High-frequency detection method and device

Abstract

A high frequency detection system (100), such as a terahertz camera, includes a first detector array (102), a second detector array (104), and a polarizing plate (106). The polarizing plate is interposed between the detector arrays such that it transmits a radiation signal (110) from a source (108) through and / or reflected to the detector arrays. A first radiation signal (112) having a first polarization passes through the polarizing plate to the first detector array, and a second radiation signal (114) having a second polarization is reflected from the polarizing plate to the second detector array. Both radiation signals come from a source (108), which may be one or more persons emitting radiation to the detection system. In some embodiments, the detector arrays (102, 104) may be connected. Each detector array includes one or more input channels for capturing radiation from a source (108) and passing received signals through other parts of the system for subsequent processing. The input channel and the local oscillator channel are aligned with an axis, and the output channel is aligned with an axis perpendicular thereto.

Description

[0001] This application is a divisional application of the invention patent application with the application date of October 16, 2020, the invention name of “High-frequency detection method and device” and the application number of 202080067640.8. Technical Field

[0002] The present disclosure relates to high frequency electronic systems, and in particular to detection systems and methods of making and using the same. Background Art

[0003] High frequency systems can be used to generate images by detecting radiation received from an object or scene and then processing the detected radiation. Both active imaging systems and passive imaging systems exist. In active imaging, a radiation source (e.g., a terahertz source) can be used to illuminate an object or field of view and provide radiation for detection. In passive imaging, there is no illumination source. Instead, the system receives radiation emitted from the object or scene itself. The detected radiation can be at a single frequency (e.g., a frequency band centered on a single frequency), or in some instances, at multiple frequencies (e.g., in multiple different frequency bands or overlapping frequency bands).

[0004] In WO2013 / 117920, a multi-frequency imaging method and apparatus are provided, wherein an imaging system is described, the imaging system having at least one terahertz receiver adapted to receive radiation of different frequencies in the same time period, an image processor and a synthetic image generator. The image processor provides image data about a field of view at each corresponding frequency, and the synthetic image generator generates synthetic image data about a common area based on at least a portion of the image data provided by the image processor.

[0005] Furthermore, the field of view may be scanned, for example, by using a scanning mirror or reflector that directs radiation toward one or more detector arrays. As described in UK patent application GB 2519233, a terahertz detection device may include one or more detectors and a scanning mechanism for scanning the field of view, the scanning mechanism comprising: (i) a detection system for locating an object of interest; and (ii) a steering mechanism that may receive a control signal based at least in part on an output of the detection system and send a steering signal for steering the scanning mechanism.

[0006] However, there remains a need for improved detection systems and methods that can fully utilize available radiation from a source or scene to provide optimized imaging in an efficient and scalable arrangement while maintaining any necessary spatial alignment requirements. Additionally, there remains a need for systems with layouts and components that can be efficiently machined. Summary of the invention

[0007] According to an embodiment, a detection system is provided, comprising a first detector array, a second detector array, and a polarization element (such as a polarization plate) interposed between the first detector array and the second detector array. The polarization plate is arranged to transmit a first radiation signal having a first polarization through to the first detector array and reflect a second radiation signal having a second polarization to the second detector array. In some embodiments, the polarization plate comprises a wire grid at a 45 degree angle to the first detector array and the second detector array, and the first polarization is a vertical polarization and the second polarization is a horizontal polarization.

[0008] According to some embodiments, a system is provided, which includes a first electronic device, a second electronic device, a power supply and an unequal power splitter. In some aspects, the power supply is coupled to the input of the unequal power splitter via a waveguide and a power signal (e.g., a local oscillator signal) is delivered to the unequal power splitter. Additionally, a first output of the unequal power splitter is coupled to the first electronic device via a waveguide, and a second output of the unequal power splitter is coupled to the second electronic device via a waveguide. In some embodiments, the unequal power splitter is configured to provide a first part of the power signal by the first output and a second part of the power signal by the second output, wherein the first part is greater than the second part. Unequal power signals can be used to drive one or more frequency multipliers with different efficiency levels.

[0009] According to some embodiments, a detection system is provided. The detection system includes, for example, a first detector block, a local oscillator (LO) source, and one or more intermediate frequency (IF) processing circuits. In some embodiments, the first detector block includes: one or more heterodyne mixer elements; one or more LO input waveguide channels configured to provide LO signals from the LO source to the one or more heterodyne mixer elements; one or more waveguide horn feeds configured to provide detected radio frequency (RF) signals to the one or more heterodyne mixer elements; and one or more IF output channels configured to provide IF signals from the one or more heterodyne mixer elements to the one or more IF processing circuits. The one or more waveguide horn feeds and the one or more LO input waveguide channels extend along a first axis of the first detector block, and the one or more IF output channels extend along a second axis of the first detector block, wherein the first axis and the second axis are perpendicular. According to an embodiment, the input channel and the output channel are in orthogonal planes. Although described as perpendicular in some examples, some embodiments may include an IF output channel in a non-orthogonal plane different from the waveguide horn feed and / or LO input.

[0010] According to an embodiment, a detection system is provided, which includes a first detector array block and a second detector array block stacked on the first detector array block. In this example, the first detector block array and the second detector block array each include at least one signal input extending along a first axis, at least one power input extending along the first axis, and at least one signal output extending along a second axis, wherein the first axis and the second axis are perpendicular. In some aspects, each of the first detector block array and the second detector block array includes one or more stacking notches. The first detector block array and the second detector block array can also be the same modular unit. Additionally, one or more signal inputs of each of the first detector array block and the second detector array block can include at least two rows of horn feeds and at least two columns of horn feeds (e.g., a 2×2 array or a 2×4 array).

[0011] According to an embodiment, a detection module for a scalable imaging system is provided. The module may include: one or more signal inputs extending along a first axis; one or more power inputs extending along the first axis; one or more signal outputs extending along a second axis; and a first stacking notch, wherein the first axis and the second axis are perpendicular. In some aspects, the signal input includes one or more radio frequency horn feeds, the power input includes one or more local oscillator channels, and the signal output includes one or more intermediate frequency output channels. According to an embodiment, the horn feed and the oscillator channel are in a first plane, and the IF channel is in a second orthogonal plane. The module may also include a second stacking notch, and the two notches may be angled. In some embodiments, the module is a block including a first side, a second side, a third side, a fourth side, a fifth side, and a sixth side, wherein the first side and the second side are opposite sides of the detection module, the third side and the fourth side are opposite sides of the detection module, and the fifth side and the sixth side are opposite sides of the detection module. Additionally, in some embodiments, the one or more signal inputs are located on the first side, the one or more power inputs are located on the second side, and the one or more signal outputs are located on the third side or the fourth side; the first stacking recess is located on the fifth side, and the second stacking recess is located on the sixth side.

[0012] According to an embodiment, a detection method is provided. The method may include the following steps: receiving a first radiation signal having a first polarization at a first detector block of a camera, wherein the first radiation signal is received from a radiation source through a polarization plate; receiving a second radiation signal having a second polarization at a second detector block of the camera, wherein the second radiation signal is received from the radiation source as a signal reflected from the polarization plate; processing the first radiation signal to form first detection information; and processing the second radiation signal to form second detection information. In some embodiments, the method includes transmitting at least one of the received first radiation signal and the second radiation signal through a polarization rotation element before the processing.

[0013] According to some embodiments, a method of manufacturing a detector block is provided. The method may include the steps of: machining a first housing component including a first radio frequency (RF) channel portion, a first local oscillator (LO) channel portion, a first intermediate frequency (IF) channel portion, a polarization rotation portion, and a first mixer mounting cavity; and machining a second housing component including a second radio frequency (RF) channel portion, a second local oscillator (LO) channel portion, a second intermediate frequency (IF) channel portion, a polarization rotation portion, and a second mixer mounting cavity. Additional steps may include: mounting a heterodyne mixer in the first mounting cavity and / or the second mounting cavity; and attaching the first housing component to the second housing component to form a first detector block. Additionally, and in some instances, the first RF channel portion and the first LO channel portion are machined along a first axis of the first housing component, and the first IF channel portion is machined along a second perpendicular axis of the first housing, and the second RF channel portion and the second LO channel portion are machined along a first axis of the second housing component, and the second IF channel portion is machined along a second perpendicular axis of the second housing. Attaching a second detector block to the first detector block may form an integrated array. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate various embodiments.

[0015] Figure 1A and Figure 1B A detection system according to some embodiments is illustrated.

[0016] Figure 2A , Figure 2B and Figure 2C A waveguide portion according to some embodiments is illustrated.

[0017] Figure 3is a schematic diagram illustrating a system according to some embodiments.

[0018] Figure 4A and Figure 4B is a diagram illustrating blocks according to some embodiments.

[0019] FIG. 5A to FIG. 5C A rotating component and a shunt component are illustrated according to some embodiments.

[0020] Figure 6 is a diagram of image formation according to an embodiment.

[0021] Figure 7 is a diagram of image formation according to an embodiment.

[0022] Figure 8 is a diagram of image formation according to an embodiment.

[0023] Fig. 9 is a diagram of image formation according to an embodiment.

[0024] Fig.10 is a flow chart illustrating a process according to some embodiments.

[0025] Fig.11 is a flow chart illustrating a process according to some embodiments.

[0026] FIG. 12A to FIG. 12C A detector block and assembly process according to some embodiments are illustrated.

[0027] Fig.13A and Fig. 13B is an illustration of a system according to some embodiments. DETAILED DESCRIPTION

[0028] In the security industry, detecting and identifying threats carried by people is a key area of ​​interest. In particular, there remains a need for a system that can achieve detection at a considerable distance, in an outdoor environment, and in real time so that threats can be addressed before escalation. However, and particularly for passive systems, such detection and identification may require the ability to handle changing outdoor weather, atmospheric, geographic, and seasonal conditions. Aspects of the present disclosure address these needs by using detector settings and geometries that can achieve maximum signal capture while maintaining the temporal and spatial alignment required for real-time threat analysis. The systems and methods described herein can be used to detect and identify weapons, threats, illegal goods, and stolen items, and can be deployed in indoor or outdoor environments.

[0029] According to an embodiment, a polarization beam combiner is used to align and cover the field of view of one or more detectors, which are used together with a waveguide polarization rotator and adjustable local oscillator power to allow the use of a wide frequency range, while reducing cost, and providing a compact and configurable front-end receiver module layout. Aspects of the present disclosure enable the use of multiple frequencies, or simultaneous capture of dual polarization single frequency data, or any combination of the above. For example, an embodiment can be used to capture data using 1 to 4 frequencies.

[0030] Figure 1A and Figure 1B A detection system 100 according to some embodiments is shown. The system may be, for example, a high frequency detection system, such as a terahertz camera. Figure 1B Shows Figure 1A A top view depiction of the system 100 is shown in FIG.

[0031] Reference now Figure 1A , the system 100 may include a first detector array 102, a second detector array 104, and a polarization element 106, such as a polarization plate. Figure 1A As shown in , the polarization plate 106 can be inserted between the detector arrays 102, 104 so that it transmits the radiation signal 110 from the source 108 through and / or reflects to the detector arrays 102, 104. According to an embodiment, a first radiation signal 112 having a first polarization (e.g., vertical polarization) is transmitted through the polarization plate 106 to the first detector array 102, and a second radiation signal 114 having a second polarization (e.g., horizontal polarization) is reflected from the polarization plate 106 to the second detector array 104. Figure 1A and Figure 1B In the illustration of , both radiated signals come from source 108, which may be, for example, one or more persons emitting radiation 110 toward detection system 100. Other sources may include, for example, a single object of interest (such as a vehicle or structure) or an entire scene with multiple objects. Additionally, radiated signal 110 from source 108 may actually originate from an auxiliary source (not shown), as in an active detection system. In this case, signal 110 may be reflected from source 108 toward system 100. That is, system 100 may be part of a passive or active detection implementation.

[0032] According to some embodiments, system 100 does not require any optical elements to be interposed between polarization plate 106 and either first detector array 102 or second detector array 104. Figure 1A and Figure 1B104, additional array blocks may be used in the system 100, such as on top of or adjacent to the arrays 102, 104. Furthermore, while the system 100 is illustrated as having the detector array blocks 102, 104 spaced apart, in some embodiments, the arrays may be joined. For example, in some embodiments, the detector array block 102 may be stacked on top of the array block 104, or placed directly adjacent to and connected to the block 104, such as in FIG. 12A to FIG. 12C In such cases, the use of polarizing plate 106 may be unnecessary.

[0033] Each of the detector arrays 102, 104 may include one or more input channels, such as horn feeds 116, 118, 120. According to an embodiment, the horn feeds capture radiation from the source 108 and pass the received signals to other parts of the system for subsequent processing. For example, the horn feed 116 may capture radiation 112 transmitted through the polarization plate and the horn feeds 118 and 120 may capture radiation 114 reflected from the polarization plate 106. Although depicted as a circular waveguide in this example, other forms of waveguides (e.g., elliptical or rectangular waveguides) may also be used.

[0034] According to some embodiments, the first detector array includes a first plurality of horn feeds having a first width and having a spacing equal to or greater than the first width, and the second detector array includes a second plurality of horn feeds having a second width and having a spacing equal to or greater than the second width. That is, the horn feeds may be substantially spaced apart. Additionally, a first processing circuit may be located between the horn feeds of the first detector array, and a second processing circuit may be located between the horn feeds of the second detector array.

[0035] Although in Figure 1A , respectively, but the first detector array 102 may have more than two horn feeds in each of the horizontal and vertical directions of the array, and similarly, the second detector array 104 may have more than two horn feeds in each of the horizontal and vertical directions of the array. According to an embodiment, the detector array blocks 102, 104 may be formed of multiple sub-blocks, for example, as in Figure 4A , Figure 4B and FIG. 12A to FIG. 12C As shown in the figure.

[0036] like Figure 1BAs shown in , and according to some embodiments, the polarizing plate 106 can be aligned at a 45-degree angle to each of the first detector array 102 and the second detector array 104. However, the plate 106 can be aligned at different angles in certain arrangements, for example, to take into account the specific alignment or spacing of one or more of the detectors 102, 104. That is, the polarizing plate can be aligned at an angle greater than or less than 45 degrees. In some embodiments, the polarizing plate includes a wire grid structure. In this example, the wire grid is used to transmit vertically polarized radiation 112 from the source 108 and reflect horizontally polarized radiation from the source 108. Although described as having a wire grid and horizontal / vertical polarization, in some instances, a multilayer dielectric polarizer plate and a frequency selective surface can be used. Although illustrated as a flat plate, the polarizing plate 106 does not need to have a flat surface and can take the form of a lens or other curved structure. According to an embodiment, the polarizing element (e.g., 106) has low insertion loss both in the through mode and in the reflection mode. In some aspects, the polarizing element is used as a free space polarization duplexer or an orthogonal mode converter.

[0037] like Figure 1A and Figure 1B , the system may further include a scanning mechanism 126. The scanning mechanism 126 may be based on one or more movable mirrors that reflect incoming radiation onto one or more detectors (such as arrays 102, 104). The image may be recovered by scanning (e.g., moving) the mirror so that the detector effectively follows a scanning raster relative to the field of view. The mirror may be moved so as to produce a scanning raster comprising spaced apart scan lines, and the mirror may be moved in different ways in different directions to produce the scanning raster. For example, the mirror may reciprocate around a first axis to form the scan lines, plus perform a step-wise rotation around a second axis to set the scan line spacing. Structurally, in some embodiments, the scanning mechanism may include: (i) a mirror structure mounted to rotate about a first axis; (ii) an intermediate support structure for carrying the mirror structure, the intermediate support structure being mounted to rotate about a second axis; (iii) a base support structure for carrying the intermediate support structure; (iv) a mirror drive mechanism, partially mounted on the intermediate support structure and partially mounted on the mirror structure to drive the mirror structure to rotate about the first axis; and (v) an intermediate drive structure, partially mounted on the base support structure and partially mounted on the intermediate support structure to drive the intermediate support structure to rotate about the second axis, whereby the mirror structure may be driven to rotate about either or both of the first and second axes. The mirror itself may be a thin metal (e.g., aluminum) mirror, comprising a thin (e.g., 0.5 mm) sheet with or without reinforcing ribs.

[0038] Adaptive scanning mirrors can be used to scan the field of interest in the continuous detection of the field of view. The "field of view" in this context is intended to refer to the area of ​​the scene observed or sensed by the detection system or by one or more of the detector elements. That is, it is intended to refer to the area of ​​the scene that is currently being imaged or sensed by the detector due to, for example, the movement of the scanning mirror. For example, in imaging, in order to give continuous frames related to the scene, each frame will show the field of view. The "field of interest" in this context is intended to refer to the maximum area of ​​the scene that the system / detector can access by turning the scanning mirror without moving the detector. With respect to the detection system 100, the field of interest refers to the angular range within which the detection system can detect objects of interest. According to an embodiment, the detector output is converted into graphic data to support a screen-based representation of the detected field of view, and can, for example, be combined to form a composite image of the field of view. Additionally, fields of view in different frequency bands can be combined to form a composite image of the field of view.

[0039] Reference now Figure 2A , showing a cross-sectional view of a portion of the detector array 102 according to some embodiments. Portions of various waveguide channels including the horn feed 116 and the local oscillator (LO) channel 202 according to an embodiment are shown. Further, detail A shows a polarization rotation element 204, which according to some embodiments may be located in one or more channels, such as in a channel of the horn feed 116 or a connected waveguide for the RF path. The polarization element 204 can rotate the polarization of the signal along the channel (e.g., from horizontal polarization to vertical polarization, or vice versa), and can include multiple steps of mode conversion. This can be, for example, to prepare the signal for subsequent processing, or to reduce propagation losses along the length of the channel. For example, the subsequent processing can be in the mixer stage 206. According to an embodiment, a three-step mode converter is provided, wherein each step couples a mode from the former into the latter, thereby each step rotates the electric field orientation by approximately 30 degrees. According to some embodiments, a two-step rotation is provided, wherein each step has a 45 degree rotation. Figure 2A Also illustrated is a signal output 208 from the mixer stage 206, such as an IF signal, which may extend upward and / or downward and perpendicular to the plane of the horn feed 116 and the LO channel 202. That is, the output signal channel may be orthogonal to the input signal channel (e.g., the horn feed and the LO channel). According to an embodiment, the IF output channel 208 may include a coaxial cable for carrying the signal.

[0040] In some embodiments, a waveguide (such as a channel of the detector arrays 102, 104) may be machined into two halves and then connected, such as Figure 2B and Figure 2CAs shown in the figure. Figure 2B A low loss waveguide is illustrated that reduces loss in some instances by using a mirrored half waveguide that branches along the top wide wall (i.e., along the wider cross section). In this example, a first half 210 is combined with a second half 212 to form a waveguide having a branch 214 such that the branch is along the wider top and bottom surfaces of the waveguide channel. In other instances, and as Figure 2C , the waveguide may be formed with a first half 222 and a second half 224 such that the shunt 226 passes through the shorter sidewall of the resulting waveguide. In some arrangements, having the shunt 214 may produce less loss than having the shunt 226. Therefore, and in accordance with some embodiments, the rotation element 204 may be used to rotate the signal from a high loss shunt waveguide (e.g., 226) to a low loss shunt waveguide (e.g., 214). Depending on the input signal, the arrangement may be reversed.

[0041] The waveguide is most easily formed by machining a slot of appropriate size into either face of a block of metal. At higher frequencies, e.g. above 30 GHz, it is often necessary to split the waveguide at the midpoint of its wide wall in order to minimize ohmic losses, e.g. Figure 2B This is because: at higher frequencies, ohmic losses dominate due to the current being limited by the skin effect, and therefore, surface finish becomes very important. Additionally, the current in a rectangular waveguide travels along the wide walls and down the narrow walls. The propagating signal is therefore relatively unaffected by small gaps in the wide walls, while gaps in the narrow walls produce signal losses because the gaps effectively form an open circuit for the current.

[0042] In certain aspects, the problem of increased losses when a waveguide is shunted across narrow and wide walls is frequency dependent. As frequency increases, any small gap between the faces effectively represents a larger portion of the wavelength and thus increases losses. As the space required for the clamping screws gets smaller, it becomes increasingly difficult to clamp the waveguides together, and therefore, the gaps are more difficult to close. Aspects of the present disclosure mitigate this problem by using a polarization rotator at relatively low frequencies (e.g., 125 GHz) and by keeping the polarization rotator as short as possible.

[0043] Reference now Figure 3, a schematic depiction of a detection system 300 according to some embodiments is provided. Radiation may be received at inputs 302, 304, and 306, which may be horn feeds of blocks 308, 310, and 312, respectively. In some embodiments, block 308 may correspond to detector array 102, and blocks 310 and 312 may each form a portion of detector array 104. Radiation signals received at inputs 302, 204, 306 are each passed to mixer elements depicted as elements 314a, 314b, and 314c. In some embodiments, one or more of the received signals may be rotated, for example by an optional polarization rotation element 316, before being processed by the mixer. Processed signals, such as one or more intermediate frequency (IF) signals, from the mixer are passed to the outputs (318a, 318b, 318c) of each block for subsequent additional processing by low noise amplifiers (LNAs) (320a, 320b, 320c), power detectors (321a, 321b, 321c), and analog-to-digital converters (ADCs) (322a, 322b, 322c). The additional processing may include filtering. The digital signal may then be passed to an image generator 324 to form an image based on the detected radiation, such as by forming a composite image of an object or scene using the radiation received at 302, 304, and 306. The image processing 324 may be coupled to, or be part of, a viewing system 336, such as a computer or monitor. In some embodiments, a coaxial cable is used within each block to output the IF signal.

[0044] Although this system is depicted as having three mixer elements or inputs, it may be implemented with more or fewer mixer elements or inputs. For example, system 300 may be expanded to include a fourth set of input horn feeds, each with a corresponding set of mixers and processing circuits.

[0045] In some embodiments, local oscillator (LO) signals are provided to the mixers of system 300 by using fewer LO sources than mixers. Figure 3In the example illustrated in , a single LO source 326 provides an LO signal to each of mixers 314a to 314c. According to an embodiment, this is accomplished by using one or more power dividers 328a, 328b and in some instances by using one or more frequency multipliers 330a to 330c (such as doublers or triplers). For example, the original LO signal from source 326 can be provided to divider 328a, and divider 328a in turn provides a signal to divider 328b and optional multiplier 330a. Multiplier 330 can be used to provide a higher LO signal than that provided by source 326 to mixer 314a. Similarly, divider 328b can provide signals to optional multipliers 330b and 330c for mixers 314b and 314c. In this regard, each of blocks 308, 310, and 312 can be configured to operate at different frequencies / wavelengths. Such configurations may include, for example, mixer design and the shape and size of the input horn feeds (116, 118, and 120). Thus, radiation signals of different wavelengths may be detected, processed, and used by processing circuitry 324 to form a composite image using data from multiple wavelengths. One or more amplifiers, such as amplifier 332, may be used to boost signals between sources, splitters, multipliers, and / or mixers. Figure 3 Other amplifiers are shown in the examples.

[0046] Depending on the application, the horn feed size should be chosen to provide optimal coupling with the chosen optics, and the spacing should be chosen to provide optimal coverage.

[0047] In certain aspects, the components are optimized to minimize the amount of LO power reflected from the RF coupling circuit over as wide a range of circuit operating conditions as possible. This limits the reflected LO signal from propagating back into one or more LO power splitters, thereby limiting interference between channels. To further reduce reflection issues, a 90 degree 3dB hybrid power splitter (such as a Magic-T) or a 3dB hybrid branch waveguide coupler may be implemented.

[0048] According to some embodiments, one or more of the distributors 328a and 328b are as described with respect to FIG. 5A to FIG. 5C The unequal dividers described. According to some embodiments, multipliers 330a and 330b are doublers, while multiplier 330c is a tripler. In some embodiments, one or more of the multipliers are not required. For example, multiplier 330a can be omitted in some embodiments.

[0049] According to some embodiments, a common local oscillator source 326 is provided, the frequency is multiplied using different order frequency multipliers (e.g., doublers and triplers), and subharmonic mixers are implemented. For example, mixers 314a to 314c can operate in frequency bands centered at frequencies of 125 GHz, 250 GHz, and 375 GHz, respectively, which can use local oscillator frequencies of 62.5 GHz, 125 GHz, and 187.5 GHz. In this example, the basic local oscillator source 326 can be a Gunn oscillator operating at 62.5 GHz providing approximately 100 mW. This is divided into two equal signals using a splitter such as divider 328a. This can be an equal power splitter such as a standard magic T, or an unequal splitter, such as with respect to FIG. 5A to FIG. 5CDescribed. Half of the splitter output pumps the 125 GHz array (block 308 in this example), and the other half is input to a power amplifier (e.g., amplifier 332 in this example) to give a signal of approximately 400 mW, which is then used to pump frequency multipliers 330 b and 330 c. In view of the use of subharmonic mixers at the exemplary frequency, multiplier 330 a is not required in this example. In some embodiments, the system is optimized by using a configurable unequal power divider to provide optimal power to the 125 GHz array and power amplifier. Each frequency mixer array requires similar local oscillator power, 30 mW to 40 mW in this example. However, the typical efficiency of a doubler is 40%, while the typical efficiency of a tripler is 15%. This means that using an equal power splitter such as the Magic T may result in too much power (80 mW) being generated for the 250 GHz array (e.g., block 310 in this example) and marginal power being generated for the 375 GHz array (e.g., block 312 in this example). Conventional power splitters such as the Magic T rely on the input power being divided into two equal halves, however, if such an approach were used for this embodiment, it would result in too much power being supplied to the 125 GHz doubler (e.g., multiplier 330 b) and insufficient power being supplied to the 187.5 GHz tripler (e.g., multiplier 330 c). Therefore, in order to supply sufficient power to the tripler, which is typically less efficient than the doubler, the power amplifier would need to be over-regulated and the power going to the doubler would be unnecessarily attenuated (otherwise it could be damaged). This is not only costly and wasteful of LO signals, but can also be difficult to implement using existing technology and results in higher electrical bias power and heat removal requirements. Thus, and in accordance with an embodiment, a configurable power divider is used that can arbitrarily split the local oscillator pump power into two or more paths, thereby allocating power to the multipliers of each local oscillator arm according to their respective power requirements. According to an embodiment, dividers 328a and / or 328b are configurable. Thus, a system can be provided in which the LO power requirements of the overall system are minimized (and thereby the cost) by matching the power splits to each frequency arm so that the delivered power matches the peak efficiency input power requirement of each corresponding multiplier.

[0050] According to some embodiments, one or more blocks configured to receive and process radiation at a fourth frequency may be provided. For example, one or more blocks may be configured at 500 GHz. The mixers for such blocks may similarly operate using the same LO source, e.g. Figure 3 One or more of the LO paths shown in FIG. 104 may have additional dividers and / or doublers in them. In some embodiments, the blocks may be sub-blocks or arrays 102 , 104 .

[0051] According to some embodiments, LO source 326 may have multiple outputs at one or more frequencies, and the initial divider 328a and / or multiplier 330a may not be required. In some embodiments, one or more of divider 328a and multiplier 330a are integrated into local oscillator source 326, so that source 326 provides multiple frequency signals at configurable powers. Although two outputs are used by way of example, this embodiment can be expanded by using additional unequal power splitters and / or multipliers.

[0052] Reference now Figure 4A and Figure 4B , illustrates one or more detector array blocks according to some embodiments. These detector array blocks may correspond to, for example, arrays 102, 104 and blocks 308, 310, 312. Arrays such as arrays 102, 104 may be formed as a single block (e.g., as Figure 4A ). Moreover, arrays such as arrays 102, 104 may be formed from multiple blocks (e.g., having Figure 4B In the example of FIG. 1 , a plurality of sub-blocks are formed to form a combined detection block having multiple rows of horn feeders and multiple columns of horn feeders. Additionally, and according to an embodiment, each sub-block may be formed of two parts, such as Fig. 12A As shown in the figure, Fig. 12A The attachment of half block portion 1202 to another half block portion 1204 is shown.

[0053] Reference now Figure 4A , block 400 according to some embodiments is provided. In one example, one or more of the detector arrays 102, 104 can include block 400. Block 400 includes one or more signal inputs 402, one or more auxiliary inputs 404, and one or more outputs 406. For example, the signal input 402 can correspond to Figure 1A , Figure 1B , Figure 2 and Figure 3 4. Similarly, the auxiliary input 404 may be an LO signal input, such as a LO signal input for a plurality of detector horn feeds 116, 118, or 120 as shown in FIG. Figure 2A and Figure 3 Output 406 may be a detected signal output, such as one or more IF signals from a mixer, such as a combination of Figure 3 According to an embodiment, the inputs are arranged in the same plane and the outputs are arranged in orthogonal planes. Figure 4AIn the example of , inputs 402, 404 are arranged along the z-axis, and output 406 is arranged along the x-axis. Each of inputs 402, 404 extends through block 400 along the z-axis, while each of outputs 406 extends through block 400 along the x-axis in an orthogonal manner. According to an embodiment, processing circuits can be connected to outputs 406. For example, multiple processing circuit units can be arranged in the y-axis direction to process signals output from block 400. Similarly, additional blocks (e.g., 400) can be stacked in the y-axis direction to expand the detector. A similar arrangement in Figure 4B Such circuits may include, for example, one or more LNAs, wideband power detectors, and / or ADCs, as described with respect to Figure 3 As shown. In some embodiments, the power detector is used to convert broadband microwave power to a baseband signal by a thermal member (e.g., a bolometer) or by using an amplitude modulation (AM) detector. Additionally, the processing circuit may include one or more filters, for example, on both sides of the LNA or ADC. According to an embodiment, a power detector such as 321a, 321b, 321c detects power across the entire frequency band and outputs a voltage related to the power.

[0054] Reference now Figure 4B , and according to an embodiment, a first block (e.g., block 400) can be combined with a second block (e.g., 450) to form a single detection array block, such as arrays 102, 104. In this example, inputs 452 and 454 of block 450 extend along the z-axis and output 456 extends along the vertical x-axis. In view of the arrangement of the inputs and outputs, processing circuits 460a to 460n can be located at the outer surface of blocks 400, 450 and stacked in the y-axis direction without interfering with signal capture from the source by input 452, or preventing LO from being delivered to input 454. Although circuits 460a to 460n are shown as being on the block 400 side of the array, the stack can also be arranged on the other side of the array (e.g., the block 450 side). In this regard, a first stack of processing circuits 460a-460n may be disposed on one side of the array, a second stack of processing circuits 460a-460n may be disposed on a second side of the array, an input signal (e.g., an RF input) may be disposed on a third side of the array, and in some embodiments, another input signal (e.g., LO) may be disposed on a fourth side of the array. The circuits 460a-460n may include, for example, one or more LNAs, AM (envelope) power detectors, and / or ADCs, and in some cases filters. Figure 4B As illustrated in , and according to some embodiments, there may be no inputs or outputs on the top or bottom of blocks 400 , 450 .

[0055] although Figure 4B The array is depicted as having two connected blocks, but the embodiment is not limited thereto. For example, according to the embodiment, the detector array such as array 102, 104 can be formed by blocks that are not directly connected and have more than two blocks. For example, processing circuits 460a to 460n can be inserted between two sub-blocks of the array (e.g., between block 400 and block 450). In some instances, three sub-blocks can be used, wherein the circuit is inserted between the first block and the second block and between the second block and the third block. In such an arrangement, the circuit between the first block and the second block can process signals from one or both of the first block or the second block, and the circuit between the second block and the third block can process signals from one or both of the second block and the third block. Additionally, another circuit stack can be arranged on one or more of the outer sides of the array, for example, to process signals from the first block or the third block. Although described using three blocks, according to the embodiment, this arrangement can be repeated to extend the width of the array beyond three blocks. The detection array can also be extended in the y direction, for example, by stacking additional blocks 400, 450. According to an embodiment, there are no inputs or outputs on the upper and lower surfaces of the array block 400, 450, and therefore, the array block can be stacked with another block without interference. Some embodiments include blocks 400, 450 with six primary sides, where the inputs and / or outputs are exposed on the outside (e.g., inputs and / or outputs in the x-direction and z-direction) rather than exposed on the top or bottom (e.g., in the y-direction). The stacking can be further improved to have a notch 1206, such as Fig. 12A and Fig. 12B as shown in .

[0056] According to an embodiment, the detection system can be optimized for up to four detection bands. For example, each of the arrays 102, 104 may include Figure 4B 400, 450. In this example, each of the input horn feeds 452 and subsequent processing may correspond to a different frequency band, thereby enabling multi-frequency detection of up to four frequency bands. Depending on the embodiment, the width of the frequency band may be set by a combination of a mixer, an IF amplifier, and / or an envelope detector. In some embodiments, the frequency band is + / - 20% of the center frequency of the waveguide.

[0057] Reference now FIG. 5A to FIG. 5C , illustrates the geometry of one or more unequal power dividers and / or polarization rotators according to some embodiments. Figure 5AAs shown in FIG. 5 , unequal power divider 500 may include input 502, and outputs 504 and 506. The power at output 504 may be different from output 506. Additionally, and as shown in FIG. Figure 5B As shown in the detailed view of FIG. 5 , one or more of the channels (i.e., input, first output, or second output) may include a polarization rotation element 508. Such a rotation element is further shown as Figure 5C 514a to 514c. Figure 5C As further depicted in , unequal power distribution can be accomplished using two waveguide openings at the split. That is, the first waveguide opening 510 can be smaller than the second waveguide opening 512 so that more power is directed to the output 506 compared to the output 504. In this example, due to the rotation elements 514a to 514c, the waveguide power split is performed with a different polarization than the signal at the input 502 or output 504, 506. In some aspects, the power split ratio may depend primarily linearly on the relative height of the waveguide at the point where the waveguide is split. If the split is at half the waveguide height (narrow dimension), then the power is divided equally. If the split is 20% of the height, for example, then the power is divided 80:20, and so on.

[0058] According to the embodiments, and with further reference to FIG. 5A to FIG. 5C , unequal configurable power splitters can be achieved by integrating a polarizer rotator at each port. The majority of the components can then be machined in a first orientation, for example, with the waveguide shunt arranged to be located in the center of a wide wall. Further, this approach can be used to provide a means to fully integrate the LO power network into a single, easily CNC-machined coupling manifold that can be used between the power amplifier and the multiplier. In some aspects, it provides the ability to arbitrarily rotate the waveguide orientation by 90 degrees depending on the overall system layout requirements. Such a LO network manifold can reduce costs, eliminate the need for flanges between components, and / or allow for a more compact system.

[0059] According to an embodiment, the detection system provides temporally and spatially aligned multi-frequency data from an outdoor (or indoor) scene that is optimized to exploit the optimal properties of the Earth's atmosphere. In doing so, aspects of the present disclosure provide data that enable a degree of material specificity that can greatly assist the decision-making process in determining the exact nature of a threat item. Due to the special properties of human tissue, it can also be used to indicate human features in real time in cluttered outdoor scenes.

[0060] The Earth's atmosphere provides unique lighting characteristics according to the observed frequency transmission through the atmosphere, which is in turn determined by the amount of water vapor present above the scene and the wavelength used for detection. Two phenomena dominate this effect. First, water molecules have rotational resonance in the millimeter to terahertz domain, so that it absorbs photons at specific frequencies. At frequencies far away from these lines, it allows photons to pass, which can be understood as a water window. In addition, as the wavelength shortens, the effective path length through the atmosphere becomes longer, thereby increasing attenuation. At the highest transmission frequency, the Earth's atmosphere is transparent, and therefore the cold background of space provides very high contrast during millimeter wave detection. Therefore, the observed outdoor scene is dominated by "cold" sky lighting. At the lower frequency of transmission through the Earth's atmosphere, the scene is dominated by "warm" lighting from the air column above the scene. According to the embodiment, and in order to provide a color scene in which different contrast types are achieved, a mixture of high transmission wavelengths, medium transmission wavelengths and low transmission wavelengths is required. Through experimental studies, these have been determined to be a frequency band of about 35GHz wide centered at 125GHz, 250GHz and 375GHz.

[0061] According to the implementation, and to maximize utility, images are generated in the shortest time, with the highest thermal sensitivity, and with the highest possible spatial resolution. The first two of these requirements are often conflicting. The thermal sensitivity of a scene is governed by the following equation:

[0062] ΔT=T sys / (tx B) 1 / 2 ,

[0063] where ΔT is the minimum resolvable temperature difference between the spatially resolved zones. The variable T sys is the system noise temperature of the detector electronics, t is the time taken to collect the sample, and B is the bandwidth of the detector.

[0064] For heterodyne detectors used in some embodiments, the system bandwidth is fixed and therefore the increased thermal sensitivity option is to reduce T sys and increase the integration time t. However, except by cooling the entire array (which may not be practical), T sys There may be little room for improvement. Increasing the integration time t is possible, but at the expense of the frame update rate. Therefore, and in accordance with an embodiment, the improvement provided is to maintain the fastest frame rate by increasing the number of detectors. This then allows each detector more time to observe the scene. In accordance with an embodiment, the number of detectors can be increased both vertically and horizontally, and additionally, the detector array can be paired with a board inserted between them. In addition, a stackable multi-frequency detector configuration is described that can be scaled to incorporate any number of detectors and up to three or more frequency bands.

[0065] According to an embodiment, a polarizer element and a power divider are integrated into the detection system. Acting in combination, these two components can realize a compact multiplexed optical feed system that provides nearly perfect spatial and temporal alignment of multi-frequency data extraction. Embodiments also provide a means of scaling detector counts by stacking detectors in a vertical plane in a repetitive manner.

[0066] According to an embodiment, to cover the field of view of each detector, a virtual array is formed using a linear polarization grid of horn feeds placed very close to the detector array. Figure 6 A schematic diagram is shown in FIG. 1 , for example, Figure 6 It is shown that incident radiation is transmitted through the linear polarization grid to the first set of horn feeds at 602, the incident radiation is reflected to the second set of horn feeds in 604, and the detected data is combined at 606. In this example, the polarization grid is completely transparent to vertical linear polarized radiation, but completely reflective to horizontal polarized radiation. When placed at 45 degrees between orthogonal arrays (such as arrays 102, 104), the horizontally polarized radiation appears as a virtual array covering the vertical polarization array at 606. In this particular example, the terms "vertical" and "horizontal" are intended to distinguish between orthogonal axes.

[0067] In practice, a small amount of signal (typically 2% to 5%) is lost through scattering and ohmic losses in the wire grid beam combiner. By accepting this loss, a very compact and configurable stacked arrangement of horn feeds can be achieved. By overlapping or spacing the horn feeds in each polarization output from the polarization beam combiner, a fully versatile and configurable "virtual" 2D array is possible. This can be composed of multiple frequencies, multiple overlapping polarizations, or arbitrary array layouts such as sparse arrays. For example, one array (e.g., 102) can be configured for a first frequency or frequency group, while a second array (e.g., 104) can be configured for a second frequency or frequency group. In this regard, multi-frequency detection can be accomplished with capture in two dimensions. Alternatively, two arrays (e.g., 102, 104) can be configured at the same frequency so that vertically polarized radiation at that frequency is captured (e.g., 602) and horizontally polarized radiation at that frequency is captured (e.g., 604) to form a composite 606 for single frequency detection. According to an embodiment, the layout of this quasi-2D array can be designed for adaptive scanning. For example, a sparse array can be "filled" by dithering the scanning mirror in small and fast increments. Additional phenomenological information can be collected by combining the two polarizations.

[0068] According to an embodiment, using a polarization grid beam combiner with overlapping beams doubles the signal collection for each position in the field of view.

[0069] Reference now Figure 7 , according to some embodiments, detection system 700 is schematically illustrated with respect to the polarization of received radiation. In this example, radiation from the field of view having vertical polarization is transmitted through element 710 to horn feeds 702 and 704. At the same time, horizontally polarized radiation from the field is reflected from element 710 to horn feeds 706 and 708. Figure 7 As illustrated in , the detected data received on horn feeds 702, 704, 706, and 708 may be combined to form a composite representation of the field of view. According to an embodiment, horn feeds 702 and 704 are spaced apart from one another, as are horn feeds 706 and 708. Thus, and as Figure 7 As shown in , the horizontal signal information and the vertical signal information may be partially overlapped at the output.

[0070] According to an embodiment, the detector layout of the system forms a sparse array.

[0071] According to some embodiments, horn feeds 702, 704, 706, and 708 are all configured for radiation of the same wavelength.By using polarization elements 710 with two sets of arrays, the amount of radiation available, received, and processed is effectively doubled.

[0072] According to the implementation scheme, Figure 7 and Figure 8 The spaced arrangement shown in FIG. 7 can be applied in a multi-frequency detection system. That is, the horn feeds 702, 704, 706, and 708 can be optimized for different frequencies.

[0073] Reference now Figure 8 , further illustrating a system 700 having LO sources 802, 806 and IF processing circuits 804, 808 according to an embodiment. According to an embodiment, since the horn feeds are sufficiently spaced apart, the IF processing circuits 804, 808 can be physically located between the horn feeds. Such circuits can include, for example, one or more LNAs, power detectors, and / or ADCs. This can be done, for example, using Figure 4A and Figure 4BThis is accomplished with the illustrated orthogonal channel arrangement. With this setup, the width of the view Xn can be expanded as needed for both the vertical array and / or the horizontal array. The height can also be set to a desired height, for example, by block stacking or block height variation. This allows for wide capture (increased number of horn feeds) without losing temporal and spatial correspondence of the field of view. Fig. 9 The resulting image depiction 900 of a paired detector array having a width of two spaced horn feeds and a height of four spaced horn feeds is shown in FIG. Fig. 9 As shown in the illustration of , the width and height of the array (and therefore, image capture) can extend Xn in either dimension as desired. In some embodiments, the horn feeds are spaced apart by a distance defined by the size of the circuit interposed between the horn feeds. For example, the horn feeds can be placed at a distance equal to the size of the circuit, 1.5 times the size, or 2 times the size.

[0074] According to the embodiment, and as Figures 7 to 9 As illustrated in the beam footprint of the combined split polarization elements shown in , the disclosed system can create a "virtual" 2D imaging array that can be expanded to n elements with alternating polarizations.

[0075] Reference now Fig.10 , providing a detection method 1000 according to some embodiments. According to the embodiments, for example, as described in Figure 1A and Figure 1B , Figure 3 as well as Fig.13A and Fig. 13B The process may be performed by one or more of the detection systems described in the invention. For example, the process may be performed by a terahertz camera.

[0076] Method 1000 may begin at step s1010, which includes receiving a first radiation signal having a first polarization at a first detector block of a camera, wherein the first radiation signal is received from a radiation source through a polarization plate. In step s1020, process 1000 includes receiving a second radiation signal having a second polarization at a second detector block of the camera, wherein the second radiation signal is received from the radiation source as a signal reflected from the polarization plate. In steps s1040 and s1050, processing the signals includes processing the first radiation signal to form first detection information and processing the second radiation signal to form second detection information, such as, for example, regarding Figure 3and FIG. 4 . This may include, for example: passing the signal to a mixer; generating an intermediate frequency signal; and further processing the signal with one or more of an LNA, a PD, and an ADC. According to some embodiments, the detection information is image data, which can be used to construct a corresponding image of the detected radiation signal (e.g., as described with respect to Figures 6 to 9 In one example, the detection information is a digital value indicating the intensity of radiation received on a given channel.

[0077] In some embodiments, process 1000 includes an optional step s1030, wherein at least one of the received first radiation signal and the second radiation signal is transmitted through a polarization rotation element prior to subsequent processing.

[0078] In optional step s1060, according to some embodiments, method 1000 further comprises combining the first detection information with the second detection information to form an image indicating one or more properties of the radiation source. Combining the detection information to form an image may be performed, for example, by combining Figure 3 The illustrated image processing 324 and / or viewing system 326 may be performed. In some embodiments, such as with respect to Figures 6 to 9 The combination is performed as described.

[0079] According to an embodiment, a portion of the image corresponding to the first detection information (e.g., information generated from a signal detected on a first horn feed) and a portion of the image corresponding to the second detection information (e.g., information generated from a signal detected on a second horn feed) completely overlap in the image; or a portion of the image corresponding to the first detection information and a portion of the image corresponding to the second detection information partially overlap in the image; or a portion of the image corresponding to the first detection information and a portion of the image corresponding to the second detection information do not overlap at all in the image.

[0080] According to an embodiment, the portion of the image corresponding to the first detection information and the portion of the image corresponding to the second detection information partially overlap or do not overlap at all (i.e., do not completely overlap) in the image. In this example, the first detector includes a first plurality of horn feeders having a first width and having a spacing equal to or greater than the first width, and the second detector includes a second plurality of horn feeders having a second width and having a spacing equal to or greater than the second width. In this example, processing the first radiation signal may be at least partially performed on a first processing circuit located between two horn feeders in the first plurality of horn feeders, and processing the second radiation signal may be at least partially performed on a second processing circuit located between two horn feeders in the first plurality of horn feeders. Additionally, according to an embodiment, the first plurality of horn feeders are arranged into a horn feed array having a height and a width both greater than two, and the second plurality of horn feeders are arranged into a horn feed array having a height and a width both greater than two.

[0081] According to an embodiment, the processing element may be adapted to color encode image data generated at different frequencies (and / or at different detector arrays) such that the combined image data contains a combined color encoding from the image data generated at the different frequencies. This combined color encoding can be used to characterize a surface. For example, a reflective metal will appear to be at ambient temperature at both low and high frequencies, whereas the epidermis will only be at ambient temperature at lower frequencies. At higher frequencies, it will appear to be at body temperature. The combined color encoding from the different frequencies may therefore show the epidermis as a different color than the metal. Data can be assigned to pixels in an image to identify areas with specified characteristics.

[0082] According to an embodiment, the detector array delivers their analog IF signals to one or more LNAs, AM detectors, and digitizers, which ultimately convert the IF signals to digital signals and filter the digital signals. This can be, for example, part of steps s1040 and s1050. In this example, a processing element (e.g., 324 and / or 326) obtains filtered digital signals from several groups of selected individual detectors, assigns image colors to each detector in the group, and then adds the signals for each pixel of the image signal 335 so that the pixel will be displayed in a color that is a combination of the colors received at different frequencies for a group of selected detector channels. According to an embodiment, the arrays may not be aligned, so that some adjustments may be necessary to ensure that the data they generate corresponds to at least a common area of ​​interest across the field of view.

[0083] According to an embodiment, the detection system described herein may use a heterodyne mixer. For example, an array of horn feeders delivers incoming radiation to a diode-based mixer via a waveguide, which has an intermediate frequency (IF) output to a processing circuit. The size of the horn feeder is scaled to give the waveguide the same coupling factor according to frequency. In the mixer, the incoming signal is coupled with a reference signal provided, for example, by a local oscillator (LO) that can be incorporated into the frequency control. The mixer may include a nonlinear element such as a Schottky diode that combines integer multiples of the radiation and the reference signal to produce a sum signal and a difference signal, including an IF. According to an embodiment, a subharmonic mixer may be used. The frequency of the IF signal is generally low relative to the received terahertz radiation and the reference signal, typically 0.1 GHz to 40 GHz for the IF versus 100 GHz to 500 GHz for the input radiation and the reference LO signal. Since the IF signal is now a relatively low frequency, it can be easily filtered, amplified, and envelope (AM) detected to produce a voltage whose intensity is proportional to the received terahertz radiation, and can then be used to form an image associated with the field of view. Depending on the embodiment, envelope detection can be omitted. In some aspects, one or more digitizers operate at a clock rate of GHz (or tens of GHz).

[0084] Reference now Fig.11 , a manufacturing process 1100 according to some embodiments is provided. The process 1100 can be used, for example, to manufacture one or more detector arrays 102, 104 and / or such according to embodiments. Figure 4A and Figure 4B Similarly, process 1100 can be used to manufacture Fig.13A One or more elements (eg, elements 1302 and 1304 ) of system 1300 are shown in . Fig. 12A Illustrated is a combination of a first machined housing component 1202 and a second machined housing component 1204 and a process 1100 in accordance with some embodiments.

[0085] Process 1100 may begin with step s1110, which includes machining a first housing component including a first radio frequency (RF) channel portion, a first local oscillator (LO) channel portion, a first intermediate frequency (IF) channel portion, a polarization rotation portion, and a first mixer mounting cavity. Similarly, step s1120 includes machining a second housing component including a second radio frequency (RF) channel portion, a second local oscillator (LO) channel portion, a second intermediate frequency (IF) channel portion, a polarization rotation portion, and a second mixer mounting cavity. In some embodiments, process 1100 includes optional steps s1130 to s1150. In step s1130, a heterodyne mixer is mounted in the first mounting cavity and / or the second mounting cavity. In step s1150, the first housing component and the second housing component are attached to form a first detector block. In step s1150, a second detector block is attached to the first detector block to form an integrated block, such as the array 102, 104 or the block 400, 450. Attaching the first detector block and the second detector block may include attaching an outer surface of the first detector block to an outer surface of the second detector block, wherein the outer surface of the first detector block is formed in the same plane as the RF and LO channel portions and in a plane orthogonal to the IF channel portion.

[0086] In some embodiments, the first block and the second block are not directly attached, but a processing circuit is interposed between them. Thus, process 1100 may include the step of providing a processing circuit between the first block and the second block.

[0087] According to an embodiment, process 1100 can be repeated to form one or more blocks on a first side of the polarizing plate, and then to form one or more blocks on a second side of the polarizing plate. Thus, process 1100 can include placing a polarizing plate (e.g., at a 45 degree angle) between the detector blocks.

[0088] Reference now Fig. 12A , block 1200 may be formed by attaching components 1202 and 1204. Block 1200 may be one or more of array blocks 102, 104, 400, and 450 or a sub-block of array blocks 102, 104, 400, and 450. Fig. 12A As shown in , the block 1200 may include notches 1206. For example, a first notch 1206a may be disposed on a first surface 1208 (e.g., a lower surface) of the block 1200, while a second notch 1206a is disposed on an opposite surface (e.g., an upper surface). In some embodiments, the notches are angled. However, in other embodiments, they may also be perpendicular to the block surface 1208. Fig. 12AAs further shown in FIG. 1 , the first notch 1206a and the second notch 1206b can be aligned with each other. These notches can be used, for example, to stack multiple blocks 1200 to expand the array size in the vertical direction, such as for arrays 102, 104 and system 100. As an example, this Fig. 12B 1200 in a stacked arrangement. Block 1210 is stacked on top of block 1212 in this example, and in some embodiments may be the same stacked module. Although illustrated as having the same block with the same horn feed size, blocks 1200 for different frequencies (and therefore horn feed sizes) may have the same overall shape and size, including one or more notches 1206, and may therefore be stacked. FIG. 12A to FIG. 12C In the example of FIG. 1 , there is no RF input, LO input, or IF output on the surface including the stack notch 1206. Fig. 12C As shown in FIG. 1 , the blocks 1200 may be arranged so that the array size is in the vertical direction (with n 1 blocks) and horizontally (with n 2 blocks) on both, for example, if combined Figures 6 to 9 Block 1200 may include a signal input or horn feed 1214, a power input or LO channel 1216, and a signal output or IF channel 1218. Fig. 12A As shown in , the inputs 1214 , 1216 extend along a first axis, while the output 1218 extends along a second, perpendicular axis.

[0089] Reference now Fig.13A and Fig. 13B , providing an image of the detection system 1300 according to some embodiments. Fig.13A As shown in , system 1300 includes first and second detector arrays 1302, 1304 and a polarization plate 1306 interposed therebetween. Processing circuitry 1308 is arranged in a stacked configuration with outputs to image processing 1310. LO signals are provided by source 1312 to splitters 1314a and 1314b. Fig. 13B An alternative angle of the system 1300 is shown, with the polarization plate 1306 and the wire grid 1320 portion of the plate introduced.

[0090] Although the embodiment uses 125 GHz, 250 GHz, 375 GHz and 500 GHz as examples, other frequency groups can be used. For example, 60 GHz, 120 GHz, 240 GHz, 360 GHz and 480 GHz can be used. This frequency group is related to the absorption properties of oxygen in the atmosphere.

[0091] Various aspects of the present disclosure relate to scanning methods and apparatus for electromagnetic detection using an electromagnetic spectrum with wavelengths in the centimeter to submillimeter range. Certain embodiments may be applied in the high frequency or terahertz region of the electromagnetic spectrum, which is of particular benefit for many applications, thereby providing high resolution in a small system. The terms high frequency and terahertz in this context may refer to the electromagnetic spectrum with wavelengths in the near millimeter, millimeter, and submillimeter ranges (e.g., 30 GHz to 1 THz).

[0092] Although various embodiments of the present disclosure are described herein, it should be understood that they are presented only by way of example and not by way of limitation. Therefore, the breadth and scope of the present disclosure should not be limited by any embodiment in the exemplary embodiments described above. In general, all terms used herein should be interpreted according to their common meanings in the relevant technical field, unless clearly given and / or different meanings are implied from the context in which it is used. Unless otherwise clearly stated, all references to one / one / the elements, devices, parts, components, steps, etc. should be openly interpreted as referring to at least one example of the elements, devices, parts, components, steps, etc. Unless otherwise noted herein or otherwise clearly contradictory with context, the present disclosure covers any combination of the elements described above in all possible variations thereof.

[0093] Additionally, although the processes described above and illustrated in the accompanying drawings are shown as a sequence of steps, this is done for illustration purposes only. Therefore, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be rearranged, and some steps may be performed in parallel. That is, the steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as being after or before another step, and / or it is implied that a step must be after or before another step.

Claims

1. A detection system (100), comprising: a first detector array (102); a second detector array (104); as well as a polarization plate (106) interposed between the first detector array and the second detector array, Wherein the polarization plate is arranged to transmit a first radiation signal having a first polarization through to the first detector array and to reflect a second radiation signal having a second polarization to the second detector array.

2. The system of claim 1, wherein the polarization plate comprises a wire grid at a 45 degree angle to the first detector array and the second detector array.

3. The system according to claim 1 or 2, wherein the first polarization is a vertical polarization and the second polarization is a horizontal polarization.

4. The system of claim 1, wherein the first detector array comprises a first plurality of horn feeds sized for a first detection frequency, and wherein the second detector array comprises a second plurality of horn feeds sized for a second detection frequency.

5. The system of claim 4, wherein the first detector array further comprises a third plurality of horn feeds sized for a third detection frequency.

6. The system of claim 5, wherein the first detection frequency is 250 GHz, the second detection frequency is 125 GHz, and the third detection frequency is 375 GHz.

7. The system of claim 1, wherein the first detector array and the second detector array each include a plurality of horn feeds sized for a single detection center frequency.

8. The system of claim 1, wherein one of the first detector array or the second detector array comprises a polarization rotation element disposed in a waveguide channel of the first detector array or the second detector array.

9. The system of claim 1, wherein the system does not include any optical elements between the polarization plate and the first detector array or the second detector array.

10. The system of claim 1, wherein the first detector array comprises a first plurality of horn feeds having a first width and having a pitch equal to or greater than the first width.

11. The system of claim 10, wherein the second detector array comprises a second plurality of horn feeds having a second width and having a pitch equal to or greater than the second width.

12. The system according to claim 1, further comprising: multiple horn feeders; a first processing circuit; as well as A second processing circuit, wherein the first processing circuit is located between horn feed horns of the first detector array, and wherein the second processing circuit is located between horn feed horns of the second detector array.

13. The system according to claim 1, further comprising: multiple horn feeders; Wherein the first detector array has more than two horn feeds in each of a horizontal direction and a vertical direction of the array, and wherein the second detector array has more than two horn feeds in each of a horizontal direction and a vertical direction of the array.

14. The system according to claim 1, further comprising: At least one unequal power splitter.

15. The system of claim 14, wherein the unequal power splitter comprises a polarization rotation element.

16. A detection method (1000), comprising: receiving (1010) a first radiation signal having a first polarization at a first detector block of a camera, wherein the first radiation signal is received from a radiation source through a polarization plate; receiving (1020) a second radiation signal having a second polarization at a second detector block of the camera, wherein the second radiation signal is received from the radiation source as a signal reflected from the polarization plate; processing (1040) the first radiation signal to form first detection information; as well as The second radiation signal is processed (1050) to form second detection information.

17. The method according to claim 16, further comprising: At least one of the received first and second radiation signals is transmitted (1030) through a polarization rotation element prior to said processing.

18. The method according to claim 16, further comprising: The first detection information and the second detection information are combined (1060) to form an image indicative of one or more properties of the radiation source.

19. The method according to claim 16, wherein processing the first radiated signal is at least partially performed using a first processing circuit located between two horn feeds, and Wherein processing the second radiated signal is at least partially performed by using a second processing circuit located between the two horn feeds.

20. The method of claim 16, wherein the first polarization is a vertical polarization and the second polarization is a horizontal polarization.

Images