System and method for imaging in the optical domain

Abstract

An optical imaging system (10) comprising a transmitter unit (100) and a receiver unit (200), the transmitter unit (100) comprising: - a light emission source (101) configured to generate at least one first light beam of a given wavelength; - a light modulator (102) associated with a first field of view (1020) configured to deflect the at least one first light beam within the first field of view (1020) along a first deflection direction by applying an external control signal to generate a first deflected light beam; - a transmissive deflection device (103) associated with a second field of view (1030) and comprising a two-dimensional (2D) arrangement of deflection units (103-i), each of the deflection units (103-i) being reachable by the first deflected light beam and being associated with a basic field of view (1030-i), the transmissive deflection device (103) being configured to generate at least one second deflected light beam from the first deflected light beam using an operative deflection unit (103-i) of the plurality of deflection units (103-i) receiving the first deflected light beam; the receiver unit (200) comprising: - a light focusing device (201) configured to focus a portion of the at least one second deflected light beam received after propagation in a target environment (20) located outside the transmitter unit (100); - at least one photodetector (202) configured to convert the focused portion of the second deflected light beam into an output electrical signal.

Description

Technical Field

[0001] This invention relates generally to optical sensing and more specifically to an optical imaging system and method. Background Technology

[0002] Optical imaging systems use light waves that propagate in free space (i.e., air, outer space, vacuum, or similar media) to image or monitor a target environment. The use of light waves is driven by many advantages, such as the maturity of technologies for generating, manipulating, and detecting light waves, the virtually unlimited bandwidth allowed by these waves, and the low cost required to deploy such technologies.

[0003] Optical imaging systems, such as LiDAR technology, are now widely deployed. Most of these systems use static laser sources for directionality, meaning the generated beam is either continuous or pulsed over time along a single pointing direction. This characteristic is incompatible with today's applications.

[0004] Several solutions have been proposed to achieve a degree of operational flexibility in such imaging systems, particularly in terms of pointing direction. Some of these solutions rely on mechanical aids to change the pointing direction of the optical imaging system. However, these solutions are only compatible with applications with limited scanning speeds. Furthermore, they require a large footprint and high power consumption.

[0005] Other known solutions rely on active optics to adjust the pointing direction of the optical imaging system. For example, US10665953 discloses an optical imaging system that relies on active optics, in which a metasurface is coupled to a liquid crystal associated with a resonant antenna, allowing modification of the local reflection phase of the output beam. However, the use of liquid crystals leads to complex electronic architecture, significantly reduced scanning speed, and limited deflection angle. Furthermore, imaging systems based on active optics suffer from high power consumption and complex driving mechanisms, among other drawbacks.

[0006] Therefore, an improved optical imaging system and method are needed. Summary of the Invention

[0007] To address these and other issues, an optical imaging system comprising a transmitter unit and a receiver unit is provided. The transmitter unit includes:

[0008] A light emitting source configured to generate at least one first beam of a given wavelength;

[0009] An optical modulator associated with a first field of view is configured to deflect the at least one first beam along a first deflection direction within the first field of view by applying an external control signal to generate a first deflected beam.

[0010] A transmission deflection device, associated with a second field of view and comprising a two-dimensional (2D) arrangement of deflection units, each of which is reachable by a first deflection beam and associated with a basic field of view, is configured to generate at least one second deflection beam from the first deflection beam using the deflection units that receive the first deflection beam.

[0011] The receiver unit includes:

[0012] An optical focusing device configured to focus a portion of the at least one second deflected beam received after propagation in a target environment located outside the transmitter unit;

[0013] At least one photodetector is configured to convert the focused portion of the second deflected beam into an output electrical signal.

[0014] According to some embodiments, the optical imaging system may also include a control unit configured to select the operation of the deflection unit by generating a corresponding external control signal.

[0015] According to some embodiments, the control unit may also be configured to change the operating deflection unit at least once during the scan cycle.

[0016] According to some embodiments, the second field of view can be wider than the first field of view.

[0017] According to some embodiments, when measured horizontally and / or vertically, the second field of view may include 120 to 180 degrees.

[0018] According to some embodiments, the light source can also be configured to modulate the at least one first beam using a modulation signal provided by the control unit.

[0019] According to some embodiments, the at least one first beam may be intensity modulated.

[0020] According to some embodiments, the at least one first beam may be frequency modulated.

[0021] According to some embodiments, the optical imaging system may also include an optical filter disposed between the spatial light modulator and the transmission deflection device to eliminate unwanted beams.

[0022] According to some embodiments, the optical imaging system may further include a processing unit configured to receive an output electrical signal and determine multiple characteristics of the target environment, including geometric characteristics.

[0023] According to some embodiments, the transmission deflection device may include one or more elements in a diffraction grating, a thermally etched grating, a thermally etched binary subwavelength grating, and / or a metasurface.

[0024] According to some embodiments, a spatial light modulator may include a horizontally oriented acousto-optic deflector and a vertically oriented acousto-optic deflector.

[0025] According to some embodiments, the light focusing device is a converging lens, preferably a passive scanning lens.

[0026] According to some embodiments, the transmission deflection device can be a passive transmission deflection device.

[0027] An imaging method is also provided, the method comprising the following steps:

[0028] At least one first beam is generated by means of a light emitting device;

[0029] By means of a spatial light modulator, by applying an external control signal to the spatial light modulator, the at least one first beam is deflected in a first deflection direction within a first field of view to generate a first deflected beam.

[0030] By means of a transmission deflection device arranged in a two-dimensional (2D) configuration including deflection units, at least one second deflection beam is generated from the first deflection beam within a second field of view, the second field of view being wider than the first field of view.

[0031] According to some embodiments, the imaging method may further include the following steps:

[0032] A portion of the at least one second deflected beam received after propagation in the target environment;

[0033] The focused portion of the at least one second deflected beam is converted into an output electrical signal;

[0034] Multiple features of the target environment are determined, including geometric features. Attached Figure Description

[0035] Various embodiments of the invention are illustrated in conjunction with the accompanying drawings, which are incorporated in and form part of this specification, and together with the general description of the invention given above and the detailed description of the embodiments given below, serve to explain the embodiments of the invention.

[0036] Figure 1 A schematic diagram showing an optical imaging system according to some embodiments of the present invention;

[0037] Figure 2 The field of view of a spatial light modulator according to some embodiments of the present invention is shown;

[0038] Figure 3 The field of view of a transmission deflection device according to some embodiments of the present invention is shown;

[0039] Figure 4 This describes an exemplary transmission deflection device according to some embodiments of the present invention;

[0040] Figure 5 This represents another exemplary transmission deflection device according to some embodiments of the present invention;

[0041] Figure 6 This is a flowchart illustrating a method for optical imaging according to some embodiments of the present invention;

[0042] Figure 7 This indicates the performance of the optical imaging system in a real-world environment;

[0043] Figure 8(a) shows a target environment illuminated by two fields of view of a transmitter unit according to some embodiments of the present invention; and

[0044] Figure 8(b) shows a multi-resolution region image generated by a receiver unit according to some embodiments of the present invention. Detailed Implementation

[0045] Figure 1 An optical imaging system 10 according to some embodiments of the present invention is shown, which is capable of characterizing a target environment 20 by utilizing a light beam. The characterization of the target environment 20 according to embodiments of the present invention depends on the use of a flexible light beam in terms of the pointing direction.

[0046] This invention can be implemented in any system that uses light to interact with or monitor a two-dimensional or three-dimensional target environment 20 that cannot be easily covered by a static camera. In an exemplary application of the invention, the imaging system 10 can be used as a LIDAR (Light Detection and Ranging) system to produce high-resolution depth maps in various fields, such as, but not limited to, geology, forestry, archaeology, and land mapping. The imaging system can also be deployed in autonomous vehicles to provide real-time information about the vehicle's surrounding environment 20. In such applications, the imaging system can replace a large number of cameras whose orientation and operating wavelength characteristics are generally static over time and cannot effectively cope with weather conditions and / or camera failure. The imaging system can also be used in robotics for perceiving the surrounding environment 20 and for classifying identified objects.

[0047] Advantageously, embodiments of the invention provide a compact and reconfigurable optical imaging system 10 with a small footprint and reduced power consumption. These features of the optical imaging system 10 are compatible with a variety of ground, airborne, and mobile applications, including astronomy and aerospace, such as satellites.

[0048] like Figure 1 As shown, an optical imaging system 10 according to an embodiment of the present invention includes a transmitter unit 100 configured to transmit a light beam to a target environment 20, which may include a plurality of target objects. Various optical phenomena may occur when the light beam interacts with the material of a given target object. These phenomena include light scattering, reflection, absorption, refraction, and diffraction. Some of these phenomena cause a portion of the transmitted light beam to return to the imaging system after a certain delay. The returned portion of the transmitted light beam may have different characteristics in terms of intensity, wavelength, phase, and / or polarization relative to the original transmitted light beam. The optical imaging system 10 also includes a receiver unit 200 configured to receive and process the returned portion of the transmitted light beam. Advantageously, the transmitter unit 100 and the receiver unit 200 may be arranged such that the light beam transmitted by the transmitter unit 100 cannot directly reach the receiver unit 200. For example, the transmitter unit 100 and the receiver unit 200 may be arranged in parallel close to each other, such as... Figure 1 As shown.

[0049] More specifically, see reference Figure 1 The transmitter unit 100 of the optical imaging system 10 includes a light emitting source 101 configured to generate a first beam of a given wavelength. The first beam may be coupled into an optical fiber or may be configured to propagate in free space along a predetermined direction. The light emitting source 101 may be configured to operate in a continuous mode, wherein characteristics of the light field representing the first beam remain constant over time. These characteristics of the light field may include intensity, center wavelength, and / or polarization state.

[0050] According to some embodiments, the light source 101 can be configured to operate in a pulsed mode, wherein the light source 101 alternately turns on and off steadily or irregularly over time. When on, the light source 101 can be configured to operate in the same manner as the continuous mode described above. The use of the pulsed mode makes it easy to determine the position of the target object by measuring the time delay in which the light beam returns to the receiver unit 200.

[0051] According to some embodiments, the light emitting source 101 is also configured to modulate the first light beam using a modulation signal, which may be electrical or optical. For example, the intensity or frequency of the light field representing the first light field may be modulated. Alternatively, the intensity and frequency of the light field may be modulated simultaneously.

[0052] According to some embodiments, the light emitting source 101 can be configured to operate in the ultraviolet, visible, or infrared regions of the electromagnetic spectrum, with infrared radiation including three bands: near-infrared, mid-infrared, and far-infrared. Advantageously, the center wavelength representing the light field of the first beam can be selected based on the light absorption characteristics of the target object in the target environment 20 and by taking into account outdoor conditions (e.g., weather conditions) occurring outside the optical imaging system 10. Specifically, the center wavelength can be selected to be sufficiently far from the wavelength absorption band of the target object in the target environment 20.

[0053] In an exemplary embodiment, the light emitting source 101 may be configured to operate in the mid-infrared region of the electromagnetic spectrum (3 μm to 50 μm). Although the invention is not limited to this embodiment, it should be noted that when the light emitting source 101 operates in the mid-infrared region of the electromagnetic spectrum, the invention has particular advantages due to the high transparency of the atmosphere at this wavelength.

[0054] like Figure 1 As shown, the transmitter unit 100 of the optical imaging system 10 also includes a spatial light modulator 102. The spatial light modulator 102 may include an optical input and an optical output. The spatial light modulator 102 is configured to receive a first light beam through its optical input. The spatial light modulator 102 presents a first field of view 1020 at its optical output, the first field of view 1020 defining a spatial volume through which the light beam from the spatial light modulator 102 can pass. Figure 2 An illustrative example of a first field of view 1020 having a conical shape is depicted. More generally, the first field of view 1020 can be measured horizontally, vertically, or diagonally relative to a reference direction. The spatial light modulator 102 is also configured to deflect a first beam received from the light emission source 101 along a first deflection direction within the first field of view 1020, thereby generating a first deflected beam.

[0055] In one embodiment, the spatial light modulator 102 may be an active spatial light modulator 102 including a modulation input, to which a modulation signal may be applied to change the behavior of the spatial light modulator 102 in terms of deflection direction. The modulation signal may be an electrically modulated signal. For example, the mapping between the modulation signal and the deflection direction operated by the spatial light modulator 102 may be pre-established through a calibration process.

[0056] The spatial light modulator 102 can be configured to change the first deflection direction multiple times during the scan period based on the applied modulation signal. The first deflection direction can be selected based on a previous first deflection direction, or it can be selected independently.

[0057] According to some embodiments, when measured horizontally and / or vertically, the first field of view 1020 of the spatial light modulator 102 may include a lower threshold (e.g., 10 degrees) to a higher threshold (e.g., 60 degrees).

[0058] In one embodiment, the spatial light modulator 102 may include two acousto-optic modulators (also referred to as acousto-optic deflectors) arranged in series and oriented perpendicularly to each other, each of the two acousto-optic modulators being configured to deflect a light beam at its light input according to its own modulation signal. In this configuration, a first light beam is initially deflected by a first acousto-optic modulator according to a first horizontally defined viewing angle (e.g., in a first field of view 1020). After being horizontally deflected, the first light beam enters a second acousto-optic modulator to be vertically deflected according to a second viewing angle defined perpendicularly to the viewing angle of the first acousto-optic modulator. In this case, a first deflection direction of the first deflected beam is defined by the two vertical viewing angles.

[0059] In some embodiments, each acousto-optic modulator is configured to diffract the incident beam into multiple deflected beams. Each of the deflected beams is associated with a diffraction order and exhibits a given power level.

[0060] According to a non-limiting example, the optically deflected beam exhibiting the maximum power level is the beam of interest and defines a first deflected beam, while all other deflected beams correspond to undesired beams. Advantageously, similar to the first deflected beam, some of the undesired beams (e.g., those exhibiting high power levels) can be used for additional measurements.

[0061] In addition to deflecting the beam, the acousto-optic modulator can also be configured to transmit a portion of the initial beam passing through its optical input to its optical output without undergoing any deflection and exhibiting a given power level from the initial beam. Specifically, this transmission portion of the initial beam can correspond to the zero-order diffraction of the acousto-optic modulator and can be associated with a transmission field of view, i.e., 1020-t (not shown in the figure). It should be noted that the transmission field of view 1020-t can include at least some propagation characteristics of the initial beam, such as the beam direction. Therefore, a spatial light modulator 102 including one or more acousto-optic modulators can also be configured to:

[0062] The transmission corresponds to the zero-order diffraction of at least one acousto-optic modulator and is associated with at least one transmission beam (i.e., a non-deflected beam or at least a partially non-deflected beam) of the transmission field of view 1020-t, and

[0063] The deflection corresponds to at least one other order of diffraction (e.g., first-order diffraction of at least one acousto-optic modulator) and is associated with at least one deflected beam in the first field of view 1020.

[0064] To facilitate understanding of the following description of the embodiments, it will be considered that the first field of view 1020 may include a transmission field of view 1020-t.

[0065] The optical imaging system 10 also includes a deflection device 103, which can be arranged in front of the spatial light modulator 102, such that the deflection device 103 is wholly or partially included in the first field of view 1020. Figure 2 As shown. The deflection device 103 includes a two-dimensional (2D) arrangement of deflection units 103-i (also referred to as phase-addressed unit units 103-i). This arrangement of deflection units 103-i can be regular or irregular. Each of the deflection units 103-i can be accessible to the first deflected beam and can be associated with a basic field of view 1030-i.

[0066] In some embodiments, the deflection device 103 may be wholly or partially included in the transmission field of view 1020-t generated by the spatial light modulator 102. Advantageously, the transmission field of view 1020-t may be aligned with the center of the deflection device 103 (not shown in the figures). Furthermore, one or more deflection units 103-i of the deflection device 103 may be accessible to the transmission (i.e., non-deflected) beam associated with the transmission field of view 1020-t and may be associated with the basic field of view 1030-i.

[0067] Similar to the spatial light modulator 102, the deflection device 103 presents a second field of view 1030 at its light output, which defines the spatial volume through which a beam from the deflection device 103 (i.e., from the deflection unit 103-i) can pass. The second field of view 1030 of the deflection device 103 can be considered as the sum of the basic fields of view of the deflection units 103-i. Furthermore, the deflection device 103 can be configured to use an operational deflection unit 103-i, which is part of a 2D arrangement belonging to the deflection unit 103-i, to generate at least one second deflection beam based on the first deflection beam received from the spatial light modulator 102. The operational deflection unit 103-i is defined as the deflection unit 103-i that receives the first deflection beam from the spatial light modulator 102.

[0068] Figure 3Operation of a deflection device 103 according to some embodiments of the present invention is illustrated. In this embodiment, each of the deflection units 103-i is characterized by a basic field of view 1030-i and by a plurality of deflected beams generated in response to receiving a transmitted (i.e., non-deflected) beam associated with a transmitted field of view 1020-t and / or a first deflected beam associated with a first field of view 1020 from the spatial light modulator 102 and / or a second deflected beam generated within the corresponding basic field of view 1030-i. For example, the size of the basic field of view 1030-i and the number of second deflected beams generated may differ between one deflection unit 103-i and another deflection unit.

[0069] In one embodiment, the deflection device 103 can be a passive deflection device, meaning that no power source is required. Additionally, the response of each of the deflection units 103-i is constant over time and cannot be adjusted after the manufacturing process. Alternatively, the deflection device 103 can be an active deflection device, which requires a power source and allows adjustment of the response of the deflection units 103-i.

[0070] In contrast to the reflection deflection device 103, the deflection device 103 can be a transmission deflection device 103. The transmission deflection device 103 allows the first beam and the second beam to propagate in two different spatial regions, which avoids interaction between the first beam and the second beam. The two different spatial regions are separated by the transmission deflection device 103.

[0071] According to some embodiments, the second field of view 1030 of the deflection device 103 can be selected to be significantly wider than the first field of view 1020 of the spatial light modulator 102. For example, the second field of view 1030 can be set to be more than twice the size of the first field of view 1020.

[0072] In an exemplary embodiment, the deflection device 103 may be configured such that its second field of view 1030 has a conical shape, meaning that any two angles measured vertically within the second field of view 1030 are approximately equal. Alternatively, the deflection device 103 may be configured such that its second field of view 1030 has an asymmetrical shape.

[0073] In some embodiments, the deflection device 103 may present at least two second fields of view. These at least two second fields of view may be superimposed on the light output of the deflection device 103. Figure 8(a) shows two second fields of view 1030-t and 1030 facing a target environment 20, which may include a plurality of target objects. According to a non-limiting example, the two second fields of view 1030-t and 1030 may correspond to:

[0074] At least one second field of view 1030-t is defined by the spatial volume through which the beam from the deflection device 103 can pass, and corresponds to the fundamental field of view 1030-i generated in response to the deflected beam generated from the transmitted (i.e., non-deflected) beam received from the spatial light modulator 102 (as associated with the transmitted field of view 1020-t), and

[0075] At least one second field of view 1030 is defined by the spatial volume through which the beam from the deflection device 103 can pass, and corresponds to the basic field of view 1030-i generated in response to the deflected beam received from the spatial light modulator 102 (as associated with the first field of view 1020).

[0076] The second field of view 1030 from the deflected beam can be selected to be significantly wider than the second field of view 1030-t from the undeflected beam, depending on the deflection device 103 and more precisely on the deflection unit 103-i. For example, the second field of view 1030 from the deflected beam can be set to be more than twice the size of the second field of view 1030-t from the undeflected beam. In some embodiments, the transmitter unit 100 of the optical imaging system 10 may further include an optical lens disposed between the spatial light modulator 102 and the passive deflection device 103. The optical lens may be a converging optical lens and may be configured to precisely focus and deflect the first beam such that the first beam is received by a single deflection unit, thereby enhancing the quality of the second deflected beam generated by the deflection device 103. Alternatively, the optical lens may be a diverging optical lens and may be configured to widen the first field of view 1020, thereby reducing the required distance between the spatial light modulator 102 and the deflection device 103, such that the deflection device 103 is completely contained within the first field of view 1020.

[0077] According to some embodiments, the light emission source 101, spatial light modulator 102, and deflection device 103 can be arranged in alignment along a common propagation axis. This alignment eliminates the need for additional optical components and provides a compact transmitter unit 100. Alternatively, the elements of the transmitter unit 100 can be arranged according to different propagation axes. In this configuration, additional optical components, such as mirrors, can be inserted between two adjacent elements of the transmitter unit 100 to ensure that the light beam reaches the light input of the other element from the light output of one element.

[0078] The optical imaging system 10 also includes a control unit 110, which is configured to select an operating deflection unit 103-i among the 2D arrangements of deflection units 103-i of the deflection device 103. The operating deflection unit 103-i is defined as the deflection unit 103-i that receives the first deflected beam. In this respect, the control unit 110 may be configured to generate a control signal and apply the generated control signal to the spatial light modulator 102, causing the first deflected beam to reach the selected deflection unit.

[0079] In one embodiment, the control unit 110 may also be configured to control the operation of the light emitting source 101. Such control operation may include determining the operating mode of the light emitting source 101, determining whether the light field representing the first beam is modulated, and, in the case of a modulated light field, determining the type of modulation, the modulation index, and the modulation signal.

[0080] According to some embodiments, the transmitter unit 100 may also include an optical filter 104 (e.g., a spatial beam blocker) disposed between the spatial light modulator 102 and the deflection device 103 to eliminate unwanted beams. Such unwanted beams may include all beams generated by the spatial light modulator 102 other than the first deflected beam. While not limited to this embodiment, the use of such an optical filter 104 is particularly advantageous when the spatial light modulator 102 includes one or two acousto-optic modulators.

[0081] Figure 4 An exemplary transmission deflection device 103 according to some embodiments is shown. The transmission deflection device 103 includes a regular two-dimensional arrangement of deflection units 103-i having the shape of a 2D matrix arranged in rows and columns, each of the deflection units 103-i occupying a given entry in the 2D matrix. Each of the deflection units 103-i is also associated with a corresponding fundamental field of view 1030-i characterized by horizontal and vertical angles measured along the rows and columns of the 2D matrix, respectively. For example, the deflection units 103-i of a given row of the 2D matrix can be configured such that their corresponding fundamental fields of view have the same horizontal angle, while the vertical angle of the corresponding fundamental field of view increases according to a given curve on the deflection units 103-i of the row under consideration. Similarly, the deflection units 103-i of a given column of the 2D matrix can be configured such that their corresponding fundamental fields of view have the same vertical angle, while the horizontal angle of the corresponding fundamental field of view increases according to a given curve on the deflection units 103-i of the column under consideration.

[0082] Figure 5Another exemplary transmission deflection device 103 according to some embodiments is shown. The transmission deflection device 103 includes an irregular two-dimensional arrangement of deflection units 103-i. Furthermore, each of the deflection units 103-i may be associated with a corresponding basic field of view 1030-i, independent of the basic field of view selection of the adjacent deflection units 103-i.

[0083] In one embodiment, the transmission deflection device 103 may be a thermally etched binary subwavelength grating, a diffraction grating, or a thermally etched grating comprising multiple pixels, each pixel being assimilated into a deflection unit 103-i corresponding to a corresponding basic field of view 1030-i.

[0084] According to some embodiments, the passive transmission deflection device 103 may be an optical metasurface device comprising a substrate and a resonator structure. The substrate may comprise silicon dioxide, silicon, or any semiconductor material. The resonator structure may comprise a metallic structure, a dielectric structure, and / or a semiconductor structure. The resonator may also comprise one or more resonator arrays formed on or on the substrate. The resonator array corresponds to a plurality of pixels, each pixel being assimilated as a deflection unit 103-i (associated with a basic field of view 1030-i).

[0085] According to a non-limiting example, the optical metasurface can have dimensions substantially ranging from 1 mm to 4 cm in the direction of the 2D arrangement of the deflection unit 103-i. The optical metasurface can be an optical plate with an overall thickness ranging from substantially 100 nm to approximately several wavelengths, depending on the material and operating wavelength. The overall thickness can take into account the thickness of the substrate and the thickness of the resonator structure. The resonator can be a metallic antenna and / or a dielectric antenna comprising one or more nanopillars (also referred to as rods) oriented substantially perpendicular to the plane of the optical plate. The nanopillars can have different geometries, characterized, for example, in terms of shape, size (or diameter of a cylindrical nanopillar), and / or height. The size of the nanopillars can, for example, range from 80 nm to 300 nm. The height h of the nanopillars can range from 10 nm to 2 μm. In some embodiments, the height h of the nanopillars can be defined as the wavelength λ of the light beam and the refractive index n of the material forming the nanopillars. p And a function of the refractive index n0 of the material surrounding the pillar, for example according to the following equation (1):

[0086]

[0087] The nanopillars can be, for example, cylindrical, circular, square, rectangular, or elliptical. Plasma antennas can include, for example, two rods joined to form a V-shape, or three rods joined to form a Y-shape. Advantageously, an optical metasurface having a single cylindrical circular antenna can be configured to generate polarization invariance according to beam propagation.

[0088] The deflection unit 103-i is a resonator array comprising two or more antennas with different geometries and / or varying nanopillar parameters to parametrically change the optical phase between 0 and 2π. In this deflection unit 103-i, the spacing between the antennas can range from 0 nanometers to approximately the wavelength of the incident light. According to a non-limiting example, the size s of the deflection unit 103-i (acting as a phase-addressing unit) can be defined as the wavelength λ of the light beam and the refractive index n of the material forming the nanopillars. p The function, for example, according to the following equation (2):

[0089]

[0090] Therefore, the geometry of the nanopillars and the resonator array can be varied in different ways. Thus, the optical metasurface realizes a wide variety of deflection units 103-i in terms of optical properties, with resolution that can be tuned (potentially achieving high resolution) according to the desired application.

[0091] The deflection unit 103-i from the optical metasurface can have, for example, nanopillar geometry and resonator array geometry, configured to generate a radial phase distribution selected from hyperboloid, spherical, and parabolic distributions. Alternatively, the deflection unit 103-i can have a conical radial phase distribution that allows the plate to be used as an axonometric prism.

[0092] When measuring horizontally and / or vertically, the second field of view 1030 of the deflection device 103 can include 120 degrees to 180 degrees, as combined with Figure 4 As shown.

[0093] Return to Figure 1 The receiver unit 200 of the optical imaging system 10 may include a light focusing device 201, which is arranged such that it does not receive the deflected beam and / or the second deflected beam directly generated by the transmitter unit 100. For example, as Figure 1 As shown, the optical focusing device 201 can be arranged along a propagation axis parallel to the central axis of the deflection device 103 of the transmitter unit 100. The optical focusing device 201 can be configured to focus all the light beams arriving at its optical input onto a given point. Among all the light beams arriving at the optical focusing device 201, there is a portion of the generated deflected beam and / or a second deflected beam (associated with the second field of view 1030-t and / or 1030) that returns after propagating in the target environment 20.

[0094] According to some embodiments, the light focusing device 201 may be fixed relative to the receiver unit 200. Alternatively, the light focusing device 201 may be a passive device that does not require a power source. For example, the light focusing device 201 may be a converging optical lens that operates within the same wavelength window as the light emitting source 101.

[0095] The receiver unit 200 also includes at least one photodetector 202, which is configured to receive the focused beam and convert it to the electrical domain via photoelectric conversion. The obtained signal is referred to as the output electrical signal when it is a second deflected beam converted to the electrical domain by the photodetector 202 and / or a return portion of the generated deflected beam. Other signals are referred to as noise signals.

[0096] According to some embodiments, the at least one photodetector 202 may be configured to convert (and / or receive and / or process) only a portion of the focused beam. This portion of the focused beam may correspond to a beam subgroup arriving at the light focusing device 201 associated with the subgroup of the basic field of view 1030-i.

[0097] For example:

[0098] A photodetector 202 may be configured to receive and / or process a portion of a focused beam from a non-deflected beam of a transmission field of view 1020-t, corresponding to a subgroup of a basic field of view 1030-i associated with a second field of view 1030-t, and / or

[0099] A photodetector 202 can be configured to receive and / or process a portion of a focused beam from a deflected beam from a first field of view 1020, corresponding to a subgroup of basic field of view 1030-i associated with a second field of view 1030. In an exemplary embodiment, an optical filter can be arranged at the light input of the photodetector 202 or at the input of the light focusing device 201 to eliminate unwanted beams that generate noise signals. This elimination of unwanted beams can also be achieved by inserting an electrical filter at the electrical output of the photodetector 202.

[0100] In one embodiment, receiver unit 200 may include a single photodetector 202. In this embodiment, the electrical output signal is a real-valued signal that represents only the intensity of the corresponding light beam.

[0101] In some embodiments, receiver unit 200 may include at least two photodetectors 202 and a local oscillator configured to allow optical heterodyne detection of the beam. In this embodiment, the electrical output signal is a complex-valued signal representing the intensity and phase of the corresponding beam. Advantageously, light source 101 can be used as a local oscillator to achieve heterodyne detection. Heterodyne detection combined with the use of a frequency-modulated beam allows, for example, the detection of both the position and velocity of a target object in the target environment 20.

[0102] According to some embodiments, the optical imaging system 10 may further include a processing unit 210, which is configured to receive and process an output electrical signal in conjunction with the characteristics of the second deflected beam provided by the control unit 110.

[0103] The processing unit 210 is also configured to detect target objects in the target environment 20 and determine multiple characteristics of the detected target objects. The characteristics of the detected target objects may include geometric characteristics (e.g., the shape and / or size of the object), as well as other characteristics that may include position and instantaneous velocity.

[0104] Advantageously, some of the characteristics of the target object can be determined by the processing unit 210 by using equation (3), which controls the transmission and reception of the beam by means of the optical imaging system 10.

[0105]

[0106] In equation (1), N laser β represents the number of transmitted photons, and β represents the angular scattering probability. The solid angle represents the collection probability, T represents light transmission in the medium, η represents the system efficiency including optical loss and laser / field overlap, and N represents the system efficiency. b This represents background noise.

[0107] According to some embodiments, the control unit 110 may be configured to keep the characteristics of the optical field representing the first beam constant over time when the deflection unit is changed. Alternatively, the control unit 110 may be configured to change at least one characteristic of the optical field representing the first beam when the deflection unit is changed. The changed characteristic of the optical field may be intensity, center wavelength, polarization state, and / or optical phase.

[0108] According to some embodiments, the control unit 110 may also be configured to change the operation deflection unit at least once during a scan cycle. For example, the control unit 110 may be configured to use multiple operation deflection units 103-i during a scan cycle according to a switching speed capable of greater than 10 MHz. The switching speed required to change the operation deflection unit 103-i may be limited by the bandwidth of the spatial light modulator 102.

[0109] Processing unit 210 may be configured to generate at least one image of the target environment 20 produced by the output of photodetector 202. In some embodiments, receiver unit 200 may also be configured to generate a multi-resolution region image for imaging the target environment 20 using only one scan (associated with a scan cycle) of spatial light modulator 102. The multi-resolution region image may be a superimposed image comprising at least one image. According to a non-limiting example, the multi-resolution region image may be generated from the following:

[0110] An image associated with a second field of view 1030-t from a non-deflected beam (e.g., zero-order diffraction) from a transmission field of view 1020-t, providing an image of a small portion of the target environment 20 with high resolution, and

[0111] An image associated with a second field of view 1030 from a deflected beam (e.g., first-order diffraction) from a first field of view 1020, which provides an image of most of the target environment 20 with low resolution.

[0112] Figure 8(b) shows an example of a multi-resolution region image of multiple target objects generated from two second fields of view 1030-t and 1030 of the illumination target environment 20 (as shown in Figure 8(a)).

[0113] As shown in Figure 8(b), the multi-resolution region image corresponds to most of the first image (X) of the target environment 20. 1030 Y 1030 The second image is a small part of the target environment 20. The superposition of images. According to some embodiments, the first image (X) 1030 Y 1030 ) and second image It can be generated using an optical metasurface configured with a radial phase distribution. Furthermore, with the second image... Compared to the first image (X) 1030 Y 1030 The first image (X) can have the same number of pixels or different numbers of pixels. More generally, the first image (X) 1030 Y 1030 ) and second image These can correspond to low-resolution and high-resolution images, respectively. Additionally, the second image... It can be relative to the image (X) 1030 Y 1030 Arranged in the center.

[0114] Therefore, the optical imaging system 10 can be configured to simultaneously (or synchronously) generate multi-resolution region images comprising two or more images of the same or different sizes and with the same or different image resolutions, representing the same or different parts of the target environment 20. This optical imaging system 10 generates multi-resolution region images with only a single scan, enabling it to replicate the behavior of the human eye.

[0115] In an exemplary embodiment, the transmitter unit 100 of the optical imaging system 10 may include at least two light emitting sources 101, each configured to generate a first beam of different or the same wavelength. In this embodiment, the spatial light modulator 102 may be configured to deflect the first beam according to the same first deflection direction or according to different first deflection directions, thereby generating a plurality of first deflected beams that can be used to illuminate different deflection units (103-i). Alternatively, a single light emitting source 101 may be used to generate the plurality of first beams.

[0116] Figure 6 This is a flowchart depicting an optical imaging method for imaging a target environment 20. The target environment 20 may include multiple target objects.

[0117] In step 601, a first light beam of a given wavelength can be generated by the light emission source 101. The characteristics of the light field representing the first light beam can remain constant or can change over time.

[0118] In step 602, the first beam can be generated by deflecting it along a first deflection direction within the first field of view 1020 using a spatial light modulator 102. The first deflection direction can be determined by applying an external control signal to the spatial light modulator.

[0119] In step 603, the first deflected beam can be received by a two-dimensional (2D) transmission deflection device 103 including deflection unit 103-i. Furthermore, at least one second deflected beam can be generated from the first deflected beam using the operating deflection unit 103-i that receives the first deflected beam. The at least one second deflected beam can be generated based on a second field of view 1030 associated with the transmission deflection device 103, the second field of view 1030 being wider than the first field of view 1020.

[0120] In step 604, the return portion of the at least one second deflected beam can be received after propagating in the target environment 20 and can be focused at a given point.

[0121] In step 605, the focused portion of the at least one second deflection beam can be converted to the electrical domain by photoelectric conversion using at least one photodetector 202, thereby generating an output electrical signal.

[0122] In step 606, multiple characteristics of the target environment 20 can be determined based on the output electrical signal. Advantageously, in step 606, a two-dimensional or three-dimensional mapping of the target environment 20 can be determined by scanning a large number of deflection units 103-i.

[0123] The optical imaging method for imaging the target environment 20 may further include the steps of generating at least two images of the target environment 20 and then generating a multi-resolution region image from the at least two images of the target environment 20. The generation of the at least two images of the target environment 20 can be performed simultaneously (or synchronously), and therefore, the generation of a multi-resolution region image from the at least two images of the target environment 20 can be achieved immediately through a single scan (i.e., a single scan).

[0124] Figure 7 The performance of the optical imaging system 10 in a real-world environment 20 is illustrated, which includes three target objects of different shapes and located at different positions. Mapping using the optical imaging system 10 according to an embodiment of the invention allows for clear differentiation of the position and shape of each of the three target objects.

[0125] It should be noted that, according to embodiments of the present invention, the functions, actions, and / or operations specified in flowcharts, sequence diagrams, and / or block diagrams can be reordered, processed sequentially, and / or processed simultaneously. Furthermore, any flowchart, sequence diagram, and / or block diagram may include more or fewer blocks than those shown in embodiments of the present invention.

[0126] While embodiments of the invention have been illustrated by way of various examples, and while these embodiments have been described in considerable detail, the applicant does not intend to limit the scope of the appended claims or in any way to such details. Additional advantages and modifications will readily be apparent to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details, representative methods, and illustrative examples shown and described.

Claims

1. An optical imaging system (10), comprising a transmitter unit (100) and a receiver unit (200), wherein, The transmitter unit (100) includes: A light emitting source (101) is configured to generate at least one first beam of a given wavelength; A spatial light modulator (102) associated with a first field of view (1020) is configured to deflect the at least one first beam in a first deflection direction within the first field of view (1020) by applying an external control signal to generate a first deflected beam; A passive transmission deflection device (103), associated with at least one second field of view (1030) and comprising an optical metasurface formed by a two-dimensional (2D) arrangement of deflection units (103-i), each of which is reachable by the first deflected beam and associated with a basic field of view (1030-i) selected independently of the basic field of view of the adjacent deflection units (103-i), the transmission deflection device (103) being configured to generate at least one second deflected beam from the first deflected beam using an operational deflection unit (103-i) among the deflection units (103-i) that receive the first deflected beam; Furthermore, the receiver unit (200) includes: A light focusing device (201) is configured to focus a portion of the at least one second deflected beam received after propagation in a target environment (20) located outside the transmitter unit (100); At least one photodetector (202) is configured to convert the focused portion of the second deflected beam into an output electrical signal.

2. The optical imaging system (10) according to claim 1, wherein, The optical imaging system further includes a control unit (110) configured to select the operation deflection unit (103-i) by generating a corresponding external control signal.

3. The optical imaging system (10) according to claim 2, wherein, The control unit (110) is also configured to change the operation deflection unit (103-i) at least once during the scan cycle.

4. The optical imaging system (10) according to claim 1, wherein, The second field of view (1030) is wider than the first field of view (1020).

5. The optical imaging system (10) according to claim 1, wherein, When measured horizontally and / or vertically, the second field of view (1030) includes 120 to 180 degrees.

6. The optical imaging system (10) according to claim 1, wherein, The light source (101) is also configured to modulate the at least one first beam using a modulation signal provided by the control unit (110).

7. The optical imaging system (10) according to claim 6, wherein, The at least one first beam is intensity modulated.

8. The optical imaging system (10) according to claim 6, wherein, The at least one first beam is frequency modulated.

9. The optical imaging system (10) according to claim 1, wherein, The spatial light modulator (102) includes a horizontally oriented acousto-optic deflector and a vertically oriented acousto-optic deflector.

10. The optical imaging system (10) according to claim 1, wherein, The optical imaging system also includes an optical filter (104) disposed between the spatial light modulator (102) and the transmission deflection device (103) to eliminate unwanted beams.

11. The optical imaging system (10) according to claim 1, wherein, The optical imaging system further includes a processing unit (210) configured to receive the output electrical signal and determine multiple characteristics of the target environment (20), including geometric characteristics.

12. The optical imaging system (10) according to claim 9, wherein, The first field of view (1020) further includes a transmission field of view (1020-t), wherein the spatial light modulator (102) is configured to transmit at least one beam associated with at least a portion of the undeflected beam within the transmission field of view (1020-t).

13. The optical imaging system (10) according to claim 12, wherein, The optical imaging system further includes a processing unit (210) and at least two photodetectors (202), each photodetector (202) being configured to convert different portions of the focused portion of the second deflection beam, the portions corresponding to subgroups of the basic field of view (1030-i), and wherein the processing unit (210) is configured to generate a multi-resolution region image from the portions of the focused portion of the second deflection beam.

14. The optical imaging system (10) according to claim 1, wherein, The light focusing device (201) is a converging lens.

15. The optical imaging system (10) according to claim 1, wherein, The light focusing device (201) is a passive scanning lens.

16. An imaging method, comprising the following steps: At least one first beam is generated (601) by means of a light emitting device (101); By means of a spatial light modulator (102), by applying an external control signal to the spatial light modulator (102), at least one first beam is deflected (602) in a first deflection direction within a first field of view (1020) to generate a first deflected beam; By means of a passive transmission deflection device (103) comprising an optical metasurface formed by a two-dimensional (2D) arrangement of deflection units (103-i), at least one second deflection beam (603) is generated from the first deflection beam within a second field of view (1030), the second field of view (1030) being wider than the first field of view (1020).

17. The imaging method according to claim 16, wherein, The imaging method further includes the following steps: A portion of the at least one second deflected beam received after the focused (604) propagates in the target environment (20); The focusing portion of the at least one second deflected beam is converted (605) into an output electrical signal; Determine (606) multiple characteristics of the target environment (20), including geometric characteristics.

18. The imaging method according to any one of claims 16 or 17, wherein, The imaging method further includes the following steps: At the same time, at least two images of the target environment (20) are generated; Multi-resolution region images are immediately generated from the at least two images of the target environment (20).

Images