CN108508619B

CN108508619B - Laser projection module, depth camera and electronic device

Info

Publication number: CN108508619B
Application number: CN201810200425.5A
Authority: CN
Inventors: 韦怡
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2018-03-12
Filing date: 2018-03-12
Publication date: 2020-01-10
Anticipated expiration: 2038-03-12
Also published as: CN108508619A

Abstract

The invention discloses a laser projection module, a depth camera and an electronic device. The laser projection module comprises a light source, a collimation element and a diffraction optical element. The light source is used for emitting laser. The collimating element is used for collimating the laser light. The collimating element comprises one or more lenses, the one or more lenses are arranged on the light emitting path of the light source, and the lenses are made of plastic materials. The diffractive optical element is used for diffracting the laser light collimated by the collimating element to form a laser light pattern. In the laser projection module, the depth camera and the electronic device, which are provided by the embodiment of the invention, the lens of the collimation element is made of plastic materials, so that the cost is lower and the mass production is convenient.

Description

Laser projection module, depth camera and electronic device

Technical Field

The invention relates to the technical field of imaging, in particular to a laser projection module, a depth camera and an electronic device.

Background

The laser projection module comprises a light source, a collimating element and a Diffractive Optical Elements (DOE). The collimating element generally includes a lens structure, and the lens is made of glass material, which results in higher cost and inconvenience for mass production of the laser projection module.

Disclosure of Invention

The embodiment of the invention provides a laser projection module, a depth camera and an electronic device.

The laser projection module of the embodiment of the invention comprises:

a light source for emitting laser light;

the collimating element is used for collimating the laser, and comprises one or more lenses, the one or more lenses are arranged on a light emitting path of the light source, and the lenses are made of plastic materials; and

a diffractive optical element for diffracting the laser light collimated by the collimating element to form a laser light pattern.

In some embodiments, the collimating element includes a first lens, the first lens includes a first light incident surface and a first light emitting surface that are opposite to each other, the first light incident surface is a concave surface, and the first light emitting surface is a convex surface.

In some embodiments, the collimating element comprises a plurality of lenses coaxially arranged in sequence in the light emitting path of the light source.

In some embodiments, the plurality of lenses include a first lens and a second lens, the first lens includes a first light incident surface and a first light emitting surface that are opposite to each other, the second lens includes a second light incident surface and a second light emitting surface that are opposite to each other, a vertex of the first light emitting surface is abutted to a vertex of the second light incident surface, the first light incident surface is a concave surface, and the second light emitting surface is a convex surface.

In some embodiments, the first light emitting surface and the second light incident surface are convex surfaces.

In some embodiments, the plurality of lenses includes a first lens, a second lens and a third lens, the first lens includes a first light incident surface and a first light emitting surface that are opposite to each other, the second lens includes a second light incident surface and a second light emitting surface that are opposite to each other, the third lens includes a third light incident surface and a third light emitting surface that are opposite to each other, the third light incident surface is a concave surface, and the third light emitting surface is a convex surface.

In some embodiments, the first light incident surface is a convex surface, the first light emitting surface is a concave surface, the second light incident surface is a concave surface, and the second light emitting surface is a concave surface.

In some embodiments, the collimating element includes a plurality of lenses, the plurality of lenses are sequentially disposed on the light emitting path of the light source, and the optical axis of at least one of the lenses is offset with respect to the optical axes of the other lenses.

In some embodiments, the collimating element comprises a plurality of lenses, and the optical centers of at least two of the lenses lie in the same plane perpendicular to a first direction from the light source to the diffractive optical element.

In some embodiments, the optical axis of at least one of the lenses is parallel to the optical axis of the other of the lenses.

In some embodiments, the light source is a vertical cavity surface emitting laser; or the light source is an edge-emitting laser.

In some embodiments, the light source is an edge emitting laser, the light source comprising a light emitting face, the light emitting face facing the collimating element.

A depth camera according to an embodiment of the present invention includes:

the laser projection module of any of the above embodiments;

the image collector is used for collecting the laser patterns projected into the target space after passing through the diffractive optical element; and

and the processor is respectively connected with the laser projection module and the image collector and is used for processing the laser pattern to obtain a depth image.

An electronic device according to an embodiment of the present invention includes:

a housing; and

the depth camera of any of the above embodiments, the depth camera disposed within and exposed from the housing to acquire a depth image.

In the laser projection module, the depth camera and the electronic device, which are provided by the embodiment of the invention, the lens of the collimation element is made of plastic materials, so that the cost is lower and the mass production is convenient.

Additional aspects and advantages of embodiments of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of a laser projection module according to some embodiments of the present invention;

fig. 2 to 4 are schematic partial structural views of a laser projection module according to some embodiments of the present invention;

FIGS. 5-16 are schematic views of a part of a collimating element of a laser projection module according to some embodiments of the present invention;

FIG. 17 is a schematic diagram of a depth camera configuration according to some embodiments of the invention;

FIG. 18 is a schematic structural diagram of an electronic device according to some embodiments of the invention;

description of the main elements and symbols:

the laser projection module 100, the substrate assembly 10, the substrate 11, the heat dissipation hole 111, the circuit board 12, the via hole 121, the lens barrel 20, the receiving cavity 21, the top 22, the bottom 23, the through hole 24, the carrier 25, the first section structure 26, the first section structure 27, the protective cover 30, the abutting surface 31, the light transmission hole 32, the light source 40, the light emitting surface 41, the side surface 42, the collimating element 50, the first lens 51, the first light incident surface 511, the first light emergent surface 512, the second lens 52, the second light incident surface 521, the second light emergent surface 522, the third lens 53, the third light incident surface 531, the third light emergent surface 532, the fourth lens 54, the fifth lens 55, the sixth lens 56, the diffractive optical element 60, the diffractive light emergent surface 61, the diffractive incident surface 62, the sealing compound 70, the supporting block 80, the depth camera 400, the projection window 401, the collection window 402, the image collector 200, the processor 300, the electronic.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for the purpose of illustrating the embodiments of the present invention and are not to be construed as limiting the embodiments of the present invention.

In the description of the embodiments of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, "a plurality" means two or more unless specifically limited otherwise.

In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other suitable relationship. Specific meanings of the above terms in the embodiments of the present invention can be understood by those of ordinary skill in the art according to specific situations.

The following disclosure provides many different embodiments or examples for implementing different configurations of embodiments of the invention. In order to simplify the disclosure of embodiments of the invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, embodiments of the invention may repeat reference numerals and/or reference letters in the various examples, which have been repeated for purposes of simplicity and clarity and do not in themselves dictate a relationship between the various embodiments and/or arrangements discussed. In addition, embodiments of the present invention provide examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.

Referring to fig. 1, a laser projection module 100 according to an embodiment of the invention includes a substrate assembly 10, a lens barrel 20, a protective cover 30, a light source 40, a collimating element 50, and a diffractive optical element 60.

The substrate assembly 10 includes a substrate 11 and a circuit board 12 carried on the substrate 11. The material of the substrate 11 may be plastic, for example, any one or more of Polyethylene Glycol Terephthalate (PET), Polymethyl Methacrylate (PMMA), Polycarbonate (PC), and Polyimide (PI). Thus, the substrate 11 is light in weight and has sufficient support strength. The circuit board 12 may be a hard board, a soft board, or a rigid-flex board. The circuit board 12 is provided with a via 121. The light source 40 is fixed on the substrate 11 through the via 121 and electrically connected to the circuit board 12. The substrate 11 may be formed with heat dissipation holes 111, heat generated by the operation of the light source 40 or the circuit board 12 may be dissipated through the heat dissipation holes 111, and the heat dissipation holes 111 may be filled with a thermal conductive adhesive to further improve the heat dissipation performance of the substrate assembly 10.

The lens barrel 20 is disposed on the substrate assembly 10 and forms an accommodation cavity 21 together with the substrate assembly 10. The light source 40, the collimating element 50, and the diffractive optical element 60 are all housed in the housing cavity 21. The collimating element 50 and the diffractive optical element 60 are disposed in sequence on the light emitting path of the light source 40. The barrel 20 includes opposing top 22 and bottom 23 portions. The lens barrel 20 is formed with a through hole 24 penetrating the top 22 and the bottom 23. The base 23 is carried on the substrate assembly 10 and may be secured to the circuit board 12, in particular by glue. An annular bearing table 25 extends from the inner wall of the lens barrel 20 toward the center of the through hole 24, and the diffractive optical element 60 is carried on the bearing table 25.

The protective cover 30 is disposed on the top portion 22, and the protective cover 30 includes an abutting surface 31 located in the receiving cavity 21 and opposing the substrate 11. The protective cover 30 and the stage 25 respectively abut against the diffractive optical element 60 from opposite sides of the diffractive optical element 60. The abutting surface 31 is a surface of the protective cover 30 that abuts the diffractive optical element 60. The laser projection module 100 uses the protection cover 30 to abut against the diffractive optical element 60 so as to accommodate the diffractive optical element 60 in the accommodating cavity 21 and prevent the diffractive optical element 60 from falling off along the light outgoing direction.

In some embodiments, the protective cover 30 may be made of a metal material, such as nano silver wire, metallic silver wire, copper sheet, and the like. The protective cover 30 is provided with a light hole 32. The light-transmissive holes 32 are aligned with the through-holes 24. The light-transmitting hole 32 is used to emit the laser light pattern projected by the diffractive optical element 60. The aperture size of the light-transmitting hole 32 is smaller than at least one of the width or the length of the diffractive optical element 60 to confine the diffractive optical element 60 within the housing cavity 21.

In some embodiments, the protective cover 30 may be made of a light-transmissive material, such as glass, Polymethyl Methacrylate (PMMA), Polycarbonate (PC), Polyimide (PI), and the like. Since the transparent materials such as glass, PMMA, PC, and PI have excellent light transmittance, the protective cover 30 does not need to be provided with the light hole 32. In this way, the protective cover 30 can prevent the diffractive optical element 60 from coming off and prevent the diffractive optical element 60 from being exposed to the outside of the lens barrel 20, thereby providing waterproof and dustproof effects to the diffractive optical element 60.

The light source 40 is used to emit laser light. The light source 40 may be a Vertical Cavity Surface Emitting Laser (VCSEL) or an edge-Emitting Laser (EEL). In the embodiment shown in fig. 1, the light source 40 is an edge emitting Laser, and specifically, the light source 40 may be a Distributed Feedback Laser (DFB). The light source 40 emits laser light into the housing chamber 21. Referring to fig. 2, the light source 40 is in a column shape, an end surface of the light source 40 away from the substrate assembly 10 forms a light emitting surface 41, the laser light is emitted from the light emitting surface 41, the light emitting surface 41 faces the collimating element 50, the light emitting surface 41 is perpendicular to the collimating optical axis of the collimating element 50, and the collimating optical axis passes through the center of the light emitting surface 51. The light source 40 is fixed on the substrate assembly 10, and specifically, the light source 40 may be adhered to the substrate assembly 10 by the sealant 70, for example, the surface of the light source 40 opposite to the light emitting surface 41 is adhered to the substrate assembly 10. Referring to fig. 1 and 3, the side surface 42 of the light source 40 may be adhered to the substrate assembly 10, and the sealant 70 may cover the side surface 42 around, or only one surface of the side surface 42 may be adhered to the substrate assembly 10 or some surfaces may be adhered to the substrate assembly 10. The encapsulant 70 may be a thermal conductive adhesive to conduct heat generated by the light source 40 to the substrate assembly 10.

The light source 40 of the laser projection module 100 adopts an edge emitting laser, on one hand, the temperature drift of the edge emitting laser is smaller than that of a VCSEL array, on the other hand, the edge emitting laser is of a single-point light emitting structure, an array structure does not need to be designed, the manufacturing is simple, and the cost of the light source 40 of the laser projection module 100 is lower.

When the laser of the distributed feedback laser propagates, the gain of power is obtained through the feedback of the grating structure. To improve the power of the distributed feedback laser, the injection current needs to be increased and/or the length of the distributed feedback laser needs to be increased, which may increase the power consumption of the distributed feedback laser and cause serious heat generation. When the light emitting surface 41 of the edge emitting laser faces the collimating element 50, the edge emitting laser is vertically placed, and due to the fact that the edge emitting laser is of a slender strip structure, the edge emitting laser is prone to falling, shifting or shaking accidents, the edge emitting laser can be fixed through the arrangement of the sealing glue 70, and the edge emitting laser is prevented from falling, shifting or shaking accidents.

In some embodiments, the light source 40 may also be fixed to the substrate assembly 10 in a fixed manner as shown in fig. 4. Specifically, the laser projection module 100 includes a plurality of support blocks 80, the support blocks 80 may be fixed on the substrate assembly 10, the plurality of support blocks 80 collectively surround the light source 40, and the light source 40 may be directly installed between the plurality of support blocks 80 when installed. In one example, the plurality of support blocks 80 collectively hold the light source 40 to further prevent the light source 40 from wobbling.

The collimating element 50 is used to collimate the laser light emitted by the light source 40. The collimating element 50 is fixed to the barrel 20, and the stage 25 is located between the collimating element 50 and the diffractive optical element 60. The collimating element 50 includes one or more lenses disposed in the light path of the light source 40, and the lenses are made of plastic. Since the lenses of the collimating element 50 according to the embodiment of the present invention are made of plastic, the cost is low and mass production is facilitated.

Referring to fig. 1 and fig. 5, in some embodiments, the collimating element 50 may only include the first lens 51, and the first lens 51 includes a first light incident surface 511 and a first light emitting surface 512 which are opposite to each other. The first light incident surface 511 is a surface of the first lens 51 close to the light source 40, and the first light emitting surface 512 is a surface of the first lens 51 close to the diffractive optical element 60. The first light incident surface 511 is a concave surface, and the first light emitting surface 512 is a convex surface. The surface type of the first lens 51 may be an aspherical surface, a spherical surface, a fresnel surface, or a binary optical surface. A diaphragm is arranged between the light source 40 and the first lens 51 for limiting the light beam.

In some embodiments, the collimating element 50 may include a plurality of lenses coaxially disposed in sequence in the light emitting path of the light source 40. The surface type of each lens can be any one of an aspheric surface, a spherical surface, a Fresnel surface and a binary optical surface.

For example: referring to fig. 1 and 6, the plurality of lenses may include a first lens 51 and a second lens 52. The first lens 51 and the second lens 52 are coaxially arranged in this order on the light emission path of the light source 40. The first lens 51 includes a first light incident surface 511 and a first light emitting surface 512 opposite to each other. The first light incident surface 511 is a surface of the first lens 51 close to the light source 40, and the first light emitting surface 512 is a surface of the first lens 51 close to the diffractive optical element 60. The second lens 52 includes a second light incident surface 521 and a second light emitting surface 522 opposite to each other. The second light incident surface 521 is a surface of the second lens 52 close to the light source 40, and the second light emitting surface 522 is a surface of the second lens 52 close to the diffractive optical element 60. The vertex of the first light emitting surface 512 is abutted against the vertex of the second light incident surface 521, the first light incident surface 511 is a concave surface, and the second light emitting surface 522 is a convex surface. The diaphragm is disposed on the second light incident surface 521 for limiting the light beam. Further, the first light emitting surface 512 and the second light incident surface 521 may be convex surfaces. Thus, the vertex of the first light emitting surface 512 is convenient to collide with the vertex of the second light incident surface 521. The curvature radius of the first light exiting surface 512 is smaller than that of the second light entering surface 521.

Referring to fig. 1 and 7, the plurality of lenses may further include a first lens 51, a second lens 52, and a third lens 53. The first lens 51, the second lens 52, and the third lens 53 are coaxially and sequentially disposed on a light emitting path of the light source 40. The first lens 51 includes a first light incident surface 511 and a first light emitting surface 512 opposite to each other. The first light incident surface 511 is a surface of the first lens 51 close to the light source 40, and the first light emitting surface 512 is a surface of the first lens 51 close to the diffractive optical element 60. The second lens 52 includes a second light incident surface 521 and a second light emitting surface 522 opposite to each other. The second light incident surface 521 is a surface of the second lens 52 close to the light source 40, and the second light emitting surface 522 is a surface of the second lens 52 close to the diffractive optical element 60. The third lens 53 includes a third light incident surface 531 and a third light emitting surface 532 opposite to each other. The third light incident surface 531 is a surface of the third lens 53 close to the light source 40, and the third light emitting surface 532 is a surface of the third lens 53 close to the diffractive optical element 60. The third light incident surface 531 is a concave surface, and the third light emitting surface 532 is a convex surface. The diaphragm is disposed on the third light emitting surface 532 and is used for limiting the light beam. Further, the first light incident surface 511 may be a convex surface, the first light emitting surface 512 is a concave surface, the second light incident surface 521 is a concave surface, and the second light emitting surface 522 is a concave surface.

In some embodiments, the collimating element 50 comprises a plurality of lenses. The plurality of lenses are sequentially disposed on a light emitting path of the light source 40, and an optical axis of at least one lens is shifted from optical axes of the other lenses. At this time, the structure of the lens barrel 20 may be one or more sections, each section being used for mounting a corresponding lens.

For example: referring to fig. 8 to 12, the collimating element 50 includes a first lens 51, a second lens 52 and a third lens 53. The first lens 51, the second lens 52, and the third lens 53 are sequentially disposed on the light emission path of the light source 40. The optical axis of the second lens 52 is offset from the optical axis of the first lens 51, the optical axis of the first lens 51 coincides with the optical axis of the third lens 53 (as shown in fig. 8), further, the optical axis of the second lens 52 may be parallel to the optical axis of the first lens 51, at this time, the structure of the lens barrel 20 may be a two-stage structure, the first stage structure 26 is used for installing the first lens 51 and the second lens 52, the second stage structure 27 is used for installing the third lens 53, the first stage structure 26 is obliquely connected to the second stage structure 27, and the second lens 52 is installed at the connection position of the first stage structure 26 and the second stage structure 27, so that the multiple lenses form a bending structure to increase the optical path length and thus reduce the overall height of the laser projection module 100, the inner walls of the first stage structure 26 and the second stage structure 27 are coated with a reflective coating for reflecting light, so that the light emitted by the light source 40 can sequentially pass through the first light incident surface 511, the second, A first light emitting surface 512, a second light incident surface 521, a second light emitting surface 522, a third light incident surface 531, and a third light emitting surface 532; of course, in other embodiments, the first stage structure 26 and the second stage structure 27 may also be reflective elements independent from the lens barrel 20, the reflective elements are disposed on the lens barrel 20, the reflective elements are prisms or mirrors, and the like, and the reflective elements are used for reflecting light to change the direction of the light path; alternatively, the optical axis of the first lens 51 may be shifted from the optical axis of the second lens 52, and the optical axis of the second lens 52 may coincide with the optical axis of the third lens 53 (as shown in fig. 9), and further, the optical axis of the first lens 51 may be parallel to the optical axis of the second lens 52; alternatively, the optical axis of the third lens 53 is offset from the optical axis of the first lens 51, the optical axis of the first lens 51 coincides with the optical axis of the second lens 52 (as shown in fig. 10), and further, the optical axis of the third lens 53 may be parallel to the optical axis of the first lens 51; alternatively, the optical axis of the second lens 52 is shifted from the optical axis of the first lens 51, the optical axis of the third lens 53 is shifted from the optical axis of the first lens 51, the optical axis of the second lens 52 and the optical axis of the third lens 53 are located on the same side of the optical axis of the first lens 51 (as shown in fig. 11), further, the optical axis of the first lens 51 may be parallel to the optical axis of the second lens 52, the optical axis of the first lens 51 is parallel to the optical axis of the third lens 53, and the optical axis of the second lens 52 is parallel to the optical axis of the third lens 53; alternatively, the optical axis of the second lens 52 is offset from the optical axis of the first lens 51, the optical axis of the third lens 53 is offset from the optical axis of the first lens 51, the optical axis of the second lens 52 and the optical axis of the third lens 53 are located on opposite sides of the optical axis of the first lens 51 (as shown in fig. 12), and further, the optical axis of the first lens 51 may be parallel to the optical axis of the second lens 52, the optical axis of the first lens 51 may be parallel to the optical axis of the third lens 53, and the optical axis of the second lens 52 may be parallel to the optical axis of the third lens 53.

Preferably, the optical axis of the second lens 52 is shifted from the optical axis of the first lens 51, the optical axis of the third lens 53 is shifted from the optical axis of the first lens 51, and the optical axis of the second lens 52 and the optical axis of the third lens 53 are located on opposite sides of the optical axis of the first lens 51. Thus, the multiple lenses form a bending structure, which is beneficial to increasing the optical path, increasing the focal length, and reducing the height of the laser projection module 100. Of course, the collimating element 50 may also include more lenses, for example, referring to fig. 13, the collimating element 50 includes a first lens 51, a second lens 52, a third lens 53, a fourth lens 54, a fifth lens 55, and a sixth lens 56. The first lens 51, the second lens 52, the third lens 53, the fourth lens 54, the fifth lens 55, and the sixth lens 56 are sequentially disposed on the light emission optical path of the light source 40. The optical axis of the second lens 52 is shifted from the optical axis of the first lens 51, the optical axis of the third lens 53 is shifted from the optical axis of the first lens 51, the optical axis of the second lens 52 and the optical axis of the third lens 53 are located on the opposite side of the optical axis of the first lens 51, the optical axis of the fourth lens 54 is overlapped with the optical axis of the second lens 52, the optical axis of the fifth lens 55 is overlapped with the optical axis of the third lens 53, and the optical axis of the sixth lens 56 is overlapped with the optical axis of the first lens 51.

It should be noted that in the laser projection module 100 shown in fig. 9 to 13, the structure of the lens barrel 20 is the same as or similar to the structure of the lens barrel 20 shown in fig. 8, and the structure of the lens barrel 20 may be a one-stage or multi-stage structure, which is not described herein again.

In some embodiments, the collimating element 50 comprises a plurality of lenses, and the optical centers of at least two of the lenses are located on the same plane perpendicular to the first direction, which is the direction from the light source 40 to the diffractive optical element 60.

For example: referring to fig. 14 to 16, the collimating element 50 includes a first lens 51, a second lens 52 and a third lens 53. The optical center of the first lens 51 and the optical center of the second lens 52 are located on the same plane (as shown in fig. 14), and the optical axis of the first lens 51 and the optical axis of the second lens 52 may be located on the opposite side of the optical axis of the third lens 53; alternatively, the optical center of the second lens 52 and the optical center of the third lens 53 may be located on the same plane (as shown in fig. 15), and the optical axis of the second lens 52 and the optical axis of the third lens 53 may be located on the opposite side of the optical axis of the first lens 51; alternatively, the optical center of the first lens 51 and the optical center of the third lens 53 are located on the same plane; alternatively, the optical center of the first lens 51, the optical center of the second lens 52, and the optical center of the third lens 53 are all located on the same plane (as shown in fig. 16). Further, the optical axis of the first lens 51 may be parallel to the optical axis of the second lens 52, the optical axis of the first lens 51 may be parallel to the optical axis of the third lens 53, and the optical axis of the second lens 52 may be parallel to the optical axis of the third lens 53.

Referring to fig. 1 again, the diffractive optical element 60 is used for diffracting the laser light collimated by the collimating element 50 to form a laser pattern. The diffractive optical element 60 includes opposing diffractive exit and entrance faces 61, 62. The protective cover 30 can be adhered to the top 22 by glue, the contact surface 31 contacts with the diffraction exit surface 61, and the diffraction incident surface 62 contacts with the carrying platform 25, so that the diffractive optical element 60 will not fall off from the receiving cavity 21 along the light exit direction. The diffractive optical element 60 may be made of glass or composite plastic (e.g., PET).

When the laser projection module 100 is assembled, the collimating element 50 and the substrate assembly 10 to which the light source 40 is attached are sequentially inserted into the through hole 24 from the bottom 23 of the lens barrel 20 along the optical path. The light source 40 may be mounted on the substrate assembly 10, and then the substrate assembly 10 mounted with the light source 40 is fixed to the bottom 23. The diffractive optical element 60 is put into the through hole 24 from the top 22 against the direction of the optical path and carried on the carrier table 25, and then the protective cover 30 is mounted such that the diffractive exit surface 61 of the diffractive optical element 60 interferes with the protective cover 30 and the diffractive entrance surface 62 interferes with the carrier table 25. The laser projection module 100 has a simple structure and is convenient to assemble.

Referring to fig. 17, a depth camera 400 according to an embodiment of the present disclosure includes the laser projection module 100, the image collector 200, and the processor 300 according to any one of the above embodiments. The image collector 200 is used to collect the laser pattern projected into the target space via the diffractive optical element 50. The processor 300 is connected to the laser projection module 100 and the image collector 200 respectively. The processor 300 is used to process the laser pattern to obtain a depth image.

Specifically, the laser projection module 100 projects a laser pattern projected into the target space through the projection window 401, and the image collector 200 collects the laser pattern modulated by the target object through the collection window 402. The image collector 200 may be an infrared camera, and the processor 300 calculates a deviation value between each pixel point in the laser pattern and each corresponding pixel point in the reference pattern by using an image matching algorithm, and further obtains a depth image of the laser pattern according to the deviation value. The Image matching algorithm may be a Digital Image Correlation (DIC) algorithm. Of course, other image matching algorithms may be employed instead of the DIC algorithm.

In the depth camera 400 according to the embodiment of the present invention, the lenses of the collimating element 50 are made of plastic material, so that the cost is low and the mass production is convenient.

Referring to fig. 18, an electronic device 1000 according to an embodiment of the invention includes a housing 500 and the depth camera 400 according to the embodiment. The depth camera 400 is disposed within the housing 500 and exposed from the housing 500 to acquire a depth image. The electronic device 1000 includes, but is not limited to, a mobile phone, a tablet computer, a notebook computer, a smart band, a smart watch, a smart helmet, smart glasses, and the like.

In the electronic device 1000 according to the embodiment of the present invention, the lenses of the collimating element 50 are made of plastic material, so that the cost is low and the mass production is convenient.

In the description herein, references to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example" or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and those skilled in the art can make changes, modifications, substitutions and alterations to the above embodiments within the scope of the present invention.

Claims

1. A laser projection module, comprising:

a light source for emitting laser light;

the collimating element is used for collimating the laser, and comprises a plurality of lenses, the lenses are coaxially and sequentially arranged on a light emitting light path of the light source, the lenses are all made of plastic materials, the lenses comprise a first lens, a second lens and a third lens, the first lens comprises a first light incoming surface and a first light outgoing surface which are opposite, the second lens comprises a second light incoming surface and a second light outgoing surface which are opposite, the third lens comprises a third light incoming surface and a third light outgoing surface which are opposite, the third light incoming surface is a concave surface, and the third light outgoing surface is a convex surface; the first light incident surface is a convex surface, the first light emergent surface is a concave surface, the second light incident surface is a concave surface, and the second light emergent surface is a concave surface; and

2. The laser projection module of claim 1, wherein the light source is a vertical cavity surface emitting laser; or the light source is an edge-emitting laser.

3. The laser projection module of claim 1, wherein the light source is an edge emitting laser and the light source comprises a light emitting face facing the collimating element.

4. A depth camera, comprising:

the laser projection module of any of claims 1-3;

5. An electronic device, comprising:

a housing; and

the depth camera of claim 4, disposed within and exposed from the housing to acquire a depth image.