CN215297842U - Diffractive optical element, projection module, and electronic apparatus - Google Patents

Abstract

The utility model relates to a diffraction optical element, throw module and electronic equipment. The diffractive optical element comprises a substrate and a plurality of microstructures arranged on the substrate along an X axis and a Y axis in a rectangular array. The first subunit and the second subunit of the microstructure are arranged diagonally, and the area of the first subunit is larger than that of the second subunit. Satisfies the following conditions: B/A is more than 1 and less than 2.5; E/D is more than 1 and less than 2.5; D/A is more than 2 and less than 2.5; E/B is more than 2 and less than 2.5; 1 < A/C < 2; a is the maximum size of the second subunit in the X-axis direction, B is the maximum size of the second subunit in the Y-axis direction, C is the shortest distance between the first subunit and the second subunit, D is the maximum size of the first subunit in the X-axis direction, and E is the maximum size of the first subunit in the Y-axis direction. The diffractive optical element can split a single beam into 3 × 3 multiple beams and has good optical performance.

Description

Diffractive optical element, projection module, and electronic apparatus

Technical Field

The utility model relates to a three-dimensional detection technology field especially relates to a diffraction optical element, throws module and electronic equipment.

Background

Time of Flight (ToF) or structured light technology is often applied to electronic devices, and three-dimensional depth information of an object to be measured is obtained by actively projecting light rays to the object to be measured and receiving light rays reflected from the object to be measured. Speckle structured light and direct Time of Flight (dtofs) technology generally uses a diffractive optical element to split light emitted from a light source to form a dot matrix light spot and project the dot matrix light spot onto an object to be detected, and the performance of the diffractive optical element has an important influence on three-dimensional detection precision.

However, the optical performance of the current diffractive optical element still needs to be improved, and it is difficult to meet the requirement of high detection precision.

SUMMERY OF THE UTILITY MODEL

Accordingly, there is a need for a diffractive optical element, a projection module and an electronic apparatus to improve the optical performance of the diffractive optical element.

A diffractive optical element for splitting a single beam of light into a plurality of 3 x 3 beams of light, the diffractive optical element comprising:

a substrate; and

the microstructures are arranged on the substrate in a rectangular array along the X-axis direction and the Y-axis direction, the X-axis direction and the Y-axis direction are two mutually perpendicular directions on a plane parallel to the substrate, the projection of the microstructures on the substrate comprises a first subunit and a second subunit which are spaced, the included angle between the connecting line of the geometric centers of the first subunit and the second subunit and the X-axis direction is 40-50 degrees, and the area of the first subunit is larger than that of the second subunit;

and the diffractive optical element satisfies the following conditional expression:

1＜B/A＜2.5；1＜E/D＜2.5；2＜D/A＜2.5；2＜E/B＜2.5；1＜A/C＜2；

wherein a is a maximum dimension of the second subunit in the X-axis direction, B is a maximum dimension of the second subunit in the Y-axis direction, C is a shortest distance between the first subunit and the second subunit, D is a maximum dimension of the first subunit in the X-axis direction, and E is a maximum dimension of the first subunit in the Y-axis direction.

The diffraction optical element is provided with the ion island type microstructure formed by the first subunit and the second subunit to form a beam splitting array, and can split a single beam into 3 x 3 multiple beams. And by adopting the microstructure, the 3 x 3 multi-beam light formed by splitting the beams by the diffractive optical element has good uniformity and diffraction efficiency, has good optical performance, and can meet the requirement of high detection precision when being applied to the three-dimensional detection technology.

In one embodiment, the X-axis direction and the Y-axis direction form a planar rectangular coordinate system;

the geometric center of the second subunit is positioned on one side of the geometric center of the first subunit in the X-axis negative direction, and the geometric center of the second subunit is positioned on one side of the geometric center of the first subunit in the Y-axis negative direction. The relative positions of the first subunit and the second subunit are designed, so that the optical performance of the diffractive optical element is improved.

In one embodiment, in the X-axis direction, the geometric centers of two adjacent first subunits are located on the same straight line, and the orientation of two adjacent first subunits is the same; and/or

In the X-axis direction, the geometric centers of two adjacent second subunits are located on the same straight line, and the orientation of two adjacent second subunits is the same. An array which is distributed regularly is formed among the plurality of microstructures, and the optical performance of the diffraction optical element is improved.

In one embodiment, the diffractive optical element satisfies the following conditional expression:

150nm≤A≤1000nm；150nm≤F≤1000nm；

and F is the shortest distance between two adjacent first subunits in the X-axis direction. The minimum size characteristic of the microstructure is not too small when the conditional expression is met, so that the manufacturing yield of the microstructure is improved; meanwhile, the size of the microstructure is close to the diffraction wavelength of the infrared band, so that the diffraction effect is good, and the optical performance of the diffraction optical element is improved.

In one embodiment, the diffractive optical element satisfies the following conditional expression:

a is more than or equal to 750nm and less than or equal to 900 nm; f is more than or equal to 700nm and less than or equal to 850 nm; B/A is more than or equal to 1.2 and less than or equal to 2.4; E/D is more than or equal to 1.2 and less than or equal to 2.4; A/C is more than or equal to 1.5 and less than or equal to 2.3. The method satisfies the conditional expression, can further reasonably design the microstructure, and is favorable for further improving the optical performance of the diffraction optical element.

In one embodiment, the diffraction angle of the diffractive optical element in the X-axis direction is between 15 ° and 25 °;

the diffraction angle of the diffractive optical element in the Y-axis direction is between 10 ° and 20 °. The design of different diffraction angles in the X-axis direction and the Y-axis direction is favorable for meeting the diversified requirements of projection angles in the three-dimensional detection technology.

In one embodiment, the first subunit and the second subunit are each substantially rounded rectangular in shape. The shapes of the first subunit and the second subunit are reasonably designed, and the optical performance of the diffraction optical element is further improved.

A diffractive optical element comprising:

a substrate; and

the beam splitting array is arranged on the substrate and comprises a plurality of first subunits and a plurality of second subunits, the number of the first subunits is equal to that of the second subunits, the first subunits are arranged in a rectangular array at intervals in the X-axis direction and the Y-axis direction, the second subunits are arranged in a rectangular array at intervals, the X-axis direction and the Y-axis direction are two mutually perpendicular directions on a plane parallel to the substrate, the first subunits correspond to the second subunits one by one, each first subunit is arranged at intervals with a corresponding second subunit, and an included angle between a connecting line of the geometric centers of each first subunit and a corresponding second subunit and the X-axis direction is 40-50 degrees;

and the beam splitting array satisfies the following conditional expression:

1＜B/A＜2.5；1＜E/D＜2.5；2＜D/A＜2.5；2＜E/B＜2.5；1＜A/C＜2；

wherein a is a maximum dimension of the second subunit in the X-axis direction, B is a maximum dimension of the second subunit in the Y-axis direction, C is a shortest distance between the first subunit and the second subunit, D is a maximum dimension of the first subunit in the X-axis direction, and E is a maximum dimension of the first subunit in the Y-axis direction.

The diffraction optical element is designed to form a beam splitting array by the first subunit and the second subunit which are arranged in an array, and can split a single beam of light into 3 × 3 multiple beams of light. And by adopting the fractional array, the 3 x 3 multi-beam light formed by splitting the beams by the diffractive optical element has good uniformity and diffraction efficiency, has good optical performance, and can meet the requirement of high detection precision when being applied to the three-dimensional detection technology.

A projection module comprising a light source and a diffractive optical element as described in any of the above embodiments, the diffractive optical element being configured to split light emitted by the light source. The diffractive optical element is adopted in the projection module, and the diffractive optical element has good optical performance, so that the projection module can meet the requirement of high detection precision when being applied to electronic equipment.

An electronic device comprises a receiving module and the projection module, wherein the projection module is used for projecting light rays to an object to be measured, and the receiving module is used for receiving the light rays reflected by the object to be measured. By adopting the projection module in the electronic equipment, the diffractive optical element has good optical performance, and the detection precision of the electronic equipment is favorably improved.

Drawings

FIG. 1 is a schematic diagram of a portion of the structure of a diffractive optical element in some embodiments;

FIG. 2 is a schematic illustration of the splitting of a diffractive optical element into 3 x 3 multiple beams in some embodiments;

FIG. 3 is a schematic illustration of microstructures in some embodiments;

FIG. 4 is a schematic view of microstructures in the first to fifteenth embodiments;

FIG. 5 is a schematic cross-sectional view of a diffractive optical element in some embodiments;

FIG. 6 is a schematic diagram of an electronic device in some embodiments.

100, a diffractive optical element; 110. a substrate; 120. a beam splitting array; 121. a microstructure; 122. a first subunit; 123. a second subunit; 124. the direction of the X axis; 125. a Y-axis direction; 130. the rest of the adhesive layer; 200. an electronic device; 210. a projection module; 211. a light source; 220. a receiving module; 230. an object to be measured.

Detailed Description

In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will be able to make similar modifications without departing from the spirit and scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1, 2 and 3, fig. 1 shows a schematic diagram of a partial structure of the diffractive optical element 100 in some embodiments, fig. 2 is a schematic diagram of the diffractive optical element 100 splitting into 3 × 3 light beams in some embodiments, and fig. 3 shows a schematic diagram of the microstructure 121 in some embodiments. In some embodiments, the diffractive optical element 100 includes a substrate 110 and a plurality of microstructures 121 disposed on the substrate 110, the plurality of microstructures 121 are arranged on the substrate 110 in a rectangular array along an X-axis direction 124 and a Y-axis direction 125 to form a beam splitting array 120, wherein the X-axis direction 124 and the Y-axis direction 125 are two mutually perpendicular directions on a plane perpendicular to the substrate 110, so that the diffractive optical element 100 can split a single beam of light into 3 × 3 multiple beams of light. Therefore, the diffractive optical element 100 can be applied to a projection module of an electronic device adopting speckle structured light or a dToF technology, and the diffractive optical element 100 is used for splitting a single light beam emitted by a light source in the projection module into 3 × 3 multiple light beams, so that a lattice light spot is formed and projected onto an object to be measured, and the requirement that the electronic device obtains the depth information of the object to be measured can be met.

Specifically, referring to fig. 1 and 3, in some embodiments, the projection of the microstructure 121 on the substrate 110 includes a first subunit 122 and a second subunit 123 which are spaced apart from each other, and a line connecting geometric centers of the first subunit 122 and the second subunit 123 forms an angle of 40 ° to 50 ° with the X-axis direction 124, for example, 45 °. In each microstructure 121, the first sub-unit 122 and the second sub-unit 123 are diagonally disposed. For example, the direction of the bisector angle between the X-axis direction 124 and the Y-axis direction 125 can be understood as the diagonal direction (not shown) formed by the X-axis direction 124 and the Y-axis direction 125. The first subunit 122 and the second subunit 123 are diagonally disposed, and it can be understood that a line connecting a geometric center of the first subunit 122 and a geometric center of the second subunit 123 is parallel to the diagonal direction. It should be noted that the first subunit 122 and the second subunit 123 are diagonally disposed, which does not mean that a connecting line of geometric centers of the first subunit 122 and the second subunit 123 is strictly parallel to a diagonal direction, as long as the geometric centers of the first subunit 122 and the second subunit 123 are staggered in the X-axis direction 124 and the Y-axis direction 125, and the first subunit 122 and the second subunit 123 are approximately arranged along the diagonal direction at intervals, the first subunit 122 and the second subunit 123 are considered to be diagonally disposed.

More specifically, in some embodiments, the X-axis direction 124 and the Y-axis direction 125 form a planar orthogonal coordinate system, in other words, the X-axis direction 124 has positive and negative directions, and the Y-axis direction 125 also has positive and negative directions. In each microstructure 121, the geometric center of the second subunit 123 is located on the X-axis negative direction side of the geometric center of the first subunit 122, and the geometric center of the second subunit 123 is located on the Y-axis negative direction of the geometric center of the first subunit 122.

Further, in some embodiments, the area of the first subunit 122 is larger than the area of the second subunit 123, and the diffractive optical element 100 satisfies the following conditional expression:

B＞A；C＞0；E＞D；D＞A；E＞B；

where a is a distance between two end points of the second subunit 123 at the outermost edge in the X-axis direction 124, i.e. a maximum dimension of the second subunit 123 in the X-axis direction 124, B is a distance between two end points of the second subunit 123 at the outermost edge in the Y-axis direction 125, i.e. a maximum dimension of the second subunit 123 in the Y-axis direction 125, C is a shortest distance between the first subunit 122 and the second subunit 123, where, in the embodiment shown in fig. 3, C can be understood as a shortest distance between the first subunit 122 and the second subunit 123 on a dashed line G, and in some embodiments, the dashed line G is parallel to the diagonal direction, D is a distance between two end points of the first subunit 122 at the outermost edge in the X-axis direction 124, i.e. a maximum dimension of the first subunit 122 in the X-axis direction 124, E is a distance between two end points of the first subunit 122 at the outermost edge in the Y-axis direction 125, i.e., the maximum dimension of the first subunit 122 in the Y-axis direction 125.

In some embodiments, the first sub-unit 122 and the second sub-unit 123 are both substantially in the shape of a rounded rectangle, and the length directions of the first sub-unit 122 and the second sub-unit 123 are parallel to the Y-axis direction 125, the width directions are parallel to the X-axis direction 124, a is the width dimension of the second sub-unit 123, B is the length dimension of the second sub-unit 123, D is the width dimension of the first sub-unit 122, and E is the length direction of the first sub-unit 122.

To sum up, the maximum dimension of the first sub-unit 122 in the Y-axis direction 125 is larger than the maximum dimension of the first sub-unit 122 in the X-axis direction 124, the maximum dimension of the second sub-unit 123 in the Y-axis direction 125 is larger than the maximum dimension of the first sub-unit 122 in the X-axis direction 124, the maximum dimension of the first sub-unit 122 in the X-axis direction 124 is larger than the maximum dimension of the second sub-unit 123 in the X-axis direction 124, the maximum dimension of the first sub-unit 122 in the Y-axis direction 125 is larger than the maximum dimension of the second sub-unit 123 in the Y-axis direction 125, and the first sub-unit 122 and the second sub-unit 123 are arranged at intervals in the diagonal direction.

In addition, in some embodiments, the microstructures 121 are arranged on the substrate 110 in a rectangular array, the shortest distance F between the first sub-units 122 of two adjacent microstructures 121 in the X-axis direction 124 is greater than 0, and F is greater than the distance between the geometric center of the first sub-unit 122 and the geometric center of the second sub-unit 123 in each microstructure 121 in the X-axis direction 124. In other words, referring to fig. 3, in two adjacent microstructures 121, two first subunits 122 are located at two sides of the geometric center of one second subunit 123.

Referring to fig. 1, it can be understood that when the plurality of microstructures 121 are arranged in a rectangular array, the number of the first subunits 122 is equal to that of the second subunits 123, and the first subunits 122 are also arranged in a rectangular array and the second subunits 123 are also arranged in a rectangular array in the X-axis direction 124 and the Y-axis direction 125. All the first subunits 122 and the second subunits 123 together form the beam splitting array 120 of the diffractive optical element 100, and each first subunit 122 is spaced apart from a corresponding one of the second subunits 123 and is disposed diagonally.

It should be noted that, the plurality of microstructures 121 are arranged in a rectangular array along the X-axis direction 124 and the Y-axis direction 125, and it is understood that, in the X-axis direction 124, the geometric centers of two adjacent first sub-units 122 are located on the same straight line, and the orientations of two adjacent first sub-units 122 are the same, for example, the length directions of two adjacent first sub-units 122 are parallel to each other. In the X-axis direction 124, the geometric centers of two adjacent second subunits 123 are located on the same straight line, and the orientations of two adjacent second subunits 123 are the same. Similarly, in the Y-axis direction 125, the geometric centers of the first sub-units 122 are located on the same straight line, the orientations of the first sub-units 122 are the same, the geometric centers of the second sub-units 123 are located on the same straight line, and the orientations of the second sub-units 123 are the same. Therefore, the microstructure 121 array forms a rectangular array with regular arrangement, so that the single light beam can be more accurately split, and the optical performance of the diffractive optical element 100 is improved. It is understood that the first sub-unit 122 and the second sub-unit 123 are alternately arranged in sequence in the X-axis direction 124 and the Y-axis direction 125.

Note that, in the present application, a plane parallel to the substrate 110 is described, and may be understood as a plane in which the substrate 110 is provided with the microstructures 121, or a virtual plane parallel to a surface of the substrate 110 on which the microstructures 121 are provided. Describing the dimensions of the first subunit 122 and the second subunit 123, it can be understood as the dimensions of the projection of the first subunit 122 and the second subunit 123 on the surface of the substrate 110. In addition, fig. 1 only shows a schematic diagram of a portion of the microstructure 121 of the diffractive optical element 100, in the portion shown in fig. 1, the number of the first sub-units 122 is not equal to that of the second sub-units 123, and actually, the microstructure 121 is the smallest unit of the beam splitting array 120, and no matter the number of the microstructures 121 in the beam splitting array 120 is increased or decreased, the number of the first sub-units 122 is equal to that of the second sub-units 123, and the relative position of each corresponding first sub-unit 122 is the same as that of the second sub-unit 123.

Referring to fig. 1 and fig. 2 again, the diffractive optical element 100 can split the single beam of light into 3 × 3 beams of light shown in fig. 2, so as to form 3 × 3 lattice spots projected on the object to be measured, and provide the electronic device to obtain the depth information of the object to be measured. The beam splitting array 120 formed by the microstructures 121 is disposed in the diffractive optical element 100, which is beneficial for the 3 × 3 multiple beams emitted by the diffractive optical element 100 to have good uniformity and diffraction efficiency, and the diffractive optical element 100 has good optical performance, and can meet the requirement of high detection accuracy of electronic equipment.

Specifically, the diffractive optical element 100 described above is proved to have good optical performance by one of the beam splitting experimental data below. In the beam splitting experiment, the size of each pixel is 200 × 264 pixels, the size of each pixel is 13nm, the wavelength of incident light is 940nm, the diffractive optical element 100 splits the incident light beam into 3 × 3 multiple beams, the uniformity of most of the split beams is 7.13%, the zero-order energy intensity accounts for 10.3% of the total energy, and the diffraction efficiency is 85.2%. The uniformity is the ratio of the energy difference of the light beam with the highest energy and the light beam with the lowest energy among the 3X 3 multi-light beams to the energy sum, and the diffraction efficiency is the ratio of the energy sum of the 3X 3 light beams to the total energy of emergent light. From experimental data, it can be seen that the diffractive optical element 100 has good optical performance and can satisfy the requirement of high detection accuracy. The specific experimental values are as follows:

design file

y pixel

X pixel

pixsel size(nm)

Uniformity of the film

Zero order

Diffraction efficiency

3 x 3 splitting

264

200

13

7.13％

10.30％

85.20％

Note that the electronic device generally detects light in a near infrared band, and thus the wavelength of incident light used for the diffractive optical element 100 may be in a near infrared band, for example, a near infrared short wave band of 780nm to 1100 nm. Further, in some embodiments, the wavelength of the incident light is 940 ± 50nm, which is beneficial to improving the optical performance of the diffractive optical element 100, thereby improving the three-dimensional detection accuracy. In addition, the microstructures 121 form a rectangular array of n × n, where n is a natural number greater than 1, in other words, the number of rows and columns of the beam splitting array 120 is the same, and the number of microstructures 121 in the beam splitting array 120 is not limited as long as the requirement of splitting the incident beam can be met, which is not limited herein. For example, when the spot size of the incident light beam is large, the number of the microstructures 121 and the occupied area of the beam splitting array 120 may be increased, so that the beam splitting array 120 can cover the whole spot range of the incident light beam, and the utilization rate of the incident light beam is improved.

Further, referring to fig. 1 and 3, in some embodiments, the diffractive optical element 100 satisfies the following conditional expression: B/A is more than 1 and less than 2.5; E/D is more than 1 and less than 2.5; D/A is more than 2 and less than 2.5; E/B is more than 2 and less than 2.5; A/C is more than 1 and less than 2. The size and shape of the second subunit 123 are designed to obtain a B/a numerical range, the size and shape of the first subunit 122 are designed to obtain an E/D numerical range, the relative sizes of the first subunit 122 and the second subunit 123 are designed to obtain D/a and E/B numerical ranges, and the relative positions of the first subunit 122 and the second subunit 123 are designed to obtain an a/C numerical range. Satisfying the above relational expression, the size and shape of the microstructure 121 can be specifically designed, and the optical performance of the diffractive optical element 100 can be further improved.

In some embodiments, the diffractive optical element 100 satisfies the following conditional expression: a is more than or equal to 150nm and less than or equal to 1000 nm; f is more than or equal to 150nm and less than or equal to 1000 nm. The lower limit of the above conditional expression is satisfied, and the sizes of a and F are not too small to cause difficulty in manufacturing the microstructure 121, which is beneficial to improving the manufacturing yield of the microstructure 121, so that the microstructure 121 is suitable for more manufacturing processes. Satisfying the above conditional expression, the size of the microstructure 121 is close to the incident wavelength, and the diffractive optical element 100 has a good diffraction effect, which is beneficial to improving the optical performance of the diffractive optical element 100. To further improve the optical performance of the diffractive optical element 100, in some embodiments, the diffractive optical element 100 satisfies the following conditional expression: a is more than or equal to 750nm and less than or equal to 900 nm; f is more than or equal to 700nm and less than or equal to 850 nm; B/A is more than or equal to 1.2 and less than or equal to 2.4; E/D is more than or equal to 1.2 and less than or equal to 2.4; A/C is more than or equal to 1.5 and less than or equal to 2.3.

The size characteristics of the microstructures 121 are different, and the diffraction angles of the diffractive optical element 100 in the X-axis direction 124 and/or the Y-axis direction 125 are also different, so that the diffractive optical element 100 can meet the projection requirements of more different scenes and different electronic devices due to the diversified diffraction angle designs. Specifically, referring to fig. 2 again, the diffraction angle of the diffractive optical element 100 in the X-axis direction 124 is between 15 ° and 25 °, and specifically may be: 15 °, 17.5 °, 20 °, 22.5 °, or 25 °, the diffraction angle in the Y-axis direction 125 is between 10 ° and 20 °, and specifically may be: 10 °, 12.5 °, 15 °, 17.5 ° or 20 °. Taking the X-axis direction 124 as an example, the diffractive optical element 100 splits into 3 rows of beams, and taking the middle row of beams as an origin, the deviation angle of the two side beams with respect to the middle row of beams can be understood as the diffraction angle of the diffractive optical element 100 in the X-axis direction 124. The diffraction angles of the diffractive optical element 100 in the X-axis direction 124 and the Y-axis direction 125 can be arbitrarily matched according to different scenes and the requirements of electronic devices.

Based on the above description, the following description will be provided with 15 specific examples, and the diffraction angle of the diffractive optical element 100 of each example is shown in table 1. Where H corresponds to the horizontal direction of the image sensor and corresponds to the X-axis direction 124, that is, H is the diffraction angle of the X-axis direction 124, and similarly, V is the diffraction angle of the vertical direction of the image sensor, that is, the Y-axis direction 125, D1 is the diffraction angle pattern of the diffractive optical element 100 in the first embodiment, in D1, the diffraction angle of the diffractive optical element 100 is 15 ° × 10 °, D2 is the diffraction angle pattern of the diffractive optical element 100 in the second embodiment, in D2, the diffraction angle of the diffractive optical element 100 is 17.5 ° × 10 °, and similarly, D3-D15 are the diffraction angle patterns of the diffractive optical elements 100 in the third embodiment to the fifteenth embodiment, respectively. It will be appreciated that the diffraction angle of the diffractive optical element 100 is 15 deg.. X10 deg., the FOI of the light projected by the diffractive optical element 100 is 30 deg.. X20 deg., the diffractive optical element 100 splits the single light beam into 3X 3 multiple beams, and only two diffraction angles need to be controlled in both the X-axis direction 124 and the Y-axis direction 125, making the design of the beam splitting array 120 simpler to produce.

TABLE 1

The dimensional characteristics of the microstructure 121 in each example are shown in table 2, the numerical units in table 2 are nm, the dimensional characteristics of the microstructure 121 in table 2 satisfy the above conditional expressions, and the diffractive optical element 100 in each example has good optical properties. As can be seen from table 2, by adjusting the size characteristics of the microstructures 121, the diffraction angle of the diffractive optical element 100 can be adjusted, so as to meet the projection requirements of different scenes or electronic devices.

TABLE 2

According to the values of table 2, in some embodiments, microstructure 121 further satisfies the following conditional expression: b is more than 1020nm and less than 2000 nm; c is more than 420nm and less than 550 nm; d is 1820 nm; 2236nm < E < 4260 nm. Satisfying the above conditional expressions, the dimensional characteristics of the microstructure 121 can be further designed, thereby further improving the optical performance of the diffractive optical element 100.

In addition, fig. 4 shows schematic views of microstructures 121 in the first to fifteenth embodiments. Wherein D1 represents a schematic view of the microstructure 121 in the first embodiment, D2 represents a schematic view of the microstructure 121 in the second embodiment, D3 represents a schematic view of the microstructure 121 in the third embodiment, and so on.

From the numerical values in table 2, data shown in table 3 can be obtained, and the data in table 3 all satisfy the above relational expressions.

TABLE 3

It is understood that in the production of the diffractive optical element 100, the parameters of one embodiment can be selected according to the required diffraction angle, and the corresponding microstructure 121 beam splitting array 120 can be manufactured according to the parameters of the embodiment. For example, when diffraction angles of 20 ° by 15 ° are required, a sixth embodiment D6 corresponding to table 1 may be used to produce a corresponding diffractive optical element 100 according to the parameters in tables 2 and 3.

Referring to fig. 1 and 5, fig. 5 shows a schematic cross-sectional view of a diffractive optical element 100 in some embodiments. The production process of the diffractive optical element 100 is not limited, and includes, but is not limited to, a nano lithography technique, a nano imprinting technique, or the like, as long as the beam splitting array 120 composed of the microstructures 121 can be formed on the surface of the substrate 110. In some embodiments, a mold corresponding to the beam splitting array 120 is manufactured by using a nano lithography technique, for example, the beam splitting array 120 is composed of a plurality of microstructures 121 protruding from the surface of the substrate 110, the mold has a concave structure corresponding to the beam splitting array 120, and a photoresist is coated on the substrate 110, so that the beam splitting array 120 is formed by imprinting the photoresist on the substrate 110 through the mold by using a nano imprinting technique. It should be noted that the beam splitting array 120 may also be formed by a plurality of microstructures 121 recessed on the surface of the substrate 110, and the mold has a convex structure corresponding to the beam splitting array 120.

Of course, the beam splitting array 120 can also be fabricated directly on the substrate 110 using nano-lithography. However, since the area of the lithography template is usually much smaller than the area of the beam splitting array 120, if the beam splitting array 120 is directly fabricated on the substrate 110 by using the nano lithography technique, the lithography template needs to be moved many times to satisfy the fabrication of the large area beam splitting array 120. The beam splitting array 120 is prepared by firstly manufacturing the mold and then impressing the mold, and the beam splitting array 120 can be rapidly produced in a mass production manner through the mold after the mold is prepared by only moving the photoetching template for many times in the mold manufacturing process, so that the production efficiency is favorably improved.

It is understood that, in order to match the manufacturing process, successfully produce the beam-splitting array 120 and avoid damaging the substrate 110, after the beam-splitting array 120 is formed by photoresist, a residual glue layer 130 is left between the substrate 110 and the microstructure 121. For example, in the embodiment shown in fig. 5, the surface of the substrate 110 is covered with a residual glue layer 130, and the microstructures 121 are formed on the residual glue layer 130. In some embodiments, the thickness of the substrate 110 is 0.3mm, the thickness of the remaining adhesive layer 130 is 3um, and the height of the microstructure 121, that is, the size of the microstructure 121 in the direction perpendicular to the surface of the remaining adhesive layer 130 is 0.8um, so that the beam splitting array 120 can be smoothly formed on the substrate 110 in accordance with the manufacturing process, and the manufactured diffractive optical element 100 can have sufficient structural strength.

In addition, the material of the substrate 110 is not limited, and can be any suitable transparent material, including but not limited to silicon, silicon dioxide, sodium borosilicate glass, sapphire, and the like. It is understood that in the embodiment shown in fig. 1, the black areas represent the substrate 110, the white areas represent the microstructures 121, and the microstructures 121 are formed on the substrate 110.

Referring to fig. 1 and 6, fig. 6 is a schematic diagram of an electronic device 200 according to some embodiments. In some embodiments, the diffractive optical element 100 and the light source 211 are assembled to form the projection module 210 and applied to the electronic apparatus 200, and the electronic apparatus 200 further includes a receiving module 220. Specifically, the electronic device 200 may employ any suitable technique such as speckle structured light or dtofs that requires depth information to be acquired by dot matrix projection. The light source 211 is capable of emitting an infrared light beam, e.g., the light source 211 emits an infrared light beam of 940 ± 50 nm. The diffractive optical element 100 is located on the light exit side of the light source 211, and the diffractive optical element 100 can split the single light beam emitted from the light source 211 into 3 × 3 multiple light beams and project the multiple light beams onto the object 230 to be measured. The light beam projected onto the object by the projection module 210 is reflected by the object 230 to be measured and then received by the receiving module 220, wherein the receiving module 220 may be configured with an image sensor. The receiving module 220 can obtain the depth information of the object 230 to be detected according to the light beam signal projected by the projecting module 210 and the light beam signal reflected by the object 230 to be detected, thereby implementing the three-dimensional detection function.

By adopting the diffractive optical element 100 in the electronic device 200, the diffractive optical element 100 can split a single beam into 3 × 3 multiple beams and has good optical performance, which is beneficial to improving the detection accuracy of the electronic device 200.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims (10)

1. A diffractive optical element for splitting a single light beam into a plurality of 3 x 3 light beams, said diffractive optical element comprising:

a substrate; and

the microstructures are arranged on the substrate in a rectangular array along an X-axis direction and a Y-axis direction, wherein the X-axis direction and the Y-axis direction are two mutually perpendicular directions on a plane parallel to the substrate, the projection of the microstructures on the substrate comprises a first subunit and a second subunit which are spaced, the included angle between the connecting line of the geometric centers of the first subunit and the second subunit and the X-axis direction is 40-50 degrees, and the area of the first subunit is larger than that of the second subunit;

and the diffractive optical element satisfies the following conditional expression:

1＜B/A＜2.5；1＜E/D＜2.5；2＜D/A＜2.5；2＜E/B＜2.5；1＜A/C＜2；

wherein a is a maximum dimension of the second subunit in the X-axis direction, B is a maximum dimension of the second subunit in the Y-axis direction, C is a shortest distance between the first subunit and the second subunit, D is a maximum dimension of the first subunit in the X-axis direction, and E is a maximum dimension of the first subunit in the Y-axis direction.

2. The diffractive optical element according to claim 1, wherein the X-axis direction and the Y-axis direction form a planar rectangular coordinate system;

the geometric center of the second subunit is positioned on one side of the geometric center of the first subunit in the X-axis negative direction, and the geometric center of the second subunit is positioned on one side of the geometric center of the first subunit in the Y-axis negative direction.

3. The diffractive optical element according to claim 1, wherein in the X-axis direction, geometric centers of two adjacent first subunits are located on the same straight line, and orientations of two adjacent first subunits are the same; and/or

In the X-axis direction, the geometric centers of two adjacent second subunits are located on the same straight line, and the orientation of two adjacent second subunits is the same.

4. The diffractive optical element according to claim 1, characterized in that the following conditional expression is satisfied:

150nm≤A≤1000nm；150nm≤F≤1000nm；

and F is the shortest distance between two adjacent first subunits in the X-axis direction.

5. The diffractive optical element according to claim 4, characterized in that the following conditional expression is satisfied:

750nm≤A≤900nm；700nm≤F≤850nm；1.2≤B/A≤2.4；1.2≤E/D≤2.4；1.5≤A/C≤2.3。

6. the diffractive optical element according to any one of claims 1 to 5, characterized in that the diffractive optical element has a diffraction angle in the X-axis direction of between 15 ° and 25 °;

the diffraction angle of the diffractive optical element in the Y-axis direction is between 10 ° and 20 °.

7. The diffractive optical element according to any one of claims 1 to 5, wherein the first and second subunits are each shaped substantially as a rounded rectangle.

8. A diffractive optical element, comprising:

a substrate; and

the beam splitting array is arranged on the substrate and comprises a plurality of first subunits and a plurality of second subunits, the number of the first subunits is equal to that of the second subunits, the first subunits are arranged in a rectangular array at intervals in the X-axis direction and the Y-axis direction, the second subunits are arranged in a rectangular array at intervals, the X-axis direction and the Y-axis direction are two mutually perpendicular directions parallel to the plane of the substrate, the first subunits correspond to the second subunits one by one, each first subunit is arranged at intervals with one corresponding second subunit, and the included angle between the connecting line of the geometric centers of each first subunit and one corresponding second subunit and the X-axis direction is 40-50 degrees;

and the beam splitting array satisfies the following conditional expression:

1＜B/A＜2.5；1＜E/D＜2.5；2＜D/A＜2.5；2＜E/B＜2.5；1＜A/C＜2；

wherein a is a maximum dimension of the second subunit in the X-axis direction, B is a maximum dimension of the second subunit in the Y-axis direction, C is a shortest distance between the first subunit and the second subunit, D is a maximum dimension of the first subunit in the X-axis direction, and E is a maximum dimension of the first subunit in the Y-axis direction.

9. A projection module comprising a light source and a diffractive optical element according to any one of claims 1-8 for splitting light emitted by the light source.

10. An electronic device, comprising a receiving module and the projecting module according to claim 9, wherein the projecting module is configured to project light toward an object to be measured, and the receiving module is configured to receive light reflected by the object to be measured.

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