light can be realized. As Achsneigeeinheit 8 a commercial parallel kinematics (eg SpaceFAB design of the company Micos GmbH, Eschbach) is used in this embodiment. With its three articulated arms so all necessary height settings and tilt angle 9 are set. The Achsneigeeinheit 8 is mounted on a granite stone, whereby a high thermal and mechanical stability is achieved. By the method of only one axis (articulated arm) for the adjustment of the tilt angle 9 also a maximum of repeatability is achieved. The maximum specimen mass is at angles 9 from 20 degrees to 60 degrees at least 1, 5 kg.

The rotation platform 4 is connected by means of solid joints / needle bearings 16 with the Achsneigeeinheit 8. The air bearing 7 is designed as H-type or alternatively as a dome and is made of stainless steel or a high-strength aluminum alloy with subsequent hard anodized surface. The rotary drive is achieved by means of a transverse force-compensated belt drive with a permanently mounted U-turn and variable drive unit with a belt reduction factor of 8: 1. The drive unit is designed for a DC motor or stepper motor, optionally equipped with backlash-free gearbox. The rotation platform 4 is also equipped with a high resolution angle measuring system.

The XY positioning unit 6 is used to hold the samples and is by means of a magnetically biased, air- or slide-mounted sample support frame 12 with lateral guide surfaces on the stator (ie fixed to the fixed part of the rotation platform 4. For rapid assembly of samples, standard interchangeable frames can also be used here, whereby sample dimensions of up to about 150 mm * 150 mm * 5 mm can be handled well The rotation axis magnetically coupled sample support frame 12 allows the positioning of each lateral position of the samples by means of retractable, that is not in contact with the rotation, linear axes The translation axes are attached to the starter, ie the fixed part of the rotation platform and touch during the scan (rotation) The object or its support frame is moved up to the support frame (in the case of the rotation platform), coupled (in the previ - ous case magnetically), and then the support frame together with the support frame By supplying compressed air through the on two side When the slide can be coupled, the sample support frame 12 can be moved floating on an air cushion or on a material with a low coefficient of sliding friction with respect to the rotation platform (eg sliding on Teflon rings), without any friction, in two travel axes from the center. The two lateral guide or coupling slides are designed as magnetically preloaded air bearings.

In a second embodiment will be explained in more detail with reference to Figures 3 and 4, the integrated laser in the rotation platform for determining the position of the axis of rotation.

For this purpose, six laser 13 are fixedly mounted on the rotation platform 4. The laser beams are not perpendicular to the axis of rotation, but inclined, so that the laser beams fan out. In a relatively large distance, eight laser detectors 14 are permanently installed for the location of the laser beams, of which one knows the spatial coordinates relative to the origin of the axis of rotation.

When rotating the rotation platform 4 then always hit two of the six laser beams on two of the eight installed laser detectors 14. From this it is possible to tilt the theoretical rotation axis to the real axis of rotation 10 to calculate. At 50 microns spatial resolution of the laser detector 14 and a distance of 2 meters from the laser detector 14 to the laser in the rotation platform 4, a correspondingly high angular resolution of aresin (50 microns / 2 m) is achieved. Since two points are always detected by opposite laser beams, a difference determination can be performed, which increases the accuracy. Upon rotation of the rotary platform 4 meet at different times, alternately, always with 60 degrees difference, two laser beams on the arranged at 45 degrees laser detectors 14. That is, one has 3 * 4 = 12 values per revolution for correction. As a result, at regular angular intervals of 360 °: 12 = 30 ° a target - actual adjustment is possible. By using more than six lasers 13 and more than eight laser detectors 14, correspondingly more angles can be controlled. The laser detectors 14 can be arranged around the rotation platform 4 such that a large angular range of the tilt angle 9 of the rotation platform 4 is covered and the x-ray beam 11 is not disturbed or influenced.

The two embodiments illustrate the technical solution of the task. The rotary table according to the invention operates with high object positioning accuracy and at the same time has a low aspect ratio (overall height to diameter) and the in-out-of-the-box rotation table (ape rtu r) for beam applications. An object can thus be examined from different directions of incidence over a large range of the laminography angle θ and has thus overcome the disadvantages of the prior art.

In FIG. 5, the rotary apparatus with the incorporated rotary bearing 17 and the rotation platform 4 connected therebetween is shown in section. Two

Embodiments are indicated: in Fig. 5a with the object 2 arranged outside the rotation bearing, in Fig. 5b with the object within the same. The former embodiment has the advantage that the object itself may be larger than the inner diameter of the rotation bearing, the latter has the advantage that the laminography angle θ can be extended over the former variant. The

Object 2, which is transilluminated by the beam 11, is located in the region of

Recess 5. The rotation platform 4 covers the inner diameter 19 of the Rotation bearing and carries the object 2 in the recess 5, which allows the beam 11 to pass.

In FIG. 5b, the object 2 is arranged within the rotation bearing in such a way that the achievable laminography angle θ (= theta) is widened. Compared to FIG. 5a, the rotation table is arranged with the object which allows the object to be irradiated at a shallower angle. The angle θ (= theta) of the beam axis of the X-ray beam 11 can be set to a maximum so that it does not touch the rotary bearings 17, that is, no shadowing takes place by the rotary bearings 17. The size t represents the distance of the sectional image of the object to be scanned from the point of intersection of the nearest upper edge 18 of the rotary bearing 17. The relationship between the maximum achievable laminography angle θ (= theta) and the rotational bearing geometry is given by the following formula:

tan θ = R / (H-t)

Here, H is the inner height of the rotary bearing 17 at the free inner radius R (= half of the free inner diameter 19) of the rotary bearing 17th

LIST OF REFERENCE NUMBERS

1 X-ray source / radiation source

2 Object to be examined / sample 3 X-ray detector

4 rotation platform

5 recess, hole of the rotation platform

6 X-Y positioning unit

7 bearings of the rotation platform 8 Achsneigeeinheit the rotation platform

9 tilt angle alpha of the rotation axis

10 rotation axis 11 optical axis of the X-ray / Strahlhchtung

12 sample support frames

13 lasers

14 Laser detectors 15 Tomographic angle theta = 90 ° - alpha

16 solid-body joint / needle roller bearings

17 rotary bearings

18 upper edge of the rotary bearing

19 Free inner diameter of rotation bearing 20 Optical elements (eg focusing X-ray optics) between source and object

21 Optical elements (eg focusing X-ray optics, filters) between

Object and detector

H height of the rotary bearing with respect to the free inner diameter R radius

Claims

claims:

A rotary apparatus comprising a rotary table with a rotation platform (4) for radiographic, tomographic and laminographic investigations by means of radiation, wherein the rotary platform (4) has a recess (5) which is arranged around the axis of rotation (10).

2. Rotary apparatus according to claim 1, characterized in that the recess (5) is designed such that the radiation (1 1) without any attenuation, scattering or deflection can pass through them.

3. Rotation apparatus according to claim 1, characterized in that on the rotation platform (4) a holder (6) for the objects to be examined (2) may be arranged, which rotates with the table about the rotation axis (10).

4. Rotary apparatus according to one of the preceding claims, characterized in that the aspect ratio of the axle bearings is such that the greatest possible variability of the tomographic angle is given at the largest possible beam cross section for the scan.

5. Rotary apparatus according to one of the preceding claims, characterized in that by the recess (5) from a radiation source (1) starting the radiation (1 1) is transmitted to a detector unit (3).

6. Rotary apparatus according to one of the preceding claims, characterized in that the radiation source (1) generates any electromagnetic radiation or particle radiation.

7. Rotation apparatus according to one of the preceding claims, characterized in that the object to be examined laterally respect. of the Rotation axis can be positioned.

8. Rotation apparatus according to one of the preceding claims, characterized in that the rotor of the rotation platform or the holder (6) with respect to an X-Y positioning unit for lateral object positioning

Has rotational axis.

9. Rotary apparatus according to one of the preceding claims, characterized in that the holder (6) by means of an attachable positioning unit or by means of a positioning robot laterally with respect to

Rotation axis can be positioned and fixed in any way on the rotor of the rotary platform (4).

10. Rotary apparatus according to one of the preceding claims, characterized in that the holder (6) different object areas are adjustable, which can be. With respect to the axis of rotation (10) can be positioned and penetrated by the radiation (11), so that successively an object area laterally scanned and assembled by computer-aided image analysis.

11. Rotation apparatus according to one of the preceding claims, characterized in that the tilt angle (9) of the rotation axis (10) of the rotation platform (4) is variably adjustable via a mechanical tilting technique.

12. Rotary apparatus according to one of the preceding claims, characterized in that the optical axis of the radiation source (1) and detector (3) can be orientable in Win angle, but must not be arranged bewegl I.

13. Rotary apparatus according to one of the preceding claims, characterized in that it comprises at least one fluid bearing (7) for the storage of Has rotational axis.

14. Rotary apparatus according to claim 13, characterized in that the fluid bearing (7) any gases such. Contains air as a fluid or consists of gas.

15. Rotary apparatus according to one of the preceding claims, characterized in that different for the phase contrast laminography

Distances between object (2) and detector (3) are adjustable.

16. Rotary apparatus according to one of the preceding claims, characterized in that between the radiation source (1) and object (2) or between object (2) and detector (3) optical elements are arranged.

17. Rotation apparatus according to claim 16, characterized in that as optical elements monochromators, filters, mirrors, focusing elements are attached.

18. A method for performing radiographic, tomographic and laminographic examination, characterized in that a rotary apparatus with rotary table (4) is used according to one of the preceding claims, wherein by computer-aided evaluation, a three-dimensional representation of the examined objects with high spatial

Resolution and artifact minimization is achieved.

19. The method according to claim 18, characterized in that neither radiation source (1) nor detector (3) are moved during the scanning movement.

20. Use of a rotary apparatus according to one of claims 1 to 17 for radiography, tomography or laminography.

21. Use according to claim 20, characterized in that the radiography at different projection angles is feasible.