Light projection module, image acquisition system and three-dimensional sensing system having the same

Abstract

The present application discloses a light projection module and an image acquisition system and a three-dimensional sensing system including the same, wherein the light projection module includes a light source and an optical device, wherein the optical device receives light from the light source and forms a structured light field and a floodlighting light field that are superimposed on each other. The light projection module having both structured light pattern projection and floodlighting capabilities can simultaneously realize a structured light field and a uniform background lighting light field, and the projected light field pattern, power and contrast are controllable, which is conducive to system integration, miniaturization and cost reduction.

Description

Technical Field

[0001] The present invention generally relates to three-dimensional sensing technology, and specifically relates to a light projection module applicable to three-dimensional sensing, an image acquisition system having the module, and a three-dimensional sensing system. Background Art

[0002] Structured light 3D sensing technology is increasingly being used in consumer electronics, robotics, logistics, industrial inspection and other fields. Traditional 3D sensing technology uses structured light fields and floodlight light fields separately, collects images under the two light fields, and processes information based on the different images obtained.

[0003] In addition, the existing structured light projection module and floodlight projection module each use different light sources and optical devices to form discrete components. The combination of the two in the application of three-dimensional sensing technology causes problems such as low system integration, large size, and high cost. Summary of the invention

[0004] The purpose of the present invention is to provide a light projection module and an image acquisition system and a three-dimensional sensing system having the light projection module, which integrates the structured light projection function and the floodlighting light field projection function, improves the system integration, is conducive to structural miniaturization, and reduces costs.

[0005] According to one aspect of the present invention, a light projection module is provided, which includes a light source and an optical device, wherein the optical device receives light from the light source and forms a structured light field and a floodlight light field that are superimposed on each other.

[0006] Advantageously, the brightness ratio of the floodlighting light field to the structured light field is in the range of 1:3 to 1:50, preferably in the range of 1:3 to 1:9.

[0007] In some advantageous embodiments, the optical device is a diffractive optical element, i.e., DOE, and the ratio of the brightness of the structured light field formed by the diffractive optical element to the brightness of the uniform background light formed by the stray light transmitted by the diffractive optical element is in the range of 3:1 to 50:1, preferably in the range of 3:1 to 9:1, and more preferably in the range of 4:1 to 8:1.

[0008] The optical device may include a first optical region and a second optical region, wherein the first optical region has a first optical microstructure for forming a structured light field, and the second optical region has a second optical microstructure for forming a flood illumination light field. Preferably, the optical device is a diffractive optical element, i.e., a DOE. Preferably, the optical device is integrally formed.

[0009] The first optical zone may include a plurality of sub-zones arranged in an array, and the second optical zone at least partially surrounds the plurality of sub-zones.

[0010] In some embodiments, light from the same light source impinges upon both the first optical zone and the second optical zone.

[0011] In other embodiments, the light source may include a first light source and a second light source different from the first light source, the first light source irradiates the first optical zone, and the second light source irradiates the second optical zone.

[0012] Alternatively, the optical device may include a first optical region and a second optical region, the first optical region having a first optical microstructure for forming a structured light field, and the second optical region having at least one lens for forming a flood illumination light field.

[0013] The at least one lens may include a microlens array.

[0014] The light projection module may further include a shell, the light source and the optical device are installed in the shell, and the inner wall of the shell is made of white diffuse reflection material.

[0015] According to another aspect of the present invention, an image acquisition system is provided, which includes the light projection module as described above, and a camera for acquiring an image of an object illuminated by the superimposed structured light field and floodlight light field projected by the light projection module. Preferably, the camera is an infrared camera.

[0016] According to another aspect of the present invention, a three-dimensional sensing system is provided, which includes: a light projection module as described above; a camera for capturing images of an object illuminated by the superimposed structured light field and floodlight light field projected by the light projection module; and a computing unit, which receives the images captured by the camera and obtains three-dimensional information of the object based on the images.

[0017] According to an embodiment of the present invention, the light projection module can simultaneously realize a structured light field and a uniform background illumination light field, and the projection light field pattern, power and contrast are controllable, which is conducive to system integration, miniaturization and cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0019] Figure 1 The structure of the light projection module and the light field projected by the light projection module according to the embodiment of the present invention are schematically shown;

[0020] Figure 2 is a schematic block diagram of a three-dimensional sensing system according to an embodiment of the present invention;

[0021] Figure 3 is a structural schematic diagram of a light projection module according to a first embodiment of the present invention;

[0022] Figure 4A and Figure 4B Shown can be used Figure 3 Examples of optical devices of light projection modules;

[0023] Figure 5 is a structural schematic diagram of a light projection module according to a second embodiment of the present invention;

[0024] Fig. 6A and Figure 6B Shown can be used for Figure 5 Examples of optical devices of light projection modules;

[0025] Figure 7 is a structural schematic diagram of a light projection module according to a third embodiment of the present invention;

[0026] Figure 8 Shown can be used Figure 7 Examples of optical devices of light projection modules;

[0027] Fig. 9 is a structural schematic diagram of a light projection module according to a fourth embodiment of the present invention; and

[0028] Fig. 10A , Fig. 10B and Fig. 10C Shown can be used Fig. 9 Examples of optics for the light projection module are shown. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0030] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] Figure 1The structure of the light projection module 10 and the light field projected by the light projection module 10 according to an embodiment of the present invention are schematically shown. As shown in the figure, the light projection module 10 includes a light source 11, an optical device 12, and an optional housing 13 for mounting / accommodating the light source 11 and the optical device 12. The optical device 12 receives light from the light source 11 and forms a structured light field LF1 and a floodlight light field LF2 that are superimposed on each other.

[0032] In some advantageous embodiments, the light source 11 may be an infrared light source; accordingly, the light projection module 10 projects a structured light field and a floodlight illumination light field of infrared light. The inventors of the present invention have found that in some application scenarios, images of human faces captured under the simultaneous illumination of infrared structured light fields and floodlight illumination light fields can be more effectively used to obtain three-dimensional information of human faces and perform face recognition. Of course, this can also be applied to the detection and recognition of other objects.

[0033] Figure 1 In the figure, the structured light field LF1 is shown as a speckle light field, but this is merely exemplary and not restrictive. Those skilled in the art will understand that the light projection module 10 according to the embodiment of the present invention may also project structured light fields of other patterns, such as light spots, stripes, other patterns with specific shapes or positional relationships, or any combination thereof; the present invention is not limited to the specific form of the structured light field. The structured light field can be realized by, for example, an optical device that diffracts light, such as a diffractive optical element (DOE) or a grating array.

[0034] The floodlighting light field refers to a light field that provides substantially uniform illumination to the target area. The floodlighting light field can be achieved by increasing the illumination angle of the light through a lens, or by a light homogenizing device, such as a microlens array or a DOE with a light homogenizing function.

[0035] The light source is preferably a laser light source, for example, a laser diode (LD) or a vertical-cavity surface-emitting laser (VCSEL); in some embodiments, a light emitting diode (LED) may also be used, but if the coherence of its light is required, a collimation device is also required to be provided on the output light path of the LED.

[0036] The structured light field and floodlight light field provided by the light projection module according to the embodiment of the present invention are superimposed on each other, but can be used to obtain different information of the object respectively. In order to enable each of the two light fields to provide sufficient and effective illumination while not generating too much noise for the information that is desired to be obtained based on the other light field, the brightness ratio of the floodlight light field projected by the light projection module according to the embodiment of the present invention to the structured light field is in the range of 1:3 to 1:50, preferably in the range of 1:3 to 1:9.

[0037] In some advantageous embodiments, the light projection module 10 may include a shell 13, which preferably uses a white diffuse reflective inner wall material to improve the optical reflection efficiency of the inner wall, so that the light irradiated on the inner wall can be reflected through the optical element and emitted to form a certain floodlighting effect.

[0038] Figure 2 The 3D sensing system 200 according to an embodiment of the present invention is schematically shown. As shown in the figure, the 3D sensing system 200 includes a light projection module 10, a camera 20 and a computing unit 30.

[0039] The light projection module 10 is a light projection module according to an embodiment of the present invention, and is used to project a structured light field and a floodlight light field that are superimposed on each other. The camera 20 is used to capture images of objects illuminated by the structured light field and the floodlight light field that are superimposed on each other and projected by the light projection module 10. The light projection module 10 is combined with the camera 20 to form an image acquisition system according to an embodiment of the present invention.

[0040] The computing unit 30 receives the image captured by the camera 20 and obtains three-dimensional information based on the image. The computing unit 30 may include a processor 31 and a memory 32, and the memory 32 may store program instructions. When the program instructions are executed by the processor 31, the processor 31 processes the image received by the computing unit 30 to obtain three-dimensional information. In some embodiments, the execution of the program instructions may also cause the processor 31 to process to obtain information other than three-dimensional information.

[0041] The three-dimensional sensing system using the light projection module according to the embodiment of the present invention can be constructed as a monocular structured light, binocular structured light or multi-eye structured light system with one, two or more cameras, and there is no need to use an independent floodlight module in the system. When the three-dimensional sensing system according to the embodiment of the present invention is working, the structured light field and the floodlight light field are projected at the same time to collect the image of the object, and the depth information can be obtained according to the structured light pattern image, and the appearance information of the photographed object can be obtained according to the floodlight image, forming data with both types of information.

[0042] According to the three-dimensional sensing system of the embodiment of the present invention, based on the light projection module according to the embodiment of the present invention, a new simplified three-dimensional sensing and object recognition algorithm and a method for using the three-dimensional sensing recognition system can be implemented, thereby reducing the system's calculation amount and calculation time and improving operating efficiency.

[0043] The following will be combined Figure 3 to Figure 1 0 will now be described in more detail the light projection module 10 according to an embodiment of the present invention.

[0044] Figure 3 It is a schematic diagram of the structure of the light projection module 10A according to the first embodiment of the present invention. As shown in the figure, the light projection module 10A includes a first light source 11a and a second light source 11b, an optical device 12A, and a housing 13 for mounting the light source and the optical device. The second light source 11b is different from the first light source 11a. The "difference" of the light source here refers to the substantial difference in the type, parameters and arrangement of the light source, for example, the first light source 11a is LD, the second light source 11b is LED, or the first light source 11a is a VCSEL with a plurality of randomly arranged emission points, and the second light source 11b is a VCSEL with a plurality of emission points arranged in a regular array.

[0045] Figure 4A and Figure 4B Shown can be used Figure 3 Examples of optical devices of a light projection module.

[0046] like Figure 4A As shown, the optical device 12A includes a first optical region 12a and a second optical region 12b, the first optical region 12a having a first optical microstructure for forming a structured light field, and the second optical region 12b having a second optical microstructure for forming a flood illumination light field. According to this embodiment, the first optical region 12a and the second optical region 12b are parallel to each other. In some embodiments, the first optical region 12a and the second optical region 12b can be formed on the same optical substrate. For example, the optical device 12A can be an integrally formed diffractive optical element, wherein the first optical region 12a and the second optical region 12b have different optical microstructure patterns, respectively, thereby substantially forming two different diffractive optical elements, which are used to provide a structured light field and a uniform light field, respectively. In other embodiments, the first optical region 12a and the second optical region 12b can be formed on separate optical substrates and spliced ​​together. In addition, the optical microstructure, especially the second optical microstructure used to form a flood illumination light field, is not limited to forming an optical microstructure pattern of a DOE element. It can also be other microstructures used to achieve uniform light through scattering and / or refraction, such as a scattering-based uniform light sheet, a microlens array, etc.

[0047] Figure 4BThe optical device 12A' shown is Figure 4A A variation of the optical device 12A shown, in which in addition to the first optical region 12a and the second optical region 12b, the optical device 12A' also includes a third optical region 12c. In the illustrated example, the third optical region 12c surrounds the first optical region 12a and the second optical region 12b. In some examples, the third optical region 12c may be an additional optical region for providing a flood illumination light field. In other examples, the third optical region 12c may also be a "blank" optical region for mounting the optical device 12A', in which no specific optical microstructure is formed.

[0048] According to this embodiment, Figure 3 As shown, the first optical region 12a and the second optical region 12b are illuminated by the first light source 11a and the second light source 11b respectively.

[0049] Figure 5 Schematic diagram of the structure of the light projection module 10B according to the second embodiment of the present invention. The light projection module 10B according to the second embodiment of the present invention has substantially the same structure as the light projection module 10A according to the first embodiment of the present invention, and the main difference is that the light projection module 10B includes only one light source, namely, the light source 11, which is used to simultaneously illuminate the first and second optical areas on the optical device 12A to form a structured light field and a flood illumination light field that are superimposed on each other. In some advantageous embodiments, the light source 11 is a laser light source, such as a laser diode or a vertical cavity surface emitting laser; in other embodiments, the light source 11 is a light emitting diode, and the light projection module 10B further includes a collimating device for collimating the light from the light emitting diode.

[0050] Compared with the light projection module using different first and second light sources according to the first embodiment of the present invention, the light projection module according to this embodiment only needs to use one light source, which advantageously reduces system power consumption. In addition, for the image acquisition system and three-dimensional sensing system including the light projection module, since only one projector needs to be controlled, the system structure and working method can be simplified, further reducing costs.

[0051] Reference above Figure 4A and Figure 4B The optical devices 12A and 12A′ described above can be applied to the light projection module 10B according to the second embodiment of the present invention, and will not be described in detail herein.

[0052] Fig. 6A and Figure 6B Other examples of optical devices that may be used in the light projection module 10B are shown. Fig. 6A Optical device 12B is shown, Figure 6BA variation of the optical device 12B is shown, namely the optical device 12B'. The optical devices 12B and 12B' each include a first optical region 12f and a second optical region 12g, and the second optical region 12g at least partially surrounds the first optical region 12f. The difference is that the first optical region 12f in the optical device 12B' includes a plurality of local sub-regions, and the second optical region 12g at least partially surrounds these sub-regions. The plurality of sub-regions are preferably arranged in an array. In some advantageous embodiments, the first optical region 12f has a first optical microstructure for forming a structured light field, and the second optical region 12g has a second optical microstructure for forming a flood illumination light field. In some advantageous embodiments, the optical devices 12B, 12B' are diffractive optical elements, namely DOEs.

[0053] When the optical devices 12B, 12B' are applied to Figure 5 When the light projection module 10B is shown, light from the same light source 11 can be used to illuminate various areas of the optical device 12B, 12B'.

[0054] Figure 7 FIG. 1 is a schematic diagram of the structure of a light projection module 10C according to a third embodiment of the present invention. The light projection module 10C according to the third embodiment of the present invention is different from the light projection module 10B according to the second embodiment of the present invention (see FIG. 1 ). Figure 5 ) have basically the same structure, the main difference being that a diffraction optical element with a uniform optical microstructure pattern is used as the optical device 12C (hereinafter also referred to as "diffraction optical element 12C") in the light projection module 10C.

[0055] Figure 8 It is only a schematic representation of the diffractive optical element 12C, in which the optical microstructure pattern is not shown. According to this embodiment, the ratio of the brightness of the structured light field formed by the diffractive optical element 12C to the brightness of the uniform background light formed by the diffractive optical element transmitting stray light is in the range of 3:1 to 50:1, preferably in the range of 3:1 to 9:1, and more preferably in the range of 4:1 to 8:1, so as to provide flood lighting by using the transmitted light amount portion that does not form structured light.

[0056] Although diffractive optical elements (DOE) are commonly used in the prior art to form structured light fields, and the structured light field (structured light pattern) projected by DOE itself is accompanied by background illumination caused by stray light, it should be noted that the DOE design in the prior art strictly suppresses such background illumination caused by stray light, and the brightness of the background light is usually controlled to be less than 1% of the brightness of the structured light, or even lower. The prior art has not yet proposed to provide a structured light field and a floodlight light field at the same time by controlling the DOE device to provide a uniform background light with appropriate brightness.

[0057] Fig. 9 is a structural schematic diagram of a light projection module 10D according to a fourth embodiment of the present invention, Fig. 10A , Fig. 10B and Fig. 10C Shown can be used Fig. 9 Examples of optical devices of the light projection module 10D are shown as optical devices 12D, 12E, and 12F.

[0058] like Fig. 9 As shown in Figure 10, the light projection module 10D according to the fourth embodiment of the present invention is basically the same as the light projection modules 10B and 10C according to the second and third embodiments of the present invention, except that the optical device adopted by the light projection module 10D includes a first optical area and a second optical area located at the center of the optical device, the first optical area has a first optical microstructure for forming a structured light field, and the second optical area has at least one lens for forming a flood lighting light field.

[0059] Fig. 10A The optical device 12D shown includes a first optical region 12k and a second optical region 12l, wherein the second optical region 12l is located at the center and includes a refractive lens. The refractive lens can be a convex lens or a concave lens, as long as it can diverge the light from the light source at its position relative to the light source 11 to form floodlighting.

[0060] Fig. 10B The optical device 12E shown includes a first optical region 12k and a second optical region 12m located at a central position. The second optical region 12m includes a Fresnel lens for diverging light entering the Fresnel lens to form flood lighting.

[0061] Fig. 10C The optical device 12F shown includes a first optical region 12k and a second optical region 12n located at a central position. The second optical region 12n includes a microlens array. The microlens array produces a uniform light effect on the light irradiated thereon, thereby forming flood lighting.

[0062] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A light projection module, comprising a light source, an optical device and a housing for accommodating the light source and the optical device, wherein: The light source is used to emit a light beam, the optical device includes a first optical area and a second optical area, the first optical area has a first optical microstructure for forming a structured light field, the second optical area has a second optical microstructure for forming a flood illumination light field, the optical device receives light from the light source, and forms a structured light field and a flood illumination light field that are superimposed on each other, wherein the flood illumination light field refers to a light field that illuminates a target area substantially uniformly; The brightness ratio of the floodlighting light field to the structured light field is in the range of 1:3 to 1:

50.

2. The light projection module according to claim 1, wherein: The brightness ratio of the floodlighting light field to the structured light field is in the range of 1:3 to 1:

9.

3. The light projection module according to claim 1, wherein: The first optical zone includes a plurality of sub-zones arranged in an array, and the second optical zone at least partially surrounds the plurality of sub-zones.

4. The light projection module according to claim 1 or 3, wherein: Light from the same light source impinges upon both the first optical zone and the second optical zone.

5. The light projection module according to claim 1, wherein: The light source includes a first light source and a second light source different from the first light source, the first light source illuminates the first optical zone, and the second light source illuminates the second optical zone.

6. The light projection module according to claim 1, wherein: The optical device is a diffractive optical element, namely, DOE.

7. The light projection module according to claim 1, wherein: The optical device is integrally formed.

8. The light projection module according to claim 1, wherein: The second optical region has at least one lens for forming a flood illumination light field.

9. The light projection module according to claim 8, wherein: The at least one lens comprises a microlens array.

10. The light projection module according to any one of claims 1 to 3 and 5 to 9, wherein: The inner wall of the shell is made of white diffuse reflection material.

11. The light projection module as claimed in claim 4, wherein: The inner wall of the shell is made of white diffuse reflection material.

12. An image acquisition system, comprising: The light projection module according to any one of claims 1 to 11; as well as The camera is used to collect images of the object illuminated by the structured light field and the floodlight light field that are superimposed on each other and projected by the light projection module.

13. The image acquisition system according to claim 12, wherein: The light source of the light projection module is an infrared light source, and the camera is an infrared camera.

14. A three-dimensional sensing system comprising: The light projection module according to any one of claims 1 to 11; A camera, used for collecting images of the object illuminated by the superimposed structured light field and floodlight light field projected by the light projection module; as well as A computing unit receives the image captured by the camera and acquires three-dimensional information of the object based on the image.

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