All-solid-state two-dimensional light beam scanning system based on assistance of structured light generator

Abstract

The invention particularly relates to an all-solid-state two-dimensional light beam scanning system based on assistance of a structured light generator. The all-solid-state two-dimensional light beam scanning system comprises an optical phased array, a lens device and the structured light generator. The optical phased array is used for performing phase modulation on an input laser beam and outputting a one-dimensional scanning beam distributed based on a first direction; the lens device is arranged on a transmission path of an output light beam of the optical phased array and is used for shaping the one-dimensional scanning light beam and outputting the shaped one-dimensional scanning light beam; wherein the shaped one-dimensional scanning light beam forms a circular light spot on the structured light generator; and the structured light generator is arranged on a transmission path of the light beam output by the lens device and is used for shaping and collimating the one-dimensional scanning light beam output by the lens device and outputting structured light distributed based on the first direction and the second direction. The system can output a two-dimensional solid-state scanning light beam, and the light beam quality of structured light is effectively ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of all-solid-state beam scanning devices, and particularly to an all-solid-state two-dimensional beam scanning system assisted by a structured light generator. Background Art

[0002] In the related art, lidar technology has become increasingly mature and is widely used in fields such as autonomous driving, surveying and mapping, geographic information, and environmental monitoring. By emitting laser pulses and receiving reflected signals, lidar can accurately measure the distance and speed of objects. A beam steering device is used to scan the surrounding environment to achieve high-resolution distance and speed information detection.

[0003] Traditional two-dimensional beam scanning systems, such as mechanical rotating mirrors and microelectromechanical system mirrors, can achieve large-field-of-view two-dimensional scanning. However, due to the presence of mechanical moving parts in the system, the scanning speed, accuracy, and reliability are limited. All-solid-state scanning technology has the advantages of high reliability, high scanning speed, and accuracy because it does not contain any mechanical moving parts. Among them, optical phased array (OPA) is a solid-state beam scanning technology with high-speed scanning ability and anti-interference. However, currently, it can only achieve one-dimensional solid-state beam scanning through phase difference tuning, which severely limits the application range of the optical phased array.

[0004] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] The present invention provides an all-solid-state two-dimensional beam scanning system assisted by a structured light generator, which can achieve two-dimensional solid-state beam scanning, and thus overcome the defects existing in the prior art to a certain extent.

[0006] Other features and advantages of the present invention will become apparent through the following detailed description, or be learned in part through the practice of the present invention.

[0007] According to a first aspect of the present invention, there is provided an all-solid-state two-dimensional beam scanning system assisted by a structured light generator, the system comprising: an optical phased array, a lens device, and a structured light generator;

[0008] The optical phased array is configured to perform phase modulation on an input laser beam and output a one-dimensional scanning beam based on a first direction distribution;

[0009] The lens device is disposed on the transmission path of the output beam of the optical phased array, and is configured to perform a first-stage shaping and collimation process on the one-dimensional scanning beam and then output the processed one-dimensional scanning beam;

[0010] The structured light generator is disposed on the transmission path of the output beam of the lens device, and is configured to perform a second-stage shaping, collimation, and fractional processing on the one-dimensional scanning beam output by the lens device, and output structured light distributed based on the first direction and the second direction.

[0011] In some exemplary embodiments, the size of the lens device is larger than the size of the radiation end face of the optical phased array; the size of the structured light generator is larger than the size of the lens device.

[0012] In some exemplary embodiments, a gap is provided between the radiation end face of the optical phased array and the lens device, and the distance for the output beam of the optical phased array to be fully coupled in the gap is greater than or equal to 120 μm.

[0013] In some exemplary embodiments, the lens device is a columnar prism assembly;

[0014] The columnar prism assembly includes a first-stage columnar prism; or,

[0015] The columnar prism assembly includes a first-stage columnar prism and a second-stage columnar prism arranged in sequence;

[0016] Wherein, the long axis of the first-stage columnar prism is arranged along the first direction, and the long axis of the second-stage columnar prism is arranged along the second direction; the front focal plane of the first-stage columnar prism is the output end face of the optical phased array, and the front focal plane of the second-stage columnar prism is the output end face of the optical phased array; the focal length of the second-stage columnar prism is greater than the focal length of the first-stage columnar prism.

[0017] In some exemplary embodiments, the area of the first-stage columnar prism is greater than 500 μm × 500 μm;

[0018] The area of the second-stage columnar prism is greater than or equal to 15 mm × 5 mm.

[0019] In some exemplary embodiments, the structured light generator is a microlens array for outputting line structured light; or,

[0020] The structured light generator is a diffractive optical element DOE / metasurface device for outputting a dot array structured light or a coded plane structured light.

[0021] In some exemplary embodiments, the lens device is an aspherical lens;

[0022] The structured light generator is a microlens array for outputting line structured light; or,

[0023] The structured light generator is a diffractive optical element DOE / metasurface device, which is used to output a dot array structured light or a coded surface structured light.

[0024] In some exemplary embodiments, the lens device is a first-order diffractive optical element DOE or a metasurface device;

[0025] The structured light generator is a second-order diffractive optical element DOE or a metasurface device, which is used to output a dot array structured light or a coded surface structured light.

[0026] In some exemplary embodiments, the system further includes: a laser light source, which is arranged at the front end of the optical phased array and is used to input a laser light source to the optical phased array.

[0027] In some exemplary embodiments, the system further includes:

[0028] An image analysis unit, which is used to collect the image to be analyzed after the structured light is projected onto the surface of the object to be measured; and process the image to be analyzed, extract the height information within the range irradiated by the structured light, and integrate based on the height information to construct a three-dimensional model of the object to be measured.

[0029] In some exemplary embodiments, the optical phased array includes: an input coupler, a beam splitter array, a phase shifter array, and a radiator, which are arranged in sequence;

[0030] The input coupler is used to receive a laser beam and couple it into the on-chip waveguide;

[0031] The beam splitter array is used to evenly divide a single waveguide coupled into the chip into 2 N waveguides;

[0032] The phase shifter array is used to control in response to an external excitation source to adjust the phase of the light beam in the waveguide; the radiator is used to output the phase-modulated light beam.

[0033] The all-solid-state two-dimensional beam scanning system assisted by a structured light generator provided by the embodiments of the present invention, by arranging an optical phased array, a lens device, and a structured light generator in the system, uses the optical phased array to perform phase modulation on the input laser beam to obtain a one-dimensional scanned beam, uses the lens device to perform the first-stage shaping and collimation processing on the one-dimensional scanned beam, and then uses the structured light generator to perform the second-stage shaping and collimation processing on the one-dimensional scanned beam output by the lens device to obtain a two-dimensional structured light, thereby realizing an all-solid-state two-dimensional beam scanning system and being able to output a two-dimensional solid-state scanned beam, effectively ensuring the beam quality of the structured light.

[0034] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and do not limit the present invention. Brief Description of the Drawings

[0035] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present invention, and are used together with the specification to explain the principles of the present invention. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0036] Figure 1 Schematically showing a schematic diagram of an all-solid-state two-dimensional beam scanning system assisted by a structured light generator according to an exemplary embodiment of the present invention;

[0037] Figure 2 Schematically showing a schematic diagram of a waveguide structure of a lithium niobate optical phased array according to an exemplary embodiment of the present invention;

[0038] Figure 3 Schematically showing a schematic diagram of a scanning system using two-stage cylindrical prisms and a metasurface according to an exemplary embodiment of the present invention;

[0039] Figure 4 Schematically showing a schematic diagram of a microlens array adopting a micro-cylindrical prism array structure according to an exemplary embodiment of the present invention;

[0040] Figure 5 Schematically showing a schematic diagram of line structured light according to an exemplary embodiment of the present invention;

[0041] Figure 6 Schematically showing a schematic diagram of the structure of a scanning system using two-stage metasurface devices to output encoded plane structured light according to an exemplary embodiment of the present invention;

[0042] Figure 7 Schematically showing a schematic diagram of the structure of a scanning system using two-stage metasurface devices to output dot array structured light according to an exemplary embodiment of the present invention;

[0043] Figure 8 Schematically showing a schematic diagram of the structure of a scanning system using an aspherical lens, a diffractive optical element or a metasurface to output dot array structured light according to an exemplary embodiment of the present invention;

[0044] Figure 9 Schematically showing a schematic diagram of a waveguide structure of a silicon-based optical phased array according to an exemplary embodiment of the present invention;

[0045] Figure 10 Schematically showing a schematic diagram of dot array structured light according to an exemplary embodiment of the present invention;

[0046] Figure 11 Schematically show a schematic diagram of a fully solid-state two-dimensional beam scanning system in an exemplary embodiment of the present invention;

[0047] Figure 12 Schematically show a schematic diagram of another fully solid-state two-dimensional beam scanning system in an exemplary embodiment of the present invention;

[0048] Figure 13 Schematically show a schematic diagram of a diffractive optical element in an exemplary embodiment of the present invention. Detailed implementation manners

[0049] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this invention will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. The features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0050] In addition, the accompanying drawings are only schematic illustrations of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures denote the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0051] In view of the disadvantages and deficiencies of the prior art, a fully solid-state two-dimensional beam scanning system assisted by a structured light generator is provided in this example embodiment. Refer to Figure 1 As shown, the scanning system includes, arranged in sequence: an optical phased array 1, a lens device 2, and a structured light generator 3.

[0052] Specifically, at the front end of the optical phased array 1, a laser light source can be provided for inputting a laser light source into the optical phased array 1. The optical phased array 1 is used to perform phase modulation on the input laser beam and output a one-dimensional scanning beam based on the first direction distribution; the lens device 2 is arranged on the transmission path of the output beam of the optical phased array 1, and is used to perform shaping and collimation processing on the one-dimensional scanning beam and then output the processed one-dimensional scanning beam; among them, the processed one-dimensional scanning beam forms a circular light spot on the structured light generator. A gap is provided between the radiation end face of the optical phased array 1 and the lens device 2, so that after the outgoing beam of the optical phased array 1 is fully coupled in the gap, collimation and shaping are performed; and it can make the target light spot larger than the minimum working area of the diffractive optical element. The structured light generator 3 is arranged on the transmission path of the output beam of the lens device 2, and is used to perform shaping and collimation processing on the one-dimensional scanning beam output by the lens device 2 and output structured light based on the first direction and the second direction distribution.

[0053] Exemplarily, the optical phased array 1 can be a silicon-based optical phased array or a lithium niobate optical phased array. Specifically, the optical phased array 1 includes an input coupler 101, a beam splitter array 102, a phase shifter array 103, and a radiator 104 arranged in sequence. Among them, the input coupler 101 is used to receive the laser beam and couple it into the on-chip waveguide; the beam splitter array 102 is used to evenly divide the one-way waveguide coupled into the chip into 2 N ways of waveguides; the phase shifter array 103 is used to control in response to an external excitation source to regulate the phase of the light beam in the waveguide; the radiator 104 is used to output the phase-modulated light beam.

[0054] Specifically, the input coupler can be an end-face coupler or a grating coupler, which is used to couple an off-chip light source into the optical phased array chip. Specifically, when using an end-face coupler, the input coupler is composed of a tapered waveguide. By slowly changing the waveguide width, the mode field size in the waveguide changes slowly to play the role of a mode spot converter. By using an end-face input coupler, it has the advantages of low insertion loss, large bandwidth, and polarization insensitivity. Or, when selecting a grating coupler, the diffraction effect of the grating is used to realize the coupling between the optical fiber and the on-chip waveguide; it has the advantages of flexible position and large coupling alignment tolerance.

[0055] For example, referring to Figure 2 As shown, the waveguide structure in the optical phased array from top to bottom is: a thin film lithium niobate layer, a silicon dioxide buried layer 120, and a silicon substrate layer 110. The thin film lithium niobate layer includes: a waveguide 130 and an electrode 140. Among them, the thickness of the lithium niobate waveguide is 0.6 μm, the thickness of the silicon dioxide cladding is 2 μm, and the thickness of the silicon substrate is 525 μm. The lithium niobate waveguide forms a ridge waveguide through an etching process, and the working wavelength is in the 1550 nm band.

[0056] Among them, the thin-film lithium niobate adopts the crystal orientation of x-cut and y-propagation, that is, the normal line of the thin-film lithium niobate is along the x-axis, the optical signal propagates along the y-axis, and the crystal axis is the z-axis. The lithium niobate waveguide is a ridge waveguide with an upper width of 1 μm, an inclination angle of 78°, and the thickness of the ridge structure is 300 nm. This parameter design can effectively confine the TE0 optical mode and achieve low-loss transmission. The waveguide is covered with a cladding layer of silica or other low-refractive-index materials to further reduce the waveguide loss.

[0057] Specifically, the beam splitter array is used to evenly divide a waveguide coupled into the chip into 2 N waveguides, and its structure can be a multimode interference beam splitter, a Y-beam splitter or a directional coupler. Among them, the waveguide is the channel for light rays to propagate in the optical device, and the waveguide confines the light rays in the channel through total internal reflection.

[0058] For example, the beam splitter can adopt a 1×2 multimode interference coupler. The uniform splitting of the light beam is realized through a binary tree structure. Compared with the Y-branch and the directional coupler, the multimode interferometer has higher tolerance to processing errors and more uniform energy distribution. The length of the multimode interference region is optimized to 65 μm, and the width is 10 μm. The shapes of the input channel and the output channel are optimized to reduce the mode mismatch between the input and output channels and the multimode interference region. The original rectangular channel is optimized to a trapezoid, with an upper width of 1 μm (the waveguide width) and a lower width of 3.5 μm, and the trapezoid height is 50 μm. The optimized multimode interference coupler has the advantages of large bandwidth and low insertion loss.

[0059] Specifically, the phase shifter array can be composed of 2 N phase shifters. It is used to respond to the control of an external excitation source to precisely regulate the phase of the light beam in 2 N waveguides. For example, a thermo-optic phase shifter or an electro-optic phase shifter can be adopted.

[0060] For example, when a thermo-optic phase shifter is selected, the phase shifter array is composed of 2 N thermo-optic phase shifters. The thermo-optic phase shifter is based on the thermo-optic effect of silicon material, and realizes phase modulation by integrating a metal heater above the silicon waveguide. Specifically, the phase shifter uses TiN material as the heater structure. When a voltage is applied across the heater, its temperature will rise with the increase of the voltage, and then heat the silicon waveguide. This heating process can change the effective refractive index of the optical field in the waveguide. After passing through a certain length of thermo-optic phase shifter, precise modulation of the optical phase can be achieved.

[0061] Or, when an electro-optic phase shifter is selected, the phase shifter array is composed of 2 NIt consists of electro-optic phase shifters. The electro-optic phase shifters utilize the electro-optic effect of lithium niobate materials. Parallel electrodes are arranged on both sides of the waveguide in the y-axis direction for the lithium niobate electro-optic phase shifter. When a voltage is applied to the electrodes, an electric field in the x-axis direction will be generated in the waveguide. Electrodes made of gold are fabricated on both sides of the lithium niobate ridge waveguide. By applying a voltage to the electrodes, a modulation electric field is generated, thereby changing the refractive index of the lithium niobate ridge waveguide, and ultimately realizing the modulation of the beam phase in the waveguide. Through the electro-optic effect of lithium niobate, this electric field can change the refractive index of the waveguide, thereby achieving precise control of the beam phase.

[0062] Specifically, the radiator is an end-face radiator, consisting of 2 N parallel emission waveguides along the laser beam transmission direction. The input end of each emission waveguide is respectively connected to the phase shifter, and the emission end face of each emission waveguide is the cross-section of the waveguide. The emission waveguide is along the y-axis direction, the chip normal is along the z-axis direction, and the radiator array is arranged along the x-axis direction.

[0063] For example, the radiator consists of 8 parallel waveguides, the waveguide direction is along the y-axis, and the array arrangement direction is along the x-axis. One end of each waveguide is connected to the electro-optic phase shifter, and the other end extends to the chip edge. The roughness of the radiator end face is reduced through the end-face polishing process, thereby reducing the loss when the beam is emitted from the waveguide to free space.

[0064] Exemplarily, the lens device can be used for the first-stage collimation and shaping of the input beam. Specifically, an elliptical light spot with a divergence angle emitted from the end face of the optical phased array can be collimated and shaped into a circular light spot. Among them, the size of the lens device needs to be larger than the size of the radiation end face of the optical phased array.

[0065] For example, the lens device can be a columnar prism assembly, including at least one columnar prism. Or, the lens device can be an aspherical lens. Or, the lens device can also be a device using a diffractive optical element DOE or a metasurface device.

[0066] Exemplarily, the structured light generator is arranged in the beam output direction of the lens device; and, the size of the structured light generator needs to be larger than the size of the lens device, aiming to ensure that the beam completely covers the working area of the structured light generator, avoiding the beam irradiation range exceeding its working range, thereby ensuring that the structured light generator can precisely control the phase of the beam. The structured light generator reshapes the circular light spot emitted after being collimated by the lens device into structured light with a vertical direction distribution, increasing the detection ability of the beam in the vertical direction, and its detection range depends on the beam shaping ability of the structured light generator.

[0067] Specifically, the structured light 4 emitted by the structured light generator can be any one of line structured light, surface structured light, dot array structured light, or surface encoded structured light. By projecting the structured light onto the surface of the object to be measured, a deformed structured light image formed due to the contour differences of the object is captured. Subsequently, the deformed image is computationally processed to extract the height information within the range irradiated by the structured light, and the extracted height information is integrated to automatically construct a three-dimensional model of the object.

[0068] For example, the structured light generator can be a microlens array for outputting line structured light; alternatively, the structured light generator is a diffractive optical element DOE / metasurface device for outputting dot array structured light or encoded surface light.

[0069] Specifically, the light propagation path of the system is as follows: The off-chip laser source couples the laser into the waveguide through the input coupler on the optical phased array chip, and then passes through a three-stage 1×2 beam splitter array to evenly divide one beam into eight beams. Next, eight independent lithium niobate electro-optic phase shifters are used to regulate the phase of each beam. Finally, the eight modulated beams are incident on the lens device through the radiation end face of the radiator, collimated and shaped into circular light spots, and then radiated into free space under the shaping effect of the structured light generator. The movement of the beam in the x direction is achieved through the optical phased array, and at the same time, the structured light generator is used to shape the beam into structured light with a z-direction distribution.

[0070] Exemplarily, the distance between the radiation end face of the optical phased array 1 and the lens device 2 can be set to be greater than or equal to 120 μm.

[0071] Exemplarily, the lens device (2) is a columnar prism assembly; the columnar prism assembly includes a first-order columnar prism; alternatively, the columnar prism assembly includes a first-order columnar prism and a second-order columnar prism arranged in sequence. Among them, the major axis of the first-order columnar prism is arranged along the first direction, and the major axis of the second-order columnar prism is arranged along the second direction; the front focal plane of the first-order columnar prism is the output end face of the optical phased array (1), and the front focal plane of the second-order columnar prism is the output end face of the optical phased array (1); the focal length of the second-order columnar prism is greater than the focal length of the first-order columnar prism.

[0072] Among them, the area of the first-order columnar prism is greater than 500 μm × 500 μm; the area of the second-order columnar prism is greater than or equal to 15 mm × 5 mm.

[0073] Correspondingly, the structured light generator is a microlens array for outputting line structured light; alternatively, the structured light generator is a diffractive optical element DOE / metasurface device for outputting dot array structured light or encoded surface light.

[0074] Exemplarily, the lens device 2 can adopt an aspherical lens.

[0075] Correspondingly, the structured light generator can be a microlens array for outputting line structured light. Alternatively, the structured light generator can adopt a diffractive optical element DOE / metasurface device for outputting a dot array structured light or a coded plane structured light.

[0076] Exemplarily, the lens device 2 can adopt a first-level diffractive optical element DOE or a metasurface device.

[0077] Correspondingly, the structured light generator 3 is a second-level diffractive optical element DOE or a metasurface device for outputting a dot array structured light or a coded plane structured light. As Figure 6 、 Figure 7 shown.

[0078] Exemplarily, the system further includes: an image analysis unit for collecting an image to be analyzed after the structured light is projected onto the surface of the object to be measured; and processing the image to be analyzed, extracting the height information within the range irradiated by the structured light, and integrating based on the height information to construct a three-dimensional model of the object to be measured.

[0079] Specifically, when the structured light is projected onto the surface of the object to be measured, due to the unevenness of the object contour, the structured light will be deformed. The deformed structured light is captured by an external camera, and the corresponding height difference is calculated. During the process of controlling the beam deflection by the optical phased array, the structured light passing through the structured light generator will also move accordingly. By repeating the above process, the height information at different positions can be obtained sequentially. Finally, by integrating these height information, the overall three-dimensional image of the object can be reconstructed, realizing high-precision three-dimensional reconstruction.

[0080] For example, an intelligent terminal device can be provided to receive the image to be analyzed collected by the imaging component and calculate the height information; and reconstruct the three-dimensional model of the object to be measured according to the calculation result of the height information.

[0081] In one embodiment, as shown in Figure 1 , a fully solid-state two-dimensional beam scanning system assisted by a structured light generator is provided. The lens device is configured to adopt a first-level cylindrical prism, and the structured light generator can adopt a microlens array; the corresponding structured light generated is line structured light. Among them, the first-level cylindrical prism is located in the propagation direction of the light beam emitted by the optical phased array. The optical axis of the cylindrical prism is parallel to the z direction, the focal length is 760 μm, the distance from the radiation end face of the optical phased array is 760 μm, and the size is 1 mm × 1 mm × 1 mm. The radiation light from the radiation end face enters from the plane side of the cylindrical prism and exits through the curved surface to obtain an elliptical beam collimated in the z direction.

[0082] The microlens array adopts a micro-cylindrical prism array structure and is located in the beam propagation direction of the collimating lens. Its structure is as shown in Figure 4 . The arrangement direction of the micro-cylindrical prisms is along the z-axis direction. The focal length of the prism is 5.4 mm, the aperture size of the sub-lens is 50 μm, and each micro-cylindrical prism is evenly arranged. The size of the micro-cylindrical prism array is 15 mm × 5 mm × 1 mm, and its center line is along the x-axis direction. The beam emitted from the collimating lens is incident from the flat end of the micro-cylindrical prism array and exits from the convex end. This micro-cylindrical prism array is used to shape the point beam emitted from the on-chip waveguide array into a homogenized line beam distributed along the z direction. The coverage range of this line beam in the z direction determines the field of view angle of the beam in this dimension. The divergence angle of the beam on the z-axis is 40°, and the obtained line structured light is as shown in Figure 5 .

[0083] When the line structured light is projected onto the surface of the object to be measured, due to the unevenness of the object contour, the structured light stripes will be deformed. By capturing these deformed stripes with an external camera and performing preprocessing such as noise reduction, short lines formed due to deflection can be extracted. The number of short lines is related to the flatness of the object surface: the more uneven the object surface, the more short lines are formed. In addition, there is a height difference in the y-axis direction for these short lines, which is called the deflection distance. Based on the principle of laser triangulation, the deflection distance can be accurately converted into the actual height difference, so as to obtain the height information of the object at this position.

[0084] During the process of controlling the beam deflection using the optical phased array, the line structured light passing through the structured light generator will also move accordingly. By repeating the above process, the height information at different positions can be obtained in sequence. Finally, by integrating this height information, the overall three-dimensional image of the object can be reconstructed to achieve high-precision three-dimensional reconstruction.

[0085] In one embodiment, a full-solid-state two-dimensional beam scanning system assisted by a structured light generator is provided. As shown in Figure 3 , a silicon-based optical phased array is adopted, and a lens device is configured with a columnar prism assembly, including a first-level columnar prism and a second-level columnar prism arranged in sequence; a diffraction optical element is configured as the structured light generator.

[0086] Among them, the major axis of the first-level columnar prism is arranged along the first direction, and the major axis of the second-level columnar prism is arranged along the second direction; the front focal plane of the first-level columnar prism is the output end face of the optical phased array 1, and the front focal plane of the second-level columnar prism is the output end face of the optical phased array 1; the focal length of the second-level columnar prism is greater than that of the first-level columnar prism. Specifically, the first-level columnar prism is used to collimate the divergence angle of the beam output by the optical phased array in the z direction. After propagating a certain distance under the action of the divergence angle in the x direction to obtain a circular light spot, after entering the second-level columnar prism, the divergence angle in the x direction is collimated, and a circular light spot is output.

[0087] The propagation path of the light beam is as follows: The off-chip laser source couples the laser into the waveguide through the input coupler on the chip, and then passes through a three-stage 1×2 beam splitter array to evenly divide one beam of light into eight beams. Next, eight independent silicon-based thermo-optic phase shifters are used to regulate the phases of each beam of light respectively. Finally, the eight modulated beams of light are incident on the cylindrical prism group through the radiation end face of the radiator, collimated and shaped into a circular light spot, and then radiated into free space under the beam splitting effect of the diffractive optical device. The movement of the light beam in the x direction is realized through the optical phased array, and the light beam is split into structured light with a z-direction distribution through the diffractive optical element.

[0088] Among them, referring to Figure 9 As shown, the waveguide structure of the silicon-based optical phased array from top to bottom is: silicon dioxide protective layer, silicon layer, silicon dioxide buried layer, and silicon substrate layer. Among them, the thickness of the silicon dioxide protective layer is 3μm, the width of the optical waveguide is 5.85μm, the height is 220nm, the thickness of the silicon dioxide buried layer is 2μm, and the thickness of the substrate silicon material is 525μm. This structure is applicable to the 1550nm band.

[0089] The on-chip input optical coupler is a radiation end face coupler of the silicon-based waveguide. The three-stage 1×2 beam splitter array adopts a multimode interferometer (MMI) structure to achieve uniform beam splitting through a binary tree structure. Compared with Y-branches and directional couplers, the multimode interferometer has higher tolerance to processing errors and more uniform energy distribution. The silicon-based thermo-optic phase shifter is provided with a TiN heater 3μm above the silicon-based waveguide in the y-axis direction. When the heater works, it increases the temperature of the optical waveguide through heat conduction, and then uses the thermo-optic effect to change the refractive index of the waveguide to achieve the regulation of the beam phase. The radiator is composed of eight waveguides arranged in parallel. The waveguide direction is along the y-axis, and the array arrangement direction is along the x-axis. One end of each waveguide is connected to the thermo-optic phase shifter, and the other end extends to the edge of the chip. The roughness of the radiator end face is reduced through the end face polishing process, thereby reducing the loss when the light beam is emitted from the waveguide to free space.

[0090] The cylindrical prism group is located in the propagation direction of the light beam emitted from the optical phased array and is divided into two levels. The optical axis of the first-level cylindrical prism is parallel to the z direction, the focal length is 577μm, the distance from the radiation end face of the optical phased array is 577μm, and the size is 10mm×5mm×1mm. The optical axis of the second-level cylindrical prism is parallel to the x axis, the focal length is 20mm, the distance from the radiation end face of the optical phased array is 20mm, and the size is 20mm×10mm×1mm. The radiation light from the radiation end face is incident from the plane side of the first-level cylindrical prism and exits through the curved surface to obtain an elliptical beam collimated in the z direction. Under the action of the divergence angle in the x direction, when it propagates to the second-level cylindrical prism, it is a circular light spot, is incident on the plane side of the second-level cylindrical prism, and exits through the curved surface to obtain a circular collimated beam with a light spot size of 2mm×2mm.

[0091] The diffractive optical element is located in the beam propagation direction of the collimating lens, and its structure is as Figure 8 shown. The device size is 30mm×15mm×1mm. The device has 8 phase orders, the pixel size is 1μm×1μm, and the on-chip structure is obtained by algorithm design. The center line of the device is along the z-axis direction, and the plane is opposite to the cylindrical prism. The beam emitted from the secondary cylindrical prism is incident on the plane of the diffractive optical element and exits from the convex surface. The diffractive optical element is used to split the point beam emitted from the on-chip waveguide array into a structured light of a point array parallel to the xoz plane. The coverage range of the surface beam in the z direction determines the field of view angle of the beam in this dimension. Since the diffractive optical element will produce pincushion distortion at a large divergence angle, the number of points is selected as 23×23, and the divergence angle is selected as 31°. The obtained structured light of the point array is as Figure 10 shown.

[0092] When the structured light of the point array is projected onto the object to be measured, the monocular structured light reconstruction system needs to be calibrated first. Subsequently, the camera captures the deformed image and performs noise reduction and image correction processing. Then, the computer decodes the image, identifies and extracts each sub-position, and corrects the sub-matrix that is difficult to identify or has disappeared. Finally, using the principle of laser triangulation, the height information within the range irradiated by the projected point array structured light is obtained. When the optical phased array deflects at an angle, the projected structured light of the point array will also move accordingly. By repeating the above process, the surface height information at different positions can be obtained, so as to realize the three-dimensional measurement of objects at different positions or the overall measurement of the same large object.

[0093] For example, in the system as Figure 3 shown, the target light field reaching the structured light generator: a 2mm×2mm circular spot without divergence angle; the divergence angle of the beam emitted from the OPA is set to 5.7°×120°.

[0094] Set the distance from the radiation end face of the optical phased array to the primary cylindrical prism as x 1 , and the distance to the secondary cylindrical prism as x 2 , the longitudinal focal length of the primary cylindrical prism is f 1 = x 1 , the transverse focal length is set to infinity, and the transverse focal length of the secondary cylindrical prism is f 2 = x 2 , and the longitudinal focal length is infinity.

[0095] When the collimated beam reaches the primary cylindrical prism, the longitudinal divergence angle is constrained. Through the formula (where d is the target longitudinal light field size and θ is the longitudinal divergence angle), x 1 = 577μm can be calculated, and the transverse divergence angle is not constrained.

[0096] When the collimated beam reaches the second-stage cylindrical prism, the lateral divergence angle is constrained. Through the formula (where d is the lateral size of the target light field and θ is the divergence angle in the lateral direction), x can be calculated 2 = 20 mm, and the longitudinal divergence angle is not constrained. At this time, a 2 mm × 2 mm circular spot without divergence angle is obtained.

[0097] Based on the above calculation results, it can be configured that the distance between the first-stage cylindrical prism and the optical phased array is 577 μm, and the distance between the second-stage cylindrical prism and the optical phased array is 20 mm.

[0098] In one embodiment, a fully solid-state two-dimensional beam scanning system assisted by a structured light generator is provided. Referring to Figure 6 as shown, the lens device is configured to use a first-stage DOE / metasurface, and the structured light generator is configured to use a diffractive optical element DOE / metasurface.

[0099] By using a metasurface for the structured light generator, the beam can be split into a point array structured light with a z-direction distribution.

[0100] For example, when the structured light generator uses a diffractive optical element or a metasurface, the generated structured light is encoded plane structured light. Before measurement, the monocular structured light reconstruction system needs to be calibrated first. Subsequently, the deformed image projected onto the object surface is captured by the camera, and noise reduction and image correction processing are performed. Then, the computer decodes the image, identifies and extracts each sub-matrix, and corrects the sub-matrices that are difficult to identify or disappear. Finally, using the laser triangulation principle, the height information within the range irradiated by the projected plane structured light is obtained. When the optical phased array deflects the angle, the projected plane structured light will also move accordingly. By repeating the above process, the surface height information at different positions can be obtained, thereby realizing three-dimensional measurement of objects at different positions or overall measurement of the same large object.

[0101] In one embodiment, a fully solid-state two-dimensional beam scanning system assisted by a structured light generator is provided. Referring to Figure 8 as shown, a lithium niobate optical phased array is used, the lens device is configured to use an aspherical lens, and the structured light generator is configured to use a diffractive optical element. The generated structured light is point array structured light.

[0102] The propagation path of the light beam is as follows: The off-chip laser light source couples the laser into the waveguide through the input coupler on the chip, and then passes through a three-stage 1×2 beam splitter array to evenly divide one beam into eight beams. Next, eight independent lithium niobate electro-optic phase shifters are used to regulate the phase of each beam. Finally, the eight modulated beams are incident on the cylindrical prism through the radiation end face of the radiator, collimated and shaped into a circular light spot, and then radiated into free space under the shaping effect of the microlens array. The movement of the light beam in the x direction is achieved through the optical phased array, and at the same time, the microlens array is used to shape the light beam into structured light with a z-direction distribution.

[0103] The aspherical lens is located in the propagation direction of the light beam emerging from the optical phased array, 760 μm away from the radiation end face of the optical phased array. Its surface structure is obtained by algorithm design, and the size is a hemisphere with a radius of 2 mm. The radiation light from the radiation end face enters from the planar side of the aspherical lens and exits through the curved surface to obtain a collimated light beam.

[0104] The diffractive optical element is located in the propagation direction of the light beam emerging from the aspherical lens, and the structure is as Figure 13 shown. The device size is configured as 30 mm × 15 mm × 1 mm. The device has an 8th-order phase order, the pixel size is 1 μm × 1 μm, and the on-chip structure is obtained by algorithm design. The center line of the device is along the z-axis direction, and the plane is opposite to the curved surface of the aspherical lens. The light beam emerging from the aspherical lens enters from the planar side of the diffractive optical element and exits from the convex side. This diffractive optical element is used to split the point light beam emitted from the on-chip waveguide array into a point array structured light parallel to the xoz plane. The coverage range of this plane light beam in the z direction determines the field of view angle of the light beam in this dimension. Since the diffractive optical element will produce pillow distortion at a large divergence angle, the number of points is selected as 5 × 15, distributed along the z direction, and the divergence angle is selected as 30° to obtain the point array structured light.

[0105] When the point array structured light is projected onto the object to be measured, the monocular structured light reconstruction system needs to be calibrated first. Subsequently, the camera captures the deformed image and performs noise reduction and image correction processing. Then, the computer decodes the image, identifies and extracts each sub-position, and corrects the sub-matrices that are difficult to identify or disappear. Finally, using the principle of laser triangulation, the height information within the range irradiated by the projected point array structured light is obtained.

[0106] During the process of controlling the light beam deflection using the optical phased array, the point array structured light passing through the structured light generator will also move accordingly. By repeating the above process, the height information at different positions can be obtained sequentially. Finally, by integrating these height information, the overall three-dimensional image of the object can be reconstructed to achieve high-precision three-dimensional reconstruction.

[0107] In one embodiment, a full-solid-state two-dimensional beam scanning system assisted by a structured light generator is provided. Refer to Figure 11 As shown, a lithium niobate optical phased array is adopted. A metasurface is configured for the lens device, and a diffractive optical element is configured for the structured light generator. The generated structured light is multiple line structured lights.

[0108] The propagation path of the beam is as follows: The off-chip laser source couples the laser into the waveguide through the input coupler on the chip, and then passes through a three-stage 1×2 beam splitter array to evenly divide one beam into eight beams. Next, eight independent lithium niobate electro-optic phase shifters are used to adjust the phase of each beam. Finally, the eight modulated beams are incident on the cylindrical prism through the radiation end face of the radiator, collimated and shaped into a circular light spot, and then radiated into free space under the shaping effect of the microlens array. The movement of the beam in the x direction is realized through the optical phased array, and at the same time, the beam is shaped into a structured light with a z-direction distribution by using the microlens array.

[0109] The metasurface is located in the propagation direction of the beam emitted from the optical phased array. The distance between the metasurface and the radiation end face of the optical phased array is 762 μm, and its on-chip structure is obtained by algorithm design. The radiation light from the radiation end face is incident from the planar side of the metasurface and exits through the curved surface, so as to collimate the divergence angles of the light spot in two directions and obtain a circular collimated beam with a light spot size of 2 mm×2 mm.

[0110] The diffractive optical element is located in the propagation direction of the beam emitted from the metasurface. The device size is 20 mm×5 mm×1 mm. The device has an 8th-order phase order, the pixel size is 1 μm×1 μm, and its on-chip structure is obtained by algorithm design. The center line of the device is along the z-axis direction, and the plane is opposite to the radiation end face of the optical phased array. The beam emitted from the metasurface is incident from the planar side of the diffractive optical element and exits from the convex side. This diffractive optical element is used to split and shape the beam emitted from the metasurface into a line array beam distributed along the z direction. The coverage range of the line array beam in the z direction determines the field of view angle of the beam in this dimension. The diffusion angle of the beam on the z-axis is 40°, and a line array structured light is obtained.

[0111] When the line array structured light is projected onto the surface of the object to be measured, due to the unevenness of the object contour, the structured light stripes will be deformed. By capturing these deformed stripes with an external camera and performing preprocessing such as noise reduction, short lines formed due to deflection can be extracted. The number of short lines is related to the flatness of the object surface: the more uneven the object surface, the more short lines are formed. In addition, there is a height difference in the y-axis direction for these short lines, which is called the deflection distance. Based on the laser triangulation principle, the deflection distance can be accurately converted into the actual height difference, so as to obtain the height information of the object at this position.

[0112] During the process of controlling beam deflection using an optical phased array, the line structured light passing through the structured light generator will also move accordingly. By repeating the above process, height information at different positions can be obtained in sequence. Finally, by integrating this height information, the overall three-dimensional image of the object can be reconstructed, achieving high-precision three-dimensional reconstruction.

[0113] In one embodiment, a fully solid-state two-dimensional beam scanning system assisted by a structured light generator is provided. Referring to Figure 12 as shown, a silicon-based optical phased array is adopted. The lens device is configured with a collimating lens group, and the structured light generator is configured with a diffractive optical element. The collimating lens group includes a concave lens and a metasurface arranged in sequence.

[0114] The propagation path of the beam is as follows: The off-chip laser source couples the laser into the waveguide through the input coupler on the chip. Subsequently, it passes through a three-stage 1×2 beam splitter array, evenly dividing the 1-way beam into 8 ways. Next, 8 independent silicon-based thermo-optic phase shifters are used to modulate the phase of each beam respectively. Finally, the 8 modulated beams are incident on the cylindrical prism group through the radiation end face of the radiator, collimated and shaped into a circular spot, and then radiated into free space under the beam splitting effect of the diffractive optical device. The beam is moved in the x direction through the optical phased array, and the beam is split into structured light with a z-direction distribution by the diffractive optical element.

[0115] The collimating lens group adopts a concave lens and a metasurface, which are sequentially located in the propagation direction of the beam emerging from the optical phased array. The optical axis direction of the concave lens is parallel to the z direction, with a focal length of 20 μm and a distance of 120 μm from the radiation end face of the optical phased array. The metasurface is 577 μm away from the center of the concave lens, and its on-chip structure is obtained by algorithm design. The radiation light from the radiation end face is incident from one side of the concave lens and exits from the other side, expanding the divergence angle in the x-axis direction to be the same as the divergence angle in the z-axis direction. Under the action of the double-direction divergence angle, when it propagates to the metasurface, it is a circular spot. It is incident on the planar side of the metasurface and exits through the curved surface, obtaining a circular collimated beam with a spot size of 2 mm × 2 mm.

[0116] Referring to Figure 13The diffraction optical element shown is located in the propagation direction of the collimated lens output beam. The arrangement direction of the diffraction optical element is parallel to the emission waveguide array, i.e., along the z-axis direction. The device size is 30mm×15mm×1mm. The device has an 8th-order phase order, a pixel size of 1μm×1μm, and the on-chip structure is obtained by algorithm design. The center line of the device is along the z-axis direction, and the plane is opposite to the metasurface. The beam emitted from the metasurface is incident from the plane of the diffraction optical element and exits from the convex surface. This diffraction optical element is used to shape the point beam emitted from the on-chip waveguide array into a coded surface structured light with a specific structure distribution parallel to the xoz plane. The coverage range of the surface structured light in the z direction determines the field of view angle of the beam in this dimension. Since the diffraction optical element will produce pincushion distortion at a large divergence angle, the divergence angle is selected as 31°.

[0117] Before the spatial coded surface structured light is projected onto the object to be measured, the monocular structured light reconstruction system needs to be calibrated first. After the camera captures the deformed image and performs noise reduction and correction processing, the computer decodes the image to identify and extract the sub-matrix, and corrects the sub-matrix that is difficult to identify or disappears. Based on the principle of laser triangulation, the height information of the structured light irradiation area can be obtained. When the optical phased array deflects the angle, the projected structured light pattern will move accordingly. By repeating the above process, the surface height information at different positions can be obtained, so as to realize the three-dimensional measurement of objects at different positions or the overall measurement of large objects.

[0118] For example, in the Figure 12 system shown, the target light field reaching the structured light generator is: a 2mm×2mm circular spot with no divergence angle, and the divergence angle of the OPA output beam is 5.7°×120°.

[0119] Set the distance from the radiation end face of the optical phased array to the concave lens as x 1 = 120μm, and the distance to the metasurface is x 2 . The transverse focal length of the concave lens is f1, and the longitudinal focal length is set to infinity. The metasurface structure is obtained by design.

[0120] The concave lens is used to laterally expand the beam after sufficient coupling. Through the formula (where θ is the transverse beam divergence angle and a is the transverse size of the spot projected onto the chip), it is calculated that f 1 = 20μm.

[0121] When the beam is projected onto the metasurface, through the formula (where d is the target light field size and θ is the beam divergence angle), it is calculated that x 2= 577 μm, and after the phase regulation of the on-chip structure, a 2 mm × 2 mm circular light spot without divergence angle is obtained. That is, the distance between the concave lens and the optical phased array is 120 μm, and the distance between the metasurface and the optical phased array is 577 μm.

[0122] In the scanning system provided by the present invention, an off-chip light source enters the on-chip waveguide through an input coupler, and a beam of light is evenly divided into 2 N beams by a beam splitter array, and then the phase difference of each beam is adjusted by a phase shifter, and finally exits from the end of the radiator to achieve beam scanning in the horizontal direction. The horizontally scanned beam is collimated by a collimating lens and is collimated and shaped into a circular light spot to enter the structured light generator. The structured light generator uses its shaping function to shape the point light source emitted by the collimating lens into structured light with a vertical distribution, increasing the detection ability of the beam in the vertical direction, thereby realizing solid-state two-dimensional beam scanning. The structured light is projected onto the object to be measured, and the deformation amount of the structured light generated due to the contour difference of the object is obtained, and the geometric features of the measured object are calculated, realizing solid-state two-dimensional beam scanning, which has the advantages of fast scanning speed and high reliability.

[0123] It should be noted that the above-mentioned drawings are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present invention, rather than for limiting purposes. It is easy to understand that the processes shown in the above-mentioned drawings do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these processes can be executed synchronously or asynchronously in, for example, multiple modules.

[0124] The flowcharts and block diagrams in the drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present invention. The units described in the embodiments of the present invention can be implemented in software or in hardware, and the described units can also be provided in a processor. Among them, the names of these units do not constitute a limitation to the unit itself in some cases.

[0125] It should be noted that although several modules or units of devices for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiments of the present invention, the features and functions of the two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0126] Other embodiments of the present invention will be readily apparent to those skilled in the art upon consideration of the specification and practice of the invention herein. This application is intended to cover any variations, uses, or adaptations of the invention following the general principles of the invention and including known or customary technical means in the art not disclosed herein. The specification and examples are only to be considered as exemplary, and the true scope and spirit of the invention are pointed out by the claims.

[0127] It should be understood that the present invention is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A fully solid-state two-dimensional beam scanning system assisted by a structured light generator, characterized in that: The system comprises: an optical phased array (1), a lens device (2), and a structured light generator (3); The optical phased array (1) is used to perform phase modulation on an input laser beam and output a one-dimensional scanning beam distributed in a first direction; The lens device (2) is arranged on the transmission path of the output light beam of the optical phased array (1), and is used to perform a first-stage shaping and collimation process on the one-dimensional scanning light beam, and output the processed one-dimensional scanning light beam; The structured light generator (3) is arranged on the transmission path of the light beam output by the lens device (2), and is used to perform second-stage shaping, collimation, and beam splitting processing on the one-dimensional scanning light beam output by the lens device (2), and output structured light distributed based on the first direction and the second direction.

2. The system according to claim 1, characterized in that The size of the lens device (2) is larger than the size of the radiation end face of the optical phased array (1); and the size of the structured light generator (3) is larger than the size of the lens device (2).

3. The system according to claim 1 or 2, characterized in that: A gap is provided between the radiation end face of the optical phased array (1) and the lens device (2) so that the outgoing light beam of the optical phased array (1) is fully coupled in the gap.

4. The system according to claim 1, characterized in that The lens device (2) is a cylindrical prism assembly; The cylindrical prism assembly includes a primary cylindrical prism; or, The cylindrical prism assembly comprises a primary cylindrical prism and a secondary cylindrical prism which are arranged in sequence; The long axis of the primary cylindrical prism is arranged along the first direction, and the long axis of the secondary cylindrical prism is arranged along the second direction; the front focal plane of the primary cylindrical prism is the exit end face of the optical phased array (1), and the front focal plane of the secondary cylindrical prism is the exit end face of the optical phased array (1); the focal length of the secondary cylindrical prism is greater than the focal length of the primary cylindrical prism.

5. The system according to claim 4, characterized in that The area of ​​the primary cylindrical prism is greater than 500 μm×500 μm; The area of ​​the secondary cylindrical prism is greater than or equal to 15 mm×5 mm.

6. The system according to claim 4, characterized in that The structured light generator is a microlens array, which is used to output line-based structured light; or, The structured light generator is a diffractive optical element DOE / metasurface device, which is used to output point array structured light or coded surface structured light.

7. The system according to claim 1, characterized in that The lens device (2) is an aspherical lens; The structured light generator is a microlens array for outputting line structured light; or, The structured light generator is a diffractive optical element DOE / metasurface device, which is used to output point array structured light or coded surface structured light.

8. The system according to claim 1, characterized in that The lens device (2) is a first-order diffractive optical element DOE or a metasurface device; The structured light generator (3) is a second-order diffractive optical element DOE or a metasurface device, and is used to output point array structured light or coded surface structured light.

9. The system according to claim 1, characterized in that The system further comprises: A laser light source is arranged at the front end of the optical phased array (1) and is used to input the laser light source into the optical phased array (1).

10. The system according to claim 1, characterized in that The system further comprises: The image analysis unit is used to collect the image to be analyzed after the structured light is projected onto the surface of the object to be measured; and to process the image to be analyzed, extract the height information within the range of the structured light illumination, and integrate it based on the height information to construct a three-dimensional model of the object to be measured.

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