Lens Design Method

Abstract

The present invention provides a lens design method, comprising: determining the first surface and the second surface of the lens according to the focal length of the target lens; determining the shape and position of the texture according to the third surface, the fourth surface and the texture surface; collapsing the second surface along the optical axis to form a Fresnel lens with a texture; wherein the third surface is located between the first surface and the second surface and is a surface formed by connecting the bottom angles of the textures of the lens, the fourth surface is a surface formed by connecting the top angles of the textures of the lens, and the texture surface is the shape of the texture when looking down at the lens. The lens design method provided by the present invention aims to solve the problem that the texture of the Fresnel lens in the traditional technology cannot collapse the free surface during design, and to form a free texture top-view shape and a free texture location.

Description

Technical Field

[0001] The present invention relates to the field of lens technology, and in particular to a lens design method. Background Art

[0002] The Fresnel lens can be understood as a lens whose continuous surface portion "collapses" into a plane, thereby retaining the portion of the lens with the ability to deflect light and removing the portion of the lens without the ability to deflect light, so as to achieve the effect of reducing the total weight of the lens.

[0003] The surface of the Fresnel lens in traditional technology is smooth on one side, and concentric grooves are engraved on the other side from small to large. From the cross-section, the spherical Fresnel lens is composed of a series of sawtooth ridges. When the spacing between the ridges is small enough, each sawtooth can be regarded as a tiny prism; from the top view, it is a rotationally symmetrical concentric ring ridge. For the Fresnel lens, its refractive power, groove spacing, groove depth or height are in a certain relationship. When the height is fixed, the refractive power decreases with the increase of the spacing between the ridges; when the width is fixed, the refractive power increases with the increase of the ridge height.

[0004] For Fresnel lenses, there are many types of texture changes to meet the needs of different usage scenarios. CN113406737A provides a combined Fresnel lens and eyewear, which achieves the effect of combining multiple types of lenses by changing the height and spacing of the annular convex edges. For simple textures, regular changes can be adopted, which is also relatively simple and convenient to design. However, in the design of more complicated textures, how to provide a simple and efficient texture determination and lens design method is a problem that technicians in this field urgently need to solve. Summary of the invention

[0005] The present invention provides a lens design method, aiming to solve the problem in the traditional technology that the texture of the Fresnel lens is difficult to locate during design, which easily affects the final molding effect and optical effect.

[0006] In view of the problems existing in the prior art, an embodiment of the present invention provides a lens design method, comprising:

[0007] Determining a first surface and a second surface of the lens according to the optical power of the target lens;

[0008] Determine the shape and position of the texture according to the third surface, the fourth surface and the texture surface;

[0009] collapsing the second surface along the optical axis to form a Fresnel lens with a texture;

[0010] Among them, the third surface is located between the first surface and the second surface, and is a surface formed by connecting the bottom angles of each texture of the lens, the fourth surface is a surface formed by connecting the top angles of each texture of the lens, and the texture surface is the shape of the texture when looking down at the lens.

[0011] According to a lens design method provided by the present invention, the target lens has a free optical power expression, that is, the optical power at each point is the same; or, the optical power of the target lens at each point is different.

[0012] According to a lens design method provided by the present invention, determining the first surface and the second surface of the lens includes:

[0013] Determining the form of the first surface includes determining a first optical power function and a first surface height function of the first surface;

[0014] The second optical power function and the second surface height function of the second surface are determined according to the optical power formula of the lens, the optical power of the target lens, the thickness of the target lens, and the material used for the lens.

[0015] According to a lens design method provided by the present invention, both the first surface and the second surface have free surface forms.

[0016] According to a lens design method provided by the present invention, determining the texture shape and position according to the third surface, the fourth surface and the texture surface includes:

[0017] Setting the third surface and the fourth surface, and determining the texture shape and position; or,

[0018] Setting the third surface and the texture surface, and determining the texture shape and position; or,

[0019] The fourth surface and the texture surface are set, and the texture shape and position are determined.

[0020] According to a lens design method provided by the present invention, the third surface and the fourth surface both have free surface forms.

[0021] According to a lens design method provided by the present invention, the texture heights within each texture are the same and / or different, and the ring distances from the origin within each texture are the same and / or different.

[0022] According to a lens design method provided by the present invention, after collapsing the second surface along the optical axis direction to form a Fresnel lens with a texture, the method further comprises:

[0023] Take an approximate straight line or approximate curve for each texture to obtain an optical power expression equal to or close to that of the target lens.

[0024] According to a lens design method provided by the present invention, after collapsing the second surface along the optical axis direction to form a Fresnel lens with a texture, the method further comprises:

[0025] Adjust the textured surface to obtain an optical power expression equal to or close to that of the target lens.

[0026] According to a lens design method provided by the present invention, the optical focal length between the textures is uniformly set and / or variably set; the optical focal length within the textures is uniformly set and / or variably set.

[0027] In the conventional technology, the texture of the Fresnel lens is not easy to locate during design, which easily affects the final molding effect and the optical effect. The present invention provides a third surface, a fourth surface and a texture surface on the basis of the first surface and the second surface of the lens. Since the third surface is a surface formed by connecting the bottom angles of the texture of the lens, and the fourth surface is a surface formed by connecting the top angles of the texture of the lens, the texture surface is the shape of the texture when looking down at the lens. Therefore, by determining any two of the third surface, the fourth surface and the texture surface, the shape and setting position of the lens texture can be effectively determined, so that the texture design of the lens is more standardized, and more possibilities are provided for the design of special-shaped textures. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the flow of the lens design method provided by the present invention;

[0030] Figure 2 It is a schematic diagram of the cross-sectional structure of an existing lens;

[0031] Figure 3 It is a schematic diagram of the cross-sectional structure of a Fresnel lens formed after the existing lens is collapsed;

[0032] Figure 4 It is a schematic diagram of the surface function of the lens design method provided by the present invention in the case of a spherical surface;

[0033] Figure 5 yes Figure 4 Schematic diagram of various surface functions in different directions when collapsed on a plane;

[0034] Figure 6 It is a schematic diagram of various surface functions of the lens design method provided by the present invention in the case of a toric surface;

[0035] Figure 7 yes Figure 6 Schematic diagram of various surface functions in different directions when collapsed on a spherical surface;

[0036] Figure 8 yes Figure 7 Schematic diagram of texture surface for medium-high texture design;

[0037] Fig. 9 It is a schematic diagram of various surface functions of the lens design method provided by the present invention in the case of a toric surface combined with a prism surface;

[0038] Fig.10 yes Fig. 9 Schematic diagram of various surface functions in different directions when collapsed on a torus (different directions have different surface curvatures);

[0039] Fig.11 yes Fig.10 Schematic diagram of texture surface for medium-high texture design;

[0040] Fig.12 yes Figure 4 Schematic diagram of various surface functions when collapsed on a non-circular texture surface with different origins;

[0041] Fig.13 It is a schematic diagram of various surface functions of the lens design method provided by the present invention when an approximate straight line or an approximate curve is taken.

[0042] Reference numerals:

[0043] 1: first surface; 2: second surface; 3: third surface;

[0044] 4: Fourth surface. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Combine the following Figure 1-Figure 11 The lens design method of the present invention is described.

[0047] See also Figure 1 The present invention provides a lens design method, comprising:

[0048] S100, determining a first surface and a second surface of a lens according to the optical power of a target lens;

[0049] S200, determining a texture shape and position according to the third surface, the fourth surface and the texture surface;

[0050] S300, collapsing the second surface along the optical axis direction to form a Fresnel lens with a texture;

[0051] In the conventional technology, the texture of the Fresnel lens is difficult to locate during design, which easily affects the final molding effect and optical effect. In view of this, the present invention provides a lens design method, please refer to Figure 1-Figure 11 According to the target lens and the first surface 1, the second surface 2 can be determined. The third surface 3 is located between the first surface 1 and the second surface 2, and is the surface formed by connecting the bottom angles of the textures of the lens, that is, the surface on which the texture is mounted, and the fourth surface 4 is the surface formed by connecting the top angles of the textures of the lens, and the texture surface is the shape of the texture when looking down at the lens. When two elements among the third surface 3, the fourth surface 4, and the texture surface are determined, the other element can be determined. When the above three elements are determined, the second surface 2 collapses along the optical axis, and a Fresnel-type lens with a determined texture shape and position can be formed. The present invention can effectively determine the shape and setting position of the lens texture by determining the third surface 3, the fourth surface 4, and the texture surface, so that the texture design of the lens is more standardized, and more possibilities are provided for the design of special-shaped textures.

[0052] It should be noted that the optical power of the target lens has a free optical power form, that is, the target lens can have the same or different optical power expressions at various points.

[0053] Further, S100, determining the first surface and the second surface of the lens includes:

[0054] S110, determining the form of the first surface, including determining a first optical power function and a first surface height function of the first surface;

[0055] S120, determining a second optical power function and a second surface height function of the second surface according to an optical power formula of the lens, the optical power of the target lens, the thickness of the target lens, and the material used for the lens.

[0056] It should be noted that the first surface 1 and the second surface 2 of the lens jointly determine the focal length of the lens, while the third surface 3, the fourth surface 4 and the textured surface are not directly related to the expression of optical focal length. However, the second surface 2 will collapse, causing the optical focal length of the collapsed area to change.

[0057] According to the focal length F at each point of the lens determined by the target lens, the refractive index n corresponding to the lens material, and the thickness d of the target lens; when the first surface form of the lens, that is, the first surface focal length function is determined, the rear surface focal length function can be determined by the lens focal length formula, and the formula is r2 = [d*f′*(n-1)^2-n*r1*f′*(n-1)] / [n*r1-n*f′*(n-1)]. In this way, the first surface 1 and the second surface 2 can be obtained, wherein r1 is the first surface curvature radius, and r2 is the second surface curvature radius. It should be noted that when the focal length or shape within the first surface shows regular changes, the focal length or shape of the first surface can be expressed and summarized by a function, thereby determining the first surface focal length function of the first surface or the first surface shape function related to the shape according to the ophthalmic optometry prescription or actual use requirements.

[0058] In order to conveniently represent the first surface 1 and the second surface 2, the first surface power function and the first surface height function as well as the second surface power function and the second surface height function are introduced. Figure 4 , Figure 6 as well as Fig. 9 , respectively represent the optical focality function and surface height function of the second surface 2 of the spherical surface, the toric surface, and the toric surface combined with the prism surface. In each figure, the horizontal coordinate of the left figure is the distance from the origin to the longitudinal section passing through the origin, and the vertical coordinate is the height of the intercepted lens surface. Depending on the interception angle, the second surface 2 will have different surface height functions; the horizontal coordinate of the right figure in each figure is the different angles of the annular section at a certain distance from the origin, and the vertical coordinate is the optical focality function of the intercepted surface. Depending on the different annular sections, the second surface 2 will have different optical focality functions. It should be noted that if the first surface 1 is the same as the second surface 2, it can also be determined in this way. The present invention only takes the second surface 2 as an example for explanation.

[0059] It should be noted that, taking the second surface 2 as an example, whether the surface function is determined by the left or right figure, when there are enough combinations of functions with regularity in multiple directions, the expression form of the entire second surface 2 can be determined to form a three-dimensional diagram of the optical power and height of the second surface. Figure 4 , Figure 6 as well as Fig. 9 It can be seen that the second surface 2 can be set as a continuous surface, which has the same or different change rates at different distances from the origin or at different angles.

[0060] Furthermore, both the first surface and the second surface have a free surface form, that is, the first surface and the second surface may have the same or different surface heights at each point, and may also have different optical power expressions at each point.

[0061] Furthermore, S200, determining the texture shape and position according to the third surface, the fourth surface and the texture surface includes:

[0062] S210, setting the third surface and the fourth surface, and determining the texture shape and position; or,

[0063] S220, setting the third surface and the texture surface, and determining the texture shape and position; or,

[0064] S230: Set the fourth surface and the texture surface, and determine the texture shape and position.

[0065] As mentioned above, if two of the three elements of the third surface, the fourth surface, and the texture surface are determined, the other element can be determined. At this time, each texture section can be approximately regarded as a tiny triangular prism, and the shape and position of this triangle are jointly defined by the attributes such as the base, the hypotenuse, the height, the vertex angle of the base, and the vertex angle of the top. Among them, the hypotenuse of the triangle is determined by the curvature of the second surface 2; the base of the triangle is determined by the width of the texture (that is, the texture spacing of the texture surface), and the height of the triangle is jointly determined by the third surface and the fourth surface; the position of the triangle is defined by the third surface and / or the fourth surface.

[0066] See also Figure 5 , assuming that the third surface 3 is a plane and the second surface 2 is a spherical surface, the height function of the second surface (f2) is continuously collapsed along the optical axis. If the upper part is equal width of texture, the collapse method of the third surface and the texture surface and the surfaces formed are determined; if the lower part is equal height of texture, the collapse method of the fourth surface and the third surface and the surfaces formed are determined (f3 is the height function of the third surface, f4 is the height function of the fourth surface);

[0067] See also Figure 7 , assuming that the third surface 3 is a spherical surface and the second surface 2 is a toroidal surface, the second surface height function (f2) is continuously collapsed along the optical axis. As shown in the figure, at different directions such as θ0 and θ90, different cross-sectional schematic diagrams are formed in different directions after collapse in the above manner: when the upper part is equal in texture width, that is, the collapse method and the surfaces formed when the third surface and the texture surface are determined, the texture formed at this time has different texture vertex angle positions in different directions, and the height variation law of the texture vertex angle position forms the corresponding fourth surface height function f4, and the transformation law of the texture vertex angle position is the same as the surface height variation law of the second surface 2; when the lower part is equal in texture height, that is, the collapse method and the surfaces formed when the fourth surface and the third surface are determined, the texture formed at this time has different texture vertex or bottom angle distances from the origin in different directions, and a corresponding texture surface is formed. At this time, the distance of the texture vertex or bottom angle from the origin corresponds to the projection of the third surface or the fourth surface to form the shape of the texture surface. Please refer to Figure 8 , when the textures are of equal height, the texture is a non-circular texture surface similar to an elliptical ring texture when viewed from above;

[0068] See also Fig.10 , assuming that the third surface 3 is a toroidal surface, and the second surface 2 is a toroidal surface combined with a prism surface, the second surface height function (f2) is continuously collapsed along the optical axis direction. As shown in the figure, at different directions such as θ0 and θ90, different cross-sectional schematic diagrams are formed in different directions after collapse in the above manner: when the upper part is a texture of equal width, that is, the collapse method and the surfaces formed when the third surface and the texture surface are determined, the texture formed at this time has different texture vertex angle positions in different directions, and the height variation law of the texture vertex angle position forms the corresponding fourth surface height function f4, and the transformation law of the texture vertex angle position is the same as the surface height variation law of the second surface 2; when the lower part is a texture of equal height, that is, the collapse method and the surfaces formed when the fourth surface and the third surface are determined, the texture formed at this time has different texture vertex angles or bottom angles in different directions. The distance from the origin, then a corresponding texture surface is formed, and the distance from the origin of the texture vertex angle or bottom angle corresponds to the projection of the third surface or the fourth surface to form the shape of the texture surface. Please refer to Fig.11 When the textures are at the same height, the texture is an arbitrary shape texture surface that is not a perfect circle when viewed from above.

[0069] Furthermore, as mentioned above, the first surface and the second surface are both free-form surfaces of any form; each texture top angle position and each texture bottom angle position have the same or different heights and / or the same or different distances from the origin, and the corresponding third surface and fourth surface formed at this time can be free-form surfaces of any form, and the texture surface can be any shape. The change of the top angle position or bottom angle or the change of the distance from the origin in each texture corresponds to the change of the second surface 2 at the corresponding position when it is not collapsed.

[0070] See also Fig.12 , assuming that the fourth surface 4 is a plane, the second surface 2 is a spherical surface, and the texture surface is as shown in the figure, the collapse method and the surfaces formed when the second surface height function (f2) is continuously collapsed along the optical axis direction. Figure 5 Compared with the original point, the position of the texture is also different, so the texture position and texture shape also change accordingly.

[0071] See also Fig.13 If the surface form of a single texture is too complex, an approximate straight line or curve can be taken for the surface power function or surface height function of the texture to obtain a power expression similar to that of the target lens, so as to facilitate the expression or production of the lens.

[0072] Furthermore, it should be noted that if the optical power expressed in the area is in a special form: for example, when the lens is set to have a microlens, that is, when there is a large difference in optical power at a certain point with the surrounding optical power, the original surface curve form needs to be retained; for example, when the lens is set to have a regional prism, the original surface curve form needs to be retained in order to maintain the optical power in the area.

[0073] It should be noted that when the texture collapses along the optical axis, the focal length of the lens in the corresponding texture will change. When the difference between the focal length after collapse and the focal length of the target lens is not within the tolerance range of the designed lens, the texture surface needs to be adjusted to obtain a focal length equal to or close to that of the target lens.

[0074] In addition, it should be noted that the textures and a single texture may have the same or different optical power expressions, texture heights, texture widths, and texture locations, and the present invention does not limit this.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lens design method, characterized in that: include: Determining a first surface and a second surface of the lens according to the optical power of the target lens; Determine the shape and position of the texture according to the third surface, the fourth surface and the texture surface; collapsing the second surface along the optical axis to form a textured Fresnel lens; The third surface is located between the first surface and the second surface and is a surface formed by connecting the bottom corners of the lens textures. The fourth surface is a surface formed by connecting the top corners of the lens textures. The texture surface is the shape of the texture when looking down at the lens. Determining a first surface and a second surface of the lens includes: Determining a form of the first surface includes determining a first optical power function and a first surface height function of the first surface; Determine a second optical power function and a second surface height function of the second surface according to an optical power formula of the lens, the optical power of the target lens, the thickness of the target lens, and the material used for the lens; Determining the texture shape and position according to the third surface, the fourth surface, and the texture surface includes: Setting the third surface and the fourth surface, and determining the texture shape and position; or, Setting the third surface and the texture surface, and determining the texture shape and position; or, Setting the fourth surface and the texture surface, and determining the texture shape and position; When two of the three elements, namely, the third surface, the fourth surface and the texture surface, are determined, the other element can be determined; each texture surface is regarded as a tiny triangular prism, and the shape and position of the triangle are jointly defined by the attributes of the base, hypotenuse, height, base vertex angle and top vertex angle; wherein the hypotenuse of the triangle is determined by the curvature of the second surface; the base of the triangle is determined by the texture spacing of the texture surface, and the height of the triangle is jointly determined by the third surface and the fourth surface; the position of the triangle is defined by the third surface and / or the fourth surface.

2. The lens design method according to claim 1, characterized in that: The target lens has a free power expression, ie the power at each point is the same and / or different.

3. The lens design method according to claim 1, characterized in that: The first surface and the second surface both have free surface forms.

4. The lens design method according to claim 1, characterized in that: The third surface and the fourth surface both have free surface forms.

5. The lens design method according to claim 1, characterized in that: The texture heights in each texture are the same and / or different, and the ring distances from the origin in each texture are the same and / or different.

6. The lens design method according to claim 1, characterized in that: After collapsing the second surface along the optical axis to form a Fresnel lens with a texture, the method further includes: Take an approximate straight line or approximate curve for each texture to obtain an optical power expression equal to or close to that of the target lens.

7. The lens design method according to claim 1, characterized in that: After collapsing the second surface along the optical axis to form a Fresnel lens with a texture, the method further includes: The textured surface is adjusted to obtain an optical power expression equal to or close to that of a target lens.

8. The lens design method according to any one of claims 1 to 7, characterized in that: The optical power between the textures is uniformly set and / or variably set; the optical power within the textures is uniformly set and / or variably set.

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