CN109579728B - Speckle structure light projection module based on holographic waveguide - Google Patents

Abstract

The invention relates to the field of 3D topography measurement. The invention provides a speckle structure light projection module based on holographic waveguide, comprising a holographic waveguide unit, an array laser light source, a collimating lens and a diffractive optical element, wherein the holographic waveguide unit is composed of a holographic optical element and a waveguide base material. The holographic optical element is used as a coupling input and output modulation device. It modulates the first spot pattern emitted by the array laser light source into a total reflection waveguide transmission in the substrate, and couples it out to the collimating lens after a certain distance, and the diffractive optical element receives the collimation. The light beam replicates and expands the first speckle pattern to form a high-density speckle array illumination, which is projected onto the scene to be tested. By using holographic waveguide transmission, the laser array light source can be spatially separated from other optical modulation devices by a certain distance, so as to add a heat dissipation device to the light source, and to achieve a light, thin and miniaturized design while ensuring good heat dissipation characteristics.

Description

Speckle structured light projection module based on holographic waveguide

technical field

The invention relates to the field of 3D topography measurement, in particular to a speckle structured light projection module based on a holographic waveguide.

Background technique

3D topography measurement technology can collect depth coordinate information of objects in the scene, providing additional data processing freedom for back-end development. With the popularization of mobile terminal devices and intelligent interactive devices, 3D measurement technology has increasingly become the core technology of the new generation of human-computer interaction, and has a wide range of applications in industrial inspection, security retail, somatosensory games, mobile payment and biomedicine prospect.

Speckle structured light technology is currently a widely used 3D data acquisition solution. It uses coded random, pseudo-random or regularly arranged speckle light clusters as optical probes, and projects them to the spatial scene. By comparing the speckle displacement, the specific scene depth information is obtained by the principle of triangulation. The projection module projects the preset structured light mode to the actual scene, which is the hardware basis of the speckle structured light depth camera. Usually the module includes a laser light source, a collimating lens and a diffractive optical element (Diffractive Optical Element, DOE).

With the wider application of depth perception technology in mobile devices, the requirements for the size of projection modules and depth cameras are getting higher and higher. Compact and thin projection modules and depth cameras have become an urgent research demand in the field; in addition, the miniaturized projection modules will face the heat dissipation of the light source due to the compact installation and arrangement of various components in them. This problem seriously restricts the development of speckle projection modules.

To sum up, in speckle structured light 3D topography measurement, how to design a speckle projection module with a light, thin and miniaturized structure and easy to dissipate heat from the light source has become one of the technical problems to be solved urgently.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present invention is to provide a speckle structured light projection module based on a holographic waveguide, so that the speckle projection module can have good heat dissipation characteristics while satisfying the design of light, thin and miniaturized structure.

In order to achieve the above object, one aspect of the embodiments of the present invention provides a speckle structured light projection module based on a holographic waveguide, including a holographic waveguide unit and an array light source for emitting a laser beam corresponding to a first speckle pattern, wherein the holographic The waveguide unit includes a waveguide substrate, a first holographic optical element and a second holographic optical element, the first holographic optical element is attached to the first end of the waveguide substrate, and the second holographic optical element is attached to the waveguide the second end of the substrate; wherein, the second holographic optical element is used for coupling the laser beam emitted by the array light source into the waveguide substrate, and the laser beam can be transmitted in the waveguide substrate , and output through the first holographic optical element.

Another aspect of the embodiments of the present invention provides a speckle structured light projection module based on a holographic waveguide, including a holographic waveguide unit and an array light source for emitting a laser beam corresponding to a first speckle pattern, wherein the holographic waveguide unit includes a waveguide a substrate and a first holographic optical element, the first holographic optical element is attached to the first end of the waveguide substrate; wherein, the plane of the waveguide substrate at the second end is cut into an inclined plane to pass through The inclined surface couples a laser beam to be waveguided, so that the laser beam can be waveguided in the waveguide substrate and output through the first holographic optical element.

Through the above technical solutions, it is proposed to set a holographic waveguide unit and an array light source in the speckle structured light projection module. The holographic waveguide unit includes a waveguide substrate, a first holographic optical element and a second holographic optical element. The laser beam emitted by the array light source is coupled in through the second holographic optical element at one end and can be waveguided in the waveguide substrate to be output through the first holographic optical element at the other end of the waveguide substrate. Therefore, the light source can be separated from other optical modulation devices by a long distance through waveguide transmission, and it is also possible to add a heat dissipation device for the light source separately.

Other features and advantages of embodiments of the present invention will be described in detail in the detailed description section that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification, and are used to explain the embodiments of the present invention together with the following specific embodiments, but do not constitute limitations to the embodiments of the present invention. In the attached image:

1 is a schematic structural principle diagram of a speckle structured light projection module based on a holographic waveguide according to an embodiment of the present invention;

2 is a schematic structural diagram of a speckle structured light projection module based on a holographic waveguide according to the first embodiment of the present invention;

3 is a schematic structural principle diagram of a speckle structured light projection module based on a holographic waveguide coupled with a holographic lens according to a second embodiment of the present invention;

4 is a schematic structural principle diagram of a speckle structured light projection module based on a holographic waveguide coupled with a composite HOE coupled out according to the third embodiment of the present invention;

5 is a schematic structural principle diagram of a speckle structured light projection module based on a holographic waveguide configured with a holographic lens coupled in and a holographic grating coupled out according to the fourth embodiment of the present invention;

6A is a schematic structural principle diagram of a speckle structured light projection module based on a holographic waveguide configured with an inclined plane coupling input according to the first embodiment of the present invention;

6B is a schematic structural principle diagram of a speckle structured light projection module based on a holographic waveguide configured with an inclined plane coupling input according to the second embodiment of the present invention;

6C is a schematic structural principle diagram of a speckle structured light projection module based on a holographic waveguide configured with an inclined plane coupling input according to the third embodiment of the present invention.

Detailed ways

The specific implementations of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

As shown in FIG. 1, a speckle structured light projection module based on holographic waveguide according to an embodiment of the present invention includes an array light source 11 and a holographic waveguide unit 20, wherein the array light source 11 can emit a laser beam corresponding to the first speckle pattern, The holographic waveguide unit 20 includes a waveguide substrate 13, a first holographic optical element 201 and a second holographic optical element 202. The first holographic optical element 201 is attached to the first end of the waveguide substrate 13, and the second holographic optical element 202 is attached to the waveguide. The second end of the substrate 13, and the array light source 11 is arranged above the second end of the waveguide substrate 13, and the laser beam emitted by the array light source 11 can be coupled to the waveguide substrate 13 through the second holographic optical element 202, and the laser beam can Waveguide transmission is performed in the waveguide substrate 13 and output through the first holographic optical element 201; although FIG. 1 shows an example in which the array light source is arranged above the second end of the waveguide substrate, it can be understood that the array light source is arranged Other positions, such as below the waveguide substrate, are also allowed, which can be flexibly adjusted according to the design of the system structure.

It should be noted that the Holographic Waveguide (HW) is an integrated optical device that uses a holographic optical element (Holographic Optical Element, HOE) as a coupling input or output device to control light in glass or other optical media for waveguide transmission. technology. Among them, HOE is an optical component processed by holographic interference method, and it can also be made into the form of holographic grating or holographic lens according to the requirements of coupling function, and attached to the surface of glass or other optical medium. Waveguide transmission is a way in which light modulates a transmitted optical signal in a medium in the form of Total Internal Reflection (TIR), which can efficiently shift the optical axis between the input end and the output end of an optical system.

In addition, the speckle structured light projection module needs to modulate the light output by the array light source corresponding to the first speckle pattern, such as collimation modulation and grating diffraction processing, so as to be able to output speckles that meet expectations and requirements. The first holographic optical element 201 in the speckle structured light projection module of FIG. 1 realizes the coupling of light in the waveguide substrate, and the second holographic optical element 202 realizes the coupling of light in the waveguide substrate, for waveguide transmission in a waveguide substrate. It should be noted that, in the speckle structured light projection module of FIG. 1, other light modulation components may be additionally arranged to realize the modulation of the light beam. end, that is, the position close to the first optical element 201, so as to achieve excellent heat dissipation performance, and the specific details will also be developed in other embodiments below. In the embodiment of the present invention, by introducing the holographic waveguide unit 20 and arranging the light source and other optical elements by utilizing the characteristics of optical axis offset, the heat dissipation function is realized without increasing the volume of the module, and the lightness and thinness of the structure are ensured. Miniaturization, can be widely and preferably used in electronic equipment.

Although the first end of the first holographic optical element 201 and the second end of the second holographic optical element 202 shown in FIG. 1 are arranged on the same side of the waveguide substrate, it can be understood that , the first holographic optical element 201 and the second holographic optical element 202 can also be arranged on opposite sides of the waveguide substrate according to the design requirements; it should be noted that the side of the array light source also needs to have the coupling modulation of the holographic optical element, so as to To form a waveguide for transmission, if the holographic optical element is not used for coupling, the waveguide substrate can be cut into inclined planes. It can be understood that the selection of the first holographic optical element 201 and the second holographic optical element 202 can also be diversified, for example, both of them can be a transmission-type holographic optical element and/or a reflection-type holographic optical element; This allows flexible arrangement of system components to achieve the desired heat dissipation effect.

Although FIG. 1 shows a projection module designed with a transmissive HOE, it can be understood that the module in the embodiment of the present invention can still use a reflective holographic optical element HOE, and accordingly, only the module needs to be adjusted. component location.

In order to ensure the good waveguide transmission effect of light in the waveguide substrate, the laser beam can be transmitted in the waveguide substrate 13 according to the preset light propagation angle to satisfy the total reflection condition, that is:

为预设的光线传播角度，

为全反射角，n为波导基底的光学折射率。in,

is the preset light propagation angle,

is the total reflection angle, and n is the optical refractive index of the waveguide substrate.

As shown in FIG. 2 , in the speckle structure light projection module based on holographic waveguide according to another embodiment of the present invention, some light modulation elements are arranged on the other end of the waveguide substrate away from the light source, so as to achieve good heat dissipation performance. Specifically, the speckle structured light projection module based on the holographic waveguide includes an array light source 11, which is arranged and designed as an array of light-emitting point sources for providing illumination in the form of a preset first speckle pattern 12, which may be vertical Cavity Surface Emitting Lasers (VCSEL), and set it as a two-dimensional regular or random array light source, infrared light with a wavelength of 940nm or other wavelength windows with high transmission efficiency; 13 is a waveguide substrate, It is made of glass or other optical medium materials with a refractive index of n; 142 is a coupling-out HOE (Holographic Optical Element, holographic optical element), in addition, the module can also include a coupling-in HOE141, and the coupling element HOE is only a layer of film Therefore, its volume is light and thin, which is convenient for miniaturization design; 15 collimating lenses are used to modulate the beam emitted by the holographic waveguide into a collimated beam and emit it, which can be a single lens, a combined lens, a microlens array or a Fresnel lens. 16 is the diffractive optical element DOE, which is used to receive the first speckle pattern 12, copy and expand it into the second speckle pattern, form a large area array of speckle light clusters, and project it into the actual scene to be measured; 17 is the to-be-measured scene Scene object; 18 is the final second speckle pattern projected by the module, so as to realize projecting the second speckle pattern to the scene object to be tested. In this embodiment, the light source is separated from other optical modulation devices by a certain distance through waveguide transmission, and a heat dissipation device can be separately added to the light source, which is very beneficial to heat dissipation for the entire system.

It should be noted that the collimating lens 15 can also be placed before the coupling input HOE 141 to couple the laser beam emitted by the array light source, collimate the light source beam, and then couple it for waveguide transmission. In addition, the position and focal length of the collimating lens 15 can be flexibly selected according to the specific system design scheme, so as to match and complete the collimation function.

As shown in FIG. 3, a speckle structured light projection module based on holographic waveguide according to another embodiment of the present invention includes an array light source 11, which is arranged and designed as an array of light-emitting point sources for providing a preset first Illumination in the form of a speckle pattern 12; 13 is a waveguide substrate, made of glass or other optical medium material with a refractive index of n; 141 is a coupling-in HOE; 143 is a HOE with a lens factor, which has the function of coupling-out, At the same time, it can also play the role of collimation, which can modulate the laser beam to be a collimated beam; 16 is DOE, which is used to receive the first spot pattern 12, and replicate and expand it into a second spot pattern to form a large area array of scattered patterns. The speckle line cluster is projected into the scene to be tested; 17 is the scene object; 18 is the final second speckle pattern projected by the module.

Compared with the embodiment shown in FIG. 2 , the coupling-out HOE 143 in FIG. 3 is a holographic lens type HOE (ie, a holographic lens optical element), which may be formed by using plane waves and spherical waves to perform interference processing. Therefore, the collimating lens and the coupling output element are combined into a modulation device, which improves the lightness and thinness of the system and facilitates the design of a miniaturized projection module. In addition, the collimating lens factor in FIG. 3 can also be added to the coupling input HOE, and the above embodiment can be flexibly adjusted according to system design requirements.

As shown in FIG. 4 , a speckle structured light projection module based on a holographic waveguide according to another embodiment of the present invention adopts a composite HOE element 144 . Among them, the speckle structure projection module includes an array light source 11, which is arranged and designed as a light-emitting point source array, which is used to provide illumination in the form of a preset first speckle pattern 12; 13 is a waveguide substrate, which is composed of a refractive index of n. 141 is a coupling-in HOE; 144 is a coupling-out HOE, which functions as both a collimating lens and a replica grating, and can also be used as a coupling-out element, which can be used to receive the first spot pattern 12, and copy and expand it into a second speckle pattern to form a large area array of speckle light clusters, which are projected into the actual scene to be tested; 17 is the scene object; 18 is the final second speckle pattern projected by the module.

Compared with the embodiment shown in FIG. 3 , the coupling-out HOE 144 in FIG. 4 is an HOE that has the functions of both a collimating lens and a replica grating, which can not only modulate the laser beam to be a collimated beam, but also realize speckle. Modulation spread of the pattern. Therefore, the collimating lens, the replica grating and the coupling output element are combined into a modulation device, which improves the lightness and thinness of the system and facilitates the design of a miniaturized projection module.

As shown in FIG. 5 , in the speckle structured light projection module based on holographic waveguide according to another embodiment of the present invention, the collimating lens factor and the replica grating are separately added to the coupling-in HOE and the coupling-out HOE. Specifically, the speckle structured light projection module based on holographic waveguide includes an array light source 11, which is arranged and designed as an array of light-emitting point sources for providing illumination in the form of a preset first speckle pattern 12; 13 is a waveguide substrate , which is made of glass or other optical medium materials with a refractive index of n; 145 is a coupling-in HOE with a collimating lens function; 146 is a coupling-out HOE with a replica grating function, which is used to receive the first spot pattern 12 and convert the Its replication is extended to the second spot pattern, forming a large area array of speckle light clusters, which are projected onto the actual scene to be measured; 17 is the scene object; 18 is the final spot pattern projected by the module. Therefore, a higher degree of system thinning can be achieved, and it is more convenient to design a miniaturized projection module.

As shown in FIGS. 6A-6C , in the speckle structured light projection module based on holographic waveguide according to another embodiment of the present invention, the glass substrate can be cut into inclined planes, and the plane of the waveguide substrate at the second end is It is cut into an inclined surface, and the laser beam to be transmitted by the waveguide can be coupled through the inclined surface, and the coupling input of the inclined surface can be directly used instead of the coupling input HOE, which improves the energy utilization efficiency of the system and saves modules. manufacturing cost. Specifically, in the speckle structured light projection module based on holographic waveguide provided in FIG. 6A , the coupling-out HOE 142 may only have the function of coupling-out, and the collimating lens 15 on one side of the HOE 142 realizes the collimation function and The modulation and copying of the light beam is realized by DOE 16; in the speckle structured light projection module based on holographic waveguide provided in FIG. 6B, the coupling output HOE 143 can be a holographic lens optical element, and the modulation of the light beam is realized by DOE 16 Replication function; in the speckle structured light projection module based on holographic waveguide as provided in FIG. 6C , the coupling output HOE 143 may be an element that has both a lens function and a replica grating function. More preferably, an anti-reflection film may also be plated on the inclined surface, thereby increasing the coupling efficiency. For some components in the speckle structured light projection module based on the holographic waveguide shown in FIGS. 6A-6C , reference may be made to the relevant descriptions of the above embodiments, and thus will not be repeated here.

In some preferred embodiments, the coupling-in HOE and/or the coupling-out HOE may be fabricated by laser interference exposure processing. Therefore, compared with the speckle structure using the DOE design based on the etching process in the current related art, the speckle structure light projection module in this embodiment adopts the holographic optical element fabricated by laser interference exposure processing. The holographic optical element processed by laser interference exposure has no ghost line interference problem and reduces stray background light, and can be produced more efficiently and with lower cost than the etching process.

Specifically, the holographic lens HOE having the function of a collimating lens may be a holographic lens prepared by the interference of a plane wave and a spherical wave. Preferably, a wavefront compensation technology can also be used in the processing to optimize the aberration design of the interference processing, so as to obtain a holographic lens with high imaging quality. Among them, the focal length of the holographic lens HOE is related to the coordinate parameters of the spherical wave used in the preparation. Therefore, the focal length value of the holographic lens can be controlled by setting the relevant parameters of the interference spherical wave, and the matching design is carried out in the system design to achieve high quality. collimation effect.

The holographic grating HOE with the function of grating replication and expansion is prepared by interference of plane waves of corresponding wavelengths. Preferably, in order to prevent the speckles obtained by the projection module from overlapping each other in each diffraction order, the grating period can also be customized by control in the preparation method. Specifically, the target grating period that can avoid overlapping between the speckles of multiple diffraction orders of the corresponding holographic optical element can be obtained first. For example, the target grating period should be matched with the array light source and can make all The input collimated beam is output to avoid overlapping between the (second speckle pattern) speckles of each diffraction order; then, based on the angle period model and the target grating period, it is determined that the two beams interfere during the laser interference process The angle between the beams, where the angle period model includes the relationship between the angle of the interfering beams and the grating period.

The position of the diffraction orders for the prepared HOE is determined by the grating equation:

和

分别为横向和竖向的衍射角度，m和n分别为横向和竖向的衍射级次，Δx与Δy分别为HOE在横向和竖向的光栅周期。为了实现在可探测的深度范围内，HOE在各个衍射级次上所复制的VCSEL斑点图案间应避免相互交叠，故可以是在HOE的加工中需控制干涉光束的夹角θ。in,

and

are the lateral and vertical diffraction angles, respectively, m and n are the lateral and vertical diffraction orders, respectively, and Δx and Δy are the horizontal and vertical grating periods of the HOE, respectively. In order to achieve a detectable depth range, the VCSEL spot patterns reproduced by the HOE in each diffraction order should avoid overlapping each other, so the angle θ of the interference beam needs to be controlled during the processing of the HOE.

Therefore, the embodiment of the present invention also proposes that the included angle periodic model may satisfy the following conditions:

Among them, Δ is the period of the target holographic grating, λ is the wavelength of the laser beam, and θ is the angle between the interfering beams; thus, the grating period of the holographic grating can be controlled by controlling the angle θ between the interfering beams.

In addition, the composite HOE has the functions of a collimating lens and a replica grating at the same time. The preparation method can be through the composite preparation technology, that is, it can be divided into two exposure records, so that the lens factor and the grating structure can be processed together on the same piece of HOE. As a result, the composite HOE can further optimize the module and achieve the purpose of lighter and thinner design.

The two HOEs coupled in and out are both holographic gratings, which are fabricated by laser interference exposure. The two interference wavefronts are both plane waves, and the intensity distribution of the grating light field formed by the interference is:

I ₁ =|exp(ik ₁ ·r)+exp(ik ₂ ·r)| ²

=2+2cos[(k ₁ -k ₂ )r]

In the formula, I ₁ is the intensity of the interference light field, i is the imaginary unit, k ₁ and k ₂ are the wave vectors of the two parallel beams, respectively, and r is the coordinate system of the beam.

On the other hand, the holographic lens HOE with holographic lens can be processed by interference between plane waves and spherical waves, and the intensity of the light field formed by the interference is:

In the formula, I ₂ is the intensity of the interference light field, i is the imaginary unit, k ₃ and k ₄ are the wave vectors of the plane wave and the spherical wave, respectively, and r is the coordinate system of the beam. Therefore, the focal length of the prepared collimating lens HOE is related to the coordinate parameters of the spherical wave, so the focal length value of the prepared collimating lens HOE can be controlled by setting the relevant parameters of the interference spherical wave.

In some embodiments, the photosensitive material used in the preparation of the holographic optical element HOE (including the coupled-in HOE and the coupled-out HOE) can also be a photosensitive material sensitive to the wavelength of the laser beam emitted by the array light source, for example, both can be 940 nm. And, the holographic optical element HOE can also be a holographic grating prepared by interference exposure with a light beam corresponding to the wavelength of the laser beam emitted by the array light source 11; When the laser is used, the corresponding HOE also needs to work at the corresponding wavelength of 940 nm, so the wavelength of the interference beam should be the same when the HOE is prepared.

In the embodiments of the present invention, various design and implementation schemes for realizing a speckle projection module with a light, thin, and miniaturized structure and easy to dissipate heat from the light source are proposed. Among them, the first design and implementation scheme includes four parts: the first part is an array light source, preferably a VCSEL light source, to output the first spot pattern; the second part is a holographic waveguide unit, which is coupled by a glass or other optical medium substrate and as a It is composed of two pieces of HOE coupled out of the device; the third part is a collimating lens, which modulates the laser beam emitted by the light source into a collimated beam; the fourth part is DOE, which receives the first spot pattern and replicates and expands it into a non-collimating beam. The second speckle patterns that overlap each other and have uniform speckle density distribution are projected onto the scene object to be tested.

In order to further improve the degree of lightness, thinness and miniaturization of the system, the collimating lens can be designed as a holographic lens type HOE, which is attached to the waveguide medium substrate and used as a coupling output element. Therefore, the second design and implementation scheme includes three parts: the first part is an array light source, preferably a VCSEL light source, to output the first spot pattern; the second part is a holographic waveguide unit, which is composed of a glass or other optical medium substrate and as a coupling and It consists of two pieces of HOE coupled out of the device; the third part is DOE, which receives the first speckle pattern and replicates and expands it into a second speckle pattern that does not overlap each other and has a uniform speckle density distribution, and projects it onto the object to be tested.

In order to further improve the light, thin and miniaturized degree of the system, the collimating lens and DOE can also be designed so that the HOE is attached to the waveguide dielectric substrate and used as a coupling output element, or the two can be designed as coupling input and output functions respectively. HOE use. Therefore, the third design implementation scheme includes two parts: the first part is the VCSEL array light source, which forms the first spot pattern; the second part is the holographic waveguide unit, which is composed of a glass or other optical medium substrate and two coupling-in and coupling-out devices. It is composed of a sheet HOE, receives the first speckle pattern, replicates and expands it into a second speckle pattern that does not overlap with each other and has a uniform speckle density distribution, and projects it onto the scene object to be tested.

More preferably, the coupling-out HOE includes both the collimating lens factor and the DOE modulation structure, both of which are designed as a composite HOE, so that the composite HOE has the functions of a collimating lens and a replica expansion grating. Regarding the preparation of the composite HOE, it can be divided into two exposure recordings. The lens factor and the DOE grating structure are processed together on the same HOE. For the specific processing, please refer to the above new lens optics and holographic grating optics. The interference exposure process of the element.

In addition, when the coupling-in HOE is a holographic lens type HOE and the coupling-out HOE includes a DOE grating structure, the coupling-in HOE and the coupling-out HOE may be fabricated separately.

In the above three design implementation schemes: in order to improve the energy utilization efficiency of the system, the glass substrate can be cut into inclined planes, and the inclined plane coupling and input method can be directly used instead of HOE. If the third implementation scheme adopts the inclined surface coupling method, the collimating lens and the DOE need to be designed into a composite HOE, which is attached to the waveguide substrate and used as a unified coupling-out functional device. In order to improve the imaging effect of the system, the above-mentioned inclined glass substrate surface can be further designed as a free-form surface and the like to optimize the system aberration.

Therefore, in the speckle projection module provided by the embodiment of the present invention, it not only has the advantages of compact structure, light weight and high miniaturization design, but also can separate the light source from the optical axis of other optical elements through the transmission function of the waveguide. It is beneficial to the overall heat dissipation design of the system by adding a heat dissipation device for the light source at a certain distance.

The optional embodiments of the embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details of the above-mentioned embodiments. A variety of simple modifications are made to the technical solution of the invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

In addition, it should be noted that each specific technical feature described in the above-mentioned specific implementation manner may be combined in any suitable manner under the circumstance that there is no contradiction. To avoid unnecessary repetition, various possible combinations are not further described in this embodiment of the present invention.

In addition, various implementations of the embodiments of the present invention may also be combined arbitrarily, as long as they do not violate the ideas of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims (11)

1. A speckle structure light projection module based on holographic waveguide comprises a holographic waveguide unit and an array light source, wherein the array light source is used for emitting laser beams corresponding to a first speckle pattern, the holographic waveguide unit comprises a waveguide substrate, a first holographic optical element and a second holographic optical element, the first holographic optical element is attached to a first end of the waveguide substrate, and the second holographic optical element is attached to a second end of the waveguide substrate; the speckle structure light projection module also comprises a diffraction optical element, a first light source and a second light source, wherein the diffraction optical element is used for receiving the first speckle pattern, copying and expanding the first speckle pattern into a second speckle pattern which is not mutually overlapped and has uniform speckle density distribution, and projecting the second speckle pattern into a scene to be measured;

the second holographic optical element is used for coupling laser beams emitted by the array light source into the waveguide substrate, and the laser beams can be subjected to waveguide transmission in the waveguide substrate and are output through the first holographic optical element;

the first holographic optical element and/or the second holographic optical element are/is a holographic grating which is prepared by processing laser interference exposure of light beams corresponding to the wavelength of the laser beams emitted by the array light source.

2. The holographic waveguide-based speckle structured light projection module of claim 1, wherein the speckle structured light projection module further comprises a collimating lens for modulating the laser beam into a collimated beam, wherein

The collimating lens is disposed near the first end for modulating the laser beam output by the first holographic optical element, or

The collimating lens is disposed near the second end for modulating the laser beam emitted by the array light source.

3. The holographic waveguide-based speckle structured light projection module of claim 2, wherein said collimating lens comprises one or more of: single lenses, combination lenses, microlens arrays, and fresnel lenses.

4. The holographic waveguide-based speckle structured light projection module of claim 1, wherein said first holographic optical element is a holographic lens optical element for modulating a laser beam into a collimated beam; or

The second holographic optical element is a holographic lens optical element for modulating the laser beam into a collimated beam.

5. The holographic waveguide based speckle structured light projection module of any of claims 2-4, wherein said first holographic optical element further comprises a grating replication function for modulating the expanded collimated light beam to form a second speckle pattern and projecting the second speckle pattern onto the scene object under test.

6. The holographic waveguide-based speckle structured light projection module of claim 1, wherein the first and second holographic optical elements comprise transmissive and/or reflective holographic optical elements, and

the first holographic optical element and the second holographic optical element are attached to the same side or different sides of the waveguide substrate.

7. The speckle structured light projection module based on the holographic waveguide of claim 1, wherein the laser beam is transmitted in the waveguide substrate according to a preset light propagation angle, and the following conditions are satisfied:

wherein,

is a predetermined angle of propagation of the light,

n is the optical refractive index of the waveguide substrate for the angle of total reflection.

8. A speckle structure light projection module based on holographic waveguide comprises a holographic waveguide unit and an array light source, wherein the array light source is used for emitting laser beams corresponding to a first speckle pattern, the holographic waveguide unit comprises a waveguide substrate and a first holographic optical element, and the first holographic optical element is attached to a first end of the waveguide substrate; the speckle structure light projection module also comprises a diffraction optical element, a first light source and a second light source, wherein the diffraction optical element is used for receiving the first speckle pattern, copying and expanding the first speckle pattern into a second speckle pattern which is not mutually overlapped and has uniform speckle density distribution, and projecting the second speckle pattern into a scene to be measured;

wherein a plane of the waveguide substrate at the second end is cut into an inclined plane to couple a laser beam to be subjected to waveguide transmission through the inclined plane so that the laser beam can be waveguide-transmitted in the waveguide substrate and output through the first holographic optical element;

the first holographic optical element is a holographic grating which is prepared by processing laser interference exposure of light beams corresponding to the wavelength of the laser beams emitted by the array light source.

9. The holographic waveguide-based speckle structured light projection module of claim 8, further comprising a collimating lens proximate to the first end for modulating the laser beam output by the first holographic optical element into a collimated beam.

10. The holographic waveguide-based speckle structured light projection module of claim 8, wherein said first holographic optical element is a holographic lens optical element for modulating a laser beam into a collimated beam.

11. The holographic waveguide based speckle structured light projection module of claim 9 or 10, wherein the first holographic optical element further comprises a grating replication function for modulating the expanded collimated light beam to form a second speckle pattern and projecting the second speckle pattern onto the scene object to be measured.

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