A diffractive optical element with high uniformity lattice and its design method and projector

Abstract

The present application discloses a diffractive optical element with high uniformity lattice and its design method and projector. The design method includes: using a scalar diffraction theory algorithm to obtain a phase distribution design diagram of the diffractive optical element; based on at least two characteristic sub-light sources in the array light source, respectively, vector simulation is performed with the phase distribution design diagram to obtain a simulated lattice energy distribution; according to the difference between the simulated lattice energy distribution and the target lattice energy distribution, the target lattice energy distribution after compensation is obtained; using a scalar diffraction theory algorithm to obtain an updated phase distribution design diagram of the diffractive optical element corresponding to each characteristic sub-light source; from the updated phase distribution design diagram, the local phase distribution design diagram corresponding to the characteristic sub-light source is cut out and spliced ​​to obtain an integrated phase distribution design diagram of the diffractive optical element. According to the present invention, by designing the diffractive optical element to be divided into regions, the overall uniformity of the lattice energy obtained by its light splitting is improved.

Description

Technical Field

[0001] The present invention generally relates to the field of diffraction optical technology, and in particular to a diffraction optical element with a high uniformity lattice and a design method and a projector thereof. Background Art

[0002] For binocular vision, 3D structured light or DTOF applications, the recognition algorithm requires that the scattered spot array energy projected by the projector has good uniformity.

[0003] At present, low-cost non-collimated projector solutions are all obtained by replicating multi-point vertical cavity surface emitting lasers (VCSEL) through diffractive optical elements (DOE) splitting dot matrix devices; the traditional DOE design method is generally designed for a single-point VCSEL placed on the central optical axis of the DOE, and the dot matrix energy obtained by the single-point VCSEL on the DOE optical axis after being split by the DOE has good uniformity; however, since the light source points in the multi-point VCSEL except the light source point on the optical axis are all deviated from the optical axis, and due to the existence of the DOE structural vector effect, the dot matrix energy uniformity obtained by splitting these light source points that deviate from the optical axis after being split by the above-mentioned DOE will become worse, and the greater the degree of deviation of the light source point from the optical axis, the worse the dot matrix energy uniformity obtained after being split by the DOE.

[0004] Therefore, it is necessary to optimize the design method of DOE to improve the overall uniformity of the dot matrix energy obtained by DOE splitting of the multi-point VCSEL light source. Summary of the invention

[0005] The object of the present invention is to provide a diffractive optical element with a high uniformity dot array and a design method and a projector thereof, which can be used to improve the uniformity of the energy of the projected scattered dot array.

[0006] According to one aspect of the present invention, there is provided a design method of a diffractive optical element, wherein the diffractive optical element is used in combination with an array light source including a plurality of sub-light sources to project a scattered spot array, the design method comprising:

[0007] (1) determining the parameters of the neutron light source in the array light source and the target lattice light field of the diffractive optical element, and obtaining a phase distribution design diagram of the diffractive optical element using a scalar diffraction theory algorithm, wherein the target lattice light field has a target lattice energy distribution;

[0008] (2) selecting at least two sub-light sources from the plurality of sub-light sources of the array light source as characteristic sub-light sources, and performing vector simulation based on each characteristic sub-light source and a phase distribution design diagram of the diffractive optical element to obtain a simulated lattice energy distribution corresponding to each characteristic sub-light source;

[0009] (3) According to the difference between each simulation dot matrix energy distribution and the target dot matrix energy distribution, the target dot matrix energy distribution is compensated so that the target dot matrix energy distribution obtains an increment opposite to the above difference, thereby obtaining a compensated target dot matrix energy distribution corresponding to each characteristic sub-light source;

[0010] (4) based on each characteristic sub-light source and its corresponding compensated target lattice energy distribution, using a scalar diffraction theory algorithm to obtain an updated phase distribution design diagram of the diffractive optical element corresponding to each characteristic sub-light source;

[0011] (5) According to the spot area of ​​each characteristic sub-light source irradiated on the diffractive optical element, the local phase distribution design diagram corresponding to each characteristic sub-light source is cut out from the updated phase distribution design diagram corresponding to each characteristic sub-light source, and the integrated phase distribution design diagram of the diffractive optical element is obtained by splicing the local phase distribution design diagram.

[0012] In some embodiments, the design method further includes: using the integrated phase distribution design diagram as the phase distribution design diagram of the diffractive optical element, and returning to execute steps (1)-(5).

[0013] In some embodiments, step (3) includes calculating the compensated target lattice energy distribution corresponding to each characteristic sub-light source based on the following formula: i =T i +α i (T i -S i ), where T′ i is the energy of the i-th speckle in the target lattice energy distribution after compensation, T i is the energy of the i-th speckle in the target lattice energy distribution, S i is the energy of the i-th speckle in the simulated lattice energy distribution, α i is the compensation coefficient of the i-th speckle, i≤m, i and m are positive integers, and m is the number of speckles in the target dot matrix light field.

[0014] Preferred α i The value range is 0.1<α i <5, more preferably 0.7<α i <1.3.

[0015] In some embodiments, step (3) includes calculating the compensated target lattice energy distribution corresponding to each characteristic sub-light source based on the following formula: Where T′ i is the energy of the i-th speckle in the target lattice energy distribution after compensation, T i is the energy of the i-th speckle in the target lattice energy distribution, S i is the energy of the i-th speckle in the simulated lattice energy distribution, β i is the compensation coefficient of the i-th speckle, i≤m, i and m are positive integers, and m is the number of speckles in the target dot matrix light field.

[0016] Preferred β i The value range is 0.1<β i <5, more preferably 0.7<β i <2.

[0017] In some embodiments, the characteristic sub-light source is n sub-light sources that are substantially evenly distributed in the entire array light source, where n is an integer and n>=2.

[0018] In some embodiments, the characteristic sub-light source includes sub-light sources at four corners of the array light source.

[0019] In some embodiments, the cut-out local phase distribution design pattern is a regular shape, and the regular shape must include at least 50% of the illumination area of ​​the corresponding characteristic sub-light source.

[0020] In some embodiments, the regular shape is a rectangle, a rhombus, a parallelogram and / or a square.

[0021] In some embodiments, the cut-out local phase distribution design pattern is an irregular shape, and the irregular shape must include at least 50% of the illumination area of ​​the corresponding characteristic sub-light source.

[0022] In some embodiments, the array light source is a randomly arranged multi-point VCSEL light source.

[0023] According to another aspect of the present invention, a diffractive optical element is provided, which is a diffractive optical element designed using the above design method.

[0024] According to another aspect of the present invention, there is also provided a diffractive optical element, comprising:

[0025] substrate;

[0026] and a plurality of diffraction units formed on the substrate and arranged in an array;

[0027] The diffractive optical element is divided into regions according to the range of the light spot regions irradiated on the diffractive optical element by the multiple sub-light sources of the array light source, and the multiple diffraction units are spliced ​​and arranged on the substrate corresponding to the divided regions of the diffractive optical element respectively;

[0028] The microstructure phase distribution of each diffraction unit is designed by using a vector design method with a dot matrix of uniform energy distribution as the target light field for the corresponding sub-light source, so that the brightness of the scattered spot array projected by the diffraction optical element is uniform.

[0029] According to another aspect of the present invention, there is also provided a diffractive optical element for use in combination with an array light source including a plurality of sub-light sources to project a scattered spot array, the diffractive optical element comprising:

[0030] a substrate comprising a plurality of regions contiguous to one another; and

[0031] A plurality of sub-diffractive optical elements are respectively formed on the plurality of regions of the substrate,

[0032] Wherein, each sub-diffractive optical element is constructed to project a first dot matrix light field when used in combination with a sub-light source in the array light source corresponding to the center position of the area where it is located; and to project a second dot matrix light field when used in combination with a sub-light source in the array light source at a position beyond the area where it is located, and the energy distribution uniformity of the first dot matrix light field is better than the energy distribution uniformity of the second dot matrix light field.

[0033] According to another aspect of the present invention, there is provided a structured light projector, comprising:

[0034] An array light source including a plurality of sub-light sources, for generating an input light field;

[0035] The diffractive optical element designed using the above design method, or the above diffractive optical element, is used to split the input light field to produce a scattered spot array with uniform brightness.

[0036] According to the present invention, by dividing the diffractive optical element into regions, the overall uniformity of the lattice energy obtained by light splitting by the diffractive optical element is improved, and the overall uniformity of the lattice energy of the projector using the diffractive optical element is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0038] Figure 1 is a schematic diagram of a structured light projector in the prior art;

[0039] Figure 2Schematically illustrates an ideal uniform light field projected by a structured light projector;

[0040] Figure 3 is a schematic flow chart of an example of a design method of a diffractive optical element according to an embodiment of the present invention;

[0041] Figure 4 A phase distribution design diagram of a diffractive optical element obtained in step (1) of the design method according to an embodiment of the present invention;

[0042] Figure 5 An example of selecting a characteristic sub-light source in the design method of an embodiment of the present invention is schematically shown;

[0043] Figure 6 The simulated lattice energy distribution obtained by vector simulation of each characteristic sub-light source and the phase distribution design diagram of the diffractive optical element is shown;

[0044] Figure 7 Shown according to Figure 6 The simulated lattice energy distribution is compared with the target lattice energy distribution to obtain the compensated target lattice energy distribution corresponding to each characteristic sub-light source;

[0045] Figure 8 An updated phase distribution design diagram of a diffractive optical element obtained by using a scalar diffraction theory algorithm based on each characteristic sub-light source and its corresponding compensated target lattice energy distribution is shown;

[0046] Fig. 9 Schematically shows Figure 5 The characteristic sub-light source selected from the above irradiates the light spot area of ​​the diffractive optical element;

[0047] Fig.10 An example of cutting and splicing the integrated phase distribution design diagram of the diffractive optical element in the design method of the embodiment of the present invention is schematically shown;

[0048] Figure 11-13 Schematically showing three examples of cutting the local phase distribution design diagram in the design method of the embodiment of the present invention;

[0049] Fig.14 The energy distribution diagram obtained by vector simulation of the diffractive optical element obtained by the conventional design method and the design method of the embodiment of the present invention is shown;

[0050] Fig.15 A schematic diagram of a diffractive optical element according to an embodiment of the present invention is shown;

[0051] Fig.16 A schematic diagram showing a diffractive optical element according to another embodiment of the present invention;

[0052] Fig.17 A schematic diagram of a structured light projector according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0053] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0054] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0055] Figure 1 Schematic diagram of a structured light projector 100 in the prior art. In the illustrated example, the structured light projector 100 includes: a VCSEL light source 101, used to generate an input light field; a diffractive optical element 102, used to split the input light field to generate a scattered light array; the energy uniformity of the scattered light array obtained by the sub-light source of the VCSEL light source 101 deviating from the optical axis 103 after being split by the diffractive optical element 102 will deteriorate, and the greater the degree of deviation of the sub-light source from the optical axis 103, the worse the energy uniformity of the scattered light array.

[0056] Figure 2 An ideal uniform light field projected by a structured light projector is schematically shown. Figure 2 The left side shows an array light source, which is a 5*5 multi-point VCSEL light source. Figure 2 The upper right side shows the scattered spot array obtained by splitting the multi-point VCSEL light source through the diffractive optical element. The overall target spot array light field corresponding to the multi-point VCSEL light source is a uniform light field. Figure 2 The lower right side shows that the sub-light source of the multi-point VCSEL light source located on the optical axis is split by the diffraction optical element to obtain a target dot matrix square that is a uniform 3*3 dot matrix, and the energy distribution of the 9 points is uniform.

[0057] Figure 3 FIG. 1 is a schematic flow chart of an example of a method for designing a diffractive optical element according to an embodiment of the present invention; FIG. Figure 3 As shown, the design method of the diffractive optical element includes:

[0058] S101: Determine the parameters of the neutron light source in the array light source and the target lattice light field of the diffractive optical element, and use a scalar diffraction theory algorithm to obtain a phase distribution design diagram of the diffractive optical element, wherein the target lattice light field has a target lattice energy distribution;

[0059] S102: selecting at least two sub-light sources from a plurality of sub-light sources of the array light source as characteristic sub-light sources, and performing vector simulation based on each characteristic sub-light source and a phase distribution design diagram of a diffractive optical element to obtain a simulated lattice energy distribution corresponding to each characteristic sub-light source;

[0060] S103: According to the difference between each simulation dot matrix energy distribution and the target dot matrix energy distribution, the target dot matrix energy distribution is compensated so that the target dot matrix energy distribution obtains an increment opposite to the difference, and the compensated target dot matrix energy distribution corresponding to each characteristic sub-light source is obtained;

[0061] S104: Based on each characteristic sub-light source and its corresponding compensated target lattice energy distribution, using a scalar diffraction theory algorithm to obtain an updated phase distribution design diagram of a diffractive optical element corresponding to each characteristic sub-light source;

[0062] S105: According to the spot area of ​​each characteristic sub-light source irradiated on the diffractive optical element, the local phase distribution design diagram corresponding to each characteristic sub-light source is cut out from the updated phase distribution design diagram corresponding to each characteristic sub-light source, and the integrated phase distribution design diagram of the diffractive optical element is obtained by splicing the local phase distribution design diagram.

[0063] The above-mentioned design method obtains the integrated phase distribution design diagram of the diffractive optical element by cutting and splicing the local phase distribution design diagrams corresponding to each characteristic sub-light source in the array light source, thereby realizing the divided area design of the diffractive optical element, thereby improving the overall uniformity of the dot matrix energy obtained by the diffractive optical element after the array light source is split.

[0064] According to different embodiments of the present invention, in step (1), the array light source may be a multi-point VCSEL light source arranged uniformly, such as Figure 2 The 5*5 multi-point VCSEL light source shown on the left. The parameters of the sub-light source may include wavelength, divergence angle, etc. Figure 2 The wavelength of the multi-point VCSEL light source shown is 940nm, the sub-light source is arranged as shown in the figure, the divergence angle of the single-point sub-light source is 22°, and the distance from the diffractive optical element is D=2.43mm. The array light source can also be a randomly arranged multi-point VCSEL light source. In order to better reduce the non-uniformity of the output light field, the randomly arranged multi-point VCSEL light source is preferably used as the array light source of the input light field.

[0065] The use of a scalar diffraction theory algorithm to obtain a phase distribution design diagram of a diffractive optical element may include any suitable method known to those skilled in the art, such as the GS algorithm and its improved algorithm, the Yang-Gu (YG) algorithm and its improved algorithm, a simulated annealing algorithm (SA), a genetic algorithm (GA) and other optimization algorithms, as well as various hybrid algorithms.

[0066] The target dot matrix light field of the diffractive optical element is a scattered dot matrix with uniform energy distribution.

[0067] Figure 4 A phase distribution design diagram of a diffractive optical element obtained in step (1) of the design method according to an embodiment of the present invention is shown, which can be obtained using a scalar diffraction theory algorithm through any sub-light source in the array light source and the target lattice light field of the diffractive optical element.

[0068] According to different embodiments of the present invention, in step (2), the designer can arbitrarily select at least two sub-light sources from the multiple sub-light sources of the array light source as characteristic sub-light sources according to actual design requirements. For example, two sub-light sources symmetrical with respect to the sub-light source on the optical axis can be selected as characteristic sub-light sources, or n sub-light sources roughly evenly distributed in the entire array light source can be selected as characteristic sub-light sources, where n is an integer and n>=2. The selection of characteristic sub-light sources is preferably able to cover the entire diffractive optical element area, so as to achieve the design of the entire diffractive optical element area.

[0069] Figure 5 An example of selecting a characteristic sub-light source in the design method of an embodiment of the present invention is schematically shown. The selected characteristic sub-light sources A, B, C, and D are respectively located at the four corners of the array light source, and the four characteristic sub-light sources are evenly distributed in the entire array light source. When the array light source has fewer sub-light sources and the area of ​​the diffractive optical element is not large, it is a simple and easy operation method to select only the sub-light sources located at the corners of the array light source as the characteristic sub-light sources. Otherwise, in addition to selecting the sub-light sources at the corners of the array light source, it is necessary to evenly select some sub-light sources inside the array light source so as to roughly cover the diffractive optical element. Based on each characteristic sub-light source A, B, C or D and the phase distribution design diagram of the diffractive optical element obtained in step (1), vector simulation is performed to obtain the simulated lattice energy distribution corresponding to each characteristic sub-light source A, B, C, and D. Figure 6 The simulated dot lattice energy distributions 1.A, 1.B, 1.C, and 1.D obtained by vector simulation of each characteristic sub-light source A, B, C, and D with the phase distribution design diagram of the diffractive optical element are shown. The four simulated dot lattice energy distributions obtained by the simulation are all 3*3 dot matrices, and it can be observed that the energy distribution of 9 points is uneven.

[0070] According to different embodiments of the present invention, the target lattice energy distribution can be compensated in step (3) by using the following formula to calculate the compensated target lattice energy distribution corresponding to each characteristic sub-light source: i =T i +α i (T i -S i ), where T′ iis the energy of the i-th speckle in the target lattice energy distribution after compensation, T i is the energy of the i-th speckle in the target lattice energy distribution, S i is the energy of the i-th speckle in the simulated lattice energy distribution, α i is the compensation coefficient of the i-th speckle, i≤m, i and m are positive integers, and m is the number of speckles in the target dot matrix light field; where 0.1<α i <5, preferably 0.7<α i <1.3. α in the above formula i (T i -T i ) is the increment in the opposite direction of the difference that the target lattice energy distribution needs to obtain; when a certain speckle energy in the simulated lattice energy distribution is less than the corresponding speckle energy in the target lattice energy distribution (i.e. the difference between a certain speckle energy in the simulated lattice energy distribution and the target lattice energy distribution (S i -T i )<0), the speckle T of the target point array energy distribution i A positive reverse incremental compensation will be obtained; and when a certain speckle energy in the simulated lattice energy distribution is greater than the corresponding speckle energy in the target lattice energy distribution (i.e., the difference between a certain speckle energy in each simulated lattice energy distribution and the target lattice energy distribution (S i -T i )>0), the target point array energy distribution speckle T i A negative value for the reverse delta compensation will be obtained.

[0071] According to different embodiments of the present invention, the target lattice energy distribution may be compensated in step (3) by using the following formula to calculate the compensated target lattice energy distribution corresponding to each characteristic sub-light source: Where T′ i is the energy of the i-th speckle in the target lattice energy distribution after compensation, T i is the energy of the i-th speckle in the target lattice energy distribution, S i is the energy of the i-th speckle in the simulated lattice energy distribution, β i is the compensation coefficient of the i-th speckle, i≤m, i and m are positive integers, and m is the number of speckles in the target dot matrix light field; where 0.1<β i <5, preferably 0.7<β i <2. The above formula It can also be listed as T′ i =T i ×(β i T i / S i ), where β i T i / Si That is, the target lattice energy distribution is to obtain an increment in the opposite direction of the difference. When a certain speckle energy in the simulated lattice energy distribution is less than the corresponding speckle energy in the target lattice energy distribution (that is, the difference S between a certain speckle energy in the simulated lattice energy distribution and the target lattice energy distribution) i / T i <1), the speckle T of the target point energy distribution i You will get a β i T i / S i >1; and when a certain speckle energy in the simulated lattice energy distribution is greater than the corresponding speckle energy in the target lattice energy distribution (i.e., the difference S between a certain speckle energy in each simulated lattice energy distribution and the target lattice energy distribution i / T i >1), the speckle T of the target lattice energy distribution i You will get a β i T i / S i Reverse incremental compensation of <1.

[0072] For the above two compensation calculation formulas, the compensation coefficient α corresponding to different speckles is i , β i The value of can be different. Those skilled in the art can select the speckle compensation coefficient in the dot matrix according to design requirements or design experience. Such compensation method enables the designed diffractive optical element to better adapt to each sub-light source of the array light source. For example, the compensation coefficient corresponding to the speckle at a larger angle in the dot matrix can be larger, while the compensation coefficient corresponding to the speckle at a smaller angle in the dot matrix can be smaller; the compensation coefficient corresponding to the sub-light source of the array light source far from the optical axis can be larger, while the compensation coefficient corresponding to the sub-light source of the array light source close to the optical axis can be smaller.

[0073] Figure 7 Shown according to Figure 6 The simulated lattice energy distribution is compared with the target lattice energy distribution to obtain the compensated target lattice energy distribution corresponding to each characteristic sub-light source. Figure 5 The characteristic sub-light sources A, B, C, and D located at the four corners of the array light source are as follows: The compensated target dot matrix energy distributions 2.A, 2.B, 2.C, and 2.D corresponding to each characteristic sub-light source A, B, C, and D are calculated and obtained respectively.

[0074] Figure 8 Shown based on Figure 5 The characteristic sub-light sources A, B, C, D and their corresponding Figure 7The target lattice energy distribution after compensation shown in 2.A, 2.B, 2.C, 2.D is an updated phase distribution design diagram of the diffractive optical element obtained by using the scalar diffraction theory algorithm. As mentioned above, the scalar diffraction theory algorithm can include any suitable method known to those skilled in the art, such as the GS algorithm and its improved algorithm, the Yang-Gu (YG) algorithm and its improved algorithm, the simulated annealing algorithm (SA), the genetic algorithm (GA) and other optimization algorithms and various hybrid algorithms.

[0075] Fig. 9 The figure schematically shows the light spot area of ​​the diffractive optical element to be designed, which is irradiated by the characteristic sub-light sources A, B, C, and D selected in the design method of the embodiment of the present invention. Fig. 9 The circular areas indicated by the four dotted lines are the light spot areas of the characteristic sub-light sources A, B, C, and D irradiating the diffractive optical element. The diffractive optical element is divided into rectangular sections according to the light spot areas of the characteristic sub-light sources, so that the area corresponding to each characteristic sub-light source is roughly equal and includes most of the irradiation area of ​​the sub-light source (at least 50% of the irradiation area of ​​the sub-light source). After the division, the various areas can also be spliced ​​into a complete diffractive optical element.

[0076] Fig.10 An example of cutting and splicing of the integrated phase distribution design diagram of the diffractive optical element in the design method of an embodiment of the present invention is schematically shown; region 1 is cut out from the updated phase distribution design diagram corresponding to the characteristic sub-light source A, region 2 is cut out from the updated phase distribution design diagram corresponding to the characteristic sub-light source B, region 3 is cut out from the updated phase distribution design diagram corresponding to the characteristic sub-light source C, and region 4 is cut out from the updated phase distribution design diagram corresponding to the characteristic sub-light source D; the cut regions 1, 2, 3, and 4 are spliced ​​to obtain the integrated phase distribution design diagram of the diffractive optical element.

[0077] According to different embodiments of the present invention, due to the different number and spot shapes of each characteristic sub-light source in step (5), the corresponding local phase distribution design diagram cut out can be a regular shape or an irregular shape. The regular shape can be a rectangle, a rhombus, a parallelogram and / or a square. The regular shape or the irregular shape must satisfy the requirement of containing at least 50% of the illumination area of ​​the corresponding characteristic sub-light source.

[0078] Figure 11-13 Three examples of cutting the local phase distribution design diagram in the design method according to the embodiment of the present invention are schematically shown. Fig.11 9 characteristic sub-light sources are shown in the figure. The dotted circles in the figure represent the spot areas formed by the 9 sub-light sources irradiating the diffractive optical element, which are represented by numbers 1-9. The corresponding local phase distribution design diagrams cut out are 9 rectangles. Fig.12The local phase distribution design diagram cut out corresponding to the characteristic sub-light source is shown in 25 rectangles, represented by numbers 1-25; Fig.13 The figure shows that the local phase distribution design corresponding to the characteristic sub-light source is 9 irregular trapezoids, represented by numbers 1-9.

[0079] Depend on Figure 11-13 It can be seen that the area of ​​the cut local phase distribution design diagram can also be different, and the shape and area of ​​the cut local phase distribution design diagram are determined by the shape of the characteristic sub-light source and its irradiation area. Cutting the local phase distribution design diagram into regular shapes can simplify the operation and reduce the amount of simulation calculation; while cutting into irregular shapes can make the cut local phase distribution design diagram better adapt to the shape of the characteristic sub-light source, and the overall uniformity of the lattice energy obtained by the final design of the diffractive optical element will be better.

[0080] like Figure 3 As shown, the design method of the diffractive optical element according to the embodiment of the present invention may further include: using the integrated phase distribution design diagram as the phase distribution design diagram of the diffractive optical element, and returning to execute steps (1)-(5). By repeating in this way, the integrated phase distribution design diagram of the diffractive optical element with the best energy distribution uniformity can be selected.

[0081] According to different embodiments of the present invention, the diffractive optical element is 2 n Step quantization, n is a positive integer.

[0082] A vector simulation of all sub-light sources of a 5*5 multi-point VCSEL light source is performed on the integrated phase distribution design diagram obtained by the design method of a diffractive optical element according to an embodiment of the present invention to obtain all 225 speckle energy distributions. Fig.14 The left and right sides of the diagram respectively show the energy distribution diagrams obtained by vector simulation of the diffractive optical element obtained by the conventional design method and the design method of the embodiment of the present invention. By comparing the two diagrams, it can be intuitively seen that the uniformity of energy distribution obtained by vector simulation of the diffractive optical element obtained by the design method of the embodiment of the present invention has been greatly improved. Calculations show that the uniformity of energy distribution obtained by vector simulation of the diffractive optical element obtained by the conventional design method is 22.5% (minimum order energy / maximum order energy), while the uniformity of energy distribution obtained by vector simulation of the diffractive optical element obtained by the design method of the embodiment of the present invention is 62.7% (minimum order energy / maximum order energy). It can be seen that the uniformity of lattice energy of the diffractive optical element obtained by the design method of the present invention is significantly improved.

[0083] According to a preferred embodiment of the present invention, the present invention further provides a diffractive optical element, which is a diffractive optical element designed using the above design method.

[0084] According to another preferred embodiment of the present invention, the present invention further provides a diffractive optical element, comprising: a substrate 10 and a plurality of diffractive units 11; the plurality of diffractive units 11 are formed on the substrate 10 and arranged in an array. The diffractive optical element is divided into regions according to the range of the light spot region irradiated on the diffractive optical element by the plurality of sub-light sources of the array light source. Fig.15 As shown in the figure, the dotted circle represents the spot area formed by the 9 sub-light sources in the array light source irradiating the diffractive optical element, which is represented by numbers 1-9; the area divided for the diffractive optical element is a regular rectangle, and the area divided for the diffractive optical element can also be other regular shapes or irregular shapes; the area divided for the diffractive optical element must include most of the spot area of ​​the sub-light source irradiating the diffractive optical element (at least 50% of the irradiation area of ​​the sub-light source).

[0085] A plurality of diffraction units 11 are spliced ​​and arranged on the substrate 10 corresponding to the divided areas of the diffraction optical element, and the microstructure phase distribution of each diffraction unit 11 is designed by using a vector design method for the sub-light source corresponding thereto with a dot matrix of uniform energy distribution as the target light field, so that the brightness of the scattered dot matrix projected by the diffraction optical element is uniform. The microstructure phase distribution of each diffraction unit 11 is obtained by using a vector design method through a uniform target dot matrix energy distribution and sub-light source parameters, and the vector design method may include any suitable method known to those skilled in the art, such as a simulated annealing algorithm (SA), a genetic algorithm (GA), etc. By designing the microstructure phase distribution of the diffraction optical element by dividing the area vector, the overall uniformity of the dot matrix energy obtained by the diffraction optical element is improved.

[0086] According to another aspect of the present invention, the present invention further provides a diffractive optical element for use in combination with an array light source including a plurality of sub-light sources to project a scattered spot array, the diffractive optical element comprising: a substrate 10' having a plurality of regions connected to each other and a plurality of sub-diffractive optical elements 11' respectively formed on the plurality of regions of the substrate 10'. Each sub-diffractive optical element 11' is constructed to project a first dot matrix light field when used in combination with a sub-light source in the array light source corresponding to the central position of the region where the sub-diffractive optical element 11' is located, and to project a second dot matrix light field when used in combination with a sub-light source in the array light source at a position beyond the region where the sub-diffractive optical element 11' is located, and the energy distribution uniformity of the first dot matrix light field is better than the energy distribution uniformity of the second dot matrix light field.

[0087] like Fig.16As shown, the dotted circle in the figure represents the spot area formed by the 9 sub-light sources in the array light source irradiating the diffractive optical element, which is represented by numbers 1 to 9. The multiple sub-diffractive optical elements 11' are regular rectangles, and they can also be other regular shapes or irregular shapes. When the sub-diffractive optical element 11' is an irregular shape, the center position of the area where it is located can be roughly determined based on design experience.

[0088] According to another aspect of the present invention, Fig.17 As shown, a structured light projector 100' is provided, which includes: an array light source 101' having a plurality of sub-light sources, for generating an input light field; a diffractive optical element 102' designed using the above design method, or a diffractive optical element 102' provided in the above embodiment, for splitting the input light field to generate a scattered spot array with uniform brightness. By designing the diffractive optical element 102' to divide the area, the overall uniformity of the dot array energy of the projector using the above diffractive optical element 102' is improved.

[0089] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A design method of a diffractive optical element, wherein the diffractive optical element is used in combination with an array light source including a plurality of sub-light sources to project a scattered spot array, the design method comprising: (1) determining the parameters of the neutron light source in the array light source and the target lattice light field of the diffractive optical element, and obtaining a phase distribution design diagram of the diffractive optical element using a scalar diffraction theory algorithm, wherein the target lattice light field has a target lattice energy distribution; (2) selecting at least two sub-light sources from the plurality of sub-light sources of the array light source as characteristic sub-light sources, and performing vector simulation based on each characteristic sub-light source and a phase distribution design diagram of the diffractive optical element to obtain a simulated lattice energy distribution corresponding to each characteristic sub-light source; (3) According to the difference between each simulation dot matrix energy distribution and the target dot matrix energy distribution, the target dot matrix energy distribution is compensated so that the target dot matrix energy distribution obtains an increment opposite to the above difference, thereby obtaining a compensated target dot matrix energy distribution corresponding to each characteristic sub-light source; (4) based on each characteristic sub-light source and its corresponding compensated target lattice energy distribution, using a scalar diffraction theory algorithm to obtain an updated phase distribution design diagram of the diffractive optical element corresponding to each characteristic sub-light source; (5) According to the spot area of ​​each characteristic sub-light source irradiated on the diffractive optical element, the local phase distribution design diagram corresponding to each characteristic sub-light source is cut out from the updated phase distribution design diagram corresponding to each characteristic sub-light source, and the integrated phase distribution design diagram of the diffractive optical element is obtained by splicing the local phase distribution design diagram.

2. The design method according to claim 1, further comprising: The integrated phase distribution design diagram is used as the phase distribution design diagram of the diffractive optical element, and the process returns to execute steps (1)-(5).

3. The design method according to claim 1, wherein: Step (3) includes calculating the compensated target lattice energy distribution corresponding to each characteristic sub-light source based on the following formula: i =T i +α i (T i -S i ), where T′ i is the energy of the i-th speckle in the target lattice energy distribution after compensation, T i is the energy of the i-th speckle in the target lattice energy distribution, S i is the energy of the i-th speckle in the simulated lattice energy distribution, α i is the compensation coefficient of the i-th speckle, i≤m, i and m are positive integers, and m is the number of speckles in the target dot matrix light field.

4. The design method according to claim 3, wherein: 0.1<α i <5。 5. The design method according to claim 3, wherein: 0.7<α i <1.3。 6. The design method according to claim 1, wherein: Step (3) includes calculating the compensated target lattice energy distribution corresponding to each characteristic sub-light source based on the following formula: Where T′ i is the energy of the i-th speckle in the target lattice energy distribution after compensation, T i is the energy of the i-th speckle in the target lattice energy distribution, S i is the energy of the i-th speckle in the simulated lattice energy distribution, β i is the compensation coefficient of the i-th speckle, i≤m, i and m are positive integers, and m is the number of speckles in the target dot matrix light field.

7. The design method according to claim 2, wherein: Step (3) includes calculating the compensated target lattice energy distribution corresponding to each characteristic sub-light source based on the following formula: Where T′ i is the energy of the i-th speckle in the target lattice energy distribution after compensation, T i is the energy of the i-th speckle in the target lattice energy distribution, S i is the energy of the i-th speckle in the simulated lattice energy distribution, β i is the compensation coefficient of the i-th speckle, i≤m, i and m are positive integers, and m is the number of speckles in the target dot matrix light field.

8. The design method according to claim 6, wherein: 0.1<β i <5。 9. The design method according to claim 6, wherein: 0.7<β i <2。 10. The design method according to claim 2, wherein: Step (3) includes calculating the compensated target lattice energy distribution corresponding to each characteristic sub-light source based on the following formula: i =T i +α i (T i -S i ), where T′ i is the energy of the i-th speckle in the target lattice energy distribution after compensation, T i is the energy of the i-th speckle in the target lattice energy distribution, S i is the energy of the i-th speckle in the simulated lattice energy distribution, α i is the compensation coefficient of the i-th speckle, i≤m, i and m are positive integers, and m is the number of speckles in the target dot matrix light field.

11. The design method according to any one of claims 1 to 10, wherein: The characteristic sub-light sources are n sub-light sources that are substantially evenly distributed in the entire array light source, where n is an integer and n>=2.

12. The design method according to any one of claims 1 to 10, wherein: The characteristic sub-light sources include sub-light sources at four corners of the array light source.

13. The design method according to any one of claims 1 to 10, wherein: The cut-out local phase distribution design diagram is a regular shape, and the regular shape must include at least 50% of the illumination area of ​​the corresponding characteristic sub-light source.

14. The design method according to claim 13, wherein: The regular shape is a rectangle, a rhombus, a parallelogram and / or a square.

15. The design method according to any one of claims 1 to 10, wherein: The cut-out local phase distribution design diagram is an irregular shape, and the irregular shape must include at least 50% of the illumination area of ​​the corresponding characteristic sub-light source.

16. The design method according to any one of claims 1 to 10, wherein: The array light source is a multi-point VCSEL light source arranged randomly.

17. A diffractive optical element, which is a diffractive optical element designed using the design method according to any one of claims 1 to 16.

18. A structured light projector, comprising: An array light source including a plurality of sub-light sources, for generating an input light field; and The diffractive optical element as described in claim 17 is used to split the input light field to produce a scattered spot array with uniform brightness.

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