Multi-line laser projector, camera assembly, and electronic device

Abstract

The application provides a multi-line laser projector, a camera assembly and an electronic device. The multi-line laser projector comprises a substrate assembly, a plurality of laser light sources and at least one diffractive optical element. The plurality of laser light sources are arranged on the substrate assembly for emitting laser light and arranged in a row along a set straight line direction. The diffractive optical element is used for diffusing the laser light emitted by the plurality of laser light sources along the set straight line direction to form M one-line type projection patterns extending along the set straight line direction, wherein M is a positive integer greater than 1. The diffractive optical element has a first minimum period Pu along the set straight line direction and a second minimum period Ph along a direction perpendicular to the set straight line direction, and the second minimum period Ph is less than or equal to 1 / 3 of the first minimum period Pu. According to the application, the transverse period of the diffractive optical element of the multi-line laser projector is significantly smaller than the longitudinal period, which is conducive to improving the signal-to-noise ratio of the projection light field.

Description

Technical Field

[0001] This application relates to the field of imaging technology, and more specifically, to a multi-line laser projector and a camera assembly and electronic device having therein. Background Technology

[0002] The application of multi-line lasers in 3D reconstruction is becoming increasingly widespread. In some special application scenarios, such as eye model reconstruction, higher requirements are placed on the quality of multi-line lasers. Conventional multi-line laser modules use LD (Light Detector) in conjunction with collimating lenses and DOE (Diffuse Array). This approach has drawbacks such as severe speckle, low contrast between signal and noise areas (e.g., below 40), and inhomogeneity exceeding 60%. Figures 1 to 3 (As shown). These shortcomings affect the recognition accuracy in specific application scenarios.

[0003] Therefore, a multi-line laser projector is needed to at least partially solve the above problems. Summary of the Invention

[0004] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0005] The first aspect of this application provides a multi-line laser projector, comprising:

[0006] Substrate assembly;

[0007] Multiple laser light sources, disposed on the substrate assembly, are used to emit laser light, and are arranged in a row along a predetermined straight line; and

[0008] At least one diffractive optical element is used to diffuse the laser emitted by the plurality of laser sources along the predetermined straight line direction to form M linear projection patterns extending along the predetermined straight line direction, where M is a positive integer greater than 1.

[0009] The diffractive optical element has a first minimum period Pu along the set straight line direction and a second minimum period Ph along the direction perpendicular to the set straight line direction. The second minimum period Ph is less than or equal to 1 / 3 of the first minimum period Pu.

[0010] According to this application, the multi-line laser has a simple structure, and the diffractive optical elements are easy to fabricate, enabling it to project multiple straight lines. By constructing the diffractive optical elements such that their transverse (direction perpendicular to the set straight line direction) period is significantly smaller than their longitudinal (set straight line direction) period, the signal-to-noise ratio of the projected light can be effectively improved, laser speckle suppression is better, and the accuracy of the multi-line laser in 3D recognition can be enhanced.

[0011] Optionally, the second minimum period Ph is calculated according to the following formula:

[0012] Ph=λ / sinθ4

[0013] Wherein, λ is the wavelength of the laser, and θ4 is the interval angle between the first diffraction order of the linear projection pattern and the 0th diffraction order of the linear projection pattern in the M linear projection patterns.

[0014] According to this application, the transverse period of the diffractive optical element is calculated based on the grating equation, and the transverse angular spacing of the multiple lines conforms to the calculated value of the grating equation.

[0015] Optionally, each of the linear projection patterns includes transition regions at both ends and an intermediate region between the two transition regions, and the multi-line laser projector is configured such that the projection angle of the transition regions is 2° to 8°, and the non-uniformity of the intensity of the projected light in the intermediate region is less than 30%.

[0016] According to this application, the multi-line laser projector can project a single line with uniform light intensity and sharp edge cutoff, which is beneficial to improving the accuracy of 3D reconstruction.

[0017] Optionally, the diffractive optical element is configured to include a Fresnel lens.

[0018] Furthermore, the first minimum period Pu is calculated according to the following formula:

[0019] Pu=2·tan(θ3 / 2)·G

[0020] Wherein, θ3 is the projection angle of the intermediate region, and G is the air gap between the laser source and the diffractive optical element.

[0021] According to this application, the longitudinal period of the diffractive optical element is as large as possible (matching the longitudinal size of the light spot formed by the laser on it), which can improve the design accuracy of the target light field in the longitudinal direction and improve the uniformity of the lines.

[0022] Optionally, the diffractive optical element is parallel to the substrate assembly, and the air gap G between the laser source and the diffractive optical element is 2 mm to 15 mm.

[0023] According to this application, the focal length selection of the Niel lens in the multi-line laser projector is flexible, which can match different module sizes and linewidth requirements.

[0024] Optionally, the interval angle θ2 between two adjacent linear projection patterns in the M linear projection patterns satisfies:

[0025] θ2>2·arctan(P1·F / 2)

[0026] Wherein, P1 is the dimension of the laser source along the direction perpendicular to the set straight line, and F is the focal length of the Fresnel lens.

[0027] According to this application, the multi-line laser projector projects multiple straight lines with a large angular spacing range, which has good adaptability.

[0028] Optionally, the multi-line laser projector further includes a collimating lens disposed between the laser source and the diffractive optical element for collimating the laser.

[0029] Furthermore, the first minimum period Pu is calculated according to the following formula:

[0030] Pu=2·tan(θ3 / 2)·f

[0031] Wherein, θ3 is the projection angle of the intermediate region, and f is the focal length of the collimating lens.

[0032] According to this application, having a longitudinal period as large as possible for the diffractive optical element (matching the longitudinal size of the light spot formed by the laser on the diffractive optical element) can improve the design accuracy of the target light field in the longitudinal direction and enhance the uniformity of the lines.

[0033] Optionally, the focal length of the collimating lens is 2mm to 15mm.

[0034] According to this application, the focal length of the collimating lens of the multi-line laser projector is flexible, which can match different module sizes and linewidth requirements.

[0035] Optionally, the interval angle θ2 between two adjacent linear projection patterns in the M linear projection patterns satisfies:

[0036] θ2>2·arctan(P1·f / 2)

[0037] Wherein, P1 is the dimension of the laser source along the direction perpendicular to the set straight line, and f is the focal length of the collimating lens.

[0038] According to this application, the multi-line laser projector projects multiple straight lines with a large angular spacing range, which has good adaptability.

[0039] Optionally, the laser source is a vertical cavity surface-emitting laser element or an edge-emitting laser element.

[0040] According to this application, the components constituting the laser light source can be flexibly selected.

[0041] Optionally, the diffractive optical element comprises a micro / nano structure with 2, 4, or 8 steps.

[0042] According to this application, the processing precision of the diffractive optical element can meet the projection requirements.

[0043] Optionally, the plurality of laser sources are incoherent with each other.

[0044] According to this application, the patterns formed by multiple incoherent light sources are superimposed in the straight line direction, which can effectively suppress laser speckle and improve the recognition accuracy of multi-line modules.

[0045] Optionally, the multi-line laser projector includes a plurality of diffractive optical elements arranged in a direction perpendicular to the set straight line, such that the total size of the plurality of diffractive optical elements in the direction perpendicular to the set straight line is greater than or equal to the size of the laser spot formed on the diffractive optical elements in the direction perpendicular to the set straight line.

[0046] According to this application, multiple elongated diffractive optical elements are arranged in a transverse array, and the size of the array is greater than or equal to the transverse size of the light spot on the diffractive optical elements, thereby improving laser energy utilization. Furthermore, the multi-period interference characteristics of the diffractive optical elements are utilized to form the desired target light field.

[0047] Optionally, the plurality of laser light sources are arranged at approximately equal intervals along the predetermined straight line direction on the substrate assembly.

[0048] According to this application, the arrangement of multiple laser light sources is simple.

[0049] Optionally, the number of laser sources is 5 to 25, and / or

[0050] The distance between two adjacent laser sources is 20 μm to 40 μm.

[0051] According to this application, the laser source has a wide range of setting parameters and high flexibility.

[0052] Optionally, the field of view θ1 of the linear projection pattern projected by the laser emitted by a single laser source is 5° to 130° along the set straight line direction.

[0053] According to this application, the angle range of the length direction of the line projected by the multi-line laser projection is large, and it has good adaptability.

[0054] A second aspect of this application provides a camera assembly comprising:

[0055] A multi-line laser projector according to any one of the above technical solutions;

[0056] An image acquisition device is used to acquire a laser image formed by the pattern projected by the multi-line laser projector; and

[0057] A processor for processing the laser image to obtain a depth image.

[0058] According to this application, the camera assembly can easily project multiple parallel lines as needed for the application, and capture and process the laser image formed by these multiple lines. Specifically, by constructing the diffractive optical element such that its lateral (perpendicular to the direction of the set line) period is significantly smaller than its longitudinal (direction of the set line) period, the signal-to-noise ratio of the projected light can be effectively improved, laser speckle suppression is better, and the accuracy of the multi-line laser in 3D recognition is enhanced.

[0059] A third aspect of this application provides an electronic device comprising:

[0060] The outer shell; and

[0061] According to the camera assembly described in the above technical solution, the camera assembly is disposed on the housing and exposed from the housing to obtain a depth image.

[0062] According to this application, an electronic device can easily project multiple parallel lines as needed for an application, and capture and process the laser image formed by these lines. Specifically, by constructing the diffractive optical element such that its lateral (perpendicular to the direction of the set line) period is significantly smaller than its longitudinal (direction of the set line) period, the signal-to-noise ratio of the projected light can be effectively improved, laser speckle suppression is better, and the accuracy of the multi-line laser in 3D recognition is enhanced. Attached Figure Description

[0063] The following drawings, which are incorporated herein by reference and are used to understand this application, illustrate embodiments of the application and their descriptions to explain the principles of the application. In the drawings:

[0064] Figure 1 A real-world image of the light field projected by a multi-line laser projector in existing technology;

[0065] Figure 2 for Figure 1 The diagram shows the light intensity distribution along the transverse direction of the light field.

[0066] Figure 3 for Figure 1The diagram shows the intensity distribution of the light field along the longitudinal direction.

[0067] Figure 4 This is a schematic diagram of a multi-line laser projector projecting multiple linear projection patterns according to the first embodiment of this application;

[0068] Figure 5 for Figure 4 The diagram shows a multi-line laser projector projecting multiple linear patterns using a single laser source.

[0069] Figure 6 for Figure 4 The diagram shows the projection effect of a multi-line laser projector. For illustrative purposes, the linear projection pattern formed by multiple superimposed single laser light sources is decomposed in space.

[0070] Figure 7 for Figure 4 A schematic diagram of a transverse array of diffractive optical elements projected by a multi-line laser projector;

[0071] Figure 8 for Figure 4 A real-world photograph of the light field of the multi-line laser projector shown in a specific example;

[0072] Figure 9 for Figure 8 The diagram shows the intensity distribution of the light field along the direction DH.

[0073] Figure 10 for Figure 8 The diagram shows the intensity distribution of the light field along the direction DU.

[0074] Figure 11 This is a schematic diagram of a multi-line laser projector projecting multiple linear projection patterns according to the second embodiment of this application.

[0075] Explanation of reference numerals in the attached figures:

[0076] 10: Substrate Assembly

[0077] 20: Laser source

[0078] 21: The light spot formed by the laser source on the diffractive optical element

[0079] 25: Laser beam

[0080] 30 / 130: Diffractive optical elements

[0081] 40: Collimating lens

[0082] 50: Projection screen

[0083] 60: A linear projection pattern projected by a single laser light source.

[0084] 62: A series of linear projection patterns projected by a single laser light source.

[0085] 65: A linear projection pattern formed by a line of laser light sources.

[0086] 100 / 200: Multi-line laser projector Detailed Implementation

[0087] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this application.

[0088] To fully understand this application, a detailed description will be provided in the following description. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art. Obviously, the implementation of the embodiments of this application is not limited to the specific details familiar to those skilled in the art. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other embodiments.

[0089] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof.

[0090] Ordinal numbers such as “first” and “second” used in this application are merely identifiers and have no other meaning, such as a specific order. Moreover, for example, the term “first component” does not imply the existence of a “second component”, and the term “second component” does not imply the existence of a “first component”.

[0091] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings.

[0092] The first aspect of this application provides a multi-line laser projector.

[0093] like Figure 4As shown, in the first embodiment, the multi-line laser projector 100 includes a substrate assembly 10, a plurality of laser light sources 20, and a diffractive optical element 30. The plurality of laser light sources 20 are disposed on the substrate assembly 10 and are used to emit laser light. The plurality of laser light sources 20 are arranged in a row (or column) along a predetermined straight line direction DU. The diffractive optical element 30 is used to diffuse the laser light emitted by the plurality of laser light sources 20 along the predetermined straight line direction DU to form M (M is a positive integer greater than 1, M = 2 in the illustrated embodiment) linear projection patterns 65 extending along the predetermined straight line direction DU.

[0094] For example, such as Figure 4 As shown, M linear projection patterns 65 are parallel to each other, and the angular interval between any two adjacent linear projection patterns 65 along the direction DH is θ2. The field of view (FOV) of each linear projection pattern 65 along the DU direction is θ. f .

[0095] Understandable, Figure 4 In the illustrated embodiment, the diffractive optical element 30 has a built-in collimation function. For example, the diffractive optical element 30 is constructed to include a Fresnel lens having a focal length F. The diffractive optical element 30 is disposed parallel to the substrate assembly 10. An air gap G is provided between the laser source 20 and the diffractive optical element 30, which is preferably equal to the focal length F of the Fresnel lens. Preferably, the air gap G is 2 mm to 15 mm. Preferably, the diffractive optical element 30 includes a micro / nano structure with 2 steps, 4 steps, or 8 steps.

[0096] Preferably, the laser source 20 is a vertical-cavity surface-emitting laser (VCSEL). Of course, the laser source 20 can also be, for example, an edge-emitting laser (EEL). The distance D between two adjacent laser sources 20 is, for example, 20 μm to 40 μm. The number of laser sources 20 is preferably 5 to 25. The multiple laser sources 20 are distributed at approximately equal intervals, with a total distribution span L of 150 μm to 600 μm. The multiple laser sources 20 are independent of each other.

[0097] Specifically, such as Figure 5 As shown, each laser source 20 of the multi-line laser projector 100 can emit a laser beam 25. The diffractive optical element 30 is configured such that the laser beam 25, after passing through the diffractive optical element 30, forms M linear projection patterns 60 extending along a predetermined straight line direction DU on the projection screen 50. Alternatively, the diffractive optical element 30 is configured to cause the laser emitted by a single laser source 20 to diffuse in a linear pattern along the predetermined straight line direction DU. The field of view angle of the linear projection pattern 60 projected by the laser emitted by a single laser source 20 along the DU direction is θ1.

[0098] When multiple (e.g., N) laser light sources 20 are arranged along a set straight direction DU, each laser light source 20 projects a set of linear projection patterns 62 (each set of linear projection patterns 62 includes M linear projection patterns 60). The N sets of linear projection patterns 62 intersect along direction DU, effectively elongating the M linear projection patterns 60 along direction DU. That is, each linear projection pattern 65 is formed by the overlap of N linear projection patterns 60, and the field of view θ of the linear projection pattern 65 along the direction DU... f The field of view θ1 along the DU direction is greater than that of the linear projection pattern 60. The angular interval between two adjacent linear projection patterns 60 along the DH direction is θ2, and thus the angular interval between two adjacent linear projection patterns 65 along the DH direction is also θ2.

[0099] Specifically, taking a linear projection pattern 65 projected by multiple laser light sources 20 as an example, such as... Figure 6 As shown, each laser source 20 forms its own linear projection pattern 60. Multiple linear projection patterns 60 are superimposed in space to form a superimposed linear projection pattern 65. The multiple linear projection patterns 60 are staggered along a set straight direction DU, making the superposition result similar to extending the linear projection pattern 60 of a single laser source 20 along the set straight direction DU. The field of view of the linear projection pattern 60 projected by the laser emitted by a single laser source 20 along the direction DU is θ1. The linear projection pattern 65 formed by the superposition of multiple linear projection patterns 60 from multiple laser sources 20 has a field of view θ along the direction DU. f θ f >θ1. Understandably, the larger the total span L of the distribution of multiple laser light sources 20, the larger the field of view θ of the linear projection pattern 65. f The larger.

[0100] The light intensity distribution characteristics of the linear projection pattern 60 or 65 are controlled by the diffractive optical element 30. The diffractive optical element 30 can be configured to make the light intensity distribution of the linear projection pattern 60 as uniform as possible. Figure 6 As shown, multiple linear projection patterns 60 are staggered along a set straight direction DU, such that in the superimposed linear projection patterns 65, the number of individual linear projection patterns 60 participating in the superposition is greater in the relatively middle part and less in the relatively end parts. Therefore, the light intensity distribution curve C of the superimposed linear projection patterns 65 is approximately trapezoidal. Each linear projection pattern 65 includes transition regions at both ends (the field of view of the transition region is θ). bThe light intensity of the intermediate region (where the field of view along direction DU is θ3) is higher than that of the transition region (where the number of individual linear projection patterns 60 participating in the superposition is smaller) than that of the transition region (where the number of individual linear projection patterns 60 participating in the superposition is smaller). The light intensity of the intermediate region is basically uniformly distributed, while the light intensity of the transition region decreases towards both ends. The following quantitative relationships exist between the various field of view angles:

[0101] θ b =arctg(L / G),

[0102] θ f =θ1+θ b ,

[0103] θ3=θ1-θ b .

[0104] In this application, preferably, the multi-line laser projector 100 is configured such that the field of view θ1 of the linear projection pattern 60 projected by the laser emitted by a single laser source 20 along the set straight direction DU is 5° to 130°, and the projection angle (i.e., the field of view θ1) of the transition region of each linear projection pattern 65 along the direction DU is such that... b The angle is 2° to 8°, and the non-uniformity of the intensity of the projected light in the middle region is less than 30%.

[0105] In this application, the method for calculating light intensity non-uniformity is as follows:

[0106] (Maximum light intensity - Minimum light intensity) / (Maximum light intensity + Minimum light intensity).

[0107] It is understandable that when a laser source consists of multiple points, the zero-order energy is distributed across multiple points, thus making the zero-order energy more dispersed and reducing the safety risk to the human eye.

[0108] In this application, the diffractive optical element 30 has a first minimum period Pu (also called the longitudinal minimum period Pu) along the set straight line direction DU, and a second minimum period Ph (also called the transverse minimum period Ph) along the direction DH perpendicular to the set straight line direction DU. The second minimum period Ph is less than or equal to 1 / 3 of the first minimum period Pu, making the diffractive optical element 30 elongated in shape. That is, the size of the diffractive optical element 30 in the direction DH perpendicular to the set straight line direction DU is significantly smaller than its size in the set straight line direction DU. The size of the transverse period controls the spacing between multiple linear projection patterns 65; using a relatively small transverse period can effectively improve the signal-to-noise ratio of the projection patterns.

[0109] Specifically, to improve the continuity of multiple linear projection patterns 60 located at the same position in the direction DH, the longitudinal minimum period Pu is designed to match the size of the spot formed by a single laser source 20 on the diffractive optical element 30. Preferably, the first minimum period Pu is calculated according to the following formula (1):

[0110] Pu=2·tan(θ3 / 2)·G(1)

[0111] In formula (1), θ3 is the projection angle of the middle region (i.e., the region with relatively uniform light intensity distribution) of the above-mentioned linear projection pattern 65, and G is the air gap between the laser source 20 and the diffractive optical element 30.

[0112] If conventional diffractive optical element design methods are used, the method for setting the transverse period is the same as that for the longitudinal period, both requiring consideration of the spot size, and the transverse period is also set to be large. To obtain the specified angular interval θ2, some orders need to be designated as target orders, while the energy of other orders needs to be suppressed as much as possible; otherwise, stray light will be generated. This is more difficult in the design and fabrication of diffractive optical elements, and the effect of eliminating stray light is not ideal.

[0113] In the first embodiment of this application, the second minimum period Ph is calculated according to the following formula (2):

[0114] Ph=λ / sinθ4(2)

[0115] In formula (2), λ is the wavelength of the laser emitted by the laser source 20, and θ4 is the interval angle between the first diffraction order of the linear projection pattern 65 and the 0th diffraction order of the linear projection pattern 65 in the M linear projection patterns 65 (see [reference]). Figure 4 ).

[0116] When the diffractive optical element 30 is configured in this way, in the first embodiment, the spacing angle θ2 of two adjacent linear projection patterns in the M linear projection patterns 65 satisfies the following inequality (3):

[0117] θ2>2·arctan(P1·F / 2)(3)

[0118] In inequality (3), P1 is the dimension of the laser source 20 along the direction DH perpendicular to the set straight line direction DU, and F is the focal length of the Fresnel lens. It can be seen from formula (3) that θ2 can take a smaller value, that is, multiple linear projection patterns 65 can be distributed relatively densely. At the same time, the diffractive optical element 30 can ensure the signal-to-noise ratio of multiple linear projection patterns 65.

[0119] Understandably, the laser source 20 can be considered a point source. The larger the air gap G between the diffractive optical element 30 and the laser source 20, the larger the size of the laser spot 21 formed by the laser source 20 on it. When the diffractive optical element 30 is elongated, its size in the direction DH (also called the lateral size) is smaller than the size of the laser spot 21. To make better use of the laser energy, preferably, as... Figure 7 As shown, the laser projector 100 includes a plurality of diffractive optical elements 30, which are arranged along a direction DH perpendicular to a set straight line direction DU. That is, a transverse array of individual diffractive optical elements 30 is formed such that the total size of the plurality of diffractive optical elements 30 in the direction DH is greater than or equal to the size of the laser spot 21 formed on it by the laser source 20. This ensures that the laser spot 21 is completely located in the area occupied by the plurality of diffractive optical elements 30, making full use of the laser energy to effectively improve the signal-to-noise ratio of the projected pattern.

[0120] In a specific example, the wavelength λ of the laser source 20 is 808 nm, the radial dimension of the light spot 21 projected by the laser source 20 onto the diffractive optical element 30 is 1.5 mm, M is 99 (that is, the multi-line laser projector 100 projects 99 linear projection patterns 65), and the angular interval θ4 between the first diffraction order linear projection pattern 65 and the 0th diffraction order linear projection pattern 65 is 0.171°. The minimum longitudinal period Pu of the diffractive optical element 30 is 1.5 mm, and the minimum transverse period Ph is 270 μm (less than 1 / 3 and less than 1 / 5 of 1.5 mm).

[0121] In this example, such as Figure 8 As shown in the photographic image of the light field of multiple linear projection patterns 65 at a working distance of 67mm, compared to... Figure 1 Compared with existing technologies, the projected pattern lines of this application are clearer and more coherent, speckle is significantly reduced, and the pattern signal-to-noise ratio is significantly improved. For example... Figure 9 As shown, the intensity distribution along direction DH of the light field of the multiple linear projection patterns 65 reveals that the signal intensity is significantly increased at the location of the linear projection pattern 65 (signal region), while the signal intensity is almost zero at the location between two adjacent linear projection patterns 65 (noise region). Figure 2 (Comparison); and the intensity of each linear projection pattern 65 is relatively uniform. For example... Figure 10 As shown, the light intensity distribution along the direction DU of the light field of a single linear projection pattern 65 indicates that the signal intensity of each linear projection pattern 65 is uniformly distributed along the set straight line direction DU (and...). Figure 3 (Comparison). In this example, the signal-to-noise ratio (SNR) exceeds 300 (SNR = 10·lg(Is)).avg / Ir avg ), where Is avg Ir is the average signal strength in the signal region. avg (The average intensity of the noise area), the non-uniformity of the linear projection pattern 65 is less than 15% (UE = (Is max -Is min ) / (Is max +Is min ), where I max I represents the maximum signal strength in the signal region. min (This represents the minimum signal strength in the region). In this example, the projection efficiency exceeds 80%, meaning that the light energy of the projected pattern exceeds 80% of the total energy emitted by the laser source 20, or in other words, the utilization rate of the total energy emitted by the laser source 20 exceeds 80%, and the energy loss of the laser source is relatively small.

[0122] like Figure 11 As shown, in the second embodiment, the diffractive optical element 130 does not have a collimation function, and the multi-line laser projector 200 also includes a collimating lens 40. The collimating lens 40 is disposed between the laser source 20 and the diffractive optical element 130 for collimating the laser. The collimating lens 40 has a focal length f, preferably f is 2 mm to 15 mm.

[0123] In the second embodiment, the second minimum period Ph (lateral minimum period Ph) of the diffractive optical element 130 is still calculated according to the above formula (2), and the first minimum period Pu (longitudinal minimum period Pu) is calculated according to the following formula (4):

[0124] Pu=2·tan(θ3 / 2)·f (4)

[0125] In formula (4), θ3 is the projection angle along direction DU of the middle region of the linear projection pattern 65, and f is the focal length of the collimating lens 40.

[0126] When the diffractive optical element 130 is configured in this way, in the second embodiment, the spacing angle θ2 of two adjacent linear projection patterns in the M linear projection patterns 65 satisfies the following inequality (5):

[0127] θ2>2·arctan(P1·f / 2) (5)

[0128] In inequality (5), P1 is the dimension of the laser source 20 along the direction DH perpendicular to the set straight line direction DU, and f is the focal length of the collimating lens 40.

[0129] In the second embodiment, the diffractive optical element 130 still achieves high quality of the M-line projection pattern 65 by making the period along the direction DH significantly smaller than the period along the direction DU.

[0130] For the remaining parts not described in the second embodiment, refer to the description in the first embodiment.

[0131] A second aspect of this application provides a camera assembly. In a preferred embodiment, the camera assembly includes the aforementioned multi-line laser projector 100 or 200, an image acquisition unit, and a processor. The image acquisition unit is used to acquire a laser image formed by the pattern projected by the multi-line laser projector 100; the processor is used to process the laser image to obtain a depth image. The camera assembly according to this application can easily project multiple parallel lines as needed for the application, and capture and process the laser image formed by the multiple lines. It is understood that the camera assembly according to this application includes all the features and effects of the multi-line laser projectors 100 and 200.

[0132] A third aspect of this application provides an electronic device. In a preferred embodiment, the electronic device includes a housing and the aforementioned camera assembly. The camera assembly is disposed to and exposed from the housing to obtain depth images. This electronic device is, for example, a mobile phone, wristband, watch, tablet computer, smart glasses, smart helmet, motion-sensing gaming device, detection device, etc. The electronic device according to this application can easily project multiple parallel lines according to application needs, and...

[0133] The resulting laser image is captured and processed. It is understood that the electronic device package 5 according to this application includes all the features and effects of the multi-line laser projectors 100 and 200.

[0134] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for descriptive purposes only and is not intended to limit the scope of this application. Features described in one embodiment herein may...

[0135] It may be applied alone or in combination with other features in another implementation, unless the feature is not applicable in the other implementation or otherwise stated.

[0136] This application has been described through the above embodiments; however, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit this application to the described embodiments. Furthermore, those skilled in the art will understand that this application is not limited to the above...

[0137] Based on the teachings of this application, many more variations and modifications can be made to the described embodiments, and all such variations and modifications fall within the scope of protection claimed in this application.

Claims

1. A multi-line laser projector, characterized in that, include: Substrate assembly; Multiple laser light sources are disposed on the substrate assembly and used to emit laser light. The multiple laser light sources are arranged in a row along a predetermined straight line. and At least one diffractive optical element is used to diffuse the laser emitted by the plurality of laser sources along the predetermined straight line direction to form M linear projection patterns extending along the predetermined straight line direction, where M is a positive integer greater than 1. The diffractive optical element has a first minimum period Pu along the set straight line direction and a second minimum period Ph along the direction perpendicular to the set straight line direction. The second minimum period Ph is less than 1 / 3 of the first minimum period Pu, so that the period of the diffractive optical element along the direction perpendicular to the set straight line direction is significantly smaller than its period along the set straight line direction.

2. The multi-line laser projector according to claim 1, characterized in that, The second minimum period Ph is calculated according to the following formula: Ph=λ / sinθ4 Wherein, λ is the wavelength of the laser, m is the diffraction order, and θ4 is the interval angle between the first diffraction order line-shaped projection pattern and the 0th diffraction order line-shaped projection pattern in the M line-shaped projection patterns.

3. The multi-line laser projector according to claim 1, characterized in that, Each of the linear projection patterns includes transition regions at both ends and an intermediate region between the two transition regions. The multi-line laser projector is configured such that the projection angle of the transition regions is 2° to 8°, and the non-uniformity of the intensity of the projected light in the intermediate region is less than 30%.

4. The multi-line laser projector according to claim 3, characterized in that, The diffractive optical element is constructed to include a Fresnel lens.

5. The multi-line laser projector according to claim 4, characterized in that, The first minimum period Pu is calculated according to the following formula: Pu=2·tan(θ3 / 2)·G Wherein, θ3 is the projection angle of the intermediate region, and G is the air gap between the laser source and the diffractive optical element.

6. The multi-line laser projector according to claim 4, characterized in that, The diffractive optical element is parallel to the substrate assembly, and the air gap G between the laser source and the diffractive optical element is 2 mm to 15 mm.

7. The multi-line laser projector according to claim 4, characterized in that, The interval angle θ2 between two adjacent linear projection patterns in the M linear projection patterns satisfies: θ2>2·arctan(P1·F / 2) Wherein, P1 is the dimension of the laser source along the direction perpendicular to the set straight line, and F is the focal length of the Fresnel lens.

8. The multi-line laser projector according to claim 3, characterized in that, The multi-line laser projector also includes a collimating lens, which is disposed between the laser source and the diffractive optical element for collimating the laser.

9. The multi-line laser projector according to claim 8, characterized in that, The first minimum period Pu is calculated according to the following formula: Pu=2·tan(θ3 / 2)·f Wherein, θ3 is the projection angle of the intermediate region, and f is the focal length of the collimating lens.

10. The multi-line laser projector according to claim 8, characterized in that, The focal length of the collimating lens is 2mm to 15mm.

11. The multi-line laser projector according to claim 8, characterized in that, The interval angle θ2 between two adjacent linear projection patterns in the M linear projection patterns satisfies: θ2>2·arctan(P1·f / 2) Wherein, P1 is the dimension of the laser source along the direction perpendicular to the set straight line, and f is the focal length of the collimating lens.

12. The multi-line laser projector according to claim 1, characterized in that, The laser source is a vertical cavity surface-emitting laser element or a side-emitting laser element.

13. The multi-line laser projector according to claim 1, characterized in that, The diffractive optical element comprises a micro / nano structure with 2, 4, or 8 steps.

14. The multi-line laser projector according to claim 1, characterized in that, The multiple laser sources are incoherent with each other.

15. The multi-line laser projector according to any one of claims 1 to 14, characterized in that, The system includes a plurality of diffractive optical elements arranged in a direction perpendicular to the set straight line, such that the total size of the plurality of diffractive optical elements in the direction perpendicular to the set straight line is greater than or equal to the size of the light spot formed by the laser on the diffractive optical elements in the direction perpendicular to the set straight line.

16. The multi-line laser projector according to any one of claims 1 to 14, characterized in that, The plurality of laser light sources are arranged at approximately equal intervals along the predetermined straight line direction on the substrate assembly.

17. The multi-line laser projector according to claim 16, characterized in that, The number of laser sources is 5 to 25, and / or The distance between two adjacent laser sources is 20 μm to 40 μm.

18. The multi-line laser projector according to any one of claims 1 to 14, characterized in that, The field of view θ1 of the linear projection pattern projected by the laser emitted by a single laser source is between 5° and 130° along the set straight line direction.

19. A camera assembly, characterized in that, include: The multi-line laser projector according to any one of claims 1 to 18; An image acquisition device is used to acquire a laser image formed by the pattern projected by the multi-line laser projector; and A processor for processing the laser image to obtain a depth image.

20. An electronic device, characterized in that, include: shell; and The camera assembly of claim 19 is disposed to and exposed from the housing to obtain a depth image.

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