Emitter macro-pixel for terahertz radiation, and transceiver unit for a corresponding imaging device

Abstract

The invention relates to an emitter macro-pixel (1) for a transmission unit (2) of an imaging device (3), comprising a plurality of emitter sub-pixels (4) designed to emit electromagnetic terahertz radiation, the emitter sub-pixels (4) being arranged on a wall (6) of the emitter macro-pixel (1) in such a way that the terahertz radiation can be emitted along the surface normal of the wall (6), and the terahertz radiation emitted by the emitter sub-pixels (4) being modulated in such a way that the emitter sub-pixels (4) each emit terahertz radiation which is incoherent in relation to that emitted by the other sub-pixels. In this way, an improved resolution in terahertz imaging is provided.

Description

[0001] EMITTER MACROPIXEL FOR TERAHERTZ RADIATION AND TRANSMITTER AND RECEIVE UNIT FOR A CORRESPONDING IMAGE DEVICE

[0002] The invention relates to an emitter macropixel for a transmitter unit of an imaging device, comprising a plurality of emitter subpixels designed to emit electromagnetic terahertz radiation. The invention further relates to a transmitter unit, the use of a receiver unit, an imaging device, and a method for operating the imaging device.

[0003] There are two fundamentally different approaches to obtaining 3D information from an imaging object. The first approach involves illuminating the object with a coherent electromagnetic wave and quantifying the phase or time change of the wavefront to obtain depth information. Microwave radar and laser holography are examples of this technique. The second approach to 3D imaging is based on light field tracking. Here, the light entering and exiting the object is considered a vector field of beams, which is quantified based on the energy density along a specific direction and position in 3D space. If the position and direction of flow of the individual light beams are known, a 3D volume of the field perturbation can be reconstructed by backpropagation.

[0004] There are various imaging techniques that, based on these approaches, make it possible to visualize a tissue object in depth for diagnostic or analytical purposes. These include techniques such as X-rays, computed tomography (CT), and magnetic resonance imaging (MRI). Computed tomography and X-rays, in particular, use X-ray sources and thus short-wave electromagnetic radiation, which, due to the interaction of this short-wave radiation, has the potential to damage tissue.

[0005] One way to circumvent this tissue-damaging effect and still enable a 3D image of the object under investigation in depth is the use of long-wave electromagnetic radiation. One such long-wave radiation is terahertz radiation. With terahertz radiation, it is possible to image the interior of objects that are opaque to electromagnetic radiation in the visible spectrum. This allows terahertz radiation to be used in quality control and even in diagnostics without posing a risk to humans.

[0006] A problem with terahertz radiation, however, is that the long wavelength in the terahertz range generally results in insufficient resolution for generating 2D and 3D images. Therefore, images produced with so-called terahertz imaging devices are always of low resolution. In 3D imaging, however, it is desirable to continuously generate new images at new depths within the object being studied. This means that the number of pixels required for a 3D image is many times higher.

[0007] Based on this, the object of the present invention is to provide improved resolution in terahertz imaging.

[0008] This problem is solved by the subject matter of the independent claims. Preferred embodiments of the invention are described in the dependent claims.

[0009] According to the invention, an emitter macropixel for a transmitting unit of an imaging device is provided with a plurality of emitter subpixels designed to emit electromagnetic terahertz radiation, wherein the emitter subpixels are arranged on a wall of the emitter macropixel so that the terahertz radiation can be emitted along the surface normal of the wall, and the terahertz radiation emitted by the emitter subpixels is modulated such that the emitter subpixels each emit terahertz radiation that is incoherent to each other.

[0010] The emitter subpixels are preferably configured as a matrix on the wall of the emitter macropixel. According to the invention, each emitter subpixel emits terahertz radiation that differs from the terahertz radiation of other emitter subpixels. In this case, the emitter subpixels are configured to emit differently modulated terahertz radiation. The emitter subpixels themselves are thus configured, for example, to emit terahertz radiation at different frequencies in response to a given input or trigger, and / or to emit phase-shifted terahertz radiation. This enables them to emit terahertz radiation at different frequencies, e.g., different chopping frequencies, or phase-shifted relative to each other, depending on the input. For this purpose, the emitter subpixels can, for example,be connected to an electronic interface that includes a control unit and specifies modulation types.

[0011] The essential aspect of the invention is that the modulation of the terahertz radiation of each emitter subpixel introduces an incoherence that enables the unambiguous identification of the terahertz radiation emitted by each subpixel. Through the interaction of the number of emitter subpixels and the identifiability provided by this incoherence, the resolution of the emitter macropixel according to the invention is increased many times over relative to the actual number of emitter subpixels. The number of effectively usable pixels or voxels in 3D imaging is thus increased. In contrast to the otherwise linear scalability of imaging devices with the number of pixels used, the inventive approach achieves a significant increase in the achievable resolution in terahertz imaging.

[0012] In principle, it is possible to design the emitter macropixel in various ways. However, according to a preferred embodiment of the invention, the emitter macropixel is formed with a housing, wherein the majority of emitter subpixels are arranged on the wall of the housing of the emitter macropixel, and an aperture is formed on a side of the housing opposite the emitter subpixels along an aperture axis, so that the terahertz radiation emitted by the emitter subpixels passes through the aperture of the housing with an angular dependence determined by the lateral distance of the emitter subpixel from the aperture axis.

[0013] The aperture is initially designed as an opening in the housing of the emitter macropixel, analogous to a pinhole aperture. In any case, the aperture is arranged along the aperture axis within the housing, which extends centrally through the aperture. With respect to the aperture axis, the emitter subpixels are positioned on the wall such that the lateral distance of each emitter subpixel from the aperture axis ensures that an angle-dependent fraction of the emitted terahertz radiation from each emitter subpixel passes through the aperture. The emitter macropixel itself thus functions in this case as a pinhole aperture or a pinhole camera.

[0014] The angular dependence introduced by the aperture causes the emitter macropixel to emit different angular components of the terahertz radiation emitted by each emitter subpixel. This allows the creation of an incoherent light field space that is specifically directed at detector subpixels of a receiver. The arrangement of the emitter subpixels relative to the aperture axis introduces angular diversity, which increases the resolution. Here, angular diversity specifically refers to the use of emitter subpixels with different angle-dependent emission directions of the emitter macropixel itself, determined by the aperture. The aperture radiates the terahertz radiation in different directions, with each emitted direction being identifiable via modulation.

[0015] The aperture can be designed in various ways. However, according to a preferred embodiment of the invention, a lens is arranged in the aperture of the emitter macropixel housing. The lens serves two purposes: firstly, it seals the housing, and secondly, it can be used to focus, defocus, and align the emitted terahertz radiation.

[0016] In principle, it is possible to modulate the emitted terahertz radiation with the emitter subpixels in various ways. However, according to a preferred embodiment of the invention, the terahertz radiation emitted by each emitter subpixel is modulated in a chopping frequency and / or phase. In this context, the chopping frequency is the frequency at which the emitter subpixels emit the terahertz radiation. Just as with the chopping frequency, a change in the phase of the emitted terahertz radiation relative to the phases of the radiation emitted by the other emitter subpixels also ensures improved identifiability of the individual emitter subpixels. In this context, a lowest chopping frequency according to a preferred embodiment of the invention is at least 25 Hz.With regard to the incoherence caused by the modulated phase, it is particularly preferred that the phase of the emitted terahertz radiation changes continuously in order to prevent a constant phase between the emitter subpixels from developing, which could lead to coherence of the emitted terahertz radiation, at least section by section.

[0017] According to a preferred embodiment of the invention, 64 emitter subpixels are arranged in each emitter macropixel. In this context, according to a further preferred embodiment of the invention, the emitter subpixels are arranged in a square matrix on the wall of the housing opposite the aperture.

[0018] The invention also relates to a transmitting unit with a plurality of emitter macropixels as described above, wherein the emitter subpixels of all emitter macropixels each emit mutually incoherent terahertz radiation, so that an incoherent light field space is formed with the emitter macropixels.

[0019] The resolution achievable with the present transmitter unit scales with the number of emitter macropixels used. The emitter macropixels provide the spatial diversity of the transmitter unit. Combining this spatial diversity with angular diversity and the modulation of the emitted terahertz radiation enables even higher resolution.

[0020] In principle, the emitter macropixels can be arranged in various ways. However, according to a preferred embodiment of the invention, the emitter macropixels are arranged side by side with aperture axes parallel to each other, so that the apertures of the emitter macropixels have the same orientation. The emitter macropixels can, for example, be arranged in a line. According to a particularly preferred embodiment of the invention, however, the emitter macropixels are arranged in a plane. This forms a source plane with the emitter macropixels, which enables an extended incoherent light field space, so that larger objects can be introduced into the incoherent light field space. The invention further relates to the use of a receiving unit for an imaging device for detecting the incoherent light field space formed by the transmitting unit described above.

[0021] The invention further relates to an imaging device with a transmitting unit as described above and a receiving unit, wherein the receiving unit has a plurality of detector macropixels, each detector macropixel of the receiving unit has a housing, wherein a plurality of detector subpixels for detecting the terahertz radiation are arranged on a wall of the housing, an aperture is formed on a side of the housing opposite the detector subpixels along an aperture axis, so that the terahertz radiation is detected with an angular dependence given by the lateral distance of the respective detector subpixel from the aperture axis, the detector macropixels are arranged next to each other with aperture axes parallel to each other, so that the apertures of the detector macropixels have the same orientation, and the apertures of the receiving unit face the apertures of the transmitting unit.The detector macropixels are preferably arranged in the form of a detector plane opposite a corresponding source plane of the emitter macropixels.

[0022] Emitter and detector subpixels are combined into a multiple-input multiple-output (MIMO) imaging device. This utilizes the availability of the incoherent light field at both the emitter and detector subpixels, along with the modulation of the individual emitter subpixels. This increases the effective number of usable pixels, enabling a large field of view and higher resolution. The effective number of pixels corresponds to the number of pixels that constitutes the final resolution and, in this case, exceeds the physical number of pixels.

[0023] In principle, the transmitting and receiving units can be aligned in various ways. However, according to a preferred embodiment, the apertures of the emitter macropixels and emitter subpixels, as well as the apertures of the detector macropixels and detector subpixels, are arranged in corresponding positions. They are thus arranged to achieve high resolution by capturing as much of the terahertz radiation emitted by the emitter subpixels as possible, exploiting the incoherence with the respective detector subpixels. Preferably, each detector subpixel has a square matrix with 1064 detector subpixels.

[0024] In this context, it is particularly advantageous that the apertures of the emitter macropixels and emitter subpixels, as well as the apertures of the detector macropixels and detector subpixels, are arranged in corresponding positions such that the terahertz radiation emitted by each emitter subpixel can be detected by each detector subpixel. The apertures are thus configured so that, under the angular dependence determined by the aperture, the terahertz radiation of each emitter subpixel of each macropixel of the transmitting unit reaches each detector subpixel. Each individual detector subpixel is therefore illuminated simultaneously by all emitter subpixels. Due to the modulated terahertz radiation, the contributions received by the detector from each emitter subpixel can be identified. Each individual emitter subpixel is thus influenced in such a way that each individual detector subpixel can identify or separate all emitter subpixels.

[0025] The number of effectively usable pixels or voxels in this case is so high that, with a transmitting unit consisting of three emitter macropixels, each with 64 emitter subpixels, and a receiving unit consisting of three detector macropixels, each with 1024 detector subpixels, a total effective pixel count of 589,824 pixels is available. This corresponds to a 2D resolution of 768 x 768 pixels and a 3D resolution of 83 x 83 x 83 voxels. The resulting number of pixels is therefore the product of the number of detector subpixels and the number of emitter subpixels.

[0026] The emitter subpixels are separable due to the different modulated emitter subpixels. The spatial resolution of the imaging device is therefore determined by the product of all detector subpixels of the detector macropixels and a number of different modulations used to modulate the emitter subpixels. For example, if only one modulation frequency is used for 64 emitter subpixels and 1024 detector subpixels, the spatial resolution is 1 x 1024 = 1024 pixels. Increasing the number of different modulations from 1 to 8 would improve the spatial resolution by a factor of 8, corresponding to a value of 8192 pixels. Due to the incoherence of the modulation frequencies and the introduction of 8 different phase shifts, this result could be increased by a further factor of 8, resulting in a total spatial resolution of 65532 pixels in this case.If, as provided for in the invention, the emitter subpixels each emit mutually incoherent terahertz radiation and the incoherence is present in both frequency and phase, a resolution of 4194304 pixels is achieved accordingly.

[0027] In principle, the imaging device can be configured in various ways. However, according to a preferred embodiment of the invention, the imaging device is additionally provided with a control unit, a storage unit, a logic unit, and a video controller. The control unit is connected to the transmitter unit, the receiver unit, and the storage unit for signal transmission. The control unit is configured to trigger the emission of terahertz radiation with the emitter subpixels using different modulations and to synchronize the emitter subpixels with the detector subpixels, so that an incoherent light field is formed and the signals detected by the detector subpixels can be separated from one another based on their respective modulations. The signals detected by the detector subpixels are then transmitted to the storage unit by the control unit and stored.The video controller is connected to the storage unit via the logic unit for signal transmission, and the stored signals are separated by the logic unit downstream of the storage unit and output by the video controller.

[0028] The terahertz radiation detected by each detector subpixel is thus superimposed temporally to form a composite high-frequency signal. This detected signal can be separated if the synchronization of the transmitting unit, the receiving unit, and the control unit is ensured. As mentioned above, the control unit triggers the emission of the terahertz radiation by the emitter subpixels and their modulation. The emitter subpixels are preferably modulated at different chopping frequencies and / or phases. In principle, the signals can be separated in various ways. However, according to a preferred embodiment of the invention, the logic unit is configured to separate the stored signals for each detector subpixel using orthogonal decomposition. Particularly preferably, the orthogonal composition is performed using a Walsh-Hadamard transform.The Walsh-Hadamard transform is a linear transformation used to transform stored signals into Walsh space. This involves decomposing the data into a series of orthogonal Walsh functions. This transformation is particularly useful because it provides a simple and efficient method for analyzing and modeling signals.

[0029] It is possible to modulate the incoherent light field space with different chopping frequencies. However, according to a preferred embodiment of the invention, the terahertz radiation emitted by the subpixel emitters is modulated with different chopping frequencies, and the lowest chopping frequency, specified by the control unit, is at least 25 Hz. With the direct temporal synthesis or generation of the light field space thus achieved, a real-time capable terahertz imaging device is provided. The lowest chopping frequency determines the temporal resolution of the image sequences. At a lowest chopping frequency of 25 Hz, a separate video image with at least 25 frames per second can be generated using images at this chopping frequency and for each higher chopping frequency. The temporal resolution can be further increased with higher chopping frequencies.

[0030] According to a preferred embodiment of the invention, the control unit comprises a high-frequency detector, a digital oscillator, and a digital counter, wherein the high-frequency detector is connected to each detector subpixel for signal transmission, the high-frequency detector is configured to convert the signal detected by the respective detector subpixel into a direct current signal, the digital oscillator is connected to the high-frequency detector for signal transmission, and the direct current signal is provided to the digital oscillator as a control signal, the digital counter is connected to the storage unit and the digital oscillator for signal transmission, and the digital counter is configured to count the oscillations in the digital oscillator and subsequently transmit them to the storage unit and store the signals in the form of counted oscillations.One advantage is the fully digital signal processing, which also enables real-time output via the video controller. Increased temporal resolution is achieved in particular through the digital oscillator and counter. The acquired images can be read directly digitally, thus enabling real-time video output, especially when considering a minimum chopping frequency of 25 Hz.

[0031] In principle, the control unit, storage unit, logic unit, and video controller can be configured in various ways. However, according to a preferred embodiment of the invention, the control unit, storage unit, logic unit, and video controller are configured as an integrated circuit, preferably on a silicon chip. This enables particularly efficient production of the imaging device. The transmitting and receiving units can be adapted to the specific requirements of the imaging application and only need to be designed to be connectable to the integrated circuit via suitable interfaces.

[0032] The invention also relates to a method for operating the imaging device described above, comprising the following method steps:

[0033] Synchronizing the transmitting unit with the receiving unit,

[0034] Generating an incoherent light field space with the transmitting unit, wherein the light field space is incoherent in the chopping frequency and / or the phase of the emitted terahertz radiation,

[0035] Introducing an object of investigation into the incoherent light field space, capturing the incoherent light field space with the receiving unit,

[0036] Converting the captured signals into direct current signals, where the captured signals correspond to superimposed high-frequency signals,

[0037] Triggering an oscillator with the DC signals,

[0038] Counting the respective oscillations with the counter,

[0039] The signals are stored in the memory unit as counted oscillations, and the stored signals are separated based on their respective modulation, with the images of each modulation then being provided. The light field space is preferably incoherent in the chopping frequency and / or the phase of the emitted terahertz radiation. Through synchronization, each modulation of the terahertz radiation emitted by the respective emitter subpixel, or the incoherence of the light field space, is uniquely defined, and consequently, the contribution of each emitter subpixel is uniquely identifiable.

[0040] According to a preferred further development, the incoherent light field space is generated with different chopping frequencies, and the procedure includes the following further steps:

[0041] Providing an image with the highest chopping frequency by calculating the difference between two consecutive memory addresses in the memory unit, and

[0042] Providing the following images of the respective chopping frequencies by adding pairwise successive signals and subsequently calculating the difference between two successive signals obtained by addition.

[0043] Preferably, the counter is reset using the lowest chopping frequency. Likewise, according to a preferred embodiment of the invention, the signals are stored in the memory unit in the form of counted oscillations at a rate that is twice the maximum chopping frequency.

[0044] According to a further preferred embodiment of the invention, the signals are acquired at a time interval of 40 ms at a lowest chopping frequency of 25 Hz, so that 25 images of the respective chopping frequency are acquired per second. With this temporal resolution, real-time 3D imaging is enabled by the method according to the invention.

[0045] The invention is described in more detail below with reference to the drawings and preferred embodiments.

[0046] The drawings show

[0047] Fig. 1 schematically shows an emitter macropixel according to a preferred embodiment of the invention, Fig. 2 schematically shows a transmitting unit and a receiving unit for a

[0048] Imaging device according to a preferred embodiment of the invention, and

[0049] Fig. 3 schematically shows an imaging device according to a preferred one.

[0050] Exemplary embodiment of the invention.

[0051] Figure 1 shows an emitter macropixel 1 of a transmitter unit 2 shown in Figure 2 according to a preferred embodiment of the invention. The emitter macropixel 1 has a housing 8 with an aperture 10 formed along an aperture axis. The aperture 10 is arranged on a side opposite a wall 6 of the housing 8. Emitter subpixels 4 are formed on the wall 6 in a square 8 x 8 matrix. The emitter subpixels 4 are configured to emit terahertz radiation, which is modulated such that the terahertz radiation of the respective emitter subpixels 4 is incoherent with respect to each other. Due to the lateral distance of the respective emitter subpixel 4 from the aperture axis, the terahertz radiation emitted by the emitter subpixels 4 passes through the aperture 10 of the housing 8 with a given angular dependence.

[0052] Figure 2 shows the transmitter unit 2 with a plurality of adjacent emitter macropixels 1 and a receiver unit 12. The emitter macropixels 1, with their angle-dependent emittance of terahertz radiation, generate an incoherent light field space from the mutually axially parallel aperture axes, so that an incoherent light field space is formed with the transmitter unit 2. A receiver unit 12 of an imaging device 3 is arranged on a side opposite the apertures 10 of the transmitter unit 2. The receiver unit 12 has a plurality of adjacent detector macropixels 14. The detector macropixels 14 have a housing 8 with an aperture 10 formed along an aperture axis and a wall 6 arranged on one side opposite the aperture 10, on which detector subpixels 16 are formed in a square matrix of 32 x 32.The terahertz radiation emitted by the emitter subpixels 4 from the incoherent light field passes through the aperture 10 of the detector macropixels 14 and is detected with an angular dependence determined by the lateral distance of the respective detector subpixel 16 from the aperture axis. The emitter macropixels 1 and the detector macropixels 13 are designed and arranged in corresponding positions such that each detector subpixel 16 simultaneously detects the terahertz radiation from all emitter subpixels 4, resulting in a temporally superimposed high-frequency signal in the respective detector subpixel 16.

[0053] Finally, Fig. 3 shows the imaging device 3 with the transmitter unit 2 and the receiver unit 12, as well as a control unit 18, a storage unit 20, a logic unit 22, and a video controller 24. The transmitter unit 2 and the receiver unit 12 are each connected to the control unit 18 for signal transmission. The control unit 18 is connected to the storage unit 20 for signal transmission. The storage unit 20 is connected to a video controller via the logic unit 22 for signal transmission. The control unit 18 has a high-frequency detector 18, which is connected to each detector subpixel 16. A digital oscillator 28 is interposed between the high-frequency detector 18 and a digital counter 30. The digital counter 30, in turn, is connected to the storage unit 20 for signal transmission.

[0054] The transmitter unit 2 and the receiver unit 12 are synchronized with the control unit 18. The figure shows various individual emitter subpixels 4, which, upon triggering by the control unit 18, emit terahertz radiation with different chopping frequencies, ranging from a lowest chopping frequency fo to a maximum chopping frequency FN. The lowest chopping frequency fo corresponds to 25 Hz. The detector subpixel 16 shown in the receiver unit detects the temporally superimposed terahertz radiation from all emitter subpixels 4 in the form of a high-frequency signal. Since the receiver unit 12 is synchronized with the transmitter unit 2 via the control unit 18, the detected signals are in a fixed frequency relationship to each other based on the chopping frequencies and are therefore separable. The high-frequency detector 26 converts the detected signal into a direct current signal and feeds it to the digital oscillator 28 as a control signal.The oscillations thus generated are counted by the digital counter 30 and then transferred to the storage unit 20, where they are stored as counted oscillations at a rate equal to twice the maximum chopping frequency. The digital counter 30 is reset between counts at the lowest chopping frequency. The logic unit 22 separates the stored signals and outputs them as images captured at the respective chopping frequency. The image corresponding to the maximum chopping frequency £N is the difference between the signal stored at chopping frequency FN and the signal stored at chopping frequency fN-i. The image corresponding to fN-i is the difference between the sum of the signals stored at fN frequency and FN-I frequency, and the sum of the signals stored at fx-2 frequency and fN-3 frequency.In the same way, all signals stored at the respective chopping frequencies are separated down to the lowest chopping frequency fo. The fo frequency also simultaneously indicates the lowest frame rate. For each chopping frequency, image sequences with at least 25 Hz, i.e., 25 frames per second, are thus obtained, which are then output as video by the video controller.

[0055] The invention underlying this patent application originated in a project supported by an ERC grant under grant number 101019972 (“DIRECTS”).

[0056] Reference symbol list

[0057] 1 emitter macropixel

[0058] 2 transmitter units

[0059] 3 Imaging device

[0060] 4 emitter subpixels

[0061] 6 Wall

[0062] 8 cases

[0063] 10 Aperture

[0064] 12 receiver units

[0065] 14 detector macropixels

[0066] 16 detector subpixels

[0067] 18 Control unit

[0068] 20 storage units

[0069] 22 logic units

[0070] 24 video controllers

[0071] 26 High-frequency detector

[0072] 28 digital oscillator

[0073] 30 digital counters

Claims

Patent claims 1. Emitter macropixel (1) for a transmitting unit (2) of an imaging device (3) comprising a plurality of emitter subpixels (4) designed to emit electromagnetic terahertz radiation, wherein the emitter subpixels (4) are arranged on a wall (6) of the emitter macropixel (1) such that the terahertz radiation can be emitted along the surface normal of the wall (6), and the terahertz radiation emitted by the emitter subpixels (4) is modulated such that the emitter subpixels (4) each emit terahertz radiation that is incoherent to each other.

2. Emitter macropixel (1) according to claim 1 with a housing (8), wherein the plurality of emitter subpixels (4) are arranged on the wall (6) of the housing (8) of the emitter macropixel (1), an aperture (10) is formed on a side of the housing (8) opposite the emitter subpixels (4) along an aperture axis, so that the terahertz radiation emitted with the emitter subpixels (4) passes through the aperture (10) of the housing (8) under an angular dependence given by the lateral distance of the emitter subpixel (4) from the aperture axis.

3. Emitter macropixel (1) according to claim 2, wherein a lens is arranged in the aperture (10) of the housing (6) of the emitter macropixel (1).

4. Emitter macropixel (1) according to one of the preceding claims, wherein the terahertz radiation emitted with the respective emitter subpixel (4) is modulated in a chopping frequency and / or phase.

5. Transmitter unit (2) with a plurality of emitter macropixels (1) according to one of claims 2 to 4, wherein the emitter subpixels (4) of all emitter macropixels (1) each emit mutually incoherent terahertz radiation, so that an incoherent light field space is formed with the emitter macropixels (1).

6. Transmitter unit (2) according to claim 5, wherein the emitter macropixels (1) are arranged side by side with aperture axes parallel to each other, so that the apertures (10) of the emitter macropixels (1) have the same orientation.

7. Use of a receiving unit (12) for an imaging device (3) for detecting the incoherent light field space formed with the transmitting unit (2) according to one of claims 5 or 6.

8. Imaging device (3) comprising a transmitting unit (2) according to claim 5 or 6 and a receiving unit (12), wherein the receiving unit (12) comprises a plurality of detector macropixels (14), each detector macropixel (14) of the receiving unit (12) comprising a housing (8), wherein a plurality of detector subpixels (16) for detecting the terahertz radiation are arranged on a wall (6) of the housing (8), an aperture (10) is formed on a side of the housing (8) opposite the detector subpixels (16) along an aperture axis, such that the terahertz radiation is detected with an angular dependence given by the lateral distance of the respective detector subpixel (16) from the aperture axis, the detector macropixels (14) are arranged side by side with aperture axes parallel to each other, such that the apertures (10) of the Detector macropixels (14) have the same orientation,and the apertures (10) of the receiving unit (12) are facing the apertures (10) of the transmitting unit (2).

9. Imaging device (3) according to claim 8, wherein the apertures (10) of the emitter macropixels (1) and the emitter subpixels (4) as well as the apertures (10) of the detector macropixels (14) and the detector subpixels (16) are arranged in corresponding positions such that the terahertz radiation emitted by each emitter subpixel (4) can be detected by each detector subpixel (16).

10. Imaging device (3) according to one of claims 8 or 9 comprising a control unit (18), a storage unit (20), a logic unit (22) and a video controller (24), wherein the control unit (18) is connected to the transmitting unit (2) and the receiving unit (12) as well as to the storage unit (20) for signal transmission, wherein the control unit (18) is configured to trigger the emission of the terahertz radiation with the emitter subpixels (4) with different modulations and to synchronize the emitter subpixels (4) with the detector subpixels (16) so that an incoherent light field space is formed and the signals detected by the detector subpixels (16) can be separated from each other based on the respective modulation, the signals detected by the detector subpixels (16) are transmitted to the storage unit (20) and stored by the control unit (18),The video controller (24) is connected to the storage unit (20) via the logic unit (22) for signal transmission, and the stored signals are separated by the logic unit (22) downstream of the storage unit (20) and output by the video controller (24).

11. Imaging device (3) according to claim 10, wherein the logic unit (22) is configured to separate the stored signals by means of orthogonal decomposition for each detector subpixel (16).

12. Imaging device (3) according to one of claims 10 or 11, wherein the terahertz radiation emitted by the subpixel emitter (4) is modulated with different chopping frequencies and a lowest chopping frequency specified by the control unit (18) is at least 25 Hz.

13. Imaging device (3) according to one of claims 10 to 12, wherein the control unit (18) comprises a high-frequency detector (26), a digital oscillator (28) and a digital counter (30), wherein the high-frequency detector (26) is connected to each detector subpixel (16) for signal transmission, the high-frequency detector (26) is configured to convert the signal detected by the respective detector subpixel (16) into a direct current signal, the digital oscillator (28) is connected to the high-frequency detector (26) for signal transmission and the DC signal is provided to the digital oscillator (28) as a control signal, the digital counter (30) is connected to the storage unit (20) and the digital oscillator (28) for signal transmission, and the digital counter (30) is configured to count the oscillations in the digital oscillator (28) and then transmit them to the storage unit (20) and store the signals in the form of counted oscillations.

14. Method for operating an imaging device (3) according to any one of claims 8 to 13, comprising the following method steps: 51) Synchronizing the transmitting unit (2) with the receiving unit (12), 52) Generating an incoherent light field space with the transmitting unit (2), 53) Introducing an object of investigation into the incoherent light field space, 54) Capturing the incoherent light field space with the receiving unit (12), 55) Converting the detected signals into direct current signals, wherein the detected signals correspond to superimposed high-frequency signals, 56) Triggering an oscillator (28) with the DC signals, 57) Counting the respective oscillations with a counter (30), 58) Storing the signals in the form of counted oscillations in a storage unit (20), and 59) Separating the stored signals based on their respective modulation and providing the images of each modulation.

15. The method of claim 14, wherein the incoherent light field space was generated with the modulated different chopping frequencies, wherein in step S9 the following step is performed instead: S9) Providing an image with the highest chopping frequency by taking the difference between two consecutive memory addresses in the memory unit (20), and comprising the following further step: S10) Providing the following images of the respective chopping frequencies by adding pairwise successive signals and subsequently calculating the difference between two successive signals obtained by addition.

Images