Multifocal lens with central axis cone

Abstract

The present invention relates to a composite diffractive intraocular lens having one or more optical magnifications or focus lengths, comprising: a base lens forming a single focus; a diffractive lens formed on the base lens, having a central region and a diffractive region surrounding the central region, and dispersing the single focus into a plurality of focuses to form a plurality of focuses; and an axial cone portion formed in the central region and protruding in a central axis direction of the base lens such that a depth of focus expands between the plurality of focal points.

Description

Technical Field

[0001] The present invention relates to a multifocal lens with a central axis cone, and more particularly, to a multifocal lens with a central axis cone capable of obtaining an extended depth of focus between generated focal points by forming an axis cone shape in a central region of a lens device. Background Art

[0002] Diffractive lenses with multiple foci or multiple focuses are widely used in optical lenses, especially in intraocular lenses for ophthalmology, and are widely used in ophthalmic treatment to provide high-quality vision for both near and far objects.

[0003] For example, a multifocal intraocular lens (MF-IOL) having a surface including more than one trifocal diffraction pattern and more than one bifocal diffraction pattern is being commercialized, such that the bifocal diffraction pattern provides myopia and hyperopia vision, and the trifocal diffraction pattern provides myopia, hyperopia, and intermediate vision.

[0004] In the technology used to manufacture commercialized multifocal diffractive lenses, a widely used method is to precisely process the anterior surface or posterior surface of a single-focus lens so that it has a surface-relief shape similar to that of a Fresnel diffraction lens.

[0005] However, as the number of focal points of a multifocal diffractive lens increases, the surface concave-convex shape of the lens that needs to be produced becomes more and more complex, making the manufacture of a multifocal intraocular lens very difficult. Due to the imperfect manufacturing state, the scattering of light will be significantly aggravated, resulting in an increase in blurred vision (blur, halo, starbust, etc.). Summary of the invention

[0006] Technical issues

[0007] The present invention is used to solve the above-mentioned problem, and its object is to provide a multifocal lens, that is, while retaining the effect of the existing diffraction multifocal lens, it is possible to extend the focal depth between the formed focal points.

[0008] Technical Solution

[0009] The multifocal lens with a central axis cone portion of the present invention for achieving the above-mentioned purpose comprises: a base lens forming a single focus; a diffraction lens formed on the base lens, having a central area and a diffraction area surrounding the central area, dispersing the single focus into a plurality of focuses to form multiple focuses; and an axis cone portion formed in the central area and protruding along the central axis direction of the base lens to extend the depth of focus between the multiple focuses.

[0010] Furthermore, in one embodiment of the present invention, the present invention is characterized in that the diffractive lens and the axicon portion are formed on the front surface, the rear surface or both surfaces of the base lens.

[0011] Furthermore, in one embodiment of the present invention, the present invention is characterized in that the shape of the shaft cone portion is modeled according to the following mathematical formula.

[0012] <Mathematical formula>

[0013]

[0014] Among them, z represents the distance from the vertex axis passing through the vertex of the axicon shape and perpendicular to the center axis to the axicon shape, A represents the distance from the vertex axis to the vertex of the axicon shape, r represents the distance from the center axis to the axicon shape (radius), and θ represents the angle between the two mother lines of the axicon shape.

[0015] Furthermore, in one embodiment of the present invention, the present invention is characterized in that the angle θ between the two generatrixes of the axicon shape is not 180°.

[0016] Furthermore, in one embodiment of the present invention, the present invention is characterized in that, when the angle θ between the two generatrixes of the axicon shape is fixed, the greater the distance A from the vertex axis to the vertex of the axicon shape, the more significant the depth of focus extension effect.

[0017] Furthermore, in one embodiment of the present invention, when the distance A from the vertex axis to the vertex of the axicon shape is fixed, the smaller the angle θ between the two generatrixes of the axicon shape is, the more significant the focal depth extension effect is.

[0018] Furthermore, in one embodiment of the present invention, the present invention is characterized in that the distance A from the vertex axis to the vertex of the axicon shape or the angle θ between the two generatrixes of the axicon shape is set in a manner such that the depth of focus extension effect on the distance between the focus generated according to the axicon shape and the near-distance focus and the medium-distance focus becomes significant.

[0019] Furthermore, in one embodiment of the present invention, the present invention is characterized in that, if the sign of the z value is (+), a concave shape is formed when looking from the central axis toward the reference vertex q.

[0020] Furthermore, in one embodiment of the present invention, the present invention is characterized in that, if the sign of the z value is (+), the distance A from the vertex axis to the vertex of the axicon shape or the angle θ between the two generatrixes of the axicon shape is set in such a manner that the depth of focus extension effect at the distance between the focus generated according to the axicon shape and the mid-distance focus and the long-distance focus becomes significant.

[0021] Furthermore, in one embodiment of the present invention, the present invention is characterized in that the size of the central area affects the light intensity level of the extended focal depth.

[0022] Furthermore, in one embodiment of the present invention, the present invention is characterized in that the heights of the multiple steps of the diffraction region increase or decrease along the radial direction of the lens component.

[0023] Furthermore, in one embodiment of the present invention, the present invention is characterized in that the vertex height of the axicon shape formed in the central region is the same as or smaller than the step height formed in the diffraction region.

[0024] Furthermore, in one embodiment of the present invention, the present invention is characterized in that the central area and the diffraction area are connected to each other based on a predetermined boundary line.

[0025] Effects of the Invention

[0026] According to the present invention, any focal depth extension effect can be obtained by manufacturing the central area of ​​the lens device into various forms of axicon shapes. In particular, when looking at a smartphone or a book, the focal depth can be extended between the desired close distance and medium distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A simplified side view showing a conventional diffractive multi-focal guide lens;

[0028] Figure 2 A simplified top view of an existing diffractive multifocal guide lens is shown;

[0029] Figure 3 A simplified side view of a multifocal lens with a central axis cone portion of the present invention is shown;

[0030] Figure 4 A diagram showing the central region and the diffraction region of a multifocal lens having a central axis cone of the present invention;

[0031] Figure 5 A diagram showing a cross section of a central axis cone of the present invention;

[0032] Figure 6 A diagram showing a surface profile of a radius of a multifocal lens having a central axis cone according to the present invention;

[0033] Figure 7 A diagram showing an embodiment of generating three focal points by a multifocal lens having a central axis cone according to the present invention;

[0034] Figure 8 A diagram showing the light intensity distribution based on the focal distance when the axicon portion is not in the central area;

[0035] Figure 9a The axicon height of the radius when θ=179.9° and A=0 μm in the axicon shape according to the present invention is shown. Figure 9b To illustrate the Figure 9a A diagram of the light intensity distribution at the focal distance formed by the multifocal lens of the axial cone;

[0036] Fig.10a The axicon height of the radius when θ=179.9° and A=0.5 μm in the axicon shape according to the present invention is shown. Fig.10b To illustrate the Fig.10a A diagram of the light intensity distribution at the focal distance formed by the multifocal lens of the axial cone;

[0037] Fig.11a The axicon height of the radius when θ=179.9° and A=1.0 μm in the axicon shape according to the present invention is shown. Fig.11b To illustrate the Fig.11a A diagram of the light intensity distribution at the focal distance formed by the multifocal lens of the axial cone;

[0038] Fig.12a The axicon height of the radius when θ=179.8° and A=0 μm in the axicon shape according to the present invention is shown. Figure 12b To illustrate the Fig.12a A diagram of the light intensity distribution at the focal distance formed by the multifocal lens of the axial cone;

[0039] Fig.13a The axicon height of the radius when θ=179.8° and A=0.5 μm in the axicon shape according to the present invention is shown. Fig.13b To illustrate the Fig.13a A diagram of the light intensity distribution at the focal distance formed by the multifocal lens of the axial cone;

[0040] Fig.14a The axicon height of the radius when θ=179.8° and A=1.05 μm in the axicon shape according to the present invention is shown. Fig.14b To illustrate the Fig.14a A diagram of the light intensity distribution at the focal distance formed by the multifocal lens in the axial cone section. DETAILED DESCRIPTION

[0041] Hereinafter, with reference to the accompanying drawings, a multifocal lens with a central axis cone of a preferred embodiment is described in detail. The same reference numerals are used for the same structures, and repeated descriptions and detailed descriptions of known functions and structures that may unnecessarily obscure the main purpose of the present invention are omitted. The embodiments of the present invention are used to more completely explain the present invention to ordinary technicians in the field. Therefore, in order to explain more clearly, the shapes and sizes of the structural elements in the drawings may be exaggerated.

[0042] Figure 1 To show a simplified side view of a conventional diffractive multi-focal guide lens, Figure 2 FIG. 1 is a simplified top view showing an existing diffractive multifocal guide lens.

[0043] The present invention has the function of changing the shape of the central area in the existing diffractive multifocal guide lens. Of course, in addition to the guide lens, it can also be applied to various lenses with existing diffractive multifocals. Figure 1 and Figure 2 In the embodiment shown, other structures of the existing diffractive multifocal guide lens except the central area can be directly applied to the present invention, so the existing diffractive multifocal guide lens is first described.

[0044] Reference Figure 1 and Figure 2 The existing diffraction type multi-focal guide lens is formed by combining a base lens and a diffraction lens, and constitutes a lens device 10 having a lens surface composed of a front surface 12 and a rear surface 11. Figure 1 and Figure 2 In the figure, the lens device is shown as an intraocular lens (Intraocular Lens: IOL), but it is not limited to this and can also be composed of a multi-purpose lens such as a contact lens, an artificial cornea or a lamellar implant.

[0045] The lens device 10 may be formed of a suitable biocompatible material, such as soft acrylic, silicone, hydrogel or other biocompatible polymer materials having a refractive index required for a specific lens, but is not limited thereto and may generally be formed of known lens materials.

[0046] On the other hand, in the present invention, the basic (radial) profiles of the two surfaces 12 and 11 of the base lens of the surface of the unprocessed lens device 10 may be the same or different. That is, the front surface and the back surface of the base lens may have any of a variety of surface profiles such as a protruding-protruding profile, a protruding-concave profile, a flat plate profile, etc.

[0047] A central region 142 having a predetermined radius with the central axis CX as the center is formed at the center of the rear surface of the lens device 10. The central axis CX may be an optical axis. The central region 142 is a region for forming a refractive focus of the lens device 10, and according to an embodiment, can provide near vision, intermediate vision, and long-distance vision together with the diffractive focus formed in the diffractive region 144.

[0048] The central region 142 may have an aspherical profile or a spherical profile to generate a single refractive focus. According to an embodiment, the central region 142 may be further enhanced by having different central region curvatures to achieve a better focus.

[0049] An annular diffraction region 144 is formed around the central region 142. The annular diffraction region 144 surrounds the central region 142 and can provide multiple focal points such as near focus, medium focus, and long focus. The diffraction region 144 can be composed of multiple annular regions, and the annular region 144 uses various diffraction orders such as 0th order, +1st order, and -1st order.

[0050] like Figure 1 As shown, grooves with multiple diffraction step heights are formed in the multi-focal diffraction region 144, and the diffraction steps forming these grooves can be distributed from a height for turning light according to the diffraction order associated with the near focus to a height for turning light according to the diffraction order associated with the far focus. The shape of the groove can be formed by a variety of shapes such as a linear shape, a spherical shape, a cosine shape based on a trigonometric function, or an aspherical shape. On the other hand, there is no limit to the number of grooves forming the diffraction region.

[0051] like Figure 1 and Figure 2 As shown, the diffraction regions 144 are separated from each other by a plurality of steps. According to the embodiment, the height of the steps of the diffraction regions can be formed in a variety of ways. For example, the step height can be uniform, non-uniform, increasing (inverse Apolda) or decreasing (Apolda) in the radial direction (radial direction) at the center of the lens device 10.

[0052] The peripheral region 146 is similar to the central region 142 and can provide a single refractive focal power. In this case, the refractive power provided by the peripheral region 146 may be substantially the same as the refractive power provided by the central region 142. Therefore, the peripheral region 146 can help provide the lens device 10 with a long-distance focal vision of incident light energy, just like the central region 142. Of course, in other embodiments, the peripheral region 146 can also be formed by extending the diffractive region 144.

[0053] On the other hand, the existing diffractive multifocal guide lens includes lens support parts 16a and 16b. The lens support parts 16a and 16b are structures for adjusting the positioning of the guide lens (IOL) in the patient's eye. Such lens support parts 16a and 16b can be formed of a suitable polymer material such as polymethyl methacrylate and polypropylene.

[0054] Figure 3 To illustrate a simplified side view of a multifocal lens having a central axis cone of the present invention, Figure 4 A diagram showing the central region and the diffraction region of the multifocal lens having a central axis cone according to the present invention, Figure 5 This is a diagram showing a cross section of a central axis cone portion of the present invention. Figure 6 FIG. 1 is a diagram showing the surface profile of the radius of a multifocal lens having a central axis cone according to the present invention.

[0055] Reference Figure 3 In one embodiment of the present invention, the multifocal lens with a central axis cone portion is based on the existing diffractive multifocal lens, and the axis cone portion 110 is further combined with the lens device 10 formed by combining the base lens 13 and the diffractive lens 14.

[0056] That is, the multifocal lens with a central axicon portion according to an embodiment of the present invention combines the axicon portion 110 with the central region 142 of various types of existing diffractive lenses (base lens+diffractive lens).

[0057] Reference Figure 3 and Figure 4 , a central area 142 is formed in the central part of the front surface 12 or the rear surface 11 of the lens device 10. The central area 142 of the present invention is combined with the axicon 110. The shape of the axicon of the axicon 110 can form a cone. Specifically, relative to the central axis CX as the optical axis, the axicon shape is roughly circular with a radius R0 along the radial direction, and along the central axis direction, it is in a shape protruding from the lens surface to have a vertex. In the present invention, the axicon shape can change its form to have a sharp vertex, or a round vertex. This will be explained below, in order to obtain a variety of depth of focus extension effects according to the purpose of use.

[0058] In one embodiment of the present invention, the diffractive region 144 is annular and surrounds the central region 142. In this case, since the diffractive region 144 is in contact with the central region 142, the boundary between the diffractive region 144 and the central region 142 is the radius R0 relative to the central axis CX. As described above, the step height of the diffractive region 144 can have various sizes from the center of the lens device 10 to the radial direction.

[0059] Of course, in other embodiments of the present invention, the central region 142 and the diffraction region 144 may also be separated from each other.

[0060] exist Figure 5 , the cross-sectional profiles of two axicon shapes formed at the center of the lens device 10 are shown. On the other hand, Figure 4 The base line BL of the axicon shape shown represents a line corresponding to a portion where the radius of the axicon shape reaches a maximum value. In one embodiment of the present invention, the base line BL is a central area of ​​the lens device 10, and therefore, the size of the base line BL is 2R0.

[0061] If you observe Figure 4 The cross section of the first axicon shape shown can form two generatrixes AX-1 symmetrically with respect to the center axis CX, with reference vertex q as the reference. The generatrix AX-1 of the first axicon shape is in a straight line form, and the angle between the two generatrixes AX-1 is θ1. The first axicon shape intersects with the generatrix AX-1 which is a straight line, so it can be called an axicon portion with a sharp vertex. On the other hand, the axis passing through the reference vertex q while being perpendicular to the center axis CX is called the vertex axis PX.

[0062] If you observe Figure 5 The cross section of the second axicon shape shown can form two generatrixes AX-2 symmetrically with respect to the center axis CX with the vertex as the reference. The generatrix AX-2 of the second axicon shape is in a curved shape, and the angle between the two generatrixes AX-2 is θ2. The second axicon shape intersects with the generatrix AX-2 which is a curve, and therefore, it can be called an axicon portion whose vertex is formed on a circle.

[0063] In the cross section of the axicon shape, the angle (θ1 or θ2) between the generatrix (AX-1 or AX-2) is greater than 0° and less than 180°. If the angle between the generatrix is ​​0° or 180°, it cannot be called an axicon shape. And, if Figure 5 As shown, in one embodiment of the present invention, if the cross section of the axicon shape is observed, the distance between the point where the generatrix (AX-1 or AX-2) and the base line BL meet at the center axis CX is R0.

[0064] On the other hand, although Figure 4 Only two axicon shapes are shown in FIG. 1 , but various axicon shapes can be formed according to the following mathematical formula. Specifically, the axicon shape of the present invention can be calculated according to the following <mathematical formula>.

[0065] <Mathematical formula>

[0066]

[0067] Among them, z represents the distance from the vertex axis passing through the vertex of the axicon shape and perpendicular to the center axis to the axicon shape, A represents the distance from the vertex axis to the vertex of the axicon shape, r represents the distance from the center axis to the axicon shape (radius), and θ represents the angle between the two mother lines of the axicon shape.

[0068] On the other hand, in the above mathematical formula, the (-) sign of the z value indicates that Figure 5 According to the embodiment, in the above formula, if the z value is a (+) sign, it means that the shape is concave when viewed from the reference vertex q.

[0069] Refer again Figure 5 If the A value is 0, a shaft cone shape with a sharp vertex is formed, and if the A value is greater than 0, a shaft cone shape with a rounded vertex is formed. In the present invention, the height of the shaft cone shape can be represented based on the base line BL, and can also be represented according to the A value. That is, the larger the A value, the smaller the height of the shaft cone shape.

[0070] Reference Figure 6 In one embodiment of the present invention, if the A value is 0, the vertex height of the axicon shape as the central region 142 is the same as the step height of the diffractive region 144. However, in other embodiments, the vertex height of the axicon shape with an A value of 0 can be set in a variety of ways based on the base line BL, in which case its height may be different from the step height of the diffractive region 144.

[0071] According to the present invention, various axicon shapes can be formed by changing the A value and the θ value in the above-mentioned mathematical formula. If the axicon shape of the present invention is formed at the center of the lens device 10, a multifocal guide lens with various extension depths can be formed.

[0072] A diffractive multifocal lens may have a near focus, a mid-range focus, and a far focus. In this case, the length of the formed focus maintaining a certain focal size is called the depth of focus. The present invention provides a depth of focus that is extended in an existing diffractive multifocal lens.

[0073] The existing diffraction multifocal lens is a technology for obtaining an extended depth of focus between medium and long distances. However, in recent years, the focal distance required for viewing a smartphone or a book is between close and medium distances, and therefore, it is necessary to propose a multifocal lens with an extended depth of focus within such a distance. In particular, the present invention can provide an extended depth of focus between close and medium distances.

[0074] On the other hand, as described above, in the mathematical formula, if the z value is a (+) sign, an extended depth of focus can be provided between medium and long distances. A variety of extended depth extension effects can be obtained by adjusting the distance A from the vertex axis to the vertex of the axicon shape or the angle θ between the two generatrixes of the axicon shape.

[0075] Figure 7 FIG. 1 is a diagram showing an embodiment of generating three focal points by a multifocal lens having a central axis cone according to the present invention. Figure 8 Graph showing the light intensity distribution depending on the focal distance when the axicon portion is not in the central area.

[0076] Figure 7 The following state is shown, that is, due to the central area 142 and the diffraction area 144 formed in the center of the lens device 10, after the incident light passes through the multi-focal lens with a central axis cone portion of the present invention, three focal points F1, F2, and F3 are formed. Among them, F1 can be called a close focus, F2 can be called a medium focus, and F3 can be called a long focus. Of course, according to the embodiment, a variety of focal points can be formed according to the shape of the base lens 13, the diffraction lens 14, or the axis cone portion 110 of the present invention. In this specification, for ease of understanding, as shown in FIG. Figure 7 As shown, the case where three focal points are formed is taken as an example for explanation.

[0077] Figure 8 In the above mathematical formula, the numerical values ​​constituting the axicon shape are θ=0° and A=0μm. If θ=0°, the central area is in a flat state. That is, the axicon shape of the present invention is not formed. In this case, as described above, three focal points F1, F2, and F3 are formed. Figure 8 The graph shown on the upper side of shows the light intensity based on the focal distance, and the graph shown on the lower side shows the light intensity distribution detected by the detector.

[0078] Figure 9a The axicon height of the radius when θ=179.9° and A=0 μm in the axicon shape according to the present invention is shown. Figure 9b To illustrate the Figure 9a The diagram of the light intensity distribution at the focal distance formed by the multifocal lens of the axis cone section, Fig.10a The axicon height of the radius when θ=179.9° and A=0.5 μm in the axicon shape according to the present invention is shown. Fig.10b To illustrate the Fig.10a The diagram of the light intensity distribution at the focal distance formed by the multifocal lens of the axis cone section, Fig.11a The axicon height of the radius when θ=179.9° and A=1.0 μm in the axicon shape according to the present invention is shown. Fig.11b To illustrate the Fig.11aA diagram of the light intensity distribution at the focal distance formed by the multifocal lens in the axicon section.

[0079] Figures 9a to 11b In the above mathematical formula, the light intensity distribution based on the axicon height and the focal distance is shown when θ=179.9° is fixed and the A value is 0μm, 0.5μm, and 1.0μm. Figure 9a , Fig.10a as well as Fig.11a In the case of A=0 μm, the height of the axicon shape is approximately 0.9 μm, in the case of A=0.5 μm, the height of the axicon shape is approximately 0.4 μm, and in the case of A=1.0 μm, the height of the axicon shape is approximately 0.2 μm.

[0080] like Figures 9a to 11b As shown, when the θ value is fixed, the larger the A value is (the height of the axis cone decreases and the curvature increases), the light intensity between F1 and F2 gradually increases (in Figure 9b , Fig.10b as well as Fig.11b The brightness between F1 and F2 detected by the detector in the image is measured, making the depth of focus extension effect more obvious.

[0081] Fig.12a The axicon height of the radius when θ=179.8° and A=0 μm in the axicon shape according to the present invention is shown. Figure 12b To illustrate the Fig.12a The diagram of the light intensity distribution at the focal distance formed by the multifocal lens of the axis cone section, Fig.13a The axicon height of the radius when θ=179.8° and A=0.5 μm in the axicon shape according to the present invention is shown. Fig.13b To illustrate the Fig.13a The diagram of the light intensity distribution at the focal distance formed by the multifocal lens of the axis cone section, Fig.14a The axicon height of the radius when θ=179.8° and A=1.05 μm in the axicon shape according to the present invention is shown. Fig.14b To illustrate the Fig.14a A diagram of the light intensity distribution at the focal distance formed by the multifocal lens in the axial cone section.

[0082] like Figures 12a to 14b As shown, when the θ value is fixed, the larger the A value is (the height of the axis cone decreases and the curvature increases), the light intensity between F1 and F2 gradually increases (in Figure 12b , Fig.13b as well as Fig.14b The brightness between F1 and F2 detected by the detector in the image is measured, making the depth of focus extension effect more obvious.

[0083] On the other hand, refer to Figure 9b and Figure 12b It can be confirmed that when the A value is fixed, the smaller the θ value is, the more obvious the depth of focus extension effect is.

[0084] On the other hand, Figures 9a to 14b As shown, not only the focal depth extension effect between F1 and F2 but also the focal depth extension effect between F2 and F3 can be confirmed according to the shape of the axicon portion 110. That is, according to the present invention, various focal depth extension effects between short distance and long distance can be obtained by setting the A value or the θ value of the axicon portion 110.

[0085] On the other hand, R0, which determines the size of the central region 142 or the size of the central region, affects the light intensity of the extended depth of focus. Fig.11b , it can be confirmed that the extended depth of focus between F1 and F2 is related to the light intensity (height). If the size of the central area (or R0) is changed, the light intensity height of the extended area will change. For example, if R0 is reduced, Fig.11b The light intensity of F3 shown may become smaller. If R0 is increased, Fig.11b The light intensity at F3 shown may become even greater.

[0086] The present invention has been described with reference to an embodiment shown in the accompanying drawings, but this is only exemplary, and it will be appreciated by those skilled in the art that various modifications may be made thereto and other equivalent embodiments may be realized. Therefore, the actual protection scope of the present invention shall be determined solely by the scope of the attached claims.

Claims

1. A multifocal lens having a central axis cone, characterized in that: include: Base lens, forming a single focus; A diffractive lens, formed on the base lens, having a central region and a diffractive region surrounding the central region, and dispersing the single focus into a plurality of focuses to form a multi-focus; as well as An axicon portion is formed in the central region and protrudes along the central axis direction of the base lens to extend the focal depth between the multiple focal points.

2. The multifocal lens with a central axis cone according to claim 1, characterized in that: The diffractive lens and the axicon portion are formed on the front surface, the rear surface or both surfaces of the base lens.

3. The multifocal lens with a central axis cone according to claim 1, characterized in that: The shape of the shaft cone is modeled according to the following mathematical formula: <Mathematical formula> Among them, z represents the distance from the vertex axis passing through the vertex of the axis cone shape and perpendicular to the center axis to the axis cone shape, A represents the distance from the vertex axis to the vertex of the axis cone shape, r represents the radius as the distance from the center axis to the axis cone shape, and θ represents the angle between the two mother lines of the axis cone shape.

4. The multifocal lens with a central axis cone according to claim 3, characterized in that: The angle (θ) between the two generatrixes of the axicon shape is not 180°.

5. The multifocal lens with a central axis cone according to claim 3, characterized in that: In a state where the angle (θ) between the two generatrixes of the axicon shape is fixed, the longer the distance (A) from the vertex axis to the vertex of the axicon shape is, the more remarkable the extended depth of focus effect is.

6. The multifocal lens with a central axis cone according to claim 3, characterized in that: In a state where the distance (A) from the vertex axis to the vertex of the axicon shape is constant, the smaller the angle (θ) between the two generatrixes of the axicon shape is, the more significant the extended depth of focus effect is.

7. The multifocal lens with a central axis cone according to claim 5 or 6, characterized in that: The distance (A) from the vertex axis to the vertex of the axicon shape or the angle (θ) between two generatrixes of the axicon shape is set so that the depth of focus extension effect at the distance between the focus generated by the axicon shape and the near focus and the medium focus becomes significant.

8. The multifocal lens with a central axis cone according to claim 3, characterized in that: If the sign of the z value is (+), a concave shape is formed when looking from the central axis toward the reference vertex (q).

9. The multifocal lens with a central axis cone according to claim 3, characterized in that: If the sign of the z value is (+), the distance (A) from the vertex axis to the vertex of the axicon shape or the angle (θ) between the two generatrixes of the axicon shape is set in such a way that the depth of focus extension effect at the distance between the focus generated according to the axicon shape and the mid-distance focus and the long-distance focus becomes significant.

10. The multifocal lens with a central axis cone according to claim 1, characterized in that: The size of the central region affects the degree of light intensity of the extended depth of focus.

11. The multifocal lens with a central axis cone according to claim 1, characterized in that: The heights of the multiple steps in the diffraction region increase or decrease along the radial direction of the lens component.

12. The multifocal lens with a central axis cone according to claim 1, characterized in that: The height of the apex of the axicon shape formed in the central region is the same as or smaller than the height of the step formed in the diffractive region.

13. The multifocal lens with a central axis cone according to claim 1, characterized in that: The central region and the diffraction region are connected to each other based on a predetermined boundary line.

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