DE102007011704A1 - Measuring device for mapping object area with terahertz radiation, has reference object arranged in object area, in which reference object is radiated by reference radiation - Google Patents

Abstract

The measuring device (1) has a reference object (4) arranged in an object area (2), in which the reference object is radiated by a reference radiation. A terahertz receiver unit (8) is provided with multiple terahertz detector unit. A deformation mirror (6) is provided, which has actuators (13). The deformation mirror receives terahertz radiation from the object area and reference radiation coming from the reference object and reflects into a light path guided by terahertz receiver unit. An independent claim is a measurement assembly comprises multiple measuring devices.

Description

The The invention relates to a measuring device for imaging with terahertz radiation, especially for imaging a large volume Object area or over long distances with an object distance of several meters with radiation in the terahertz spectral range.

Under Terahertz radiation becomes electromagnetic radiation in the spectral range between the far infrared and the microwave range. Thus, terahertz radiation is in a frequency band of 30 THz to 300 GHz is enough, which is wavelengths of some Microns to a few millimeters corresponds.

by virtue of low photon energies of the order of magnitude less milli-electron volts acts in contrast to terahertz radiation non-ionizing to X-rays and therefore is harmless to biological tissue. This advantageous Property is particular for the application of terahertz radiation for medical diagnostic purposes and for realization relevant to security and surveillance systems. About that In addition, most dielectric materials are transparent to terahertz radiation, so that clothing, paper, plastic and leather of terahertz radiation can be irradiated. By contrast, metallic objects or generally electrically conductive objects highly reflective for terahertz radiation, so this particularly advantageous for detecting under clothing or weapons hidden in suitcases and thus for surveillance from public areas, such as airports and Stations, can be used.

In addition, due to the aforementioned selective reflection and absorption properties with terahertz radiation, it is possible to be able to detect different materials, for example explosives, through clothing or packaging materials, or to use terahertz radiation for material testing technology and for food and drug technology. An example will be given to the application of terahertz radiation on the pamphlets EP 0 093 566 B1 and the WO 2006/12 91 13 A1 directed.

A Another characteristic of terahertz radiation is its high degree of absorption for water, so that terahertz radiation in a water-containing System and therefore also in the human body only until penetrates to a shallow depth. This sets medical-diagnostic Applications of terahertz radiation limits and limited on near-surface areas, such as for the diagnosis of Caries or skin cancer. In addition, through the water vapor in the air already after a running distance of a few meters a strong performance weakening such that monitoring systems based on terahertz radiation are typical Ranges less than 10 m.

To mitigate the above problem, highly sensitive sensory systems for terahertz radiation are being developed. One of the principles for the detection of terahertz radiation is the use of antenna-coupled bolometers, which, as in the EP 0 903 566 B1 represented, can be assembled into a sensor matrix. Alternatively, as terahertz detector elements heterodyne detectors are used, which, as by the WO 2006/129113 A1 disclosed, can take a larger field of view by successive scanning. Furthermore, it is possible to connect photonic crystals produced by microstructuring for the detection of terahertz radiation by microstructuring with electro-optical components and thus to use the terahertz radiation emitted by a heated object, for example a human, without further illumination sources for terahertz imaging , Further, for a terahertz camera, the disclosure of the WO 2004/038854 directed.

For imaging in the terahertz spectral range is usually the area in which the object to be examined is lit by a terahertz radiation source. Terahertz radiation can be generated according to different principles. The simplest is a thermal generation by black body radiation or gas discharge lamps, preferably connected to a spectral filtering. However, terahertz radiation can also be generated electronically, for example by semiconductor oscillators with subsequent frequency multiplication or by superconducting Josephson oscillators or by means of quantum cascade lasers, as described, for example, by US Pat US 2006/0153262 A1 and the US 2005/0058166 A1 be revealed. Alternatively, by irradiation of an electrically biased semiconductor with a short laser pulse by the release of charge carriers and their acceleration in the electric field terahertz radiation can be emitted. The generated radiation pulses correspond to a terahertz spectrum in the frequency range, wherein the radiation produced is coherent by coupling to the phase of the exciting laser pulse. However, the generated terahertz radiation pulses have a broadband frequency spectrum in the range of 10 GHz to 50 THz. For such a terahertz radiation source is exemplified on the US 5729017 directed. Another possibility for generating terahertz radiation is the use of two mutually frequency-tuned laser, wherein the difference frequency radiation components in the Has terahertz range.

Of the Invention has for its object to provide a measuring device used to image an object area using terahertz radiation this particular for monitoring of larger outdoor areas, such as from Entrance or transit passageways in public buildings or from platforms, or to carry out a testing task should be suitable in a production line. Furthermore, should the measuring device over a distance of preferably several meters a diffraction limited resolution for achieve the imaging, so for example in the case of a monitoring task a detection of hidden objects, in particular of Hazardous substances, weapons, explosives and A, B and C weapons becomes.

The inventive object is achieved by the features of the independent claim.

The Inventors have recognized that a measuring device for imaging with terahertz radiation, which solves the above problem, a terahertz receiver unit upstream, deformable Mirror should include. This deformable mirror represents one spatially resolving phase modulator, the in conjunction with a wavefront sensor and a reconstruction computer Making corrections to the wavefront in real time, to a diffraction-limited To strive for illustration. Here is the connection between a Point image in the image plane and the assigned phase function in a pupil of the system exploited. Will therefore be the wavefront sensor arranged in a pupil of the measuring device so it is possible by examining a reference object whose wavefront is known (usually an approximately punctiform Object), to detect phase faults at the wavefront sensor, those from statistical fluctuations of the refractive index along the path of the radiation from the reference object to the measuring device arise. These, in turn, become turbulent attributable temporal and spatial Variations in the temperature and the water content of the air causes. In this way, starting from a reference object, by a difference of the actually present Wavefront from the well-known ideal case for compensation the deformed wave necessary correction values determine which is then applied to the deformable mirror become. For this purpose, the deformable mirror is corresponding arranged to the wavefront sensor in a pupil of the measuring device.

The principle of correction of phase aberrations known from applications for astronomy is accordingly transferred to a measuring device for imaging in the terahertz range. For the field of astronomy, a fixed star is usually used as a reference. For the invention, there are two different possibilities for the choice of the reference object, which is located in the imaged object area. According to a first variant, the reference object emits terahertz radiation, wherein it is embodied either as a reflector or as a terahertz radiation source. For a second variant of the invention, the radiation emanating from the reference object differs with respect to its wavelength from the terahertz radiation used for imaging, preferably a reference wavelength in the infrared range and particularly preferably in the region of the water lines of the spectrum, ie the absorption bands for water in the gas state , for example at the wave numbers 1595 cm ^-1 , 3652 cm ^-1 and 3756 cm ^-1 , is used.

For the first variant is used as a reference object, its ideal wavefront is known, preferably a terahertz radiation emitting object, in particular a reflector used, whose expansion is preferred so small enough that his picture is punctiform can be accepted. Advantageously, a reflector with a metallic surface used and this imbildenden Object area positioned so that it is not from a through obscured the object area moving object or a person can be. In addition, its arrangement should be chosen that the radiation emanating from the reflector substantially the same atmosphere as the one to be examined Object traversing outgoing radiation. For this purpose, it is preferred that Reflector in the background of the selected object area to place.

For the second variant, in which the radiated from the reference object Reference radiation, which the wavefront sensor on the deformable mirror is supplied, not the sensitivity range which corresponds to terahertz detector elements is preferred for execution the phase corrections to a reference radiation in the far infrared resorted. This can be done as a reference object again a mirror can be used by a separate radiation source is illuminated to generate the reference radiation.

Although the second variant for the reference radiation leads to the simplification of the formation of the wavefront sensor, no sensory elements sensitive to the terahertz range have to be used for this purpose. In addition, no fraction of the terahertz radiation used to image the object is diverted to the wavefront sensor. A disadvantage of using a reference radiation outside of the Tera Hertz radiation range is the unavoidable statistical error due to uneven optical paths of the terahertz radiation used for imaging and the reference radiation. This error is within the skill of the art with other sources of error, such as the photon noise of the detectors of the wavefront sensor and due to the finite distance of the reflector to the measuring device related focal anisoplanatism to compare and to use a preferred frequency for the reference radiation. In this case, an IR line for water in the gaseous state is selected in particular as the reference frequency, since variations in the water content in the pathway in addition to the non-correctable absorption effects contribute significantly to the aberration of the wavefronts of the terahertz radiation due to statistical differences in the optical path length.

According to one Embodiment of the invention is the natural of the to be examined objects or persons radiated Terahertz radiation is processed by the imaging system, so an illumination of the object area using a terahertz radiation source is not necessary. In this case, the reference object must be for the first variant is designed as a terahertz radiation source, in the simplest case, the generation of radiation will be thermal. For the second variant, the reference object is preferred Generate radiation in the infrared range. This can be a spectrum one or more IR lines, in particular absorption bands of water are preferred. In addition to the above Absorption bands for gaseous water is a wavelength in the range of λ = 1500 nm is preferred. According to a preferred embodiment alternative a broadband or tunable spectrum is again preferred used in the IR range.

Especially preferred is the embodiment of the measuring device with a device for illuminating the object area by means of a terahertz radiation source. Furthermore, advantageously, the components of the measuring device grouped as a unit, in particular the deformable Mirror, the wavefront sensor and the associated control system and the terahertz receiver unit are integrated. The Interior of this unit can then be continuously by means of a Protective gas flushed and air conditioned. For the second variant of the reference radiation is also for the case that a reference radiation source for illuminating a reflective reference object is used, this preferred in the Integrated unit.

Of the Advantage of a summarized as a unit arrangement exists in that for the execution of a measurement only that in the object area arranged reference object, typically a reflector for Terahertz radiation, installed to realize the measuring device must be, so that several of these invention, as building units combined measuring devices to a measuring arrangement can be combined, with each individual Overlap measuring devices associated object areas so that a large volume of space can be examined. Alternatively, you can the measuring device for forming a measuring arrangement certain Angle positions to each other occupy, so for example a Multi-directional observation or tomographic images can be realized.

According to one preferred embodiment of the measuring device is high-energy terahertz radiation in the border region to the infrared, for example, with one wavelength of 10 microns, worked. This is advantageous because on the one hand, the diffraction-limited resolution is high and at the same time availed of the above-mentioned advantages of terahertz radiation can be.

following the invention will be described in more detail with reference to figures, these show in detail the following:

1 schematically represents a measuring device according to the invention.

2 shows the combination of several inventive measuring devices to a measuring arrangement for monitoring larger volumes.

1 shows schematically the structure of the measuring device according to the invention 1 , This includes a terahertz receiver unit 8th , which prefers for imaging a plurality of terahertz detector elements, which are described in detail 1 not shown, has. This receives terahertz radiation from an object to be imaged 3 , being in the beam path between object 3 and terahertz receiver unit 8th at least one deformable mirror 6 is arranged, which has a variety of actuators 13 so that the mirror surface can be adjusted for phase modulation.

Possible embodiments of the deformable mirror 6 include customizable monolithic mirrors, segmented mirrors, membrane mirrors, or micromechanical corrector arrays. For example, a membrane mirror may comprise a thin, highly flexible membrane made of silicon, quartz or mylar, which may additionally comprise a metallic reflection layer for the terahertz radiation. This membrane is powered by associated actuators 13 deformed in accordance with the phase modulation, wherein for Aktuation piezoelectric, mag netostatic or electrostatic forces can be applied. Possible embodiments include bimorph actuators, for example, a piezoceramic, such as lead zirconate titanate (PZT) and a substrate, such as amorphous SiO ₂ , are joined together. This compound can be prepared as an adhesive bond or the piezoceramic is applied via a sol-gel process with subsequent sintering and polarizing step. As a possible embodiment, the actuators can perform an axial or tangential to the support surface extending adjusting movement.

A further preferred embodiment of the deformable mirror comprises individually controllable facet elements, which are carried by a multiplicity of actuators. By controlling the actuators, which in turn preferably comprise an adaptive material and in particular a ferroelectrics, a shape memory alloy or an electrically active polymer, a single mirror facet can be translated nanometer-accurate in three spatial directions and tilted according to the Euler angle. It is also advantageous to use a composite material comprising a passive carrier substrate and an adaptive material for forming the actuators. For possible embodiments of the deformable mirror and the actuators used for the deformation, the monographs " Principles of Adaptive Optics ", Robert K. Tyson, Academic Press Inc., 1991, ISBN 0-12-705900-8 and "A contribution to the investigation of bimorph mirrors for the precision optics", Dr. Timo Richard Möller, Shaker publishing house Aachen, 2002, ISBN 3-8322-0555-1 the disclosure of which is incorporated in full in the present application. Further, the term deformable mirror used in the present application includes any form of phase modulator that can be used to perform phase conjugation for wavefront correction.

The actuating signals for the actuators 13 become the deformable mirror 6 from a control device 10 which signals from the wavefront sensor 9 processed. This wavefront sensor 9 Radiation is supplied to the beam path after the deformable mirror 6 and therefore between the terahertz receiver unit 8th and the deformable mirror 6 is decoupled. This can be done, for example, by means of a partially transparent optical component 7 , such as a polarization beam splitter. In the case of the second variant, in which a reference radiation outside the terahertz spectrum is used, this decoupling is preferably frequency-dependent, so that only the reference radiation is supplied to the wavefront sensor.

The wavefront sensor 9 determined in a pupil of the measuring device 1 the currently present phase front and leads these measurements of the control device 10 in, in which this phase front compared to the stored ideal data. The ideal data is based on the knowledge of a reference object 4 , in the object area 3 is arranged so that the from the reference object 4 radiated reference radiation substantially the same optical path as the object to be measured 3 passed object radiation from the terahertz spectrum. The reference radiation is phase-deformed according to the object radiation through the atmosphere between the object area and the measuring device. In this way it is possible, from the ideal data of the known wavefront for the reference radiation in the control system 10 To calculate correction terms that are phase shifted in real time by 180 ° to the phase modulation on the deformable mirror 6 be switched on. There is thus a phase conjugation. Accordingly, the control of the deformable mirror 6 assigned actuators 13 ,

As wavefront sensor 9 For example, according to the Shack-Hartmann principle, a regular matrix of microlenses of matching refractive index can be provided, wherein each microlens is assigned a sensory element for the given wavelength of the reference radiation. From the lateral deviation of the center of illumination for each of the microlenses from the expected desired position, the average inclination of the wavefront and thus its gradient over the microlens are measured. From this measurement of the subaperture can be calculated back to the wavefront itself, this calculation is usually done via Zernike polynomials or Karhunen-Loeve functions. As an alternative to the Shack or Hartmann sensor, the wavefront can be determined by means of curvature sensors, pyramid sensors or by means of interferometric measurements, the latter assuming sufficient coherence of the reference radiation.

For the measuring device according to the invention 1 There are different design alternatives with regard to the illumination of the object region with a terahertz radiation source and with respect to the design of the reference object used for the wavefront correction:
According to a first preferred embodiment, the object area 2 through a terahertz radiation source 5 illuminated so that the object to be examined 3 according to its characteristic reflection and absorption properties, reflects back a portion of the incident terahertz radiation which is then used for imaging. This arrangement is particularly preferred in view of an object radiation sufficient for imaging. For this design alternative, the reference object is in the simplest case a reflector for Terahertz radiation, that is an object with a metallic surface, so that the reference radiation and the object radiation are both due to the irradiation by the terahertz radiation source 5 arise and thus lie in the matching frequency range. Accordingly, the wavefront sensor becomes 9 For terahertz radiation, that is to say in the case of a wavefront sensor according to the Shack-Hartmann principle, the sensory elements assigned to the individual microlenses will detect the incident terahertz radiation.

According to a refinement instead of a reflector is a reference object 4 which emits reference radiation that is not within the terahertz radiation range used for imaging. For example, for the preferred case of using the 10 μm radiation range for terahertz imaging, reference radiation that is further displaced into the infrared range may be used. The advantage is that the wavefront sensor can be easily formed with respect to its sensory elements. The disadvantage, however, is that additional statistical errors arise due to different optical path lengths of object radiation and reference radiation.

According to a further embodiment of the measuring device according to the invention 1 becomes a terahertz radiation source 5 and instead omits the natural terahertz radiation emitted directly from the object with the aid of a highly sensitive terahertz receiver unit 8th detected. Also in this case, according to the invention, a phase correction is provided by means of a deformable mirror based on data from a wavefront sensor, again using as a reference object a radiation source for terahertz radiation (a thermal element) or a spectrally different reference from the object radiation, for example in the infrared can.

According to a preferred embodiment of the invention, all components of the measuring device 1 with the exception of the reference object 4 as a structural unit 12 in particular, these are the terahertz receiver unit 8th , the deformable mirror 6 , the partially transmissive optical component 7 , the wavefront sensor 9 and the regulatory system 10 , Furthermore, additional refractive optics can be provided for beam guidance and additional system components 11 , such as a power supply or device for data acquisition and data storage for the terahertz receiver unit 8th , If a separate reference radiation source 15 is used, it is preferably in the assembly 12 added. Furthermore, an embodiment is advantageous in which the inner region of the structural unit 12 or that part thereof in which the terahertz radiation and the reference radiation are guided is continuously rinsed by means of a protective gas in order to keep the content of water vapor as low as possible. Furthermore, an air-conditioning or the most uniform possible temperature adjustment, at least in the region of the beam path, leads to a reduction of the wavefront aberrations additionally occurring in the structural unit.

Due to the preferred compact design including all essential components in a structural unit 12 it is possible to have a measuring arrangement with a large number of measuring devices according to the invention 1 train. This can be, for example, a tomographic arrangement for the three-dimensional detection of an object to be examined, for example for testing purposes or for the medical-diagnostic area.

Another advantageous use is in the monitoring of large volumes of space, for example, according to the invention, imaging measuring devices that are installed in a public area. An example of this is in 2 shown. Schematically simplified are three measuring devices according to the invention 1.1 . 1.2 and 1.3 shown, each from the building units 12.1 . 12.2 and 12.3 as well as the assigned reference objects 4.1 . 4.2 and 4.3 which are advantageously reflectors for terahertz radiation. Every single measuring device 1.1 . 1.2 and 1.3 are each the object areas 2.1 . 2.2 and 2.3 assigned. In this case, an object region is determined in each case by the optical properties of the associated measuring device, in particular by the depth of field of focus and the size of the image field and of the area illuminated by the terahertz radiation source.

Advantageously, for a measuring arrangement according to the invention, the object areas of the measuring devices combined with one another overlap, so that, for example, a large-volume room area can be covered for safety monitoring. Exemplary is this in 2 a passage represented by the two walls 21 and 22 is limited and in particular an access area via a staircase 20 is to be monitored. These are the two measuring devices according to the invention 1.1 and 1.2 arranged successively with respect to their associated object areas, while the third measuring device according to the invention 1.3 covers a different line of sight.

By the measuring device according to the invention, it is possible to record images of an object in the spectral range of terahertz radiation with a diffraction-limited resolution, so that even over a sufficient distance high-resolution images arise. Here it is due to the pre The compact compact package comprising the components for receiving the terahertz radiation, for the phase correction and possibly for the terahertz radiation source, makes it possible to use a multiplicity of such measuring devices according to the invention to design a measuring arrangement with which a large-volume spatial area is monitored by means of terahertz imaging can. Furthermore, monitoring from different spatial directions is possible, with a corresponding arrangement of the measuring devices a 3-dimensional evaluation of the image data is possible.

1, 1.1, 1.2, 1.3

measuring device

2, 2.1, 2.2 2.3

Property area

3

object

4, 4.1, 4.2, 4.3

reference object

5

Terahertz radiation source

6

deformable mirror

7

partially transparent optical component

8th

Terahertz receiver unit

9

Wavefront sensor

10

control system

11

system components

12 12.1, 12.2, 12.3

unit

13

actuators

15

Reference radiation source

20

stairway

21 22

walls

100

measuring arrangement

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 0093566 B1 [0004]
• WO 2006/129113 A1 [0004, 0006]
• EP 0903566 B1 [0006]
• WO 2004/038854 [0006]
• US 2006/0153262 A1 [0007]
• US 2005/0058166 A1 [0007]
• US 5729017 [0007]

Cited non-patent literature

• - Principles of Adaptive Optics ", Robert K. Tyson, Academic Press Inc., 1991, ISBN 0-12-705900-8 [0024]
• - "A contribution to the investigation of bimorph mirrors for the precision optics", Dr. Timo Richard Möller, Shaker publishing house Aachen, 2002, ISBN 3-8322-0555-1 [0024]

Claims (20)

Measuring device ( 1 ) for mapping an object area ( 2 ) with terahertz radiation, comprising 1.1 in the object area ( 2 ) arranged reference object ( 4 ) which emits reference radiation; 1.2 a terahertz receiver unit ( 8th ) having a plurality of terahertz detector elements; 1.3 a deformable mirror ( 6 ) with actuators ( 13 ), the terahertz radiation from the object area ( 2 ) and the reference object ( 4 ) receives incoming reference radiation and into a terahertz receiver unit ( 8th ) leading beam path is reflected; 1.4 a partially transmissive optical component ( 7 ) in the terahertz receiver unit ( 8th ) leading beam path to the deformable mirror ( 6 ) and which at least part of the reference radiation to a wavefront sensor ( 9 reflected); 1.5 a regulatory system ( 10 ), the measurement data from the wavefront sensor ( 9 ) and from this control signals for the actuators ( 13 ) of the deformable mirror ( 6 ) to perform a wavefront correction. Measuring device ( 1 ) according to claim 1, characterized in that the measuring device ( 1 ) further comprises a terahertz radiation source ( 5 ), the terahertz radiation in the object area ( 2 ) emitted. Measuring device ( 1 ) according to claim 2, characterized in that the reference object ( 4 ) is a reflector for terahertz radiation. Measuring device ( 1 ) according to one of claims 1 or 2, characterized in that the reference object ( 4 ) is a terahertz radiation source. Measuring device ( 1 ) according to at least one of claims 1 or 2, characterized in that from the reference object ( 4 ) is emitted a reference radiation having a wavelength outside the terahertz spectrum and the partially transmitting optical component ( 7 ) substantially the reference radiation to the wavefront sensor ( 9 ) reflected. Measuring device ( 1 ) according to claim 5, characterized in that as reference radiation Absorbtionsbande is selected for gaseous water. Measuring device ( 1 ) according to claim 5, characterized in that a water line in the IR spectrum and particularly preferably a wavelength of λ = 1500 nm is selected for the reference radiation. Measuring device ( 1 ) according to claim 5, characterized in that as reference radiation, a broadband or tunable IR spectrum is selected. Measuring device ( 1 ) according to at least one of claims 5-8, characterized in that the reference object ( 4 ) is designed as a reflector and from a reference radiation source ( 15 ) is illuminated with radiation outside the terahertz spectrum. Measuring device ( 1 ) according to at least one of claims 2-9, characterized in that the terahertz radiation source ( 5 ), the terahertz receiver unit ( 8th ), the deformable mirror ( 6 ), the partially transmissive optical component ( 7 ) and the wavefront sensor ( 9 ) Part of a structural unit ( 12 ) are. Measuring device ( 1 ) according to claim 10, characterized in that at least the radiation-carrying areas of the structural unit ( 12 ) are rinsed with a protective gas for the elimination of water and / or at least there is provided a temperature for homogenizing the temperature distribution. Measuring device ( 1 ) according to at least one of claims 1-11, characterized in that the image is carried out with terahertz radiation in the spectral range around 10 microns. Measuring device ( 1 ) according to at least one of claims 1-12, characterized in that the deformable mirror ( 6 ) is designed as an adaptable monolithic mirror, segmented mirror or membrane mirror or comprises an arrangement of micromechanical correctors. Measuring device ( 1 ) according to at least one of claims 1-13, characterized in that it comprises mirror elements comprising a composite material of a passive carrier substrate and an adaptive material, in particular a ferroelectrics, a magnetostrictive or an electrostrictive material, a shape memory alloy or an electrically active polymer , Measuring device ( 1 ) according to at least one of claims 1-14, characterized in that the reference object ( 4 ) is chosen so small that it is approximately punctiform imaged. Measuring device ( 1 ) according to at least one of claims 1-15, characterized in that the reference object ( 4 ) in the background of the object area ( 2 ) is arranged. Measuring arrangement ( 100 ) comprising a plurality of measuring devices ( 1.1 . 1.2 . 1.3 ) according to any one of the preceding claims. Measuring arrangement ( 100 ) according to claim 17, characterized in that the object areas ( 2.1 . 2.1 . 2.3 ) of the individual measuring devices ( 1.2 . 1.2 . 1.3 ) adjoin one another or partially overlap one another. Measuring arrangement ( 100 ) according to one of claims 17 or 18, characterized in that the measuring arrangement ( 100 ) a common object area is assigned and the individual measuring devices ( 1.1 . 1.2 . 1.3 ) Map parts of the common object area from different directions. Measuring arrangement ( 100 ) according to claim 19, characterized in that a 3-dimensional image is executed.