Design method of emission module and structured light depth camera

Abstract

The invention provides a design method of a transmitting module, which comprises the following steps of: selecting an initial design parameter of a beam splitter, and obtaining an imaging position corresponding to an initial speckle image; after a copy block in the initial speckle image is adjusted, a first ideal speckle image is obtained, and the first ideal speckle image is close to an ellipse during spherical imaging; constructing a beam splitter based on an imaging position corresponding to the ideal speckle image; by adjusting the copy block in the initial speckle image, the adjusted first ideal speckle image is close to an ellipse during spherical imaging, so that the first ideal speckle image during planar imaging is close to a rectangle corresponding to the waist field of view, the light spot ratio within the waist field of view can be increased, and the imaging efficiency is improved. And the energy utilization rate of the transmitting module is further improved.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a design method for a transmitting module and a structured light depth camera. Background Art

[0002] A structured light depth camera projects a specific structured light image (such as a speckle image) onto the surface of an object through a transmitting module, and collects it through a receiving module. It calculates the position and depth information of the object based on the changes in the light signal caused by the object, and then restores the entire depth space.

[0003] The emission module in the prior art usually includes a light source and a beam splitter. When designing the beam splitter, it usually generates M diffraction orders in one direction and N diffraction orders in another direction. The superposition of the beam splitting functions in the two directions generates M×N diffraction orders.

[0004] like Figure 1 As shown, the above matrix beam splitting replication method makes the speckle image formed during plane imaging present a pincushion-shaped distortion, and the final available field of view is usually limited to the waist field of view (such as Figure 1 The light spot within the waist field of view is the effective point, while the light spot outside the waist field of view is the invalid point. However, when the light spot outside the waist field of view accounts for a large proportion, the proportion of the light spot within the waist field of view will be reduced accordingly, and the light spot outside the waist field of view carries a part of the energy, which leads to a decrease in the energy utilization rate of the transmitting module. Summary of the invention

[0005] The object of the present invention is to provide a design method of a transmitting module and a structured light depth camera for improving energy utilization.

[0006] To achieve one of the above-mentioned purposes of the invention, an embodiment of the present invention provides a design method of a transmitting module, comprising:

[0007] Selecting initial design parameters of the beam splitter to obtain an imaging position corresponding to an initial speckle image;

[0008] After adjusting the replica block in the initial speckle image, a first ideal speckle image is obtained, and the first ideal speckle image is close to an ellipse when imaging on a spherical surface;

[0009] A beam splitter is constructed based on the imaging position corresponding to the ideal speckle image.

[0010] As a further improvement of an embodiment of the present invention, the copy block in the initial speckle image is adjusted, specifically including:

[0011] The number of replicated blocks in the initial speckle image is adjusted so that the number of replicated blocks in the diffraction orders on both sides of the first ideal speckle image is smaller than the number of replicated blocks in the middle diffraction order of the first ideal speckle image.

[0012] As a further improvement of an embodiment of the present invention, adjusting the number of replication blocks in the initial speckle image specifically refers to:

[0013] The number of replicated blocks located in at least two diffraction orders on both sides of the initial speckle image is reduced.

[0014] As a further improvement of an embodiment of the present invention, the copy block in the initial speckle image is adjusted, specifically including:

[0015] The position of the replica block in the initial speckle image is adjusted so that the first ideal speckle image presents an axisymmetric pattern.

[0016] As a further improvement of an embodiment of the present invention, when the replication block in the initial speckle image is adjusted along the first direction and / or the second direction, the first direction and the second direction are perpendicular to each other.

[0017] As a further improvement of an embodiment of the present invention, after rotating the first ideal speckle image, a second ideal speckle image is obtained, and a beam splitter is constructed based on an imaging position corresponding to the first ideal speckle image or the second ideal speckle image.

[0018] As a further improvement of an embodiment of the present invention, after the first ideal speckle image is rotated, the position of the replica block in the first ideal speckle image is adjusted to obtain a second ideal speckle image.

[0019] As a further improvement of an embodiment of the present invention, after obtaining the imaging position corresponding to the ideal speckle image, the beam splitting phase of the beam splitter is obtained by an iterative algorithm;

[0020] Alternatively, after obtaining the imaging position corresponding to the ideal speckle image, the beam splitter is determined by a rigorous coupled wave analysis method.

[0021] As a further improvement of one embodiment of the present invention, when the splitting phase of the beam splitter is obtained using an iterative algorithm, the target amplitude distribution is obtained according to the imaging position of one of the point light sources of the light source, and the outgoing light of the aforementioned point light source is vertically incident on the beam splitter.

[0022] As a further improvement of an embodiment of the present invention, a collimation phase is provided on the beam splitter.

[0023] As a further improvement of an embodiment of the present invention, after adjusting the initial design parameters, ideal design parameters corresponding to the first ideal speckle image are obtained, and the imaging position corresponding to the first ideal speckle image is obtained according to the angular dispersion formula of the grating.

[0024] In order to achieve one of the purposes of the above invention, the present invention also provides a structured light depth camera, which includes a transmitting module designed by any of the above design methods.

[0025] Compared with the prior art, in the embodiments of the present invention, the replica blocks in the initial speckle image are adjusted so that the adjusted first ideal speckle image is close to an ellipse during spherical imaging, thereby making the first ideal speckle image during plane imaging close to a rectangle corresponding to the waist field of view, thereby increasing the proportion of the light spot within the waist field of view, and further improving the energy utilization rate of the emission module. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the effect diagram of the speckle image in the prior art when it is imaged in a plane;

[0027] Figure 2 is a schematic diagram of the optical path of the emission module in one embodiment of the present invention;

[0028] Figure 3 is a schematic diagram of the optical path of the emission module in another embodiment of the present invention;

[0029] Figure 4 It is a flow chart of a design method of a transmitting module in a preferred embodiment of the present invention;

[0030] Figure 5 and Figure 6 It is a schematic diagram of various parameters when using the angular dispersion formula of the grating to obtain the imaging position;

[0031] Figure 7 is a schematic diagram of a replica block formed when the beam splitter has M×N diffraction orders;

[0032] Figure 8 is an imaging effect diagram corresponding to the initial speckle image in spherical imaging and planar imaging in one embodiment of the present invention;

[0033] Fig. 9 is an imaging effect diagram corresponding to the first ideal speckle image in spherical imaging and planar imaging in one embodiment of the present invention;

[0034] Fig.10 It is the imaging effect diagram corresponding to the speckle image in plane imaging and spherical imaging under ideal conditions;

[0035] Fig.11 is an imaging effect diagram corresponding to an initial speckle image and a first ideal speckle image in another embodiment of the present invention;

[0036] Fig.12The imaging effect diagrams corresponding to the first ideal speckle image after rotation before and after adjustment;

[0037] Fig.13 This is a flow chart of using the GS algorithm to solve the phase;

[0038] Fig.14 are some exemplary phase distribution formulas for the collimation phase. DETAILED DESCRIPTION

[0039] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0040] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0041] In various drawings of the present invention, for the convenience of illustration, some sizes of structures or parts are exaggerated relative to other structures or parts, and thus, only the basic structure of the subject matter of the present invention is illustrated.

[0042] A preferred embodiment of the present invention provides a structured light depth camera, including a transmitting module (such as a TX transmitting module) and a receiving module (such as an RX receiving module), which projects a specific structured light image (such as a speckle image) onto the surface of an object through the transmitting module, and collects it through the receiving module, and calculates the position and depth information of the object according to the change of the light signal caused by the object, thereby restoring the entire depth space. For example, the depth information of the object is obtained by methods such as ToF (Time of Flight) and binocular vision.

[0043] In some embodiments, Figure 2 As shown, the emission module includes a light source 10 and a beam splitter 20. The light source 10 may be a point light source or a point light source array, and the point light source array includes a plurality of point light sources 101 arranged in an array.

[0044] Among them, the point light source 101 can be a light source of the type of Vertical Cavity Surface-Emitting Laser (VCSEL) or the like.

[0045] The beam splitter 20 can be a diffractive optical element (such as DOE, Diffractive Optical Elements) or a beam splitting optical element based on a metasurface.

[0046] Among them, metasurface refers to an artificial layered material with a thickness less than the wavelength, which can be regarded as the two-dimensional counterpart of metamaterial. Metasurface can control the polarization, phase, amplitude, frequency, propagation mode and other characteristics of electromagnetic waves through the sub-wavelength nanostructure of the surface, and realize beam shaping, beam deflection, super lens, super holography, optical rotation, anti-reflection and anti-reflection, etc.

[0047] In some embodiments, the beam splitter 20 has a beam splitting phase, so as to split the incident light to form a structured light image (ie, a speckle image), that is, to form replica blocks of the plurality of light sources 10 .

[0048] In some embodiments, the emission module further includes a collimator 30, and the light source 10, the collimator, and the beam splitter 20 are arranged in sequence along the light path transmission direction. The collimator 30 can collimate the output light of the light source 10, for example, it can be a focusing lens or a Fresnel collimator, so that the light incident on the beam splitter 20 is collimated light, thereby simplifying the design of the beam splitter 20.

[0049] In other embodiments, the collimator 30 may be eliminated, for example, the light source 10 may directly emit collimated light.

[0050] In some embodiments, Figure 3 As shown, the beam splitter 20 also has a collimation phase. In this embodiment, the beam splitter 20 has both a beam splitting phase and a collimation phase, and can collimate and split the incident light, so that the emission module can eliminate the collimator 30, simplifying the structure of the emission module.

[0051] The specific implementation of the present invention also relates to a design method of a transmitting module. The structure and function of the transmitting module are as described above and will not be repeated here.

[0052] Specific, with reference Figure 4 As shown, a design method of a transmitting module comprises the following steps:

[0053] Step S10: Select the initial design parameters of the beam splitter 20 to obtain the imaging position corresponding to the initial speckle image. In this embodiment, the design parameters of the beam splitter 20 (ie, the initial design parameters) include the refractive index n of the output medium. k , operating wavelength λ, period d along the first direction (eg, X-axis direction) x , the period d along the second direction (eg, the Y-axis direction) y The imaging position corresponding to the initial speckle image refers to the coordinates of each replica block (for example, when the light source 10 is a point light source) or each light spot (for example, when the light source 10 is a point light source array) of the speckle image (i.e., the initial speckle image) on the imaging surface (for example, plane imaging or spherical imaging).

[0054] In addition, in step S10, before the initial design parameters of the beam splitter 20 are selected, some parameters of the emission module need to be selected first. The parameters of the emission module include the parameters of the light source 10 (for example, the number of point light sources 101 when the light source 10 is a point light source array) and the target field of view (for example, 110°×80°). Then, according to the selected light source 10 and the target field of view, the diffraction order of the beam splitter 20 (for example, 8×7) is selected accordingly. After the above parameters are selected, the imaging position corresponding to the initial speckle image is calculated.

[0055] Exemplary, reference Figure 5 As shown, when the light source 10 is a point light source array, the position of the kth point light source on the point light source array relative to the center of the light source 10 is (x k ,y k ), the distance between the center of the light source 10 and the center of the beam splitter 20 is z, and the center of the light source 10 and the center of the beam splitter 20 are located on the same optical axis.

[0056] The polar angle θ of each point light source 101 relative to the center of the beam splitter 20 k and azimuth φ k for:

[0057]

[0058] refer to Figure 6 As shown, after the incident light incident to the beam splitter 20 is modulated, the polar angle and azimuth angle of each diffraction order can be calculated by the angular dispersion formula of the grating. Taking the k-th point light source as an example, after diffraction beam splitting, the diffraction angles of the outgoing light of the m-th diffraction order along the X-axis direction and the n-th diffraction order along the Y-axis direction can be calculated by the angular dispersion formula of the grating. The angular dispersion formula of the grating is:

[0059]

[0060] In formula (3) and formula (4), n k is the refractive index of the output medium, d x is the transverse period of the beam splitter 20 along the X-axis direction, d y are respectively the longitudinal periods of the beam splitter 20 along the Y-axis direction.

[0061] Using formula (3) and formula (4), the light spot (i.e., speckle) position of each point light source 101 after passing through the beam splitter 20 can be calculated. In addition, Figure 6 Two imaging surfaces are also shown, namely spherical imaging (or hemispherical imaging) and planar imaging. Among them, spherical imaging can show the frequency domain information of the incident light field, and its imaging is also closer to the imaging effect received back to the sensor after the receiving module and the transmitting module cooperate with each other for distortion correction.

[0062] On the spherical surface, for the kth point light source, the calculation formulas for the imaging positions x1 and y1 are:

[0063] x1 kmn =f·sinθ kmn ·cosφ kmn ; (5)

[0064] y1 kmn =f·sinθ kmn ·sinφ kmn ; (6)

[0065] On the plane, for the kth point light source, the calculation formulas for the imaging surface formulas x2 and y2 are:

[0066] x2 kmn = f·tanθ kmn ·cosφ kmn ; (7)

[0067] y2 kmn = f·tanθ kmn ·sinφ kmn ; (8)

[0068] Wherein, in formula (5) to formula (8), f is the distance between the imaging surface and the beam splitter 20.

[0069] It should be noted that in structured light applications, the X-axis direction is defined as the H (Horizontal) direction, and the Y-axis direction is defined as the V (Vertical) direction. Figure 7 As shown, after the light source 10 is taken as a whole, it generates M copies in the X-axis direction and N copies in the Y-axis direction, and finally generates M×N copies. Since the copies show the arrangement of diffraction orders, its essence is a spherical imaging effect, that is, M×N copies (e.g., 8×7) distributed regularly.

[0070] Exemplarily, the number of point light sources 101 in the light source 10 is 90, and the distance f between the imaging surface and the beam splitter 20 is set to 600 mm, and an initial speckle image is obtained. Figure 8 a, is the imaging effect diagram of the initial speckle image when it is imaged on a spherical surface. Figure 8 b is the imaging effect diagram of the initial speckle image when imaging in a plane. Since the number of light sources 101 is 90, the total number of spots after passing through the beam splitter 20 reaches 8×7×90=5040. At this time, the waist field of view (such as Figure 8 As shown in the dashed line frame in b, for example, there are 4304 light spots within 110°×80°, and the proportion of effective light spots is 85.4%. Among them, the proportion of effective light spots = the number of light spots in the waist field of view / the total number of light spots.

[0071] Step S20: After adjusting the replica block in the initial speckle image, a first ideal speckle image is obtained. The first ideal speckle image is close to an ellipse when imaging on a spherical surface. Figure 8 ) is adjusted, the first ideal speckle image is obtained as follows Fig. 9 As shown. Among them, Fig. 9 a is the imaging effect diagram of the first ideal speckle image when imaging on a spherical surface, Fig. 9 b is the imaging effect diagram of the first ideal speckle image when imaging in a plane.

[0072] from Fig. 9 It can be seen from a that the first ideal speckle image is close to an ellipse when imaged on a spherical surface, that is, the outer diameter of the middle part is larger than the outer dimensions of the two end parts. Figure 8 The initial speckle image in b, Fig. 9 The first ideal speckle image in b is also more rectangular, that is, close to the rectangle of the waist field of view. Therefore, the adjusted initial speckle image (that is, the first ideal speckle image) has a larger proportion of effective light spots than that before adjustment, thereby improving the energy utilization rate of the emission module.

[0073] In addition, compared to Figure 8 The initial speckle image in b, Fig. 9 The distortion around the first ideal speckle image in b is also reduced, which can also increase the field of view to a certain extent.

[0074] For example, due to the geometric correspondence between spherical imaging and plane imaging, the imaging position of spherical imaging and the imaging position of plane imaging can be converted to each other, such as Fig.10 The plane imaging effect under this correspondence is shown (such as Fig.10 a) and spherical imaging effects (such as Fig.10 b) If you want to increase the proportion of effective light spots, that is, the light spots formed by the beam splitter 20 are located in the waist field of view as much as possible, as long as the speckle image during plane imaging (such as Fig.10 a) Match the shape of the waist field of view, that is, ensure that the speckle image during planar imaging is closer to a rectangle.

[0075] It can be seen that when the plane is imaged, the speckle image (such as Fig.10 a) When it is close to a rectangle, the corresponding speckle image during spherical imaging (such as Fig.10 b) should be close to an ellipse, or a quasi-ellipse. Therefore, in step S20, the first ideal speckle image (i.e., the adjusted initial speckle image) is close to an ellipse when imaged on a spherical surface, which can make the first ideal speckle image close to a rectangle when imaged on a plane, thereby increasing the proportion of effective light spots and improving the energy utilization rate of the emission module.

[0076] In addition, when adjusting the replica blocks in the initial speckle image, it is ensured as much as possible that there is no overlap and no obvious gap between the replica blocks, so as to facilitate the identification of the number and position of the replica blocks and meet the use requirements of the emission module.

[0077] Step S30: construct the beam splitter 20 based on the imaging position corresponding to the ideal speckle image. In this embodiment, the beam splitter 20 is constructed using the imaging position corresponding to the ideal speckle image (for example, the first ideal speckle image or the second ideal speckle image). Then, Figure 2 , and then arranging the light source 10, the collimator 30, and the beam splitter 20 along the transmission direction of the light path; or, as Figure 3 , and then arrange the light source 10 and the beam splitter 20 along the transmission direction of the light path to complete the design of the emission module.

[0078] Considering that the plane imaging effect is the standard surface in structured light applications, the spherical imaging effect is more convenient for observing the relative positions of the replica blocks, and the following description of the first ideal speckle image imaging effect is preferably based on spherical imaging.

[0079] In some embodiments, in step S20, adjusting the replica block in the initial speckle image specifically includes:

[0080] The number of replicated blocks in the initial speckle image is adjusted so that the number of replicated blocks in the diffraction orders on both sides (for example, along the X-axis direction and / or the Y-axis direction) of the first ideal speckle image is smaller than the number of replicated blocks in the middle diffraction order of the first ideal speckle image.

[0081] In this embodiment, Fig. 9 a. By adjusting the number of replica blocks in the initial speckle image, the number of replica blocks in the diffraction orders on both sides of the adjusted initial speckle image (i.e., the first ideal speckle image) is made smaller than the number of replica blocks in the middle diffraction order, so that the first ideal speckle image is close to an ellipse when imaging on a spherical surface, that is, the first ideal speckle image is close to a rectangle when imaging on a plane, thereby increasing the proportion of effective light spots and improving the energy utilization rate of the emission module.

[0082] When adjusting the number of replica blocks in the initial speckle image, the number of replica blocks in the initial speckle image may be increased or decreased, as long as the number of replica blocks in the diffraction orders on both sides of the first ideal speckle image is ensured to be smaller than the number of replica blocks in the middle diffraction order of the first ideal speckle image.

[0083] In some embodiments, in step S20, adjusting the number of replication blocks in the initial speckle image specifically refers to:

[0084] The number of replicated blocks in at least two diffraction orders on both sides of the initial speckle image (eg, on both sides along the X-axis direction and / or the Y-axis direction) is reduced.

[0085] In this embodiment, by reducing the number of replica blocks in the diffraction orders on both sides of the initial speckle image (for example, on both sides along the X-axis direction and / or the Y-axis direction), the number of replica blocks in the diffraction orders on both sides of the adjusted initial speckle image (that is, the first ideal speckle image) is made smaller than the number of replica blocks in the middle diffraction order of the adjusted initial speckle image (that is, the first ideal speckle image). This adjustment method can reduce the number of replica blocks in the diffraction orders on both sides of the initial speckle image [or in the corresponding replica blocks, for example Figure 7 The parts with greater distortion in the (1, 1), (N, 1), (1, M), (N, M) replica blocks are removed, so that the distortion degree of the first ideal speckle image during plane imaging is reduced.

[0086] Exemplarily, the number of replica blocks in two diffraction orders located on both sides of the initial speckle image (for example, along both sides of the X-axis direction and / or the Y-axis direction) is reduced, that is, only the number of replica blocks in the two diffraction orders is adjusted, which can meet the adjustment requirements and simplify the design. For example, along the first diffraction order and the eighth diffraction order in the X-axis direction (that is, the H direction), the original 7 replica blocks in the Y-axis direction (that is, the V direction) are reduced to 6 replica blocks. At this time, the total number of spots after passing through the beam splitter 20 reaches (6×2+6×7)×90=4860, and the waist field of view (such as Fig. 9 There are 4325 light spots in (as shown by the dotted line frame in b), and the proportion of effective light spots is 92.4%, which is 5% higher than that before adjustment.

[0087] In other embodiments, the number of replica blocks in the middle diffraction order of the initial speckle image may be increased, as long as the number of replica blocks in the diffraction orders on both sides of the first ideal speckle image is ensured to be smaller than the number of replica blocks in the middle diffraction order of the first ideal speckle image.

[0088] In some embodiments, the number of replica blocks in s (s is greater than 2, for example, 4) diffraction orders located on both sides of the initial speckle image is reduced, that is, the number of replica blocks in diffraction orders greater than two is adjusted, so as to further reduce the degree of distortion of the first ideal speckle image during planar imaging.

[0089] Exemplarily, the original 8×7=56 replica blocks are reduced to 2×5+2×6+4×7=50 replica blocks. That is, along the first diffraction order and the eighth diffraction order in the X-axis direction (i.e., the H direction), the original 7 replica blocks in the Y-axis direction (i.e., the V direction) are reduced to 5 replica blocks; along the second diffraction order and the seventh diffraction order in the X-axis direction (i.e., the H direction), the original 7 replica blocks in the Y-axis direction (i.e., the V direction) are reduced to 6 replica blocks. That is, in the eight diffraction orders along the X-axis direction (i.e., the H direction), the number of replica blocks is 5, 6, 7, 7, 7, 7, 6, 5, respectively.

[0090] It can be seen that within the diffraction order along the X-axis direction (and / or the Y-axis direction), the number of replica blocks increases first and then decreases, so that the first ideal speckle image during spherical imaging is closer to an ellipse, the proportion of effective light spots is increased, and the distortion degree of the first ideal speckle image during plane imaging is smaller.

[0091] For example, after adjusting the target field of view to 120°×90°, the imaging effect of the initial speckle image during plane imaging is as follows: Fig.11 a, at this time the waist field of view (such as Fig.11 There are 4096 spots in the image (shown by the dotted line frame in a), and the proportion of effective spots is 81.27%. The imaging effect of the first ideal speckle image during plane imaging is as follows: Fig.11 b. At this time, the total number of light spots after passing through the beam splitter 20 reaches 50×90=4500. At this time, the waist field of view (such as Fig.11 As shown in the dotted line frame in b, for example, there are 4036 light spots within 120°×88°, and the proportion of effective light spots is 89.76%, which increases by 8%.

[0092] In other embodiments, the number of replica blocks in the diffraction orders arranged along the X-axis direction (and / or the Y-axis direction) may be changed linearly. For example, in the eight diffraction orders arranged along the X-axis direction (and / or the Y-axis direction), the number of replica blocks is 5, 6, 7, 8, 8, 7, 6, 5 in sequence; or, in the eight diffraction orders arranged along the X-axis direction (and / or the Y-axis direction), the number of replica blocks is 4, 5, 6, 7, 7, 6, 5, 4 in sequence; or, in the odd number (for example, nine) of diffraction orders arranged along the X-axis direction (and / or the Y-axis direction), the number of replica blocks is 5, 6, 7, 8, 9, 8, 7, 6, 5 in sequence.

[0093] In some embodiments, in step S20, adjusting the replica block in the initial speckle image specifically includes:

[0094] The position of the replica block in the initial speckle image is adjusted so that the first ideal speckle image presents an axisymmetric pattern.

[0095] In this embodiment, Fig. 9 a, by adjusting the position of the replica block in the initial speckle image, the adjusted initial speckle image (i.e., the first ideal speckle image) is an axisymmetric figure, for example, an axisymmetric figure relative to the X-axis and / or the Y-axis. Fig. 9 The first ideal speckle image is an axisymmetric figure in both spherical imaging and plane imaging, so that the field of view is optimal. In addition, since the waist field of view is also an axisymmetric figure (i.e., axisymmetric relative to the X-axis and the Y-axis), the first ideal speckle image is an axisymmetric figure, which makes it easy for the effective light spot to cover the entire waist field of view, increasing the proportion of effective light spots and improving the capacity utilization of the emission module.

[0096] Exemplarily, after adjusting the number of replica blocks in the initial speckle image, for example, by reducing the number of replica blocks in the diffraction orders on both sides of the initial speckle image (for example, on both sides along the X-axis direction and / or the Y-axis direction), if the first ideal speckle image does not present an axisymmetric figure, the axisymmetric figure can be achieved by adjusting the positions of the replica blocks in the initial speckle image. For example, when the original 8×7=56 replica blocks are reduced to 2×5+2×6+4×7=50 replica blocks, the original 7 replica blocks in the Y-axis direction (that is, the V-direction) are reduced to 6 replica blocks in the second diffraction order and the seventh diffraction order in the X-axis direction (that is, the H-direction). At this time, the replica blocks in the second diffraction order and the seventh diffraction order in the X-axis direction (that is, the H-direction) need to be adjusted, that is, moved along the Y-axis direction, so that the first ideal speckle image is axisymmetric relative to the X-axis.

[0097] In some embodiments, in step S20, when the replicated blocks in the initial speckle image are adjusted along the first direction and / or the second direction, the first direction is perpendicular to the second direction.

[0098] In this embodiment, when adjusting the number of replication blocks in the initial speckle image and adjusting the positions of replication blocks in the initial speckle image, it may be along the first direction and / or the second direction, that is, along at least one direction.

[0099] Exemplarily, the replica blocks in the initial speckle image are adjusted along two directions (i.e., the first direction and the second direction) so that the first ideal speckle image is closer to an ellipse during spherical imaging, thereby increasing the proportion of effective light spots as much as possible, thereby improving the capacity utilization of the emission module.

[0100] Of course, the replicated blocks in the initial speckle image may be adjusted along only one direction (ie, the first direction or the second direction) to simplify the design.

[0101] Exemplarily, the first direction may be the X-axis direction, that is, the H direction; and the second direction may be the Y-axis direction, that is, the V direction.

[0102] In some embodiments, in step S20, the first ideal speckle image is rotated to obtain a second ideal speckle image.

[0103] In this embodiment, the first ideal speckle image is rotated, for example, rotated around the Z axis, so as to improve the randomness of the second ideal speckle image (that is, the rotated first ideal speckle image) (for example, the randomness along the X axis), increase the robustness of the structured light depth camera detection algorithm, and avoid the black hole problem in the generated depth image.

[0104] For example, Figure 2 After the light source 10, the collimator 30 and the beam splitter 20 are rotated synchronously, the first ideal speckle image is rotated, thereby obtaining the second ideal speckle image. Figure 3 After the light source 10 and the beam splitter 20 are rotated synchronously, the first ideal speckle image is rotated, thereby obtaining the second ideal speckle image.

[0105] In some embodiments, in step S30, a beam splitter 20 is constructed based on an imaging position corresponding to the first ideal speckle image or the second ideal speckle image.

[0106] In this embodiment, the beam splitter may be constructed based on the imaging position corresponding to the first ideal speckle image, which can simplify the design of the beam splitter 20. The beam splitter may also be constructed based on the imaging position corresponding to the second ideal speckle image, which can increase the randomness of the speckle image.

[0107] Exemplarily, the imaging position corresponding to the second ideal speckle image can be obtained by using a coordinate transformation formula, and the coordinate transformation formula is:

[0108] x1 kmn ′=cos(r_angle)*x1 kmn -sin(r_angle)*y1 kmn ; (9)

[0109] y1 kmn ′=sin(r_angle)*x1 kmn +cos(r_angle)*y1 kmn ; (10)

[0110] x2 kmn ′=cos(r_angle)*x2 kmn -sin(r_angle)*y2 kmn ; (11)

[0111] y2 kmn ′=sin(r_angle)*x2 kmn+cos(r_angle)*y2 kmn ; (12)

[0112] In formulas (9) to (10), r_angle is the rotation angle (for example, the angle of counterclockwise rotation around the Z axis, which can be 5°), (x1 kmn ,y1 kmn ) is the imaging position coordinate of the first ideal speckle image on the spherical surface before rotation, (x2 kmn , y2 kmn ) is the imaging position coordinate of the first ideal speckle image before rotation, (x1 kmn ′,y1 kmn ′) is the imaging position coordinate of the first ideal speckle image after rotation (i.e., the second ideal speckle image) on the spherical surface, (x2 kmn ′,y2 kmn ′) is the imaging position coordinate of the first ideal speckle image after rotation (ie, the second ideal speckle image) in the plane.

[0113] In some embodiments, in step S20, after the first ideal speckle image is rotated, the position of the replica block in the first ideal speckle image is adjusted to obtain a second ideal speckle image.

[0114] In this embodiment, after the first ideal speckle image is rotated, the position of the replica block in the first ideal speckle image is continuously adjusted, for example, the light spots outside the waist field of view are moved as much as possible into the waist field of view, so as to increase the effective light spot ratio in the second ideal speckle image. Alternatively, the adjustment method may also be to reduce the distorted replica block at the edge.

[0115] For example, the imaging effect after the first ideal speckle image is rotated (for example, rotated 5° counterclockwise around the Z axis) is as follows: Fig.12 a, at this time the waist field of view is 120°×82°, the waist field of view (such as Fig.12 There are 3872 light spots in the image (as shown by the dotted line frame in a), and the proportion of effective light spots is 86.04%.

[0116] Exemplarily, the imaging effect after adjusting the rotated first ideal speckle image is as follows: Fig.12 b, for example, adjusting the position of the replica block, that is, the replica blocks in the diffraction order on both sides of the first ideal speckle image (for example, on both sides along the X-axis direction and / or the Y-axis direction) rotate clockwise until the waist field of view is filled with replica blocks. At this time, the waist field of view is 120°×88°, and the waist field of view (such as Fig.12 There are 4072 spots in the image (shown by the dotted line frame in b), and the proportion of effective spots is 90.49%. Compared with the solution of only rotating the first ideal speckle image to form the second ideal speckle image, the proportion of effective spots increases by 4.45%.

[0117] In some embodiments, in step S30, after the imaging position corresponding to the ideal speckle image is obtained, the beam splitting phase of the beam splitter 20 is obtained through an iterative algorithm.

[0118] In this embodiment, after the imaging position corresponding to the ideal speckle image (for example, the first ideal speckle image or the second ideal speckle image) is obtained, the beam splitting phase of the beam splitter 20 is obtained by an iterative algorithm, and then the beam splitter 20 is constructed according to the beam splitting phase (that is, phase distribution information), for example, a diffractive optical element (that is, DOE) or a beam splitting optical element based on a metasurface is constructed.

[0119] In some other embodiments, in step S30, after the imaging position corresponding to the ideal speckle image is obtained, the beam splitter is determined by rigorous coupled wave analysis.

[0120] In this embodiment, the specific structure of the beam splitter 20 can be obtained by rigorous coupled wave analysis (RCWA), thereby determining the diffractive optical element (i.e., DOE) or the beam splitting optical element based on the metasurface. When obtaining the specific structure of the beam splitter 20, the incident light can be incident on the beam splitter 20 in the form of collimated light, for example, vertical incidence. According to the ideal speckle image (such as the first ideal speckle image or the second ideal speckle image), the corresponding diffraction order in the grating structure is calculated, and the specific structure of the beam splitter 20 is optimized and solved by rigorous coupled wave analysis.

[0121] In some embodiments, in step S30 , when the splitting phase of the beam splitter 20 is obtained using an iterative algorithm, the target amplitude distribution is obtained according to the imaging position of one of the point light sources 101 of the light source 10 , and the outgoing light of the point light source 101 is vertically incident on the beam splitter 20 .

[0122] In this embodiment, when the splitting phase of the beam splitter 20 is obtained by using an iterative algorithm (such as the GS algorithm), the incident light must satisfy vertical incidence, so a point light source 101 vertically incident on the beam splitter 20 is selected, such as the point light source 101 at the coordinate (0, 0). The target amplitude distribution (or speckle image imaging effect) of the point light source 101 at the coordinate (0, 0) is as follows: Fig.13 The imaging effect is shown on the right.

[0123] Exemplarily, an iterative algorithm is used to solve the phase (such as beam splitting phase and / or collimation phase), and then the actual structure is used for phase matching, so that the beam splitter 20 can achieve the corresponding function (such as beam splitting and / or collimation). The iterative algorithm can be a GS (Gerchberg-Saxton) algorithm or a gradient descent algorithm.

[0124] Among them, the specific flow chart of GS algorithm is as follows Fig.13 ,include:

[0125] Step Sa, the initial object plane complex amplitude, that is, the object-side light field, is formed by combining the object-side amplitude with the random phase, and the image-side light field is obtained through forward diffraction propagation.

[0126] Step Sb, extract the image side phase and combine it with the image side amplitude. At this time, the diffraction propagation algorithm should be Fraunhofer diffraction propagation.

[0127] Step Sc, the light field constrained by the image-side amplitude is propagated in reverse, the phase of the obtained reverse light field is extracted, and then combined with the object-side amplitude to form a new object-side light field.

[0128] Step Sd, through the iterative cycle from object side to image side and then back to object side, the amplitude distribution of the image side light field will gradually be consistent with the target amplitude. At this time, the phase in the object side light field is the phase required by the beam splitter 20 (for example, the beam splitting phase and / or the collimation phase).

[0129] In some embodiments, in step S30, the beam splitter is provided with a collimation phase. In this embodiment, after the beam splitting phase is obtained, the collimation phase is superimposed on the beam splitting phase. Figure 3 In the illustrated embodiment, the focusing phase can be directly superimposed when the phase is solved by an iterative algorithm, so that the beam splitter 20 can simultaneously realize the collimation and beam splitting functions.

[0130] In other embodiments, Figure 2 As shown, the beam splitter 20 is only provided with a beam splitting phase, that is, the beam splitter 20 only has a beam splitting function, and the collimator 30 (such as a focusing lens, a Fresnel collimator) is used to collimate the light emitted by the light source 10.

[0131] For example, Fig.14 The collimation phase can be a spherical phase, a Gaussian phase, or a binary phase optimized by a formula.

[0132] In some embodiments, in step S20, after adjusting the initial design parameters, ideal design parameters corresponding to the first ideal speckle image are obtained, and the imaging position corresponding to the first ideal speckle image is obtained according to the angular dispersion formula of the grating.

[0133] In this embodiment, when the replica block in the initial speckle image is adjusted, it is achieved by changing the design parameters of the beam splitter 20, that is, the speckle image formed by the beam splitter 20 corresponds to the design parameters.

[0134] Exemplarily, the replica block in the initial speckle image is adjusted by adjusting the parameters such as m / dx and n / dy in formula (3) and formula (4). In the process of adjusting the design parameters of the beam splitter 20, other variables may be controlled to remain unchanged, such as the refractive index of the emitting medium, the working wavelength and other parameters; or other parameters in the emission module may be controlled to remain unchanged, such as the area of ​​the light source 10, the distance z between the center of the light source 10 and the center of the beam splitter 20, the distance f between the imaging surface and the beam splitter 20 and other parameters.

[0135] In other embodiments, the replica blocks in the initial speckle image may be adjusted by changing other parameters, such as reducing the area of ​​the light source 10, increasing the number of diffraction orders of the beam splitter 20, increasing the distance z between the center of the light source 10 and the center of the beam splitter 20, etc.

[0136] Exemplarily, in step S10, after determining the initial design parameters of the beam splitter 20, the imaging position corresponding to the initial speckle image is obtained according to the angular dispersion formula of the grating, that is, according to formula (3) and formula (4). In step S20, after adjusting the initial design parameters, the ideal design parameters are obtained, and then the imaging position corresponding to the first ideal speckle image is obtained according to the angular dispersion formula of the grating, that is, according to formula (3) and formula (4).

[0137] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0138] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A design method for a transmitting module, characterized in that: include: Selecting initial design parameters of the beam splitter to obtain an imaging position corresponding to an initial speckle image; After adjusting the replica block in the initial speckle image, a first ideal speckle image is obtained, and the first ideal speckle image is close to an ellipse when imaging on a spherical surface; A beam splitter is constructed based on the imaging position corresponding to the ideal speckle image.

2. The design method of the transmitting module according to claim 1, characterized in that: Adjust the replicated blocks in the initial speckle image, including: The number of replicated blocks in the initial speckle image is adjusted so that the number of replicated blocks in the diffraction orders on both sides of the first ideal speckle image is smaller than the number of replicated blocks in the middle diffraction order of the first ideal speckle image.

3. The design method of the transmitting module according to claim 2, characterized in that: Adjust the number of replicated blocks in the initial speckle image, specifically: The number of replicated blocks located in at least two diffraction orders on both sides of the initial speckle image is reduced.

4. The design method of the transmitting module according to claim 1, characterized in that: Adjust the replicated blocks in the initial speckle image, including: The position of the replica block in the initial speckle image is adjusted so that the first ideal speckle image presents an axisymmetric pattern.

5. The design method of the transmitting module according to claim 2 or 4, characterized in that: When the replicated block in the initial speckle image is adjusted along the first direction and / or the second direction, the first direction and the second direction are perpendicular to each other.

6. The design method of the transmitting module according to claim 1, characterized in that: After rotating the first ideal speckle image, a second ideal speckle image is obtained, and a beam splitter is constructed based on an imaging position corresponding to the first ideal speckle image or the second ideal speckle image.

7. The design method of the transmitting module according to claim 6, characterized in that: After the first ideal speckle image is rotated, the position of the replica block in the first ideal speckle image is adjusted to obtain a second ideal speckle image.

8. The design method of the transmitting module according to claim 1, characterized in that: After obtaining the imaging position corresponding to the ideal speckle image, the beam splitting phase of the beam splitter is obtained through an iterative algorithm; Alternatively, after obtaining the imaging position corresponding to the ideal speckle image, the beam splitter is determined by a rigorous coupled wave analysis method.

9. The design method of the transmitting module according to claim 8, characterized in that: When the beam splitting phase of the beam splitter is obtained by using an iterative algorithm, the target amplitude distribution is obtained according to the imaging position of one of the point light sources of the light source, and the outgoing light of the aforementioned point light source is vertically incident on the beam splitter.

10. The design method of the transmitting module according to claim 1, characterized in that: The beam splitter is provided with a collimation phase.

11. The design method of the transmitting module according to claim 1, characterized in that: After adjusting the initial design parameters, ideal design parameters corresponding to the first ideal speckle image are obtained, and the imaging position corresponding to the first ideal speckle image is obtained according to the angular dispersion formula of the grating.

12. A structured light depth camera, characterized in that: It includes a transmitting module designed by any one of the design methods described in claims 1-11 above.

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