TW202113455A - Structured light emission module and depth sensing device using same - Google Patents

Abstract

The present disclosure provides a structured light emission module. The structured light emission module includes a light source group and a diffractive optical component. The light source group includes at least two light sources, the light sources can be controlled independently. Each of the light sources is configured to emit coherent light as source light. The diffractive optical component includes at least two diffractive units. The source light from each of the light sources enters to one the diffractive unit respectively. Diffractive light emitted from each of the diffractive units forms a plurality of projecting patterns in a projecting region. The plurality of projecting patterns are not overlapped with each other. The projecting patterns formed by any one of the diffractive units , any two of the diffractive units, or any more than two of the diffractive units form a projecting image. The present disclosure also provides a depth sensing device using the structured light emission module.

Description

Structured light emitting module and depth sensing equipment using the same

The invention relates to a structured light emitting module and a depth sensing device using the same.

The structured light emitting module used to project a beam with a specific pattern in the prior art includes a light source and a multi-piece diffractive optical element (DOE), and the light source is mostly a vertical cavity surface emitting laser (Vertical Cavity Surface). Emitting Laser, VCSEL), multi-piece diffractive optical components are usually stacked and arranged. Since the light wave of the incident diffractive optical component has a greater impact on the projection pattern, the multi-piece diffractive optical components stacked must use alignment technology when in use. Aligning multiple diffractive optical components makes it more difficult to assemble. By designing the luminous mode of the vertical cavity surface emitting laser and using the stacked multi-piece diffractive optical components, the distribution density of the projection pattern (for example, speckle) can be controlled, but the range of the projection area (or the projection area can not be controlled) The range of change is extremely small), and the light source is limited to the use of vertical cavity surface emitting lasers. In the prior art, the structured light emitting module may use multiple pieces of diffractive optical components for assembly and splicing, and the multiple pieces of diffractive optical components need to be cut and assembled in multiple passes. The mechanical tolerances caused by mechanical processing can reach the micron level, so the incident light waveform of the diffractive optical component is quite different from the design value, and the imaging quality of the projection is affected.

Generally speaking, because the projected image is a fixed pattern, the horizontal resolution, frame number, and illumination range of the projected image are all fixed values and cannot be adjusted according to usage requirements. Taking WO2017176901A1 as an example, the method for dynamically adjusting projection graphics proposed in this case includes a non-single light source that emits light containing multiple wavelengths and enters a diffractive component group. The diffractive component group includes more than two diffractive components. Switch alternately so that the above-mentioned light is diffracted to the designated projection range. Another device for dynamically adjusting the projection pattern, take US20160178915A1 as an example. The device proposed in this case includes a semiconductor substrate, an array type optical radiation device, placed on the aforementioned substrate, a projection lens, and a diffractive optical component. The projection lens is used to focus the light beam emitted by the array type optical radiation device to the diffractive optical component, and the diffractive optical component is used to divide the incident light beam into multiple exit lights and project them into a projection range. The light-emitting points of the optical array It is divided into two areas, and the light output is controlled by the control component, and the number of light spots in the projection range can be adjusted. The devices for dynamically adjusting projection graphics mentioned in the above two patents cannot meet the requirements of simultaneously adjusting the number of light points in the projection range and the projection range.

The present invention provides a structured light emitting module, including: The light source group includes at least two light sources that can be independently controlled on and off, and each light source is used to emit coherent light as the light source light; and The diffractive optical assembly includes at least two diffractive units, the light source light emitted by each light source is incident on a diffractive unit, and the diffracted light emitted by each diffractive unit respectively forms a plurality of non-overlapping projection patterns in the projection area , The projection pattern corresponding to any single diffraction unit, or the combination of the projection patterns corresponding to any two or more diffraction units, constitute a frame of projection image.

A second aspect of the present invention provides a depth sensing device, including: The above-mentioned structured light emitting module; A light detector for collecting the projection image of the projection area; and A processor, configured to perform feature comparison on the projection image collected by the light detector, and calculate the depth information of the projection area; and The controller controls the driving current of each light source in the light source group according to the feedback signal generated by the processor.

The structured light emitting module provided by the present invention can control the distribution density of the projection pattern and the range of the projection area at the same time, without assembling and positioning multiple diffractive optical components, and the selection of the light source is not limited to the vertical cavity surface emitting laser , It is beneficial to reduce the difference between the actual incident light waveform of the diffractive optical component and the design value, to ensure better projection imaging quality, and to achieve high-resolution and high-sampling-rate deep vision applications. The depth sensing device provided by the present invention can be applied to the fields of three-dimensional face recognition, machine vision applications, posture and body motion recognition and the like.

Example one

As shown in FIG. 1, the depth sensing device 10 provided by the first embodiment of the present invention includes a structured light emitting module 10A, a light detector 13, a processor 14, and a controller 15. Among them, the structured light emitting module 10A includes a light source group 11 and a diffractive optical component 12. The light source group 11 includes at least two independently controllable light sources 11a, and each light source 11a is used to emit coherent light as light source light; The assembly 12 includes at least two diffractive units 12a. The light source light emitted by each light source 11a is incident on a diffractive unit 12a. The diffracted light emitted by each diffractive unit 12a forms a plurality of non-overlapping light in the projection area 16. The projection pattern 17, the projection pattern 17 corresponding to any single diffraction unit 12a, or the combination of the projection patterns 17 corresponding to any two or more diffraction units 12a, constitute a frame of projection image 18. In the embodiment shown in FIG. 1, all the projection patterns 17 corresponding to all the diffraction units 12a are combined into one frame of projected image 18. In other embodiments, it may only be the projection pattern corresponding to a single diffraction unit 12a. 17. Or a combination of any two or more of the projection patterns 17 corresponding to the diffraction units 12a constitutes a frame of projection image 18. The light detector 13 is used to collect the projection image 18 of the projection area 16. The processor 14 is configured to perform feature comparison on the projection image 18 collected by the light detector, and calculate the depth information of the projection area 16. The controller 15 controls the driving current of each light source 11a in the light source group 11 according to the feedback signal of the processor 14, so as to control the distribution of the projection pattern 17 by increasing or decreasing the number of the diffractive units 12a of the light source light entering the diffractive optical assembly 12 The density or the extent of the projection area 16.

In this embodiment, the diffracted lights emitted by all the diffractive units 12a are projected in the same projection area 16, and the projection patterns 17 formed by the diffracted lights emitted by the diffractive units 12a do not overlap each other.

In this embodiment, the light source group 11 is a laser group, which includes a plurality of lasers as the light source 11a, and emits lasers as the light source. Each light source 11a in the light source group 11 can be independently controlled on and off. The laser used in this embodiment is an infrared laser, such as a vertical cavity surface emitting laser or an edge emitting laser (EEL). It can be understood that the structured light emitting module 10A provided in this embodiment is suitable for light sources 11a with different beams, different shapes, and different sizes. In this embodiment, the structured light emitting module 10A further includes a collimating lens (not shown) for collimating and shaping the light source light emitted by the light source group 11, so that the light source light is incident on the diffracted light in the form of collimated light (plane wave). Optical assembly 12.

Please refer to FIGS. 1 and 2 together. For convenience of description, only three diffraction units 12a of the diffractive optical assembly 12 are shown in FIG. 1. The specific number can be designed according to the actual situation, and the present invention does not do this. limit. Different diffraction units 12a have different diffraction microstructures to obtain the distribution of different projection patterns 17 in the corresponding projection area. As shown in FIG. 2, the three diffraction units 12a of the diffraction optical assembly 12 can respectively correspond to With structures A, B, and C with different diffractive microstructures, the diffracted light emitted by the three diffractive units 12a projected on the same projection area 16 has different distributions of the projection patterns 17 so that the projection area 16 The distributions of the projected patterns 17 do not overlap, and the diffractive microstructure of the diffractive optical component 12 can be specifically designed according to actual conditions, which is not limited in the present invention. The diffractive optical component 12 in this embodiment can be manufactured by a semiconductor photolithography process. 1 and 3 together, the projected image 18a, the projected image 18b, and the projected image 18c are respectively the diffracted light emitted by the three diffraction units 12a of the diffractive optical assembly 12 can be formed on the same projection area 16. When the controller 15 simultaneously controls at least two light sources 11a in the light source group 11 to emit light source light to the corresponding diffractive unit 12a, the same projection area 16 can obtain the overlapped image as shown in FIG. Projection image 18.

In this embodiment, the structured light emitting module 10A only uses a single diffractive optical component 12, and there is no need to assemble and align multiple diffractive optical components as in the prior art, which simplifies the process flow. The diffractive optical component 12 in this embodiment can be manufactured by a semiconductor lithography exposure process. Since the alignment error of the semiconductor lithography exposure process (approximately 10 nm to 100 nm) is much smaller than the mechanical tolerance caused by mechanical processing, it is compared with In the prior art, a plurality of aligned diffractive optical components are assembled, and the structured light emitting module 10A provided by the present invention is beneficial to reduce the difference between the actual incident light waveform and the design value, and ensure better projection imaging quality.

Please refer to FIG. 1 again, the projection patterns 17 are spaced apart and randomly distributed. In this embodiment, the projection patterns 17 are dot patterns spaced apart and randomly distributed. In other embodiments, the projection pattern 17 may also be a linear pattern. It can be understood that the specific pattern of the projection figure 17 can be designed according to the actual situation, and the present invention does not limit this. The light source light emitted by the light source 11a has a specific known code pattern. When a high-density projection pattern 17 is projected on the surface of an object (not shown) in the projection area 16, since the points on the surface of the object are usually not on the same plane, Therefore, the code pattern on the surface of the object collected by the light detector 13 has a certain amount of deviation compared with the known code pattern. The processor 14 compares the features of the projection image 18 collected by the light detector 13 and analyzes the projection image. 18 Compared with the deformation and displacement of the known encoding pattern, the depth information of the object in the projection area 16 is calculated, so as to restore the three-dimensional image of the object in the projection area 16. Projecting the projection image 17 on the surface of the object is beneficial to reduce the uniqueness window used by the processor 14 when comparing features. The uniqueness window refers to the minimum range of the algorithm comparing the known coding patterns and analyzing the deviation. The smaller the sexual window, the higher the lateral resolution, which helps to improve the speckle in the projected image 18.

By increasing or decreasing the number of the diffractive units 12a of the light source light incident on the diffractive optical assembly 12, the distribution density of the projection pattern 17 can be controlled. Please refer to FIGS. 1, 4A and 4B together. If the number of diffractive units 12a of the light source light incident on the diffractive optical assembly 12 is reduced (for example, the diffractive optical assembly 12 has only one light source 11a that emits light from the light source to the corresponding diffracted Unit 12a) can project a projection pattern 17 with a lower distribution density. Through a specific algorithm (for example, binning, max pooling), the resolution of the projection image 18 collected by the photodetector 13 can be reduced, so that Accelerate the acquisition of the projection image 18 by the light detector 13 and the feature comparison of the projection image 18 by the processor 14 to achieve high frame rate applications. 5A and 5B, if the number of diffractive units 12a of the light source light incident on the diffractive optical assembly 12 is increased (for example, the diffractive optical assembly 12 has three light sources 11a that emit light from the light source to the corresponding diffractive unit 12a), then The projection graphics 17 with higher distribution density can be projected, which is beneficial to reduce the unique window used by the processor 14 for feature comparison of the projected image 18, thereby realizing the application of high horizontal resolution and improving the broken image of the projected image 18. phenomenon. Therefore, according to the required distribution density of the projection pattern 17 of the projected image 18, the number of the diffractive units 12a of the diffractive optical assembly 12 irradiated by the light source light can be adjusted to realize the application of high resolution or high frame number. Example two

6 and 7 together, the main difference between the depth sensing device 10 provided in the second embodiment of the present invention and the first embodiment is that the diffracted light emitted by the diffraction unit 12a is projected on different projection areas 16 respectively. The areas 16a, 16b, and 16c are adjacent to each other, and the diffracted light emitted by each diffractive unit 12a is projected into a corresponding projection area (for example, the projection area 16a, the projection area 16b, and the projection area 16c in FIG. 6). Projection graphics 17. The projected image 18 can be formed by combining the projection patterns 17 of all the projection areas 16, or by combining the projection patterns 17 of any two adjacent projection areas 16, and can also be formed by the projection patterns 17 of any one projection area 16. FIG. 6 is an example in which the projection patterns 17 of all the projection areas 16 are combined to form a projection image 18.

In this embodiment, the range of the projection area 16 can be controlled by increasing or decreasing the number of the diffractive units 12a of the light source light incident diffractive optical assembly 12. As shown in FIG. 8, if the number of diffractive units 12a of the light source light incident diffractive optical assembly 12 is reduced (for example, only one light source 11a emits light source light to the corresponding diffractive unit 12a), the range of the projection area 16 is smaller. The non-projection area 19 in the projection image 18 collected by the photodetector 13 can be removed by a specific algorithm, thereby reducing the resolution of the projection image 18 collected by the photodetector 13, which is conducive to speeding up light detection The acquisition of the projection image 18 by the device 13 and the feature comparison of the projection image 18 by the processor 14 realize the application of high frame number. As shown in FIG. 9, increasing the number of diffractive units 12a of the light source light incident diffractive optical assembly 12 (for example, there are three light sources 11a emitting light source light to the corresponding diffractive unit 12a), and the range of the projection area 16 is increased. It is beneficial to obtain the projection image 18 of the full field of view. Therefore, according to the range of the projection area 16 required for the projected image 18, adjusting the number of the diffractive units 12a of the diffractive optical assembly 12 irradiated by the light source light can realize the application of high frame number or wide field of view.

In the prior art, a single light source with dual diffractive optical components is often used to diffract the light source at a large viewing angle. The length of the optical path of the diffracted light in the central part and the peripheral part of the projection area is different. The light path is longer, and the light spot presents a wider projection. When the projection area is rectangular, the light path at the four corners of the projection area is the longest, so the four corners of the projection area visually present elongated pincushion deformation aberrations. In this embodiment, the projection image 18 can be acquired by a combination of a plurality of smaller projection areas 16 to reduce the diffraction angle of view of the diffracted light. Each diffraction unit 12a on the diffractive optical assembly 12 corresponds to The difference between the optical path length of the light spot in the central part and the peripheral part of the projection area 16 is smaller than the above-mentioned prior art. Therefore, the structured light emitting module 10A of this embodiment is beneficial to improve the phenomenon of pincushion deformation aberration.

Compared with the prior art, the structured light emitting module 10A provided by the present invention can control the distribution density of the projection pattern 17 and the range of the projection area 16 at the same time, and there is no need to assemble and align the multiple diffractive optical components 12 to the light source 11a. The selection of is not limited to the vertical cavity surface emitting laser, which is beneficial to reduce the difference between the actual incident light waveform of the diffractive optical component 12 and the design value, and to ensure a better projection imaging quality.

The structured light emitting module 10A provided by the present invention uses the passive diffractive optical component 12 and the active light source 11a to achieve the regulation of the range of the projection area 16, the distribution density of the projection pattern 17, and the lateral resolution, which is beneficial to achieve high resolution. The application of depth vision with high sampling rate and high sampling rate can be applied to the fields of 3D face recognition, machine vision application, posture and movement recognition.

10: Depth sensing equipment 10A: Structured light emission module 11: Light source group 11a: light source 12: Diffraction optical components 12a: Diffraction unit 13: Light detector 14: processor 15: Controller 16, 16a, 16b, 16c: projection area 17: Projection graphics 18, 18a, 18b, 18c: projected image 19: Non-projection area

FIG. 1 is a schematic diagram of the working principle of the depth sensing device provided by the first embodiment of the present invention.

FIG. 2 is a schematic diagram of the corresponding structure of three diffractive units of the diffractive optical assembly provided by the first embodiment of the present invention.

3 is a projection image respectively projected on a projection area by three diffractive units of the diffractive optical assembly provided by the first embodiment of the present invention.

4A and 4B are respectively a schematic diagram of a projection area of the depth sensing device provided in the first embodiment of the present invention in a lower resolution state and a projection image collected by a photodetector.

5A and 5B are respectively a schematic diagram of a projection area of the depth sensing device provided in the first embodiment of the present invention in a higher resolution state and a projection image collected by a photodetector.

FIG. 6 is a schematic diagram of the working principle of the depth sensing device provided by the second embodiment of the present invention.

FIG. 7 is a schematic diagram of the structure corresponding to three diffractive units of the diffractive optical assembly provided by the second embodiment of the present invention.

FIG. 8 is a schematic diagram of the projection area of the depth sensing device provided by the second embodiment of the present invention in a high frame rate application.

FIG. 9 is a schematic diagram of the projection area of the depth sensing device provided by the second embodiment of the present invention in a wide field of view application.

10: Depth sensing equipment

10A: Structured light emission module

11: Light source group

11a: light source

12: Diffraction optical components

12a: Diffraction unit

13: Light detector

14: processor

15: Controller

16: projection area

17: Projection graphics

18: Projected image

Claims (10)

A structured light emitting module, which is improved in that it includes: The light source group includes at least two light sources that can be independently controlled on and off, and each light source is used to emit coherent light as the light source light; and The diffractive optical assembly includes at least two diffractive units, the light source light emitted by each light source is incident on a diffractive unit, and the diffracted light emitted by each diffractive unit respectively forms a plurality of non-overlapping projection patterns in the projection area , The projection pattern corresponding to any single diffraction unit, or the combination of the projection patterns corresponding to any two or more diffraction units, constitute a frame of projection image. The structured light emitting module according to claim 1, wherein the diffracted lights emitted by all the diffractive units are projected in the same projection area, and the projection patterns formed by the diffracted lights emitted by the diffractive units do not overlap each other. The structured light emitting module according to claim 1, wherein the diffracted light emitted by the diffraction unit is respectively projected on different projection areas, and the diffracted light emitted by each diffraction unit is respectively projected in the corresponding projection area A plurality of different overlapping projection patterns, and the different projection areas are adjacent to each other. The structured light emitting module according to claim 2 or 3, wherein different diffractive units have different diffractive microstructures to obtain the distribution of different projection patterns in the corresponding projection area. The structured light emitting module according to claim 3, wherein the projection image is formed by a combination of projection graphics of all projection areas; or It is formed by the combination of projection graphics of any two adjacent projection areas; or It is composed of projection graphics of any projection area. The structured light emitting module according to claim 1, wherein the structured light emitting module further includes a controller, and the controller increases or decreases the diffractive unit of the diffractive optical component by which the light from the light source is incident The number controls the distribution density of the projected graphics or the range of the projected area. The structured light emitting module according to claim 1, wherein the projection patterns are spaced apart and randomly distributed. The structured light emitting module according to claim 1, wherein the light source is an infrared laser. The structured light emitting module according to claim 1, wherein the structured light emitting module further includes a collimating lens for collimating and shaping the light source light emitted by the light source group. A depth sensing device is improved in that it includes: The structured light emitting module according to any one of claims 1-9; A light detector for collecting the projection image of the projection area; and A processor, configured to perform feature comparison on the projection image collected by the light detector, and calculate the depth information of the projection area; and The controller controls the driving current of each light source in the light source group according to the feedback signal generated by the processor.

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