Fresnel lens, structural design method thereof, electronic device and storage medium

Abstract

The embodiment of the application relates to the optical field, and discloses a Fresnel lens, a design method thereof, electronic equipment and a storage medium. The Fresnel lens comprises: a light surface as an exit surface of the Fresnel lens, and a plurality of concentric circles with different radii are engraved on an entrance surface, a longitudinal cross-section of the plurality of concentric circles through a circle center is in a continuous sawtooth shape, and one side of each sawtooth close to the circle center is a refractive surface, and the other side far from the circle center is a total reflection curved surface; when incident light irradiates on the refractive surface, the incident light is refracted to form refracted light, the refracted light is totally reflected through the total reflection curved surface of the same sawtooth to form collimated light and is emitted from the exit surface. The original draft surface is used as the refractive surface, the light is deflected to the total reflection surface to form the collimated light, the original lost light energy is utilized, and therefore the light emission efficiency of the Fresnel lens is improved.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of optics, and in particular to a Fresnel lens, a structure design method thereof, an electronic device, and a storage medium. BACKGROUND

[0002] A Fresnel lens, also known as a thread lens, is usually a thin sheet made of polyolefin material by injection molding, and is also made of glass. One side of the lens surface is a smooth surface, and the other side is engraved with concentric circles from small to large. The texture is designed according to the interference and scattering of light, as well as the relative sensitivity and receiving angle requirements. From the cross section, the surface is composed of a series of sawtooth grooves, and the central part is an elliptical arc. Each groove has a different angle with the adjacent groove, but all the light rays are concentrated at the center focus, which is the focal point of the lens. Each groove can be regarded as an independent small lens that adjusts the light rays into parallel light or convergent light.

[0003] The commonly used projection Fresnel lens has a demolding surface, which causes total reflection when the light rays are incident on the exit surface at a large angle, resulting in energy loss and low light output efficiency. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a Fresnel lens, a structure design method thereof, an electronic device, and a storage medium. The original demolding surface is used as a refractive surface to deflect the light rays onto the total reflection surface to form collimated light rays, and the originally lost light energy is utilized, thereby improving the light output efficiency of the Fresnel lens.

[0005] To solve the above technical problems, the embodiments of the present application provide a Fresnel lens. The exit surface of the Fresnel lens is a smooth surface, and the entrance surface is engraved with a plurality of concentric circles with different radii. The longitudinal cross section of the plurality of concentric circles passes through the center of the circle and is continuous sawtooth-shaped. One side of each sawtooth corresponding to the two sides is a refractive surface, and the other side is a total reflection curved surface. When the incident light rays are incident on the refractive surface, the incident light rays are refracted to form refracted light rays. The refracted light rays are totally reflected by the total reflection curved surface of the same sawtooth to form collimated light rays and are emitted from the exit surface.

[0006] The embodiment of the present application further provides a structure design method of a Fresnel lens, which is applied to the Fresnel lens described in the above embodiment, and the method comprises the following steps: calculating a refraction relationship between an incident light ray, a refracted light ray and a first normal vector at an intersection point of the incident light ray and a refractive surface on the refractive surface based on optical design parameters of the Fresnel lens, and calculating a reflection relationship between the refracted light ray, a collimated light ray and a second normal vector at an intersection point of the refracted light ray and a total reflection surface on the total reflection surface; obtaining a collinear relationship between the refracted light ray and a unit vector of the refracted light ray, and obtaining a perpendicular relationship between the total reflection surface and the second normal vector; obtaining a point coordinate on the total reflection surface based on the refraction relationship, the reflection relationship, the collinear relationship and the perpendicular relationship; and determining the total reflection surface of the Fresnel lens and the refractive surface associated with the total reflection surface according to the point coordinate.

[0007] The embodiment of the present application further provides an electronic device, which comprises: at least one processor; and a memory connected with the at least one processor in communication; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the structure design method of the Fresnel lens described in the above embodiment.

[0008] The embodiment of the present application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the structure design method of the Fresnel lens mentioned in the above embodiment.

[0009] The Fresnel lens provided by the embodiment of the present application sets one side of each sawtooth of the Fresnel lens incident surface close to the center as a refractive surface, and sets the other side far from the center as a total reflection surface, so that when the incident light ray irradiates on the refractive surface, the incident light ray is refracted to form a refracted light ray, the refracted light ray irradiates on the total reflection surface belonging to the same sawtooth to be totally reflected, and the collimated light ray is emitted from the exit surface. That is, the present application sets the draft surface of the existing Fresnel lens as a refractive surface, and sets the refractive surface of the existing Fresnel lens as a total reflection surface, so that the light ray can be deflected to the total reflection surface to form a collimated light ray, and the lost light energy is utilized, thereby improving the light emission efficiency of the lens. BRIEF DESCRIPTION OF DRAWINGS

[0010] One or more embodiments are illustrated by way of example in the figures that form a part of this patent document, these example are not intended to limit the embodiments, elements having the same reference numbers in the figures indicate like elements, unless otherwise specifically noted, the figures in the drawings are not to scale.

[0011] Figure 1 is a sectional structure diagram of the existing conventional Fresnel lens;

[0012] Figure 2 is a light path diagram of a conventional Fresnel lens when a large-angle light is incident;

[0013] Figure 3 is a cross-sectional structure diagram of a Fresnel lens provided by the embodiments of the present application;

[0014] Figure 4 is a light path diagram of a Fresnel lens provided by the embodiments of the present application when a large-angle light is incident;

[0015] Figure 5 is a flow chart of a structure design method of a Fresnel lens provided by the embodiments of the present application;

[0016] Figure 6 is a calculation schematic diagram of a structure design method of a Fresnel lens provided by the embodiments of the present application;

[0017] Figure 7 is a structure schematic diagram of an electronic device provided by the embodiments of the present application. DETAILED DESCRIPTION

[0018] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. However, those skilled in the art can understand that, in the embodiments of the present application, many technical details are presented in order to make the readers better understand the present application. However, the technical solutions claimed by the present application can be implemented even without these technical details and based on various changes and modifications of the following embodiments.

[0019] The implementation details of the Fresnel lens and the structure design method thereof in the embodiments will be described below. The following content is only provided for the implementation details for the convenience of understanding, and is not necessary for implementing the present solution.

[0020] The exit surface of the currently commonly used Fresnel lens is a smooth surface, and the incident surface is engraved with a plurality of concentric circles with different radii. The longitudinal cross section of the plurality of concentric circles passing through the center of the circle is continuous sawtooth-shaped, and the sawtooth-shaped structure formed by the plurality of concentric circles is composed of two parts, as shown in Figure 1 The first area is a transmission part, including a transmission curved surface; the second area is a refraction part, composed of a plurality of sawteeth, each sawtooth including a draft surface and a refraction surface. The draft surface is a surface naturally formed during the manufacturing cutting process of the Fresnel lens, and is a major cause of energy loss. Figure 1The point O is the position of the light source. When the light ray is incident on the demolding surface at a large angle from the point O, the incident light ray is refracted to form a refracted light ray. The refracted light ray is emitted from the emitting surface and also undergoes total reflection on the emitting surface, resulting in light energy loss, so that the light emission efficiency of the Fresnel lens is low. Figure 2 FIG. 1 is a schematic diagram of the light path of the prior art Fresnel lens when the light is incident at a large angle.

[0021] The embodiment of the present application relates to a Fresnel lens, the emitting surface 10 is a light surface, and a plurality of concentric circles with different radii are engraved on the incident surface 20, as shown in FIG. 2. Figure 3 As shown in FIG. 3, the longitudinal cross-section of the plurality of concentric circles through the center of the circle is continuous sawtooth-shaped, and one side of each sawtooth near the center of the circle is a refractive surface 201, and the other side far from the center of the circle is a total reflection curved surface 202.

[0022] When the incident light ray is incident on the refractive surface 201, the incident light ray is refracted to form a refracted light ray. The refracted light ray undergoes total reflection on the total reflection curved surface 202 of the same sawtooth to form a collimated light ray and is emitted from the emitting surface 10. As shown in FIG. 4, it is a schematic diagram of the light path of the Fresnel lens of the present application when the light is incident at a large angle. As can be seen from the figure, the Fresnel lens provided by the present application can collimate the light ray emitted from the emitting surface without total reflection, thereby reducing the energy loss of the light ray and improving the light emission efficiency. Figure 4

[0023] Further, in the embodiment, the tooth tips of each sawtooth of the Fresnel lens are on the same horizontal line. That is, each sawtooth is equal in thickness. The surface of the smallest concentric circle of the incident surface of the Fresnel lens is a transmission curved surface 203. When the incident light ray is incident on the transmission curved surface 203, the incident light ray is refracted to form a collimated light ray and is emitted from the emitting surface 10.

[0024] The Fresnel lens provided by the embodiment can improve the light emission efficiency by 48.85% compared with the conventional Fresnel lens. When the focal length is small, the conventional Fresnel lens will produce a large amount of loss on the demolding surface when the light is incident at a large angle, resulting in a large amount of stray light generated at the edge. The light at the edge angle of the Fresnel lens provided by the present application can be well collimated from the total reflection surface, and the lens efficiency is greatly improved under the same focal length.

[0025] The embodiment of the present application relates to a structure design method of a Fresnel lens, which is applied to the Fresnel lens as described in the above embodiment, as shown in FIG. 6, and includes the following steps. Figure 5

[0026] ​​Step 101, based on the optical design parameters of the Fresnel lens, the incident light ray of the refractive surface, the refracted light ray and the first normal vector between the incident light ray and the refractive surface on the refractive surface are calculated, and the refracted light ray of the total reflection surface, the collimated light ray and the second normal vector between the refracted light ray and the total reflection surface on the total reflection surface are calculated.

[0027] In this embodiment, the optical design parameters of the Fresnel lens include: the refractive index n of the Fresnel lens, the maximum incident angle θ of the transmission surface max , the maximum radius R of the Fresnel lens max , the focal length h and the number of sampling points N. Wherein the refractive index n is determined by the material of manufacturing the Fresnel lens, the maximum incident angle of the transmission surface is the angle between OC0 and y axis, O point is the position of the light source, C0 point is the end point of the transmission surface. The focal length h is the distance from the light source O point to the center of the concentric circle.

[0028] As Figure 6 shown, C0, C1, C2,..., C i are the intersection points of the refractive surface x = l when the incident angle is α0, α1, α2,..., α i , wherein α0 = θ max . D0, D1, D2,..., D i are the intersection points of the light rays emitted from the refractive surface and the total reflection surface. E0, E1, E2,..., E i are the intersection points of the light rays emitted from the total reflection surface and the exit surface. That is, OC i is the incident light ray, C i D i is the refracted light ray, D i E i is the collimated light ray. The refractive relationship between the incident light ray OC i , the refracted light ray C i D i and the first normal vector between C i point on the refractive surface is calculated, and the reflection relationship between the refracted light ray C i D i , the collimated light ray D i E i and the second normal vector between D i point on the total reflection surface is calculated.

[0029] In an embodiment, the calculating of the refraction relationship between the incident light ray of the refractive surface, the refracted light ray and the first normal vector of the intersection point of the incident light ray and the refractive surface comprises: obtaining a unit vector of the incident light ray based on an incident angle of the incident light ray of the refractive surface; obtaining a refraction bias constant based on the refractive index in the optical design parameters, the unit vector of the incident light ray and the first normal vector; and obtaining the refraction relationship according to the refractive index, a unit vector of the refracted light ray, the unit vector of the incident light ray and the refraction bias constant.

[0030] wherein the incident angle of the incident light ray of the refractive surface is obtained according to the intersection point coordinate (x=l) of the incident light ray and the refractive surface, the maximum incident angle θ of the transmission surface in the optical design parameters, the focal length h and the sampling point number N. max The incident angle of the incident light ray of the refractive surface is obtained according to the intersection point coordinate (x=l) of the incident light ray and the refractive surface, the maximum incident angle θ of the transmission surface in the optical design parameters, the focal length h and the sampling point number N. i

[0031]

[0032] wherein the intersection point coordinate (x=l) of the incident light ray and the refractive surface can be obtained according to the horizontal coordinate of the end point C0 of the transmission surface after obtaining the point coordinate on the transmission surface. Further, the unit vector of the incident light ray is The first normal vector of the refractive surface through the point C i is Then the refraction bias constant K obtained according to the refractive index n, the unit vector and the first normal vector i is:

[0033]

[0034] Accordingly, the refraction relationship is obtained according to the vector form of the refraction law as follows:

[0035]

[0036] wherein is the unit vector of the refracted light ray C i D i .

[0037] In an embodiment, the calculating of the reflection relationship between the refracted light ray of the total reflection surface, the collimated light ray and the second normal vector of the intersection point of the refracted light ray and the total reflection surface comprises: obtaining the unit vector of the refracted light ray according to the refraction relationship; and obtaining the reflection relationship according to the refractive index in the optical design parameters, the unit vector of the collimated light ray, the unit vector of the refracted light ray and the second normal vector.

[0038] ​According to formula (3), the unit vector of the refracted ray can be obtained. for:

[0039]

[0040] Then, according to the refracted ray C i D i unit vector Collimated ray D i E i The unit vector (0,1) on the total reflection surface via D i The second normal vector of the point The reflection relationship can be obtained as follows:

[0041]

[0042] Step 102: Obtain the collinearity between the unit vectors of the refracted rays and the total internal reflection surface and the second normal vector.

[0043] In this embodiment, point D on the total internal reflection surface i The coordinates are (X i Y i Point C on the refracting surface i The coordinates are (l, l·cotα) i Refracted light Therefore, the collinear relationship can be expressed as:

[0044]

[0045] Furthermore, the total internal reflection surface is represented as The second normal vector is expressed as The vertical relationship is then expressed as:

[0046] (X i+1 -X i )·N Xi +(Y i+1 -Y i )·N Yi =0 (7)

[0047] Step 103: Based on the refraction relationship, reflection relationship, collinear relationship, and perpendicular relationship, obtain the coordinates of the points on the total reflection surface.

[0048] In this embodiment, based on the refraction relationship (Formula 3), reflection relationship (Formula 5), ​​collinearity relationship (Formula 6), and perpendicularity relationship (Formula 7), point D on the total internal reflection surface can be obtained. i The coordinates are (X i Y i ):

[0049]

[0050] In step 104, the total reflection surface of the Fresnel lens and the refractive surface associated with the total reflection surface are determined according to the point coordinates.

[0051] In this embodiment, the total reflection surface of the Fresnel lens can be obtained based on the point coordinates on the total reflection surface. Of course, the more the number of point coordinates, the more accurate the total reflection surface of the Fresnel lens obtained, that is, the greater the number of sampling points N, the more accurate the total reflection surface determined. Once the total reflection surface is determined, the corresponding refractive surface is also determined. In addition, the abscissa of the point coordinates on the total reflection surface is less than or equal to the maximum radius Rmax of the Fresnel lens in the optical design parameters.

[0052] The structure design method of the Fresnel lens provided by the embodiment of the application determines the total reflection surface and the refractive surface according to the refractive relationship, the reflection relationship, the collinear relationship and the perpendicular relationship, so that when the incident light is irradiated on the refractive surface, the incident light is refracted to form refracted light, the refracted light is totally reflected on the total reflection surface belonging to the same sawtooth to form collimated light, and the collimated light is emitted from the exit surface. That is, the present application takes the extraction surface of the existing Fresnel lens as the refractive surface, takes the refractive surface of the existing Fresnel lens as the total reflection surface, makes the light deflected to the total reflection surface to form collimated light, utilizes the originally lost light energy, and thus improves the light extraction efficiency of the lens.

[0053] The step division of the above various methods is only for the purpose of clear description. In implementation, one step can be combined or some steps can be split and decomposed into multiple steps, as long as the same logical relationship is included, which is within the protection scope of the patent. Irrelevant modifications or irrelevant designs can be added to the algorithm or the process, but the core design of the algorithm and the process is not changed, which is within the protection scope of the patent.

[0054] The embodiment of the application relates to an electronic device, such as Figure 7 as shown in the figure, comprising:

[0055] at least one processor 701; and a memory 707 connected with the at least one processor 701; wherein the memory 707 stores instructions executable by the at least one processor 701, and the instructions are executed by the at least one processor 701 to enable the at least one processor 701 to perform the design method of the Fresnel lens mentioned in the above embodiments.

[0056] The electronic device comprises one or more processors 701 and a memory 707, Figure 7 The processor 701, the memory 707 can be connected through a bus or other ways, Figure 7The bus is taken as an example. The memory 707 is a non-volatile computer readable storage medium, which can be used to store non-volatile software programs, non-volatile computer executable programs and modules. The processor 701 executes various functional applications and data processing of the device by running the non-volatile software programs, instructions and modules stored in the memory 707, that is, the design method of the Fresnel lens is realized.

[0057] The memory 707 can include a program storage area and a data storage area. The program storage area can store an operating system and at least one application required by a function; and the data storage area can store an option list and the like. In addition, the memory 707 can include a high-speed random access memory and can also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device or other non-volatile solid-state memory device. In some embodiments, the memory 707 can optionally include a memory remotely arranged relative to the processor 701, which can be connected to an external device through a network. Examples of the network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0058] One or more modules are stored in the memory 707 and executed by the one or more processors 701 to perform the structure design method of the Fresnel lens in any of the above embodiments.

[0059] The product described above can perform the method provided by the embodiments of the present application, has the corresponding functional modules and beneficial effects of performing the method, and the technical details not described in detail in the embodiments can be referred to the structure design method of the Fresnel lens provided by the embodiments of the present application.

[0060] The embodiments of the present application relate to a computer readable storage medium storing a computer program. The computer program is executed by a processor to implement an embodiment of the structure design method of the Fresnel lens.

[0061] That is, those skilled in the art can understand that all or part of the steps of the above-mentioned embodiment methods can be completed by programs instructing related hardware, the programs are stored in a storage medium, and include a plurality of instructions for causing a device (which can be a single-chip microcomputer, a chip, etc.) or a processor to execute all or part of the steps of the various embodiment methods of the present application. The foregoing storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk and various program code storage media.

[0062] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present application, and in actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application.

Claims

1. A method of designing a structure of a Fresnel lens, characterized by, The application is applied to a Fresnel lens, an exit surface of the Fresnel lens is a smooth surface, a plurality of concentric circles with different radii are engraved on an entrance surface, a longitudinal cross-section of the plurality of concentric circles through a circle center is continuous sawtooth-shaped, and one side of each sawtooth corresponding to two sides is a refractive surface, and the other side is a total reflection curved surface; when an incident light ray is irradiated on the refractive surface, the incident light ray is refracted to form a refracted light ray, the refracted light ray is totally reflected through the total reflection curved surface of the same sawtooth to form a collimated light ray and is emitted from the exit surface; The method comprises: Based on the optical design parameters of the Fresnel lens, the refractive relationship between the incident light ray of the refractive surface, the refracted light ray and the first normal vector of the intersection point of the incident light ray and the refractive surface on the refractive surface is calculated, and the reflection relationship between the refracted light ray, the collimated light ray and the second normal vector of the intersection point of the refracted light ray and the total reflection curved surface on the total reflection curved surface is calculated; The collinear relationship between the refracted light ray and the unit vector of the refracted light ray is obtained, and the perpendicular relationship between the total reflection curved surface and the second normal vector is obtained; Based on the refractive relationship, the reflection relationship, the collinear relationship and the perpendicular relationship, the point coordinates on the total reflection curved surface are obtained; The total reflection curved surface of the Fresnel lens and the refractive surface associated with the total reflection curved surface are determined according to the point coordinates.

2. The method of designing a Fresnel lens structure according to claim 1, wherein The calculation of the refractive relationship between the incident light ray of the refractive surface, the refracted light ray and the first normal vector of the intersection point of the incident light ray and the refractive surface on the refractive surface comprises: Based on the incident angle of the incident light ray of the refractive surface, the unit vector of the incident light ray is obtained; Based on the refractive index in the optical design parameters, the unit vector of the incident light ray and the first normal vector, a refractive deviation constant is obtained; According to the refractive index, the unit vector of the refracted light ray, the unit vector of the incident light ray and the refractive deviation constant, the refractive relationship is obtained.

3. The method of designing a Fresnel lens structure according to claim 1 or 2, characterized in that, The calculation of the reflection relationship between the refracted light ray, the collimated light ray and the second normal vector of the intersection point of the refracted light ray and the total reflection curved surface on the total reflection curved surface comprises: According to the refractive relationship, the unit vector of the refracted light ray is obtained; According to the refractive index in the optical design parameters, the unit vector of the collimated light ray, the unit vector of the refracted light ray and the second normal vector, the reflection relationship is obtained.

4. The method of designing a Fresnel lens structure according to claim 2, wherein The incident angle of the incident light ray of the refractive surface is obtained by the following steps: According to the intersection point coordinates of the incident light ray and the refractive surface, the maximum incident angle of the transmission curved surface in the optical design parameters, the focal length and the sampling point number, the incident angle of the incident light ray of the refractive surface is obtained.

5. The method of designing a Fresnel lens structure according to claim 1, wherein The abscissa of the point coordinates on the total reflection curved surface is less than or equal to the maximum radius of the Fresnel lens in the optical design parameters.

6. An electronic device, comprising: It comprises: At least one processor; And A memory connected in communication with the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the method for structural design of a Fresnel lens according to any one of claims 1 to 5.

7. A computer readable storage medium storing a computer program, characterized in that, The computer program, when executed by a processor, implements the method for structural design of a Fresnel lens according to any one of claims 1 to 5.

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