Generating hologram datasets with reconfigurable smart surfaces
By using digital controlled scatterer (DCS) and control codeword technology, the problems of slow speed, accumulated errors and high cost in the traditional hologram data set generation method are solved, and fast, accurate and low-cost hologram data set generation is achieved.
Patent Information
- Application Number
- CN202280101143.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-24
- Publication Date
- 2025-05-27
AI Technical Summary
The traditional hologram data set generation method has problems such as slow data acquisition speed, accumulated errors and high system setup costs.
Using a reconstructible intelligent surface provided by digital controlled scattering (DCS), the position changes of the transmitter and receiver are simulated by controlling codewords, and the rapid and accurate hologram data set generation of the target object is achieved.
The speed improvement, error reduction and system cost reduction of hologram data set generation is achieved, providing a compact and low-cost device and method.
Smart Images
Figure CN120051710A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to holograms and hologram dataset generation. The present invention provides an apparatus and method for generating a hologram dataset of a target object. The apparatus and method utilize a reconfigurable intelligent surface provided by a digitally controllable scatterer (DCS) to illuminate the target object and obtain a hologram dataset based on the electromagnetic signals reflected from the target object. Background Art
[0002] Electromagnetic radio wave imaging technologies such as terahertz and millimeter wave imaging have been widely used in the fields of biomedicine, non-invasive assessment, quality control, and security, and thus have attracted much attention. These technologies rely on the measurement of the electric field scattered by the target object of interest irradiated or illuminated.
[0003] For example, Figure 1 shows a monostatic scanning setup for obtaining a hologram dataset of a target object 101, where the transmitter (Tx) and the receiver (Rx) are collocated and placed on a moving scanning arm 102. The scanner moves on the scanning plane, and the Rx measures the scattered signal of the target object 101 at each position on the scanning plane. The total electric field measurement values obtained constitute the hologram dataset of the target object 101, which is necessary for image restoration.
[0004] Unfortunately, Figure 1 the shown scanning process has the problem of slow data acquisition speed because the raster scanning process generates an undesired delay, which affects the speed of hologram generation. During the hologram generation process, the time of the scanning process mainly depends on the speed of the scanning device and the number of scanning positions considered on the scanning plane. In fact, the measurement speed depends on the speed of the scanning process, and the scanning process is mainly delayed by the moving arm 102. Therefore, as the number of scanning positions increases, in order to obtain accurate high image resolution during the restoration process, the required scanning time will increase proportionally. As the number of sampling points increases, the acquisition time may be as long as several hours.
[0005] In addition, the scanning process itself is not without errors. In fact, during the entire scanning process of the target object 101, due to the continuous displacement of the scanning arm 102, positioning errors may occur each time the moving arm changes its position to scan the next target point, and these errors will accumulate continuously.
[0006] If a dedicated lens is used to increase the aperture of the Tx antenna, additional system setup costs are incurred. In practice, an adapted lens is typically used to irradiate the entire target object 101 at once from any position. However, this is not without consequences, as the performance of the lens is closely related to the construction quality, i.e., to the material used to construct the lens, which is capable of deflecting the signal with minimal signal distortion. Summary of the Invention
[0007] In summary, the present invention aims to improve conventional methods and setups for generating hologram datasets. One objective is to generate hologram datasets of a target object more quickly. Another objective is to minimize errors during the generation of hologram datasets, e.g., by providing a more reliable and accurate scanning method. Another objective is to provide a device for generating hologram datasets that is compact, inexpensive, or allows for flexible deployment of Tx and Rx.
[0008] These and other objectives are achieved by the present invention according to the technical solutions described in the independent claims. Advantageous implementations are further described in the dependent claims.
[0009] A first aspect of the present invention provides a device for generating a hologram dataset of a target object. The device comprises: a DCS, wherein the DCS comprises one or more scattering surfaces, the one or more scattering surfaces comprising a set of scattering elements, each scattering element having a controllable phase shift; a transmitter for emitting an electromagnetic signal onto the DCS during a scanning period; a controller for controlling the DCS during the scanning period using a set of control codewords to scatter the electromagnetic signal onto the target object and to focus the electromagnetic signal reflected from the target object onto a receiver; the receiver for receiving the electromagnetic signal focused by the DCS, wherein each control codeword defines a corresponding phase shift configuration for at least one subset of the scattering elements of the DCS, and for each control codeword, the electromagnetic signal scattered by the DCS onto the target object is irradiated at an angle different from other control codewords, and / or the electromagnetic signal reflected from the target object is focused onto the receiver at an angle different from other control codewords, and the controller is further configured to generate the hologram dataset of the target object based on the focused electromagnetic signal received by the receiver during the scanning period.
[0010] During the scan cycle of the scanning process, the positions of related entities such as the transmitter, the receiver, and one or more DCS surfaces can be static and fixed. By applying a set of control codewords that define a specific phase shift configuration on one or more DCS surfaces, the position changes required conventionally for any of these entities can be simulated. For example, each codeword can, in a sense, simulate different positions of the transmitter and / or the receiver, that is, although the transmitter and the receiver do not move, the controlled scattering generated by one or more DCS surfaces makes the electric field at the receiver the same as if the receiver and / or the transmitter were moving and scanning from different positions. Applying the entire set of control codewords can provide a set of received measurements that correspond to the desired hologram data set of the target object.
[0011] Since there is no need to move the entity or the entity with multiple antennas, the cost of the device is low. Additionally, compared with the need to move related entities, the hologram data set of the target object can be generated faster. At the same time, since positioning errors are avoided, the errors in generating the hologram data set can also be minimized.
[0012] In one implementation of the first aspect, the positions of the transmitter, the position of the receiver, and the positions and orientations of the one or more scattering surfaces of the DCS are fixed relative to each other and relative to the target object during the scan cycle.
[0013] In an implementation of the first aspect, the transmitter and the receiver are collocated; the DCS includes a scattering surface, and the scattering surface includes the set of scattering elements; the controller is configured to use the set of control codewords to control the set of scattering elements of the scattering surface during the scan cycle to scatter the electromagnetic signal onto the target object and focus the electromagnetic signal reflected from the target object onto the receiver.
[0014] This implementation provides a technical solution for collocating the transmitter and the receiver (e.g., a transceiver), where a single DCS surface can be used. This provides a compact and inexpensive setup.
[0015] In one implementation of the first aspect, the transmitter and the receiver are non - collocated; the DCS includes a scattering surface, and the scattering surface includes the set of scattering elements; the controller is configured to use a first subset of the control codewords to control a first subset of the scattering elements of the scattering surface to scatter the electromagnetic signal onto the target object during the scan cycle; the controller is configured to use a second subset of the control codewords to control a second subset of the scattering elements of the scattering surface to focus the electromagnetic signal reflected from the target object onto the receiver during the scan cycle.
[0016] The first subset of the scattering elements and the second subset of the scattering elements can be non-overlapping subsets, that is, the scattering elements of the first subset are not in the second subset, and vice versa. However, the first subset of the scattering elements and the second subset of the scattering elements can also be overlapping subsets, that is, one or more scattering elements in the first subset can be included in the second subset, and vice versa.
[0017] This implementation provides a technical solution for non-collocated transmitters and receivers, where a single DCS surface can be used. This provides a compact and flexible technical solution.
[0018] In an implementation of the first aspect, in addition to the scattering surface including the set of scattering elements, the DCS does not include other scattering surfaces.
[0019] In an implementation of the first aspect, the transmitter and the receiver are non-collocated; the DCS includes a first scattering surface and a second scattering surface, the first scattering surface includes a first subset of the scattering elements, and the second scattering surface includes a second subset of the scattering elements; the controller is configured to use a first subset of the control codewords to control the first subset of the scattering elements of the first scattering surface during the scanning period to scatter the electromagnetic signal onto the target object; the controller is configured to use a second subset of the control codewords to control the second subset of the scattering elements of the second scattering surface during the scanning period to focus the electromagnetic signal reflected from the target object onto the receiver.
[0020] This implementation provides a technical solution for non-collocated transmitters and receivers, where two or more than two DCS surfaces can be used. This can generate hologram datasets very precisely.
[0021] In an implementation of the first aspect, the first scattering surface and the second scattering surface are independent parts of the DCS and can be independently controlled by the controller.
[0022] In an implementation of the first aspect, for each control codeword, the controller is configured to control the DCS to scatter the electromagnetic signal onto the target object as a plane electromagnetic wave.
[0023] This can irradiate the entire target object and improve hologram dataset generation.
[0024] In an implementation of the first aspect, the set of control codewords forms a codebook, and the codebook is adapted to the characteristics of the transmitter, the receiver, and the one or more scattering surfaces of the DCS.
[0025] These characteristics can be related to the position and orientation of each surface in one or more DCS surfaces and / or to each scattering element in the DCS scattering elements. Specifically, these characteristics can include the position and orientation of one or more DCS surfaces and the DCS scattering elements of these DCS surfaces.
[0026] In one implementation of the first aspect, the controller is configured to generate the codebook based at least on the relative positions of the transmitter, the receiver, the one or more scattering surfaces of the DCS, and the target object.
[0027] In one implementation of the first aspect, the controller is configured to generate the codebook, the codebook including the set of control codewords, and the set of control codewords is selected such that: when the set of control codewords is used within the scan period, the DCS scatters the electromagnetic signal onto the target object, simulating the reflection of a perfect electric conductor (PEC) having the shape of a paraboloid of revolution.
[0028] In this way, a very accurate holographic data set of the target object is obtained.
[0029] In one implementation of the first aspect, the controller is configured to obtain the respective relative positions of the transmitter, the receiver, the target object, and the one or more scattering surfaces of the DCS and the respective characteristics of the one or more scattering surfaces of the DCS through signaling of at least one of the transmitter and the receiver.
[0030] In one implementation of the first aspect, at least one of the transmitter and the receiver is configured to perform measurements on the relative position of the target object with respect to the transmitter and the receiver.
[0031] A second aspect of the present invention provides a method for a device to generate a holographic data set of a target object. The device includes: a DCS, wherein the DCS includes one or more scattering surfaces, the one or more scattering surfaces include a set of scattering elements, and each scattering element has a controllable phase shift; a transmitter for emitting an electromagnetic signal onto the DCS during a scanning period; a receiver for receiving, during the scanning period, an electromagnetic signal that is reflected from the target object onto the DCS and focused by the DCS onto the receiver; the method includes: using a set of control codewords to control the DCS during the scanning period to scatter the electromagnetic signal onto the target object and focus the electromagnetic signal reflected from the target object onto the receiver, wherein each control codeword defines a corresponding phase shift configuration for at least one subset of the scattering elements of the DCS, and for each control codeword, the electromagnetic signal scattered by the DCS from the target object is irradiated at an angle different from that of the other control codewords, and / or the electromagnetic signal reflected from the target object is focused onto the receiver at an angle different from that of the other control codewords; generating the holographic data set of the target object based on the focused electromagnetic signal received by the receiver during the scanning period.
[0032] In one implementation of the second aspect, the positions of the transmitter, the position of the receiver, and the positions and orientations of the one or more scattering surfaces of the DCS are fixed relative to each other and relative to the target object during the scanning period.
[0033] In one implementation of the second aspect, the transmitter and the receiver are collocated; the DCS includes a scattering surface, and the scattering surface includes the set of scattering elements; the method includes: using the set of control codewords to control the set of scattering elements of the scattering surface during the scanning period to scatter the electromagnetic signal onto the target object and focus the electromagnetic signal reflected from the target object onto the receiver.
[0034] In one implementation of the second aspect, the transmitter and the receiver are non-collocated; the DCS includes a scattering surface, and the scattering surface includes the set of scattering elements; the method includes: using a first subset of the control codewords to control a first subset of the scattering elements of the scattering surface during the scanning period to scatter the electromagnetic signal onto the target object; the method includes: using a second subset of the control codewords to control a second subset of the scattering elements of the scattering surface during the scanning period to focus the electromagnetic signal reflected from the target object onto the receiver.
[0035] In one implementation of the second aspect, the DCS does not include other scattering surfaces except the scattering surface including the set of scattering elements.
[0036] In one implementation of the second aspect, the transmitter and the receiver are non - collocated; the DCS includes a first scattering surface and a second scattering surface, the first scattering surface includes a first subset of the scattering elements, and the second scattering surface includes a second subset of the scattering elements; the method includes: using a first subset of the control codewords to control the first subset of the scattering elements of the first scattering surface during the scanning period to scatter the electromagnetic signal onto the target object; the method includes: using a second subset of the control codewords to control the second subset of the scattering elements of the second scattering surface during the scanning period to focus the electromagnetic signal reflected from the target object onto the receiver.
[0037] In one implementation of the second aspect, the first scattering surface and the second scattering surface are independent parts of the DCS and can be independently controlled.
[0038] In one implementation of the second aspect, the method includes: for each control codeword, controlling the DCS to scatter the electromagnetic signal onto the target object as a plane electromagnetic wave.
[0039] In one implementation of the second aspect, the set of control codewords forms a codebook, and the codebook is adapted to the characteristics of the transmitter, the receiver, and the one or more scattering surfaces of the DCS.
[0040] In one implementation of the second aspect, the method includes: generating the codebook based at least on the relative positions of the transmitter, the receiver, the one or more scattering surfaces of the DCS, and the target object.
[0041] In one implementation of the second aspect, the method includes: generating the codebook, where the codebook includes the set of control codewords, and the set of control codewords is selected such that when the set of control codewords is used during the scanning period, the DCS scatters the electromagnetic signal onto the target object, simulating the reflection of a perfect electric conductor with the shape of a paraboloid of revolution.
[0042] In one implementation of the second aspect, the method includes: obtaining the respective relative positions of the transmitter, the receiver, the target object, and the one or more scattering surfaces of the DCS and the respective characteristics of the one or more scattering surfaces of the DCS through signaling of at least one of the transmitter and the receiver.
[0043] In one implementation of the second aspect, at least one of the transmitter and the receiver is configured to perform measurements on the relative position of the target object with respect to the transmitter and the receiver.
[0044] The method of the second aspect and its implementation achieve the same advantages as the apparatus of the first aspect and its corresponding implementation described above.
[0045] A third aspect of the present invention provides a computer program comprising instructions. When the program is executed by a processor, the instructions cause the processor to execute the method according to the second aspect or its implementation, specifically for controlling the DCS and for generating the hologram data set.
[0046] A fourth aspect of the present invention provides a non-transitory storage medium storing executable program code. When the executable program code is executed by a processor, the method according to the second aspect or its implementation is performed.
[0047] Based on the above, the present invention proposes an apparatus for generating a hologram data set. The apparatus is designed to use the surface or metasurface of a DCS, which is used to manipulate the propagating electromagnetic waves emitted by a transmitter and scattered by a target object, such that a set of signals observed at a receiver corresponds to hologram data set measurements.
[0048] The surface or metasurface of any DCS can consist of a large number (e.g., hundreds or thousands) of elementary units, each of which is a scattering element with a controllable phase shift. Thus, the phase of the electromagnetic waves scattered by the elementary elements of the DCS surface can be controlled. The proposed apparatus is capable of using one or more DCS surfaces to scan a target object, which surfaces have a set of specific configurations defined by control codewords that are specifically designed for the scanning process and are capable of generating a hologram data set.
[0049] Therefore, during a scanning period, the positions of related entities such as one or more transmitting antennas, one or more receiving antennas, and one or more DCS surfaces can be static and fixed. By applying control codewords on one or more DCS surfaces, any desired position change of any of these entities can be simulated. Thus, codewords can be defined for the DCS as the corresponding phase shift values for each scattering element, and a set of different codewords can define a codebook for the DCS.
[0050] In the present invention, there is no need to move the antenna element or multiple antenna elements. Instead, the described DCS programming can be used to manipulate the propagating electromagnetic wave such that the electric field measurements required to generate the hologram data set can be obtained at the receiver. A codebook can be used to configure the DCS, which includes control codewords and is applicable to the transmitter, receiver, DCS, and the target object to be scanned. Each control codeword in the codebook can, in a sense, simulate different positions of the transmitter and / or receiver, that is, although the transmitter and receiver do not move, the controlled scattering generated by the DCS makes the electric field at the receiver the same as if the receiver and / or transmitter were moving and scanning from different positions. Applying the entire codebook can provide a set of received measurements that correspond to the desired hologram data set of the target object.
[0051] The technical solution of the present invention can be integrated into a stand-alone device or implemented as a network-assisted technical solution for environmental or object scanning. For example, the proposed device can be embedded in a stand-alone device such as a smart phone, where the transmitter, receiver, and DCS are fixed and their positions are known. The position of the scanned target object can also be known before the scanning process. This can be achieved by placing the target object or the scanner in a specific area or by using the available sensors (e.g., proximity sensors) on the device to estimate. With these devices, there is no need to change the position when scanning the target object and generating the hologram. It may only be necessary to place the device at a certain fixed position away from the target object.
[0052] Alternatively, for example, one or more base stations (BS) in the propagation environment and the known positions of various deployed DCS surfaces can also be utilized to perform the scanning. In fact, the BS (Tx / Rx) positions and the deployed DCS surfaces are known, so the technical solution of the present invention can be used to scan a fixed target object without moving the BS (i.e., Tx / Rx) or the DCS. Of course, in order to update the phase shifts of the DCS scattering elements of one or more DCS surfaces of the DCS, signaling and synchronization may be required between the BS and the DCS. This can simulate the effect of irradiating the target object and focusing the reflected signal to the desired Rx antenna, and can also control the transmit / receive process each time a new codeword in the codebook is selected.
[0053] Advantages of the present invention include alleviating the above problems. For example, the traditional acquisition time for generating hologram datasets is too long, positioning errors may accumulate during raster scanning, and high-quality lenses are required, which are necessary for irradiating the entire target object with parallel rays and refocusing the reflected rays back to the receiver. Since the technical solution of the present invention does not require a scanning arm, the delay caused by the placement of the scanning arm is eliminated, and the errors that usually accumulate during the scanning process by the robotic arm are removed. In fact, in the present invention, once the positions of the transmitter, receiver, DCS, and target object are fixed and clearly identified, the positioning errors will naturally disappear.
[0054] Therefore, the method of the present invention may include permanently fixing the positions of the transmitter, receiver, and target object once and for all during the scanning / acquisition process of the scanning cycle to avoid being affected by the cumulative errors caused by the moving arm of the scanner. With one or more static DCS surfaces configured with carefully designed codewords, the entire target object can be irradiated simultaneously, and the electromagnetic waves reflected by the target object can be focused onto the receiver. In addition, according to the present invention, only by updating the codewords that configure the phase shifts of the DCS scattering elements can the position changes of any one of the transmitter, receiver, or target object be simulated. Selecting the codewords in the codebook can also determine the quality of the generated hologram dataset.
[0055] The present invention also proposes a method for generating a DCS codebook. This method is customized for the above-mentioned hologram dataset acquisition. The proposed codebook generation method can be based on the reflection characteristics of a paraboloid, which meet the requirements of irradiating the entire target object (by generating plane waves, e.g., parallel rays) and focusing the reflected waves onto the receiver (e.g., paraboloid focusing). The DCS phase shifts of the codewords can be selected such that the waves scattered by the DCS are the same as the waves reflected by a parabolic mirror.
[0056] It should be noted that all the devices, elements, units, and apparatuses described in this application can be implemented in software or hardware elements or any combination thereof. All the steps performed by the various entities described in this application and the functions described as being to be performed by the various entities are intended to indicate that the respective entities are adapted or used to perform their respective steps and functions. Although in the description of the following specific embodiments, the specific functions or steps performed by external entities are not reflected in the description of the specific detailed elements of the entities performing the specific steps or functions, those skilled in the art should clearly understand that these methods and functions can be implemented by the corresponding software or hardware elements or any combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS
[0057] In conjunction with the accompanying drawings, the description of the following specific embodiments will elaborate on the above aspects and implementation manners.
[0058] Figure 1Shows an example of a conventional monostatic scanning setup for generating a hologram dataset.
[0059] Figure 2 Shows an apparatus for generating a hologram dataset provided by the present invention, having two exemplary DCS surfaces.
[0060] Figure 3 Shows a flowchart of an exemplary hologram dataset generation method using a codebook.
[0061] Figure 4 Shows an example of two scattered waves generated by applying two different codewords to a DCS having one DCS surface.
[0062] Figure 5 Shows the scattered wave of an optimized DCS having one DCS surface.
[0063] Figure 6 Shows the construction of the tangent point P.
[0064] Figure 7 Shows the construction of the directrix D.
[0065] Figure 8 Shows the construction of a paraboloid.
[0066] Figure 9 Shows the situation where a plane electromagnetic wave scattered from a DCS surface irradiates a target object.
[0067] Figure 10 Shows a phase shift compensation calculation, for example, a codeword calculation based on a paraboloid geometry method.
[0068] Figure 11 Shows an example of an apparatus having two exemplary DCS surfaces in a bistatic configuration for hologram dataset generation.
[0069] Figure 12 Shows the exchanged messages for hologram dataset generation in the case where the transmitter and receiver are in the same independent device.
[0070] Figure 13 Shows the exchanged messages for network-assisted hologram dataset generation.
[0071] Figure 14 Shows the method for generating a hologram dataset provided by the present invention.
[0072] Figure 15 Shows an exemplary configuration of the scattering surface of a DCS. Detailed Description
[0073] Figure 2The apparatus 200 provided by the present invention is shown. The apparatus 200 is used to generate a hologram dataset of the target object 201. The apparatus 200 includes a DCS 202, and the DCS 202 includes one or more scattering surfaces 202a, 202b. Just for example, in Figure 2 the DCS 202 includes two scattering surfaces 202a and 202b. As will be shown later, the DCS 202 may also include only one scattering surface, or may include more than two scattering surfaces. The apparatus 200 further includes a transmitter 204, a receiver 208, and a controller 206. The position of the receiver 208 and the position and orientation of one or more scattering surfaces 202a, 202b of the DCS 202 may be fixed relative to each other and relative to the target object 201 during a scanning period, within which the apparatus 200 acquires the hologram dataset, that is, performs a scanning process. The relative positions of the transmitter 204, the receiver 208, the DCS 202, and the target object 201 are at least fixed and known during this scanning period.
[0074] One or more scattering surfaces 202a, 202b of the DCS 202 include a set of scattering elements 203. Just for example, in Figure 2 the DCS 202 includes a first scattering surface 202a and a second scattering surface 202b. Each scattering element 203 of each scattering surface 202a, 202b has a controllable phase shift, which can be controlled by the controller 206. Specifically, the controller 206 is used to control the DCS 202 using a set of control codewords 207 during a scanning period. The transmitter 204 is used to transmit an electromagnetic signal 205a onto the DCS 202 during a scanning period. The control codewords 207 are selected and designed such that the electromagnetic signal 205a is scattered by the DCS 202 into a scattered electromagnetic signal 205b and scattered onto the target object 201. In addition, the controller 206 can also control the DCS 202 to focus the reflected electromagnetic signal 205c reflected from the target object 201 onto the receiver 208 as a focused electromagnetic signal 205d. The receiver 208 is used to receive the electromagnetic signal 205d focused by the DCS 202.
[0075] It should be noted that each control codeword 207 defines a corresponding phase shift configuration for at least one subset of the scattering elements 203 of the DCS 202. For each control codeword 207, the target object 201 is irradiated by the electromagnetic signal 205b scattered by the DCS 202 at an angle different from that of other control codewords 207. Additionally or alternatively, for each control codeword 207, the electromagnetic signal 205c reflected from the target object 201 is focused onto the receiver 208 at an angle different from that of other control codewords 207.
[0076] Then, the controller 206 is further configured to generate a hologram data set of the target object 201 based on the focused electromagnetic signal 205d received by the receiver 208 within a scanning period. The arrows from the receiver 208 to the controller 206 represent exchanges that provide the controller 206 with the measurements collected at the receiver 208 to generate the hologram.
[0077] The controller 206 may include a processor or processing circuitry (not shown) for performing, conducting, or initiating the various operations of the controller 206 described herein. The processing circuitry may include hardware and / or the processing circuitry may be controlled by software. The hardware may include analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuitry may include components such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), or a general-purpose processor. The controller 206 may also include a storage circuitry that stores one or more instructions that may be executed by the processor or the processing circuitry (specifically, under the control of the software). For example, the storage circuitry may include a non-transitory storage medium that stores executable software code that, when executed by the processor or the processing circuitry, performs the various operations of the controller 206. In one embodiment, the processing circuitry includes one or more processors and a non-transitory memory coupled to the one or more processors. The non-transitory memory may carry executable program code that, when executed by the one or more processors, causes the controller 206 to perform, conduct, or initiate the operations or methods described herein.
[0078] Figure 3 A flowchart of an exemplary hologram data set generation method is shown, which may be performed by the apparatus 200 using a given codebook 301 (codebook to execute. Each codeword 207 (codeword ) in the codebook 301 may meet a set of requirements described as follows:
[0079] · Each codeword 207 in the codebook 301 simulates different positions of the transmitter 204 and / or the receiver 208.
[0080] · The signal 205b scattered by the DCS 202 towards the target object 201 includes plane waves, i.e., parallel rays that illuminate the target object 201.
[0081] · When the target object 201 is irradiated, the reflected signal 205c of the target object 201 is focused onto the receiver 208 through a preconfigured DCS surface or DCS surface group of the DCS 202.
[0082] According to the above characteristics, a set of codewords 207 or a phase shift configuration of the scattering elements 203 of the DCS 202 can be selected from an infinite number of phase shift configurations. Once the phase distribution configuration satisfies these characteristics, it forms the codewords 207, and the set of these codewords 207 forms the codebook 301.
[0083] Therefore, since the phase distribution configuration of the scattering surface of the DCS 202 is implemented according to the codewords 207 in the codebook 301, for each codeword 207, the target object can be radiated or irradiated at an angle different from other codewords 207. For this purpose, the device 200 can iterate 302 over all the codewords 207 in the codebook 301. In each iteration, the device 200 can configure 303 the DCS 202 according to the codeword 207, start 304 irradiating the target object 201 through the DCS 202, acquire 305 the signal 205c reflected from the target object 201, and store 306 the measurement values. Applying the entire codebook 301 provides a set of acquired measurement values, and this set of measurement values corresponds to and obtains 307 the desired hologram data set of the scanned target object 201. The hologram data set can be obtained by collecting all the measurement values of a given codebook of all measurement values to obtain.
[0084] Next, how to construct the codebook 301 is described. Any codeword 207 in the desired codebook 301 may need to satisfy the following conditions:
[0085] · Each codeword 207 in the codebook 301 simulates different positions of the transmitter 204 and / or the receiver 208.
[0086] · The signal 205b scattered by the DCS 202 towards the target object 201 includes plane waves, that is, parallel rays irradiating the target object 201.
[0087] · When the target object 201 is irradiated, the reflected signal 205c of the target object 201 is focused onto the receiver 208 through a preconfigured DCS surface or DCS surface group of the DCS 202.
[0088] Several tools and methods can be considered when constructing these codewords 207, including geometric methods, selection from a larger random codebook, machine learning-based construction (using online and / or offline learning methods), ray-tracing-based approximation and simulation, and / or EM field simulation combined with an optimization process.
[0089] In the following, taking the codeword construction as an example, the present invention describes in detail the construction process based on the geometric method. In fact, according to the conditions defined above, a codeword 207 can be designed to simulate the reflection behavior of a reflector or PEC in the shape of a paraboloid of revolution, where the transmitter 204 is the focus of the paraboloid, and the DCS 202 scatters and emits a signal 205a as a plane wave towards the target object 201. At the same time, the reflected signal 205c of the target object 201 is focused on the position of the receiver 208 using the same DCS configuration in a monostatic configuration. To facilitate the construction of the codeword 207 that meets the above requirements, the codeword design can only consider the paraboloid of revolution that is tangent to the DCS surface.
[0090] Figure 4 An example showing the positions of the transmitter 204 and the receiver 208 is presented. The codeword 207 for each application is used to irradiate or radiate the target object 201 with a plane wave at different viewing angles. Therefore, for each corresponding codeword 207, the data obtained measures the reflected signal 205c of the target object 201 at different viewing angles. Thus, the total number of codewords 207 forming the codebook 301 is proportional to the number of viewing angles considered for irradiating the target object 201.
[0091] The process of constructing the codeword 207 for a given viewing angle position and a given focus is described below. Specifically, a codeword construction method for one measurement acquisition is proposed. The codeword 207, i.e., the desired phase shift configuration of the DCS element 203 applied to the DCS 202, is used to transform the impact signal 205a at one or more DCS surfaces into a plane wave signal 205b, as Figure 5 shown, taking a scattering surface 202a of the DCS 202 as an example here. Then, without changing the monostatic measurement, the same setup configuration is used to collect the reflected signal 205c of the target object 201 and focus the reflected signal on the position of the receiver 208.
[0092] Since the paraboloid shape satisfies the characteristics of the above DCS phase shift configuration, the present invention describes below how to simulate a paraboloid of revolution that is tangent to the DCS surface 202a and has the positions of the transmitter 204 and the receiver 208a as the foci in a monostatic configuration (i.e., the transmitter 204 and the receiver 208 are collocated). The bistatic configuration is introduced later. The method proposed here is a geometric method based on simple geometric operations.
[0093] To be able to irradiate the entire target object 201 at one time, the DCS 202 is configured such that the scattered wave 205b of the DCS 202 is the same as the wave reflected by the paraboloid reflector. In other words, the DCS 202 simulates the reflection behavior of a paraboloid of revolution with the following characteristics:
[0094] · The positions of the transmitter 204 and the receiver 208 are the foci of a rotating paraboloid.
[0095] · The directrix plane of the paraboloid is perpendicular to the parallel rays irradiating the target object 201.
[0096] · Select a paraboloid that is tangent to the DCS surface 202a to ensure the uniqueness of such a paraboloid. This provides a simple and computable technical solution, while relaxing the latest constraints will provide a technical solution for the overall shift of the phase shift pattern, so the result of the phase distribution structure of the codeword 207 will not be changed.
[0097] · The reflected signal 205c of the target object 201 irradiated by a plane wave (i.e., parallel rays) is focused on a point corresponding to the focus of the paraboloid (i.e., the position of the receiver 208).
[0098] The necessary steps for constructing a codebook based on the paraboloid are described next.
[0099] Based on the positions of the transmitting and receiving antennas of the transmitter 204 and the receiver 208, the coordinates of the target object 201, and the DCS position, the determination process of the optimal paraboloid for codeword construction can be carried out as follows:
[0100] Step 1. Construct the first point P of the paraboloid that is tangent to the DCS 202. The construction process will be introduced later.
[0101] Step 2. Obtain the directrix plane of the paraboloid.
[0102] Step 3. Calculate the equation of the rotating paraboloid.
[0103] Step 4. Calculate the phase to be applied to the DCS element 203, i.e., the codeword 207.
[0104] Step 5. Apply the obtained codeword 207 to the DCS scattering element 203.
[0105] For more details on paraboloid construction, please refer to the following.
[0106] In the first step, the first point P of the desired paraboloid (i.e., the rotating paraboloid) can be constructed, and this paraboloid is tangent to the DCS surface 202a at P. This step, although not necessary, can ensure the uniqueness of the proposed paraboloid and can provide a practical and simple technical solution for calculating the paraboloid. Relaxing this condition will provide a technical solution with a similar phase pattern but differing by a modulus factor. Figure 6 The construction process of the tangent point is shown.
[0107] The tangent point P can be obtained by performing the following steps:
[0108] a. Fix the center of the main object O.
[0109] b. Construct O’, the image of O, by orthogonal symmetry with respect to the plane of the DCS surface 202a.
[0110] c. At this time, the point P is the intersection between the line (RxO’) and the plane of the DCS surface 202a. This point is the tangent point between the desired paraboloid and the plane of the DCS surface.
[0111] d. Select the object plane as the vertical plane passing through O and perpendicular to the line (PO).
[0112] The directrix axis of a parabola is a line perpendicular to the axis of symmetry of the parabola, and the distance from any point on the parabola to the parabola focus and the line called the directrix axis is equal. Since a rotational paraboloid is obtained by rotating a parabola around its axis of symmetry, the directrix plane of the paraboloid is a plane perpendicular to the axis of symmetry of the paraboloid The distance from any point on the paraboloid to the paraboloid focus and the directrix plane of the rotational paraboloid is equal. Therefore, in order to construct the directrix plane of the paraboloid that is tangent to the DCS surface 202a at the point P and has the Tx / Rx (transmitter 204 / receiver 208) as the focus, the following steps can be taken:
[0113] a. In the plane defined by the points (O, P, Rx), the axis perpendicular to the line (PRx) at the Rx position intersects the DCS plane at the point Q, which belongs to the directrix plane
[0114] b. The directrix plane can be obtained by two methods
[0115] i. Method 1: The directrix is the second tangent of the circle with center P and radius RxP, and this second tangent passes through Q
[0116] ii. Method 2: The directrix plane is the vertical plane passing through Q and perpendicular to RxQ
[0117] Figure 7 Shows the construction process of the directrix plane of the rotational paraboloid with Tx / Rx as the focus and tangent to the DCS surface 202a at the point P of the rotational paraboloid.
[0118] In the next step, the equation of the rotational paraboloid can be defined, which has Tx / Rx as the focus, is tangent to the DCS surface 202a at the point P, and has the directrix plane defined in step 2
[0119] a. The orthogonal projection of the focus Tx / Rx on the directrix can obtain the parameter p (semi-latus rectum), that is, the distance between Tx / Rx and the directrix plane The minimum distance between.
[0120] b. Once the parameter p is determined, the equation of the paraboloid of revolution can be obtained:
[0121] x 2 +y 2 = 2pz (1)
[0122] Figure 8 The result of constructing the paraboloid according to the above steps is shown.
[0123] After calculating the parameters of the paraboloid defined by equation (1), the phase shift that needs to be applied to the DCS scattering element 203 can be calculated in order to perform scattering using the same characteristics as the construction of the paraboloid reflection. This ensures that the target object 201 is irradiated by parallel rays as Figure 9 shown.
[0124] To this end, it can be assumed that if the signal 205a emitted from the Tx hits the DCS 202 at point M as Figure 10 shown, then the scattered signal 205b on the DCS surface should be parallel to the paraboloid axis and hit the object plane at V, and the scattered signal of M intersects the paraboloid at point U. As Figure 10 shown, the path difference between the first path defined by Tx, M, and B and the second path defined by Tx, U, and V generates an additional phase that needs to be compensated at the DCS 202 to match the reflection of the paraboloid. Mathematically, the phase shift that needs to be applied to each DCS scattering element 203 is calculated as follows:
[0125]
[0126] where λ is the wavelength and ‖.‖ is the Euclidean norm operator.
[0127] For each desired scan point V on the object plane, steps 1 to 5 can be performed to obtain the desired phase shift or codeword 207, as follows:
[0128]
[0129] The codebook 301 is obtained by constructing a codeword for each scan point in a set of scan points on the target object plane.
[0130] At this point, it is worth mentioning that since the construction is geometry-based, the codeword 207 can be obtained in the form of an analytical solution, which is a function of the relative positions of the transmitter 204, the receiver 208, and the DCS 202. Therefore, only one expression may need to be stored in the device 200.
[0131] In addition, the present invention describes below how to acquire or generate a hologram data set in a bistatic configuration (i.e., the transmitter 204 and the receiver 208 are not collocated). In such a configuration, two (or more than two) DCS surfaces 202a, 202b will be used, one surface 202a for illuminating the target object, and the second surface 202b for focusing the reflected rays onto the position of the receiver 208. It is also possible to use a single DCS surface 202a, which is divided into two categories, each category either for illuminating the target object 201 or for focusing the reflected rays of the target object onto the receiver 201. Both of these categories can include subsets of the scattering elements 203 of the DC surface 202a, where the two subsets of the scattering elements 203 can overlap or not. It is also possible to use a single DCS surface 202a, where the scattering elements 203 are used for illuminating the target object during a first time period and for focusing the reflected rays onto the receiver 208 during a second time period.
[0132] In Figure 11 a, an example of such a setup is shown, where two DCS surfaces 202a, 202b are used to acquire the data set in a bistatic configuration.
[0133] The first DCS surface 202a (i.e., DCS1) is responsible for illuminating the target object 201, while the second DCS surface 202b (i.e., DCS2) is responsible for focusing the reflected rays 205c of the target object 201 onto the Rx (receiver 208) antenna.
[0134] DCS1 is used to illuminate the target object 201 with parallel rays. DCS2 focuses the signal 205d onto the receiver 208 because DCS2 is configured with a codeword 207 that simulates the reflection of a PEC, the shape of which is a paraboloid of revolution with the position of the receiver 208 as the focus. The codeword update process is performed according to the steps described above (Steps 1 to 5). To obtain the codeword for DCS1, the transmitter 204 is the focus of the desired paraboloid of revolution. To obtain the codeword for DCS2, the receiver 208 is the focus of the desired paraboloid of revolution.
[0135] The bistatic setup can minimize the self-interference between the antennas of the transmitter 204 and the receiver 208.
[0136] To implement the proposed technical solution, the transmitter 204 and the receiver 208 can be embedded in an independent device, e.g., a smartphone or any device that embeds a fixed transmitter 204 and a fixed receiver 208 (whether juxtaposed or not). The DCS surface can be located in the same independent device or can maintain a fixed distance from the transmitter 204, the receiver 208, and the object plane. The position of the scanned object 201 can be estimated using the available sensors on the device (e.g., using a proximity sensor or lidar) or any other sensor that provides a range for each entity. According to the concept of the present invention, there is no need to obtain the hologram of the object 201 through a scanning motion. Instead, the device can be placed at a certain fixed position from the target object to be scanned. The DCS phase shift configuration can be managed by the controller 206, which can assign one or more appropriate codewords 207 to the DCS surface.
[0137] Figure 12 Shows different messages that may be exchanged between the DCS controller 206 and related entities to perform hologram measurements. Figure 12 Particularly shows an example of the exchange signaling that can use the proposed concept when the transmitter 204 and the receiver 208 are part of an independent device and the DCS 202 is not part of such a device.
[0138] In step 1, any related entity can initiate the scanning process.
[0139] In steps 2 and 3, the DCS controller 206 can attempt to obtain the position of the related device for target object scanning. Tx / Rx are the transmitter 204 and the receiver 208, which can be juxtaposed or not.
[0140] The target object 201 can be any object that can communicate with the scanner or can be a simple random object. If the target object 201 is active and knows its position, the DCS controller 206 can directly request the target object 201 to send its position in step 4a. However, if the target object 201 is inactive, the DCS controller 206 can request the transmitter 204 and / or the receiver 208 to perform a relative position measurement of the target object 201 in step 4b.
[0141] Then, in step 5, the transmitter 204 and / or the receiver 208 can perform all necessary measurements to estimate the relative position of the target object 201. After that, in step 6, the transmitter 204 and / or the receiver 208 can provide the estimated position of the target object 201 to the DCS controller 206.
[0142] Once the DCS controller 206 has acquired all the required information, the DCS controller 206 can generate the codebook 301 in step 7 to configure the DCS scattering surface.
[0143] In step 8.1, the DCS controller 206 can send the codewords to one or more DCS surfaces to configure the scattering elements 203. Additionally, in step 8.2, the DCS controller 206 can notify the transmitter 204 and / or the receiver 208 to perform signal transmission and data acquisition. Each codeword 207 in the codebook 301 can configure one or more DCS surfaces 202a, 202b such that the transmitted signal 205a is scattered towards the target object 201. Then, the reflected signal 205c of the target object 201 is focused on the location of the receiver 208 through the same one or more DCS surfaces or different one or more DCS surfaces.
[0144] The acquired measurements can constitute one measurement in the entire hologram dataset. Steps 8.1 and 8.2 can iterate over all the codewords 207 in the codebook 301, which can generate the desired hologram in step 9.
[0145] It should be noted that when the DCS 202 is part of an independent device, and at the same time the transmitter 204, the receiver 208, and the DCS controller 206 are also part of independent devices, Figure 12 the signaling shown will disappear because the signaling itself is part of the device. The only external information required is to detect / acquire / request the location of the target object 201 to be scanned.
[0146] The hologram dataset generation can also be performed in a network configuration application, where network entities such as user equipment (UE) or BS are part of the scanning system. Of course, in these configurations, it can be assumed that one or more DCS scattering surfaces 202a, 202b of the DCS 202 have been deployed, and the network also knows their locations. It can be assumed that there is an entity in the network, which can be called a "location server", and this location server is used to manage all the location information required by all entities in the network. This entity can be distributed or not, and can also be integrated into any other entity in the network.
[0147] Figure 13 Shows the exchange signaling between relevant network devices (e.g., BS and UE), one or more DCS surfaces of the DCS 202, the target object 201 (if it is part of a network element), and the DCS controller 206.
[0148] In step 1, any relevant entity in the network can initiate the scanning process.
[0149] In step 2, once the DCS controller 206 receives the message to start the scan, the DCS controller 206 may request the relative position of the target object 201 or the target area from the network device responsible for transmission and data acquisition.
[0150] In step 3, the network device 1301 performs all necessary measurements to estimate the relative position of the target object 201 or the scanned area.
[0151] In step 4, the network device 1301 sends the relative position of the target object 201 or the area to the DCS controller 206.
[0152] In step 5, the DCS controller 206 requests the position of the transmitter 204 (i.e., the Tx antenna) from the location server 1302.
[0153] In step 6, the location server 1302 sends the position of the transmitter 204 to the DCS controller 206.
[0154] In step 7, the DCS controller 206 requests the position of the receiver 208 (i.e., the Rx antenna) from the location server 1302.
[0155] In step 8, the location server sends the position of the receiver 208 to the DCS controller 206.
[0156] In step 9, the DCS controller 206 requests the position of one or more relevant DCS scattering surfaces during the scan.
[0157] In step 10, the location server 1302 sends the position of one or more scattering surfaces of the DCS 202 to the DCS controller 206.
[0158] In step 11, the DCS controller 202 generates the codebook required to configure the DCS scattering surface.
[0159] In step 12.1, the DCS controller 206 sends the codeword 207 to the DCS 202. In step 12.2, the DCS controller 206 triggers signal transmission and data acquisition.
[0160] Steps 12.1 and 12.2 iterate over all the codewords 207 in the codebook 301 in order to generate the desired hologram in step 13.
[0161] Optionally, the different functions provided by the controller 206 may be distributed among different entities of the network. For example, codeword generation may be performed at the BS, while hologram generation may be performed at the UE.
[0162] A direct generalization of this last implementation could be to consider multiple transmitters 204, receivers 208, and DCS scattering surfaces 202a, 202b available in the network and use them for synchronous measurements to generate holograms. The advantage of this extension is that different transmitters 204 and / or receivers 208 are used to provide multiple holograms, and these transmitters and / or receivers can be scanned simultaneously, thus providing different holograms of the target object 201.
[0163] Figure 14 Method 1400 provided by the present invention is shown. Method 1400 is used to control device 200 to generate a hologram dataset of target object 201. Similar to the above, device 200 includes DCS 202, transmitter 204, and receiver 208.
[0164] Method 1400 includes step 1401: using a set of control codewords 207 to control DCS 202 during a scanning period to scatter electromagnetic signal 205a onto target object 201 and focus the electromagnetic signal 205c reflected from target object 201 onto receiver 208. For each control codeword 207, the electromagnetic signal 205b scattered by DCS 202 to target object 201 irradiates at an angle different from other control codewords 207, and / or the electromagnetic signal 205c reflected from target object 201 is focused onto receiver 208 at an angle different from other control codewords 207. Method 1400 further includes step 1402: generating a hologram dataset of target object 201 based on the focused electromagnetic signal 205d received by receiver 208 during the scanning period.
[0165] It should be noted that in the present invention, the scattering surfaces 202a, 202b of DCS 202 can have different configurations. As Figure 15 exemplarily shown, the scattering surfaces 202a, 202b of DCS 202 can have different shapes. For example, the scattering surfaces 202a, 202b of DCS 202 can be planar and non-planar. DCS 202 can include a first scattering surface 202a with a first configuration and a second scattering surface 202b with a second configuration.
[0166] The present invention has been described in conjunction with various embodiments as examples and implementations. However, upon study of the drawings, the present invention, and the independent claims, those skilled in the art will be able to understand and implement other variations when implementing the claimed subject matter. In the claims and the specification, the word "comprising" does not exclude other elements or steps, and the quantifier "a" does not exclude a plurality. A single element or other unit can fulfill the functions of several entities or items described in the claims. Listing certain measures in mutually different dependent claims does not mean that a combination of these measures cannot be used in an advantageous implementation.
Claims
1. An apparatus (200) for generating a hologram data set of a target object (201), characterized in that, the apparatus (200) comprises: a digitally controllable scatterer (DCS) (202), wherein the DCS (202) includes one or more scattering surfaces (202a, 202b), the one or more scattering surfaces (202a, 202b) include a set of scattering elements (203), and each scattering element (203) has a controllable phase shift; a transmitter (204) for transmitting an electromagnetic signal (205) onto the DCS (202) during a scanning period; a controller (206) for controlling the DCS (202) using a set of control codewords (207) during the scanning period to scatter the electromagnetic signal (205) onto the target object (201) and focus the electromagnetic signal (205) reflected from the target object (201) onto a receiver (208); the receiver (208) for receiving the electromagnetic signal (205) focused by the DCS (202), wherein, each control codeword (207) defines a corresponding phase shift configuration for at least one subset of the scattering elements (203) of the DCS (202), for each control codeword (207), the electromagnetic signal (205) scattered by the DCS (201) to the target object (201) is irradiated at an angle different from other control codewords (207), and / or the electromagnetic signal (205) reflected from the target object (201) is focused onto the receiver (208) at an angle different from other control codewords (207), the controller (206) is further configured to generate the hologram data set of the target object (201) according to the focused electromagnetic signal (205) received by the receiver (208) during the scanning period.
2. The apparatus (200) according to claim 1, characterized in that, the positions of the transmitter (204), the receiver (208), and the positions and orientations of the one or more scattering surfaces (202a, 202b) of the DCS (200) are fixed relative to each other and relative to the target object (201) during the scanning period.
3. The apparatus (200) according to claim 1 or 2, characterized in that, the transmitter (204) and the receiver (208) are juxtaposed; the DCS (202) includes a scattering surface (202a), and the scattering surface (202a) includes the set of scattering elements (203); The controller (206) is configured to use the set of control codewords (207) to control the set of scattering elements (203) of the scattering surface (202a) within the scan period to scatter the electromagnetic signal (205) onto the target object (201) and to focus the electromagnetic signal (205) reflected from the target object (201) onto the receiver (208).
4. The apparatus (200) according to claim 1 or 2, wherein, the transmitter (204) and the receiver (208) are non - collocated; the DCS (202) includes a scattering surface (202a), and the scattering surface (202a) includes the set of scattering elements (203); the controller (206) is configured to use a first subset of the control codewords (207) to control a first subset of the scattering elements (203) of the scattering surface (202a) within the scan period to scatter the electromagnetic signal (205) onto the target object (201); the controller (206) is configured to use a second subset of the control codewords (207) to control a second subset of the scattering elements (203) of the scattering surface (202a) within the scan period to focus the electromagnetic signal (205) reflected from the target object (201) onto the receiver (208).
5. The apparatus (200) according to claim 3 or 4, wherein, except for the scattering surface (202a) including the set of scattering elements (203), the DCS (202) does not include other scattering surfaces.
6. The apparatus (200) according to claim 1 or 2, wherein, the transmitter (204) and the receiver (208) are non - collocated; the DCS (202) includes a first scattering surface (202a) and a second scattering surface (202b), the first scattering surface (202a) includes a first subset of the scattering elements (203), and the second scattering surface (202b) includes a second subset of the scattering elements (203); the controller (206) is configured to use a first subset of the control codewords (207) to control the first subset of the scattering elements (203) of the first scattering surface (202a) within the scan period to scatter the electromagnetic signal (205) onto the target object (201); the controller (206) is configured to use a second subset of the control codewords (207) to control the second subset of the scattering elements (203) of the second scattering surface (202b) within the scan period to focus the electromagnetic signal (205) reflected from the target object (201) onto the receiver (208).
7. The apparatus (200) according to claim 6, wherein, The first scattering surface (202a) and the second scattering surface (202b) are independent parts of the DCS (202) and can be independently controlled by the controller (206).
8. The apparatus (200) according to any one of claims 1 to 7, wherein, for each control codeword (207), the controller (206) is configured to control the DCS (202) to scatter the electromagnetic signal (205) onto the target object (201) as a plane electromagnetic wave.
9. The apparatus (200) according to any one of claims 1 to 8, wherein, the set of control codewords (207) forms a codebook (301), wherein the codebook (301) is adapted to the characteristics of the transmitter (204), the receiver (208), and the one or more scattering surfaces (202a, 202b) of the DCS (202).
10. The apparatus (200) according to claim 9, wherein, the controller (206) is configured to generate the codebook (301) at least based on the relative positions of the transmitter (204), the receiver (208), the one or more scattering surfaces (202a, 202b) of the DCS (202), and the target object (201).
11. The apparatus (200) according to claims 9 and 10, wherein, the controller (206) is configured to generate the codebook (301), the codebook (301) includes the set of control codewords (207), and the set of control codewords (207) is selected such that: when the set of control codewords (207) is used during the scanning period, the DCS (202) scatters the electromagnetic signal (205) onto the target object (201), simulating the reflection of a perfect electric conductor having the shape of a paraboloid of revolution.
12. The apparatus (200) according to any one of claims 1 to 11, wherein, the controller (206) is configured to obtain the corresponding relative positions of the transmitter (204), the receiver (208), the target object (201), and the one or more scattering surfaces (202a, 202b) of the DCS (202) and the corresponding characteristics of the one or more scattering surfaces (202a, 202b) of the DCS (202) through signaling of at least one of the transmitter (204) and the receiver (208).
13. The apparatus (200) according to claim 11 or 12, wherein, at least one of the transmitter (204) and the receiver (208) is configured to perform measurements on the relative position of the target object (201) relative to the transmitter (204) and the receiver (208).
14. A method (1400) for controlling an apparatus (200) to generate a holographic data set of a target object (201), wherein, the apparatus (200) comprises: Digitally controllable scatterer (DCS) (202), wherein the DCS (202) includes one or more scattering surfaces (202a, 202b), and the one or more scattering surfaces (202a, 202b) include a set of scattering elements (203), and each scattering element (203) has a controllable phase shift; A transmitter (204) for transmitting an electromagnetic signal (205) onto the DCS (202) during a scan period; A receiver (208) for receiving, during the scan period, an electromagnetic signal (205) that is reflected from the target object (201) onto the DCS (202) and focused by the DCS (202) onto the receiver (208); The method (1400) includes: During the scan period, using a set of control codewords (207) to control (1401) the DCS (202) to scatter the electromagnetic signal (205) onto the target object (201) and to focus the electromagnetic signal (205) reflected from the target object (201) onto the receiver (208), wherein Each control codeword (207) defines a corresponding phase shift configuration for at least one subset of the scattering elements (203) of the DCS (202), For each control codeword (207), the electromagnetic signal (205) scattered by the DCS (202) to the target object (201) is irradiated at an angle different from other control codewords (207), and / or the electromagnetic signal (205) reflected from the target object (201) is focused onto the receiver (205) at an angle different from other control codewords (207); Generating (1402) the hologram dataset of the target object (201) based on the focused electromagnetic signal (205) received by the receiver (208) during the scan period.
15. A computer program comprising instructions, Characterized in that, When the program is executed by a processor, the instructions cause the processor to execute the method (1400) for controlling (1401) the DCS (202) and for generating (1402) the hologram dataset according to claim 14.