Refractive diffractive lens and method for manufacturing the same

Abstract

The present application provides a refractive-diffractive lens and a method for manufacturing the same. The refractive-diffractive lens comprises: a substrate having a first refractive surface and a second refractive surface opposite to each other along an optical axis; and a plurality of microstructured rings disposed on the first refractive surface with the optical axis as the center, the microstructured rings being discontinuous in the ring direction.

Description

Technical Field

[0001] The present application relates to the field of optical elements, and more specifically, to a refractive-diffractive lens, an optical imaging lens, and a method for manufacturing a refractive-diffractive lens. Background Art

[0002] In the existing display field, for example, optical imaging lenses refract light to produce a clear image on the imaging surface. However, the refractive properties of light of different wavelengths at the same location are not exactly the same, ultimately causing chromatic aberration in the image on the imaging surface.

[0003] When designing various display devices, adjustments to the optical path structure are often made to reduce or even eliminate chromatic aberration. For example, two or more lenses are used to form a cemented lens to achieve this goal. However, this method of eliminating chromatic aberration can increase aberration. To achieve a good final imaging effect, various performance aspects must be compromised. Furthermore, to improve image quality, the imaging device structure is often designed to be larger.

[0004] The industry needs an optical lens that has smaller chromatic aberration and at least one of the following effects: miniaturization, small aberration, and good resolution. Summary of the Invention

[0005] An embodiment of the present application provides a refractive-dioptric lens, which includes: a substrate having a first refractive surface and a second refractive surface opposite to each other along the optical axis; and a plurality of microstructure rings arranged at the first refractive surface with the optical axis as the center, and the microstructure rings are discontinuous in the ring direction.

[0006] In one embodiment, the first refractive surface includes a plurality of annular regions, wherein a plurality of microstructure rings are provided in the annular regions; the plurality of microstructure rings are used to cause phase delay of light passing through the microstructure rings along the optical axis.

[0007] In one embodiment, the microstructure ring includes a plurality of spaced microstructures arranged in a circumferential direction.

[0008] In one embodiment, the heights of the plurality of microstructures along the optical axis are consistent.

[0009] In one embodiment, among the plurality of microstructures, heights of some of the microstructures in the direction of the optical axis are inconsistent with heights of another portion of the microstructures in the direction of the optical axis.

[0010] In one embodiment, among the multiple microstructure rings, the radius difference between any two adjacent microstructure rings is the same.

[0011] In one embodiment, the multiple microstructure rings include a first microstructure ring, a second microstructure ring and a third microstructure ring arranged in sequence from the inside to the outside; the radius difference between the first microstructure ring and the second microstructure ring is different from the radius difference between the second microstructure ring and the third microstructure ring.

[0012] In one embodiment, the microstructures are cylinders.

[0013] In one embodiment, the plurality of microstructured rings include a first microstructured ring and a second adjacent microstructured ring; the diameter of the cylinder in the first microstructured ring is different from the diameter of the cylinder in the second microstructured ring.

[0014] In one embodiment, the microstructures are prisms.

[0015] In one embodiment, the prisms in a plurality of microstructure rings have the same shape.

[0016] In one embodiment, the prism has a pointing axis in a cross section perpendicular to the optical axis; and in each of the microstructure rings, the pointing axes of the prisms are parallel to each other.

[0017] In one embodiment, the plurality of microstructure rings include a first microstructure ring and a second adjacent microstructure ring; the directional axes of the prisms in the first microstructure ring are not parallel to the directional axes of the prisms in the second microstructure ring.

[0018] In one embodiment, the material of the plurality of microstructure rings is glue, silicon or titanium dioxide.

[0019] In one embodiment, the first refractive surface is a plane, a spherical surface, or a free-form surface.

[0020] In one embodiment, in each microstructure ring, glue exists between at least one pair of adjacent microstructures.

[0021] In one embodiment, in each microstructure ring, there is a gap between any pair of adjacent microstructures.

[0022] Another aspect of the present application provides an optical imaging lens, which includes: the aforementioned refractive diffractive lens.

[0023] The present application also provides a method for manufacturing a refractive diffractive lens, which includes: setting a substrate, the substrate having a first refractive surface and a second refractive surface opposite to each other along the optical axis; setting a plurality of microstructure rings at the first refractive surface of the substrate, wherein the microstructure rings are centered on the optical axis and are discontinuous in the ring direction.

[0024] In one embodiment, providing the plurality of microstructure rings includes: providing a prefabricated layer on the first refractive surface of the substrate; and etching the prefabricated layer to obtain the plurality of microstructure rings.

[0025] In one embodiment, the material of the prefabricated layer is glue, silicon or titanium dioxide.

[0026] In one embodiment, before setting the substrate, the method further includes: obtaining the preset optical focal length of the substrate of the refractive diffractive lens based on the preset optical focal length of the refractive diffractive lens, and obtaining the preset optical focal length of multiple microstructure rings of the refractive diffractive lens; and before setting the multiple microstructure rings, the method further includes: obtaining the parameters of the microstructure in each microstructure ring based on the preset optical focal length of the multiple microstructure rings.

[0027] The diffractive lens provided in the embodiments of the present application is relatively small in size, can achieve a good achromatic effect, and has a high resolution performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0029] Figure 1 shows a schematic structural diagram of a refractive diffractive lens according to an embodiment of the present application;

[0030] Figure 2 shows a schematic structural diagram of multiple microstructure rings according to an embodiment of the present application;

[0031] Figure 3 shows a schematic structural diagram of another microstructure ring according to an embodiment of the present application;

[0032] Figure 4 1 shows a schematic structural diagram of an optical imaging lens according to Comparative Example 1 of the present application;

[0033] Figure 5 shows a vertical axis chromatic aberration curve of the optical imaging lens according to Comparative Example 1;

[0034] Figure 6 shows an MTF diagram of the optical imaging lens according to Comparative Example 1;

[0035] Figure 7 1 shows a schematic structural diagram of an optical imaging lens according to the first embodiment of the present application;

[0036] Figure 8 shows a vertical axis chromatic aberration curve of the optical imaging lens according to Example 1;

[0037] Figure 9 shows an MTF diagram of the optical imaging lens according to the first embodiment;

[0038] Figure 10 1 shows a schematic structural diagram of an optical imaging lens according to comparative example 2 of the present application;

[0039] Figure 11 shows a vertical axis chromatic aberration curve of the optical imaging lens according to comparative example 2;

[0040] Figure 12 shows the MTF diagram of the optical imaging lens in the visible light region according to Comparative Example 2;

[0041] Figure 13 shows the MTF diagram of the optical imaging lens corresponding to the invisible light region according to Comparative Example 2;

[0042] Figure 14 shows a schematic structural diagram of an optical imaging lens according to the second embodiment of the present application;

[0043] Figure 15 shows a vertical axis chromatic aberration curve of the optical imaging lens according to Example 2;

[0044] Figure 16 shows the MTF diagram of the optical imaging lens in the visible light region according to the second embodiment;

[0045] Figure 17 shows the MTF diagram of the optical imaging lens corresponding to the invisible light region according to the second embodiment;

[0046] Figure 18 A block diagram of a method for manufacturing a refractive diffractive lens according to an embodiment of the present application is shown; and

[0047] Figure 19 A flow chart of a method for manufacturing a refractive diffractive lens according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0048] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of exemplary embodiments of the present application and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0049] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not represent any limitation of the features. Thus, without departing from the teachings of this application, the first microstructured ring discussed below could also be referred to as the second microstructured ring, and vice versa.

[0050] In the accompanying drawings, the thickness, size, and shape of components have been slightly adjusted for ease of illustration. The drawings are for illustration purposes only and are not drawn strictly to scale. For example, the height of the microstructure rings is not proportional to the thickness of the substrate as would be used in actual production. As used herein, the terms "substantially," "approximately," and similar terms are intended to indicate approximations, not degrees, and are intended to account for inherent variations in measurements or calculations that would be recognized by one of ordinary skill in the art.

[0051] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application." And, the term "exemplary" is intended to refer to an example or illustration.

[0052] Unless otherwise defined, all words used herein (including engineering terms and scientific and technological terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that, unless otherwise specified in this application, words defined in commonly used dictionaries should be interpreted as having the same meaning as they do in the context of the relevant technology, and should not be interpreted in an idealized or overly formal sense.

[0053] It should be noted that, unless otherwise specified or inconsistent with the context, the embodiments and features of the embodiments in this application may be combined with each other. Furthermore, unless expressly limited or inconsistent with the context, the specific steps included in the methods described in this application are not necessarily limited to the order in which they are described, but may be performed in any order or in parallel. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0054] refer to Figure 1 The folding diffraction lens 100 provided in the embodiment of the present application includes: a substrate 1 and a plurality of microstructure rings.

[0055] Figure 1 In the figure, the upper surface of the substrate 1 is a first refractive surface 11, and the lower surface is a second refractive surface 12. The outer periphery of the substrate 1 can be used for installation and positioning. The first refractive surface 11 and the second refractive surface 12 are arranged opposite each other along the optical axis L. A plurality of microstructured rings are arranged on the first refractive surface 11, such as the first microstructured ring 2, the second microstructured ring 3, and the third microstructured ring 4. These microstructured rings are centered around the optical axis L.

[0056] refer to Figure 2 and Figure 3 , these microstructure rings are discontinuous in the circumferential direction of the optical axis L. These microstructure rings are usually made in one piece on the first refractive surface 11 of the substrate 1, and the microstructure rings are fixed to the substrate 1. There is usually an air gap between adjacent microstructure rings, but it may also include, for example, residual glue. The microstructure ring has a very thin size in the direction of the optical axis L, for example, hundreds of nanometers. Generally speaking, the height of the residual glue is smaller than the height of the microstructure ring in the direction of the optical axis L. The spacing between adjacent microstructure rings is also small.

[0057] When using the refractive diffraction lens 100 provided in the embodiment of the present application, light can be incident along the optical axis L, specifically, it can be incident at the second refractive surface 12, or it can be incident at multiple microstructure rings. The substrate 1 mainly refracts the light, and the light can be refracted at the first refractive surface 11 and the second refractive surface 12. The multiple microstructure rings mainly diffract the light, causing the light to destructive or constructive at different positions in space. The substrate 1 will cause the light passing through it to have chromatic aberration, and the multiple microstructure rings will also cause the light passing through themselves to have chromatic aberration. Due to the opposite chromatic aberration characteristics between the substrate 1 and the multiple microstructure rings, when the light passes through the substrate 1 and then passes through the multiple microstructure rings (or passes through the substrate 1 after passing through the multiple microstructure rings). There is almost no chromatic aberration.

[0058] For example, the optical power of the substrate 1 is a, the optical power of the plurality of microstructure rings is b, and the total optical power of the refractive-diffractive lens 100 is c, then: c=a+b.

[0059] If the working wavelength range of the diffraction lens 100 is λ F ~λ C , the central wavelength is λ D , then the refractive diffractive lens 100 can satisfy:

[0060]

[0061]

[0062] Among them, f d are multiple microstructure rings at the central wavelength λ D focal length at r is the substrate 1 at the center wavelength λ D The focal length at the center wavelength λ is f, which is the focal length of the diffractive lens 100. D focal length at are multiple microstructure rings at wavelength λ F The focal length at are multiple microstructure rings at wavelength λ F The focal length at are multiple microstructure rings at wavelength λ C The focal length at is the substrate 1 at wavelength λ C The focal length at .

[0063] The focal length of the entire dioptric lens 100 can be determined according to the above formula, and the focal length of the substrate 1 and the focal lengths of the multiple microstructure rings can be calculated respectively, thereby making the dioptric lens 100 have an achromatic effect.

[0064] The refractive-diffractive lens 100 provided in the embodiments of the present application is thin in the direction of the optical axis L and has a small overall volume, capable of achieving achromatic aberration. This refractive-diffractive lens 100 can be used to form high-quality images with minimal aberrations. Furthermore, the discontinuous microstructure rings provide the refractive-diffractive lens 100 with higher resolution and better image resolution, and reduce stray light generation when the refractive-diffractive lens 100 is positioned in an optical path.

[0065] refer to Figure 1 In an exemplary embodiment, the first refractive surface 11 is a plane. Optionally, the first refractive surface 11 may be a spherical surface or a free-form surface. Exemplarily, the second refractive surface 12 is a convex surface, and specifically a spherical surface. Optionally, the second refractive surface 12 may be a concave surface or a plane; alternatively, the second refractive surface 12 may be an aspherical surface or a free-form surface. The two refractive surfaces of the substrate 1 are used to refract light, and their specific shapes can be adjusted according to needs.

[0066] In an exemplary embodiment, the material of the plurality of microstructure rings is glue, silicon or titanium dioxide.

[0067] In an exemplary embodiment, the microstructure ring includes a plurality of microstructures spaced apart and arranged in a circular direction. Figure 2 The first microstructure ring 2 includes first and second microstructures 21 and 22 arranged circumferentially, and the second microstructure ring 3 includes third and fourth microstructures 31 and 32 arranged circumferentially. The first and second microstructure rings 2 and 3 may each further include more microstructures arranged circumferentially. The distance between adjacent microstructures within a microstructure ring may be the same or different.

[0068] refer to Figure 2 In an exemplary embodiment, the microstructures are cylinders. For example, the microstructures within the same microstructure ring have the same morphology, such as cylinders.

[0069] In an exemplary embodiment, the plurality of microstructured rings includes a first microstructured ring 2 and a second microstructured ring 3 adjacent to each other; the diameter of the cylinder in the first microstructured ring 2 is different from the diameter of the cylinder in the second microstructured ring 3 .

[0070] In an exemplary embodiment, the heights of the microstructures may be the same or different. For example, the microstructures within the same microstructure ring may have the same height. Alternatively, the multiple microstructures may be divided into multiple sections, each section having a different height. The height of a microstructure refers to its dimension along the optical axis.

[0071] In an exemplary embodiment, the radius difference between any two adjacent microstructure rings in the plurality of microstructure rings is the same. In a cross section perpendicular to the optical axis L, the cross-sectional shape of the microstructure generally has a centroid. Figure 1 and Figure 2 For example, the first microstructure 21 is a cylinder having a circular cross section in a cross section perpendicular to the optical axis L. The distance between the center of the circular cross section and the optical axis L is the radius of the first microstructure ring 2. The difference between the radius R2 of the first microstructure ring 2 and the radius R3 of the second microstructure ring 3 can be equal to the difference between the radius of the second microstructure ring 3 and the third microstructure 4.

[0072] Exemplarily, the multiple microstructure rings include a first microstructure ring 2, a second microstructure ring 3 and a third microstructure ring 4 arranged in sequence from the inside to the outside; the radius difference between the first microstructure ring 2 and the second microstructure ring 3 is different from the radius difference between the second microstructure ring 3 and the third microstructure ring 4.

[0073] In an exemplary embodiment, when the microstructure is a cylinder, a plurality of microstructure rings may constitute a microstructure that can realize encoding. The diameter of the cylinder can be obtained by screening the finite difference time domain algorithm. Specifically, the axis of the cylinder is parallel to the optical axis L, the height of the cylinder is within 400nm to 800nm, and the diameter is within 20nm to 400nm. Furthermore, the period of the plurality of cylinders arranged in sequence is within 100nm to 450nm. The incident light may have different phases after passing through microstructures of different diameters. Specifically, a microstructure in the form of a cylinder may have eight configurations. These eight configurations correspond to eight gradient phases from pi / 4 to 2π, respectively. As shown in Table 1:

[0074] Table 1 Phase delay of different cylindrical configurations

[0075]

[0076] refer to Figure 3 In an exemplary embodiment, the microstructures are prisms. Exemplarily, the microstructures within the same microstructure ring have the same morphology.

[0077] In an exemplary embodiment, the shapes of the prisms in the plurality of microstructure rings are the same.

[0078] Exemplarily, the prism has a polygonal cross section in a cross section perpendicular to the optical axis L, and the distance between the center of the minimum circumscribed circle of the polygon and the optical axis L is the radius of the microstructure ring where the prism is located.

[0079] In an exemplary embodiment, the prisms have a major axis and a minor axis that are perpendicular to each other in a cross section perpendicular to the optical axis L. The major axis serves as the directional axis of the prism. For example, the prisms may be square in a cross section perpendicular to the optical axis. Within each microstructure ring, the major axes of the prisms are parallel to each other. The dimension of the prisms along their major axis may be greater than or equal to their dimension along their minor axis.

[0080] Exemplarily, the substrate 1 may be divided into a plurality of annular regions, specifically, a first annular region 101 and a second annular region 102. In particular, a circular region may be provided at the optical axis.

[0081] Each annular region may be provided with multiple microstructure rings. For example, the first annular region 101 may be provided with eight microstructure rings, including a first microstructure ring 2, a second microstructure ring 3, and a third microstructure ring 4. Light passing through adjacent microstructure rings has a phase delay.

[0082] refer to Figure 3 The prism is a quadrangular prism. In the exemplary embodiment, the first microstructure ring 2 includes a first microstructure 21 and a second microstructure 22. The first microstructure 21 has a rectangular cross-section in a cross section perpendicular to the optical axis L. The first microstructure 21 has a first major axis 21a along the length of the rectangle. Meanwhile, the second microstructure 22 has a second major axis 22a. The first major axis 21a is parallel to the second major axis 22a.

[0083] In an exemplary embodiment, the plurality of microstructure rings includes a first microstructure ring 2 and a second microstructure ring 3 adjacent to each other; the major axes of the prisms in the first microstructure ring 2 are non-parallel to the major axes of the prisms in the second microstructure ring 3. For example, the first microstructure 21 in the first microstructure ring 2 has a first major axis 21a, and the third microstructure 31 in the second microstructure ring 3 has a third major axis 31a. The fifth microstructure 41 in the third microstructure ring 4 has a fifth major axis 41a. The first major axis 21a, the third major axis 31a, and the fifth major axis 41a are non-parallel to each other.

[0084] In an exemplary embodiment, when the microstructure is a prism, a plurality of microstructure rings may constitute a microstructure that can realize encoding. The specific parameters of the prism may be obtained by screening the finite difference time domain method algorithm. Specifically, the height of the prism in the direction of the optical axis L may be in the range of 300nm to 1000nm. For example, the height is 580nm, and the length and width of the prism may be between 20nm and 400nm. The period of the plurality of continuous prisms may be 400nm. Figure 3 The prisms in the first microstructure ring 2 may have configuration 1, and the prisms in the second microstructure ring 3 may have configuration 2. The microstructures in the form of prisms may have eight configurations, as shown in Table 2:

[0085] Table 2 Phase retardation of different prism configurations

[0086]

[0087] According to the phase coefficients calculated in the ZEMEX software, specifically including the quadratic coefficient A1 and the quartic coefficient A2, the normalized radius r of the kth ring zone from the inside to the outside in the radial direction of the optical axis L in the multiple microstructure rings can be obtained. k for:

[0088]

[0089] In addition, the normalized radius in the ZEMEX software is R, and the ratio of the radius of the diffraction surface to the normalized radius R in the ZEMEX software is the normalized radius r0 of the diffraction surface. Thus, the radius k' of the kth microstructure ring satisfies:

[0090] r k’ =Rr k (4).

[0091] The maximum number of microstructure rings K max Can meet:

[0092]

[0093] The following is combined with Figures 4 to 17 The comparative examples and embodiments provided in this application are described in detail.

[0094] Comparative Example 1

[0095] refer to Figure 4 The optical imaging lens of this comparative example includes a first lens E1, a second lens E2, a third lens E3, an aperture, a fourth lens E4, a fifth lens E5, a sixth lens E6 and a filter E7, which are arranged in sequence from the object side to the image side.

[0096] The object-side surface of the first lens E1 may be convex, and the image-side surface may be concave. The object-side surface of the second lens E2 may be concave, and the image-side surface may be concave. The object-side surface of the third lens E3 may be convex, and the image-side surface may be convex. The object-side surface of the fourth lens E4 may be convex, and the image-side surface may be convex. The object-side surface of the fifth lens E5 may be concave, and the image-side surface may be concave. The object-side surface of the sixth lens E6 may be convex, and the image-side surface may be convex.

[0097] The second lens E2 and the third lens E3 are cemented into a first cemented lens, and the fourth lens E4 and the fifth lens E5 are cemented into a second cemented lens.

[0098] Figure 5 : is the vertical axis chromatic aberration curve of this comparative example, where the reference wavelength is 0.546070 μm. Figure 6 is the resolution (MTF) of this comparative example, specifically, the MTF in the wavelength range of 0.4358 μm to 0.6563 μm.

[0099] Example 1

[0100] Referring to Comparative Example 1, the optical imaging lens of this embodiment is obtained by replacing the fourth lens element E4 and the fifth lens element E5 in Comparative Example 1 with the refractive diffractive lens 100 and adjusting the position of the imaging plane. The overall length of the optical imaging lens of this embodiment is shortened by approximately 1 mm compared to the overall length of the optical imaging lens of Comparative Example 1.

[0101] refer to Figure 7 The first refractive surface 11 of the diffractive lens 100 faces the image side, and the second refractive surface 12 faces the object side. The first refractive surface 11 can be flat, and the second refractive surface 12 can be convex. Multiple microstructured rings are provided on the first refractive surface 11. The parameters of the multiple microstructured rings are shown in Table 3. The normalized radius is the value of R.

[0102] Table 3

[0103]

[0104] As shown in Table 3, the phase coefficient A1 is -414.687 and the phase coefficient A2 is 40.179. Substituting the data in Table 3 into formulas (4) and (5) yields: K max The value of is 62, the maximum microstructure ring width (radius difference) is 246μm, and the minimum microstructure ring width (radius difference) is 16μm. The details are shown in Table 4:

[0105] Table 4

[0106]

[0107]

[0108] For example, each microstructure ring in an annular region can achieve eight phase delays. For example, each microstructure ring in an annular region can achieve any delay less than eight phases. The microstructure ring can be a cylindrical microstructure or a prismatic microstructure.

[0109] Figure 8: is the vertical axis chromatic aberration curve of this comparative example, where the reference wavelength is 0.546070 μm. Figure 9 is the resolution (MTF) of this comparative example, specifically the MTF in the wavelength range of 0.4358μm to 0.6563μm. Compared to Comparative Example 1, the optical imaging lens of this embodiment is smaller in size while maintaining substantially unchanged vertical axial chromatic aberration and resolution.

[0110] Comparative Example 2

[0111] refer to Figure 10 This comparative example provides an optical imaging lens that can be used in the visible light region and near-infrared region. The optical imaging lens includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, and a sixth lens E6, arranged in order from the object side to the image side.

[0112] The object-side surface of the first lens E1 may be convex, and the image-side surface may be concave. The object-side surface of the second lens E2 may be concave, and the image-side surface may be concave. The object-side surface of the third lens E3 may be convex, and the image-side surface may be convex. The object-side surface of the fourth lens E4 may be convex, and the image-side surface may be convex. The object-side surface of the fifth lens E5 may be convex, and the image-side surface may be concave. The object-side surface of the sixth lens E6 may be convex, and the image-side surface may be concave.

[0113] The second lens E2 and the third lens E3 are cemented together to form a first cemented lens, and the fifth lens E5 and the sixth lens E6 are cemented together to form a second cemented lens.

[0114] refer to Figure 11 、 Figure 12 、 Figure 13 The optical imaging lens has large vertical chromatic aberration and low resolution. The MTF of the optical imaging lens in the visible light region is as follows: Figure 12 As shown in Figure 1, specifically, it is the MTF corresponding to the wavelength range of 400nm to 700nm. The MTF of the optical imaging lens in the near infrared region is as follows: Figure 13 As shown, it specifically corresponds to the MTF in the wavelength range of 700nm to 900nm.

[0115] Example 2

[0116] Referring to Comparative Example 2, the image-side surface of the fifth lens element E5 in Comparative Example 2 is set to a flat surface, resulting in an adjusted fifth lens element E5'. The sixth lens element E6 is replaced with a refractive-diffractive lens 100, and the position of the imaging surface is adjusted to obtain the optical imaging lens of this embodiment. The adjusted fifth lens element E5' and the refractive-diffractive lens 100 are not cemented together. The overall length of the optical imaging lens of this embodiment is approximately 1 mm longer than that of the optical imaging lens of Comparative Example 2.

[0117] refer to Figure 14The first refractive surface 11 of the folding diffractive lens 100 faces the object side, and the second refractive surface 12 faces the image side. The first refractive surface 11 can be a plane, and a plurality of microstructure rings are provided on the first refractive surface 11. The second refractive surface 12 can be a concave surface. The parameters of the plurality of microstructure rings are shown in Table 5:

[0118] Table 5

[0119] category Number of items Normalized radius Quadratic term Binay2 4 100 -9.696322E+004 category quartic term Sixth term Octant Binay2 -3.285388E+006 1.675726E+009 1.435377E+011

[0120] As shown in Table 5, the phase coefficient A1 is -96963.22, and the phase coefficient A2 is -3285388. Substituting the data in Table 5 into formulas (4) and (5) yields: K max The value of is 63, the largest microstructure ring width is 800μm, and the smallest microstructure ring width is 58μm.

[0121] For example, each annular region can achieve a delay of less than or equal to eight phases. In the microstructure ring within the annular region, a microstructure in the form of a cylinder or a microstructure in the form of a prism can be selected.

[0122] The vertical axis chromatic aberration of the optical imaging lens of this embodiment is as follows Figure 15 As shown, its vertical axis chromatic aberration is smaller than that of comparative example 2. The MTF of the optical imaging lens of this embodiment in the visible light region is as follows: Figure 16 As shown, the MTF in the near infrared region is Figure 17 The resolution performance of the optical imaging lens of this embodiment is greatly improved compared with that of the comparative example 2.

[0123] refer to Figure 18 The present invention also provides a method 1000 for manufacturing a refractive-diffractive lens, the method comprising the following steps:

[0124] S1010 , providing a substrate, wherein the substrate has a first refractive surface and a second refractive surface opposite to each other along an optical axis direction.

[0125] S1020, disposing a plurality of microstructure rings on the first refractive surface of the substrate, wherein the microstructure rings are centered on the optical axis and are discontinuous in the ring direction.

[0126] The microstructured ring typically needs to be fixedly connected to the substrate. A generative approach can be used to manufacture the microstructured ring. Due to its small size, etching can reduce the processing difficulty.

[0127] refer to Figure 19 In an exemplary embodiment, the method 2000 for manufacturing a refractive diffractive lens may include the following steps:

[0128] S2010 , providing a substrate, wherein the substrate has a first refractive surface and a second refractive surface opposite to each other along an optical axis direction.

[0129] S2020, setting a prefabricated layer on the first refractive surface of the substrate.

[0130] S2030, etching the prefabricated layer. The etched prefabricated layer may form a plurality of microstructure rings.

[0131] Exemplarily, the material of the prefabricated layer may be glue, silicon or titanium dioxide.

[0132] In an exemplary embodiment, a method of manufacturing a diffractive lens may include the following steps:

[0133] A substrate is provided, wherein the substrate has a first refractive surface and a second refractive surface opposite to each other along an optical axis direction.

[0134] A silicon layer or a titanium dioxide layer is disposed on the first refractive surface of the substrate.

[0135] A mask is placed on the silicon layer or the titanium dioxide layer, and covers the area where a plurality of microstructure rings are to be formed along the optical axis.

[0136] The silicon layer or titanium dioxide layer is etched to form a plurality of microstructure rings.

[0137] Remove the mask.

[0138] Illustratively, before setting the substrate, the method further includes: obtaining a preset optical focal length of the substrate and a preset optical focal length of the plurality of microstructure rings based on a preset optical focal length of the refractive-diffractive lens.

[0139] Before setting the multiple microstructure rings, the method further includes: obtaining parameters of the microstructure in each microstructure ring based on the preset optical powers of the multiple microstructure rings.

[0140] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of protection involved in this application is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also includes other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the technical concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions in this application.

Claims

1. A diffractive lens, characterized in that: include: A substrate having a first refractive surface and a second refractive surface opposite to each other along an optical axis, wherein the substrate is a refractive mirror having optical power; as well as a plurality of microstructure rings, arranged on the first refractive surface with the optical axis as the center, wherein the microstructure rings are discontinuous in the ring direction; The central wavelength of the working wavelength range of the refractive diffractive lens is λ D , the diffractive lens satisfies: Among them, f d The central wavelength λ of the multiple microstructure rings D focal length at r The substrate at the center wavelength λ D The focal length at the center wavelength λ is f, which is the focal length of the diffractive lens. D focal length at In which, the first refractive surface includes multiple annular areas, and several microstructure rings are arranged in the annular areas; the several microstructure rings in the annular areas are used to make the light passing through them along the optical axis have eight phase delays, and the eight phase delays include eight gradient phases from π / 4 to 2π.

2. The diffractive lens according to claim 1, wherein: The microstructure ring includes a plurality of spaced microstructures arranged along a ring direction.

3. The diffractive lens according to claim 2, wherein: The heights of the plurality of microstructures in the direction of the optical axis are consistent.

4. The diffractive lens according to claim 2, wherein: Among the plurality of microstructures, heights of some of the microstructures in the direction of the optical axis are inconsistent with heights of another portion of the microstructures in the direction of the optical axis.

5. The diffractive lens according to claim 2, wherein: Among the multiple microstructure rings, the radius difference between any two adjacent microstructure rings is the same.

6. The diffractive lens according to claim 2, wherein: The multiple microstructure rings include a first microstructure ring, a second microstructure ring and a third microstructure ring arranged in sequence from the inside to the outside; A radius difference between the first microstructure ring and the second microstructure ring is different from a radius difference between the second microstructure ring and the third microstructure ring.

7. The diffractive lens according to claim 2, wherein: The microstructures are cylinders.

8. The dioptric lens according to claim 7, wherein: The plurality of microstructure rings include a first microstructure ring and a second adjacent microstructure ring; The diameter of the cylinder in the first microstructure ring is different from the diameter of the cylinder in the second microstructure ring.

9. The diffractive lens according to claim 2, wherein: The microstructures are prisms.

10. The dioptric lens according to claim 9, wherein: The prisms in the plurality of microstructure rings have the same shape.

11. The dioptric lens according to claim 9, wherein: The prism has a pointing axis in a cross section perpendicular to the optical axis; In each of the microstructure rings, the directional axes of each of the prisms are parallel to each other.

12. The dioptric lens according to claim 11, wherein: The plurality of microstructure rings include a first microstructure ring and a second adjacent microstructure ring; The directional axes of the prisms in the first microstructure ring are not parallel to the directional axes of the prisms in the second microstructure ring.

13. The dioptric lens according to claim 1, wherein: The material of the multiple microstructure rings is glue, silicon or titanium dioxide.

14. The dioptric lens according to claim 1, wherein: The first refractive surface is a plane, a spherical surface or a free-curved surface.

15. The dioptric lens according to claim 2, wherein: In each of the microstructure rings, residual glue exists between at least one pair of adjacent microstructures.

16. The diffractive-refracting lens according to claim 2, wherein: In each of the microstructure rings, there is a gap between any pair of adjacent microstructures.

17. An optical imaging lens, characterized in that: include: A diffractive lens as claimed in any one of claims 1 to 16.

18. A method for manufacturing the diffractive lens according to any one of claims 1 to 16, characterized in that: include: Provide a substrate having a first refractive surface and a second refractive surface opposite to each other along the optical axis; A plurality of microstructure rings are provided on the first refractive surface of the substrate, wherein the microstructure rings are centered on the optical axis and are discontinuous in a ring direction; In which, the first refractive surface includes multiple annular areas, and several microstructure rings are arranged in the annular areas; the several microstructure rings in the annular areas are used to make the light passing through them along the optical axis have eight phase delays, and the eight phase delays include eight gradient phases from π / 4 to 2π.

19. The method according to claim 18, wherein The step of providing a plurality of microstructure rings comprises: Disposing a prefabricated layer on the first refractive surface of the substrate; The prefabricated layer is etched to obtain the plurality of microstructure rings.

20. The method according to claim 19, wherein The material of the prefabricated layer is glue, silicon or titanium dioxide.

21. The method according to claim 18, wherein Before the base is set, the method further comprises: Based on the preset optical power of the refractive-diffractive lens, obtaining the preset optical power of the substrate of the refractive-diffractive lens and obtaining the preset optical power of the multiple microstructure rings of the refractive-diffractive lens; Before the setting of the plurality of microstructure rings, the method further comprises: The parameters of the microstructure in each of the microstructure rings are obtained based on the preset optical powers of the multiple microstructure rings.

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