Zoom lens

Abstract

A zoom lens includes a first metalens and a second metalens arranged sequentially along the optical axis from the magnification side to the reduction side. The first metalens has a first phase distribution, and the second metalens has a second phase distribution. The first and second phase distributions are conjugate to each other, and their superposition forms a superimposed phase distribution with moiré patterns. The first and second metalenses are adapted to rotate relative to each other along the optical axis. This zoom lens improves focusing performance and allows for a reduction in lens size.

Description

Technical Field

[0001] This invention relates to a lens, and more particularly to a zoom lens. Prior Technology

[0002] Lenses are typically composed of multiple lens elements and can be categorized into prime lenses and zoom lenses based on whether they can change the focal length. For zoom lenses, the common zoom mechanism involves moving the lenses, changing the relative distance between them to achieve the zoom effect. Zoom lenses are generally larger, and current trends in lens design focus on miniaturization and weight reduction. Therefore, lens manufacturers concentrate on designing suitable lens architectures to reduce weight and size. However, achieving these advantages often comes at the cost of image quality. Thus, designing lenses with good image quality while balancing size and weight remains a significant challenge for lens manufacturers. Summary of the Invention

[0003] This invention provides a zoom lens to improve focusing performance and reduce lens size.

[0004] The zoom lens provided by this invention includes a first metalens and a second metalens arranged sequentially along the optical axis from the magnification side to the reduction side. The first metalens has a first phase distribution, and the second metalens has a second phase distribution. The first phase distribution and the second phase distribution are conjugate to each other, and the superposition of the first phase distribution and the second phase distribution forms a superimposed phase distribution. The superimposed phase distribution has a moiré pattern, and the first metalens and the second metalens are adapted to rotate relative to each other along the optical axis.

[0005] In one embodiment of the present invention, the first meta-lens includes opposing first and second surfaces and a plurality of first phase adjustment structures, wherein the first surface is closer to the magnification side, and the plurality of first phase adjustment structures are disposed on the first or second surface, and are adapted to give the first meta-lens a first phase distribution. The second meta-lens includes opposing third and fourth surfaces and a plurality of second phase adjustment structures, wherein the fourth surface is closer to the reduction side, and the plurality of second phase adjustment structures are disposed on the third or fourth surface, and are adapted to give the second meta-lens a second phase distribution.

[0006] In one embodiment of the present invention, the plurality of first phase adjustment structures described above are disposed on the second surface, and the plurality of second phase adjustment structures are disposed on the third surface.

[0007] In one embodiment of the present invention, the plurality of first phase adjustment structures described above are disposed on a first surface, and the plurality of second phase adjustment structures are disposed on a fourth surface.

[0008] In one embodiment of the present invention, the plurality of first phase adjustment structures described above are disposed on a first surface, and the plurality of second phase adjustment structures are disposed on a third surface.

[0009] In one embodiment of the present invention, the plurality of first phase adjustment structures described above are disposed on the second surface, and the plurality of second phase adjustment structures are disposed on the fourth surface.

[0010] In one embodiment of the present invention, the superimposed phase distribution has multiple concentrically distributed phases, each phase having multiple phase orders, wherein each phase order is less than 1.3 radians.

[0011] In one embodiment of the present invention, the material of the first superlens is silicon or germanium, and the material of the second superlens is silicon or germanium.

[0012] In one embodiment of the present invention, the first phase distribution of the first meta-lens conforms to formula (I), where Φ1 is the phase of the first meta-lens, ρ1 is the radius of the first meta-lens, and A1 and A2 are parameters, where A1 = +32.7249 and A2 = -0.0409. Φ1 = A1ρ12 + A2ρ14 Formula (I)

[0013] In one embodiment of the present invention, the second phase distribution of the second superlens conforms to formula (I), where Φ2 is the phase of the second superlens, ρ2 is the radius of the second superlens, and A1 and A2 are parameters, where A1 = +32.7249 and A2 = -0.0409. Φ 2=A1ρ 2 2+A2ρ 2 4 Formula (I)

[0014] The present invention employs a first super-lens and a second super-lens suitable for relative rotation, thereby improving the focusing effect and reducing the lens size.

[0015] To make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings for detailed explanation. Simple Explanation of the Diagram

[0016] Figure 1 is a perspective view of a zoom lens according to an embodiment of the present invention. Figure 2 is a schematic diagram of the phase distribution and focal length in the zoom lens space according to an embodiment of the present invention. Figure 3 is a schematic diagram of the phase distribution and focal length in the zoom lens space according to an embodiment of the present invention. Figure 4 is a schematic diagram of the phase distribution and focal length in the zoom lens space according to an embodiment of the present invention. Figure 5 is a schematic diagram of the phase distribution along the cross section AA in Figure 2. Figure 6 is a schematic diagram showing the relationship between phase order and focusing efficiency. Figures 7 to 9 are perspective schematic diagrams of a zoom lens according to another embodiment of the present invention. Implementation

[0017] Figure 1 is a schematic diagram of the configuration of a zoom lens according to an embodiment of the present invention. Figure 2 is a schematic diagram of the spatial phase distribution and focal length of a zoom lens according to an embodiment of the present invention. Referring to Figures 1 and 2, the zoom lens 100 of this embodiment includes a first metalens 110 and a second metalens 120 arranged sequentially along the optical axis OA from the magnification side to the reduction side. The first metalens 110 has a first phase distribution P1, and the second metalens 120 has a second phase distribution P2. The first phase distribution P1 and the second phase distribution P2 are conjugate to each other, and the first phase distribution P1 and the second phase distribution P2 are superimposed to form a superimposed phase distribution P3. The superimposed phase distribution P3 has moiré patterns, and the first metalens 110 and the second metalens 120 are adapted to rotate relative to each other along the optical axis OA.

[0018] Specifically, in this embodiment, the zoom lens 100 changes the superimposed phase distribution P3 by rotating the first meta-lens 110 and the second meta-lens 120 relative to each other along the optical axis OA, thereby achieving the effect of changing the focus position. Furthermore, since the zoom effect can be achieved without changing the relative positions of the first meta-lens 110 and the second meta-lens 120, the size of the zoom lens 100 in this embodiment can be reduced.

[0019] The aforementioned first metalens 110 includes, for example, opposing first surfaces 111 and second surfaces 112, and a plurality of first phase adjustment structures 113. The first surface 111 is closer to the magnification side. The first phase adjustment structures 113 can be disposed on either the first surface 111 or the second surface 112, and are adapted to give the first metalens 110 a first phase distribution P1. This embodiment uses the example of the first phase adjustment structure 113 being disposed on the second surface 112. Furthermore, the second metalens 120 includes, for example, opposing third surfaces 121 and fourth surfaces 122, and a plurality of second phase adjustment structures 123. The fourth surface 122 is closer to the reduction side. The second phase adjustment structures 123 can be disposed on either the third surface 121 or the fourth surface 122, and are adapted to give the second metalens 120 a second phase distribution P2. This embodiment uses the example of the second phase adjustment structure 123 being disposed on the third surface 121. In addition, the first phase adjustment structure 113 of this embodiment includes, for example, multiple subwavelength structures of different sizes, and the second phase adjustment structure 123 of this embodiment also includes, for example, multiple subwavelength structures of different sizes, but the present invention does not impose specific limitations on this.

[0020] On the other hand, in this embodiment, the material of the first meta-lens 110 is, for example, silicon or germanium, and the material of the second meta-lens 120 is, for example, silicon or germanium, thus the zoom lens 100 is an infrared zoom lens. The incident light suitable for the above-mentioned infrared zoom lens is, for example, mid-infrared light, with an incident light wavelength, for example, between 8μm and 14μm. However, the present invention does not specifically limit the materials of the first meta-lens 110 and the second meta-lens 120, nor does it limit the wavelength band of the incident light.

[0021] In this embodiment, the first phase distribution P1 of the first meta-lens 110 conforms to formula (I), where Φ 1 is the phase of the first meta-lens 110, ρ 1 is the radius of the first meta-lens 110, and A1 and A2 are parameters, where A1 = +32.7249 and A2 = -0.0409. Φ1 = A1ρ12 + A2ρ14 Formula (I) In this embodiment, the second phase distribution P2 of the second meta-lens 120 conforms to formula (I), where Φ 2 is the phase of the second meta-lens 120, ρ 2 is the radius of the second meta-lens 120, and A1 and A2 are parameters, where A1 = +32.7249 and A2 = -0.0409. Φ 2=A1ρ 2 2+A2ρ 2 4 Formula (I)

[0022] In this embodiment, taking the first meta-lens 110 as an example, for example, a first phase distribution P1 is first designed, and then, for example, a first phase adjustment structure 113 corresponding to each phase is selected from a structure database. Then, multiple first phase adjustment structures 113 are fabricated on the first meta-lens 110 using a semiconductor process. The first meta-lens 110 of the zoom lens 100 in this embodiment can be fabricated using a semiconductor process, which includes, for example, photolithography and etching processes, but this invention does not impose specific limitations on this. The second meta-lens 120 of the zoom lens 100 in this embodiment can also be fabricated using the above method, and will not be described in detail here.

[0023] Please continue referring to Figures 1 and 2. In this embodiment, taking the rotation of the second metalens 120 as an example, when facing the fourth surface 122, the second metalens 120 is rotated counterclockwise, and the rotation angle is represented by θ, for example. Figure 3 is a schematic diagram of the phase distribution and focal length in the zoom lens space according to an embodiment of the present invention. Figure 4 is a schematic diagram of the phase distribution and focal length in the zoom lens space according to an embodiment of the present invention. For example, as shown in Figures 1 and 2, the first metalens 110 and the second metalens 120 are rotated relative to each other along the optical axis OA. When the rotation angle θ is, for example, 45°, the first phase distribution P1 and the second phase distribution P2 are superimposed to form, for example, a superimposed phase distribution P3. In the light focusing schematic diagram in Figure 2, the point of maximum light intensity is marked by arrow W1, which is the focal point of the light. At this time, the focal length F is, for example, 12.55 mm. Continuing from the previous description, referring to Figure 3, the first meta-lens 110 and the second meta-lens 120 are rotated relative to each other along the optical axis OA. When the rotation angle θ is, for example, 90°, the change in the relative rotation angle of the first meta-lens 110 and the second meta-lens 120 causes the superimposed phase to change, for example, from the superimposed phase distribution P3 to the superimposed phase distribution P3a. As shown by arrow W2 in the light focusing diagram of Figure 3, the focal length F at this time is, for example, 6.32 mm. Referring to Figure 4, the first meta-lens 110 and the second meta-lens 120 are rotated relative to each other along the optical axis OA. When the rotation angle θ is, for example, 135°, the superimposed phase changes, for example, to the superimposed phase distribution P3b. As shown by arrow W3 in the light focusing diagram of Figure 4, the focal length F at this time is, for example, 4.185 mm. Therefore, it can be seen that the zoom lens 100 in this embodiment can change the superimposed phase distribution P3 and thus adjust the focal length by rotating the first meta-lens 110 and the second meta-lens 120 relative to each other.

[0024] It should be noted that in this embodiment, for example, the second meta-lens 120 is rotated while the first meta-lens 110 remains stationary, but the present invention is not limited thereto. In another embodiment, the first meta-lens 110 can be rotated while the second meta-lens 120 remains stationary, for example. In another embodiment, both the first meta-lens 110 and the second meta-lens 120 can be rotated simultaneously, but the first meta-lens 110 and the second meta-lens 120 rotate relative to each other. Furthermore, although the above description refers to rotating the second meta-lens 120 counterclockwise when facing the fourth surface 122, the present invention does not limit the direction of rotation. In another embodiment, the second meta-lens 120 can also be rotated clockwise when facing the fourth surface 122. Similarly, the direction of rotation of the first meta-lens 110 is also not limited.

[0025] Figure 5 is a schematic diagram of the phase distribution along the cross section of line segment AA in Figure 2. Referring to Figures 2 and 5, the left side of Figure 5 corresponds to the position near the center of the circle in Figure 2, and the right side of Figure 5 corresponds to the position near the circumference of the circle in Figure 2. As can be seen from Figure 5, the superimposed phase distribution P3 has, for example, multiple concentrically distributed phases Q, each phase Q having, for example, multiple phase orders D. Specifically, the superimposed phase distribution P3 is presented as a line graph along line segment AA in Figure 2, as shown in Figure 5. Figure 5 includes, for example, four phases Q (Q1~Q4), where each phase Q has, for example, multiple phase orders D, but this invention is not limited thereto. For example, phases Q1 to Q4 are arranged sequentially from the center to the edge of the circle, where phase Q1 has, for example, seven phase orders D. Phases Q2 to Q4 are shown in Figure 5, and will not be described further here.

[0026] The number of phase orders D of phase Q in this embodiment, or the degree of change in the radian of phase Q, is merely illustrative and is not intended to limit the invention. It should be noted that the superimposed phase distribution P3 of the zoom lens 100 in this embodiment is, for example, discontinuous, as shown in Figure 5, but this invention does not impose specific limitations on it. In one embodiment of the invention, each phase Q varies from 0 to 2π, for example.

[0027] Figure 6 is a schematic diagram illustrating the relationship between phase order and focusing efficiency. Referring to Figure 6, it can be seen that when each phase order D is, for example, less than 1.3 radians, the focusing efficiency of the zoom lens 100 is better, meaning that, for example, more than 35% of the light can converge at the focal point. Conversely, if the phase order D is, for example, greater than 1.3 radians, the focusing efficiency is poor, for example, less than 35% of the light can converge at the focal point. Therefore, in one embodiment of the present invention, the phase order D of the zoom lens 100 is designed to be, for example, less than 1.3 radians, which helps to improve the imaging quality of the zoom lens 100. For example, the phase orders D shown in Figure 5 are all, for example, less than 1.3 radians. Furthermore, although the phase order D of the superimposed phase distribution P3a in Figure 3 and the phase order D of the superimposed phase distribution P3b in Figure 4 are not shown, they are, for example, less than 1.3 radians. It should be noted that the rotation angle θ between the first meta-lens 110 and the second meta-lens 120 in this embodiment of the invention will affect the superimposed phase distribution. Specifically, when the rotation angle θ changes, the number of phases in the superimposed phase distribution will be adjusted accordingly. For example, the number of phases Q in the superimposed phase distribution P3b in Figure 4 is greater than the number of phases Q in the superimposed phase distribution P3 in Figure 2.

[0028] Although Figure 1 illustrates an example where the first phase adjustment structure 113 is disposed on the second surface 112 and the second phase adjustment structure 123 is disposed on the third surface 121, the present invention is not limited thereto. The present invention may include zoom lenses of three other embodiments, as described below. Figures 7 to 9 are perspective views of zoom lenses according to another embodiment of the present invention. Referring first to Figure 7, in one embodiment of zoom lens 100a, the first phase adjustment structure 113 is disposed, for example, on the first surface 111, and the second phase adjustment structure 123 is disposed, for example, on the fourth surface 122. Referring to Figure 8, in another embodiment of zoom lens 100b, the first phase adjustment structure 113 is disposed, for example, on the first surface 111, and the second phase adjustment structure 123 is disposed, for example, on the third surface 121. Referring to Figure 9, in another embodiment of zoom lens 100c, the first phase adjustment structure 113 is disposed, for example, on the second surface 112, and the second phase adjustment structure 123 is disposed, for example, on the fourth surface 122.

[0029] It should be noted that, since different first phase distributions P1 may be obtained when the first phase adjustment structure 113 is disposed on the first surface 111 or the second surface 112, the size, shape, or arrangement of the first phase adjustment structure 113 may be adjusted depending on the surface on which it is disposed in different embodiments of the present invention. In other words, the size, shape, or arrangement of the first phase adjustment structure 113 may be slightly different when it is disposed on the first surface 111 or the second surface 112 in different embodiments of the present invention. Similarly, the size, shape, or arrangement of the second phase adjustment structure 123 may also be adjusted depending on the surface on which it is disposed in different embodiments of the present invention.

[0030] In summary, the zoom lens of the present invention, by employing a first super-lens and a second super-lens suitable for relative rotation, can improve the focusing effect and reduce the lens size.

[0031] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0032] 100, 100a, 100b, 100c: Zoom lenses 110, 110a, 110b, 110c: First super-sensitive lens 111: First Surface 112: Second Surface 113: First phase adjustment structure 120, 120a, 120b, 120c: Second super-lens 121: Third Surface 122: Fourth Surface 123: Second phase adjustment structure AA: Line segment D: Phase order P1: First phase distribution P2: Second phase distribution P3, P3a, P3b: Superimposed phase distribution Q, Q1, Q2, Q3, Q4: Phase W1, W2, W3: Arrows OA: Optical Axis θ: Rotation angle

Claims

1. A zoom lens comprising a first metalens and a second metalens arranged sequentially along an optical axis from a magnifying side to a reducing side; wherein the first metalens has a first phase distribution, the second metalens has a second phase distribution, the first phase distribution and the second phase distribution are conjugate to each other, and the first phase distribution and the second phase distribution are superimposed to form a superimposed phase distribution, the superimposed phase distribution having moiré patterns, and the first metalens and the second metalens are adapted to rotate relative to each other along the optical axis; the material of the first metalens is silicon or germanium, and the material of the second metalens is silicon or germanium; wherein the first phase distribution of the first metalens conforms to formula (I), where Φ1 is the phase of the first metalens, ρ1 is the radius of the first metalens, and A1 and A2 are parameters, where A1 = +32.7249, A2 = -0.0409. The second phase distribution of the second meta-lens conforms to equation (II), where Φ2 is the phase of the second meta-lens, ρ2 is the radius of the second meta-lens, and A1 and A2 are parameters, where A1 = +32.7249 and A2 = -0.0409.

2. The zoom lens as described in claim 1, wherein: The first meta-lens includes a first surface and a second surface opposite to each other, and a plurality of first phase adjustment structures. The first surface is close to the magnification side, and the first phase adjustment structures are disposed on the first surface or the second surface and are adapted to give the first meta-lens the first phase distribution. The second meta-lens includes a third surface and a fourth surface opposite to each other, and a plurality of second phase adjustment structures. The fourth surface is close to the reduction side, and the second phase adjustment structures are disposed on the third surface or the fourth surface and are adapted to give the second meta-lens the second phase distribution.

3. The zoom lens as claimed in claim 2, wherein the first phase adjustment structures are disposed on the second surface and the second phase adjustment structures are disposed on the third surface.

4. The zoom lens as claimed in claim 2, wherein the first phase adjustment structures are disposed on the first surface and the second phase adjustment structures are disposed on the fourth surface.

5. The zoom lens as claimed in claim 2, wherein the first phase adjustment structures are disposed on the first surface and the second phase adjustment structures are disposed on the third surface.

6. The zoom lens as claimed in claim 2, wherein the first phase adjustment structures are disposed on the second surface and the second phase adjustment structures are disposed on the fourth surface.

7. The zoom lens as claimed in claim 1, wherein the superimposed phase distribution has a plurality of concentrically distributed phases, each of the phases having a plurality of phase orders, wherein each of the phase orders is less than 1.3 radians.

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