Spectacle lens, spectacles, computer-implemented method for designing a spectacle lens and method for producing a spectacle lens

Abstract

The invention relates to a spectacle lens (1) comprising - a spectacle lens rear surface (11) facing towards the eye; - a spectacle lens front surface (13) facing away from the eye; - a Fresnel structure (3) comprising at least two Fresnel zones (3-1 to 3-6) providing a focusing effect, wherein the focusing effect of the Fresnel structure (3) is based at least partially on a refractive index gradient within the Fresnel zones (3-1 to 3-6), and the Fresnel structure (3) has boundary surfaces (5a to 5e) at which a high refractive index of one Fresnel zone (3-1 to 3-6) and a low refractive index of an adjacent Fresnel zone (3-1 to 3-6) adjoin one another. The at least one boundary surface (5a to 5e) has a rear-side intersection line (4a to 4e) with the spectacle lens rear surface (11) and a front-side intersection line (6a to 6e) with the spectacle lens front surface (13). The rear surface region of the spectacle lens rear surface (11) enclosed by the innermost rear-side intersection line (4a) has a rear-side geometric centre of gravity (RS) and the front-side surface region of the spectacle lens front surface (11) enclosed by the innermost front intersection line (6a) has a front-side geometric centre of gravity (VS). The rear-side intersection line (4a to 4e) has a smaller distance from the rear-side geometric centre of gravity (RS) than the front-side intersection line (6a to 6e) from the front-side geometric centre of gravity (VS), for at least 25% of all azimuth angles.

Description

[0001] Spectacle lens, spectacles, computer-implemented method for designing a spectacle lens and method for manufacturing a spectacle lens

[0002] The present invention relates to a spectacle lens with a Fresnel structure providing a focusing effect. Furthermore, the invention relates to a computer-implemented method for designing such a spectacle lens and a method for manufacturing such a spectacle lens.

[0003] Conventional lenses become thicker and heavier the higher the required vision correction. In addition to the choice of material, weight reduction is primarily achieved by reducing the size, i.e., choosing a smaller frame.

[0004] Weight is particularly relevant for vision correction applications in augmented reality (so-called AR glasses), as the system weight is already significantly higher than that of a conventional lens due to the additional components such as fiber optics, cameras, sensors, etc. However, reducing the diameter is often not a feasible option due to the required size of the fiber optics to project the virtual image into the wearer's field of vision.

[0005] For example, Fresnel structures for reducing the weight of ophthalmic lenses are known from EP 0 927 905 A, GB 1 154,360 A, JP 2019174647 A, and US 2013 / 0120707 A1. However, Fresnel structures are challenging to manufacture due to their sharp steps. Furthermore, the susceptibility of exposed Fresnel structures to contamination makes them necessary to cover or fill them. Furthermore, the steps in Fresnel structures lead to shadowing effects and scattered light.

[0006] From WO 2018 / 134037 A2, gradient index lenses (GRIN lenses) for ophthalmic applications are also known, but they do not offer any weight advantages compared to a classic glass with a constant refractive index.

[0007] US 2022 / 0252931 A1 shows a segmented liquid crystal optic that can be used as a Fresnel GRIN lens with variable refractive power in augmented reality devices.

[0008] Fresnel GRIN lenses, i.e. lenses in which the Fresnel structure is realized by variations in the refractive index, are known from the literature on micro-optics for coupling light into optical fibers. Examples of publications on micro-optical Fresnel GRIN lenses include Suhara et al., "Graded-index Fresnel lenses for integrated optics", Appl. Opt. 21 (1982), pp. 1966-1971; P. Dellulier et al., "Femtosecond Laser Direct Writing of Gradient Index Fresnel Lens in GeS2-Based Chalcogenide Glass for Imaging Applications", Appl. Sci 12 (2022), 4490; and R. Buczynski et al. R 2019, 'Achromatic nanostructured gradient index microlenses', Optics Express, vol. 27, no. 7, pp. 9588-9600. The Fresnel GRIN lenses described therein are designed for use in the infrared spectral range.

[0009] Diffractive Fresnel GRIN lenses are known from A. Zhang, "Multifocal diffractive lens design in ophthalmology," Applied Optics, Vol. 59, No. 31 (1 November 2020), pp. 9807-9823. Diffractive Fresnel GRIN lenses are used, for example, in intraocular lenses to create, in addition to the refractive focal point determined by the geometric shape of the intraocular lens, another point of sharp vision determined by the diffractive effect of the Fresnel structure. This allows the intraocular lens to enable sharp vision at different distances.

[0010] WO 97 / 10527 A1 discloses contact lenses designed as Fresnel GRIN lenses. Compared with the cited prior art, a first object of the present invention is to provide an advantageous spectacle lens and advantageous spectacles with a Fresnel structure providing a focusing effect, in which the focusing effect of the Fresnel structure is based at least partially on a gradient of the refractive index within the Fresnel zones. The term "focusing effect" in the sense of the invention according to DIN EN ISO 13666:2019-12, Section 3.10.2, is a collective term for the spherical and astigmatic vertex power of a spectacle lens, which according to DIN EN ISO 13666:2019-12, Section 3.10.7, is in turn the inverse of the paraxial focal length of the spectacle lens.

[0011] A second object of the present invention is to provide a computer-implemented method for designing a spectacle lens as well as a computer program and a computer for carrying out the method.

[0012] Finally, a third object of the present invention is to provide an advantageous method for producing a spectacle lens.

[0013] The first object is achieved by a spectacle lens according to claim 1 and by spectacles according to claim 26, the second object by a computer-implemented method according to claim 18 and the third object by a method according to claim 25. The dependent claims contain advantageous embodiments of the invention.

[0014] According to a first aspect of the invention, a spectacle lens is provided. The term "spectacle lens" encompasses both unprocessed round spectacle lenses and spectacle lenses adapted to a spectacle frame. Furthermore, the term "spectacle lens" also encompasses numerical representations of spectacle lenses. A spectacle lens according to the invention can therefore exist as a physical spectacle lens or as a numerical model of a spectacle lens.

[0015] A spectacle lens according to the invention has a rear lens surface facing the eye, a front lens surface facing away from the eye, and a Fresnel structure comprising at least two Fresnel zones. The Fresnel structure provides a focusing effect which, in at least one of the Fresnel zones, in particular in a plurality of the Fresnel zones or in all Fresnel zones, is based at least partially, but in particular completely, on a gradient of the refractive index within the corresponding Fresnel zone, and has interfaces at which a high refractive index of one Fresnel zone and a low refractive index of an adjacent Fresnel zone adjoin one another. A Fresnel structure providing a focusing effect differs from a Fresnel structure providing a diffractive effect by its structural dimensions, in particular by the width and / or height of the Fresnel zones.In the context of the present invention, the minimum width of a Fresnel zone is 0.5 mm and preferably 1 mm. In contrast, in diffractive Fresnel structures, the Fresnel zones typically have widths of less than 0.25 mm and heights that result in path length differences of less than 20 pm, preferably less than 10 pm, and typically less than 5 pm.

[0016] A Fresnel structure is to be understood as a structure comprising at least two zones, so-called Fresnel zones, which have a jump in the arrow height and / or a jump in the refractive index at the boundary between adjacent zones.

[0017] The at least one boundary surface has a rear intersection line with the rear surface of the lens and a front intersection line with the front surface of the lens. The rear surface region of the rear surface of the lens enclosed by the innermost rear intersection line has a rear geometric center of gravity, and the front surface region of the front surface of the lens enclosed by the innermost front intersection line has a front geometric center of gravity.

[0018] In the spectacle lens according to the invention, the rear intersection line has a smaller distance from the rear geometric center of gravity than the front intersection line from the front geometric center of gravity for at least 25% of all azimuth angles, preferably for at least 50% of all azimuth angles, and more preferably for at least 90% of all azimuth angles. In particular, the rear intersection line can have a smaller distance from the rear geometric center of gravity than the front intersection line from the front geometric center of gravity for any given azimuth angle.Furthermore, in particular, in the spectacle lens according to the invention, for at least two interfaces and preferably for all interfaces, the rear intersection line of the respective interface for at least 25% of all azimuth angles, preferably for at least 50% of all azimuth angles and more preferably at least 90% and in particular any arbitrarily predetermined azimuth angle, can have a smaller distance from the rear geometric center of gravity than the front intersection line of this respective interface from the front geometric center of gravity.

[0019] For the purposes of the invention, the azimuth angle is defined as the angle between a straight line passing through the geometric center of gravity of the enclosed front surface area in a tangential plane tangential to the geometric center of gravity of the enclosed front surface area of ​​the lens front surface, and a straight reference line passing through the geometric center of gravity of the enclosed front surface area in this tangential plane. The azimuth angle of a connecting line running on the lens front surface, which connects the geometric center of gravity of the enclosed front surface area with a point on a front-side intersection line of a boundary surface by the shortest route, is then the azimuth angle between the projection of this connecting line onto the tangential plane and the reference line running in the tangential plane.This azimuth angle is also considered, within the context of the present invention, to be the azimuth angle of the point connected by the corresponding connecting line to the geometric center of gravity of the enclosed front surface area. Accordingly, the azimuth angle of a connecting line running on the back surface of the spectacle lens, which connects the geometric center of gravity of the enclosed rear surface area with a point on a rear intersection line of an interface by the shortest path, is the azimuth angle between the projection of this connecting line onto the tangential plane and the reference line running in the tangential plane. This azimuth angle is also considered, within the context of the present invention, to be the azimuth angle of the point connected by the corresponding connecting line to the geometric center of gravity of the enclosed rear surface area.Instead of a tangential plane running tangentially to the geometric center of gravity of the enclosed front surface area of ​​the front surface of the lens, a tangential plane running tangentially to the geometric center of gravity of the enclosed rear surface area of ​​the rear surface of the lens can also be used to determine the azimuth angle.

[0020] The inventive design of the interface between adjacent Fresnel zones allows for the wearer to reduce disturbing shadows and reflections at the interface by suitably aligning the interface, for example by tilting it accordingly. Its alignment can also be adapted to the respective viewing direction when looking along the interface. In particular, it is possible to individually adapt the alignment to each wearer. Alternatively, it is also possible to use a standard eye based on average values ​​for a standard head geometry as the basis for aligning the interface in the respective viewing direction. Overall, the inclination of the interface and the associated reduction in shadows and reflections increases the wearing comfort of a spectacle lens with a Fresnel structure based on gradients in the refractive index.

[0021] In the spectacle lens according to the invention, at least one interface or several of the interfaces, in particular all interfaces, can be aligned in such a way that those rays which run along this interface within a cutting plane, after exiting the rear surface of the spectacle lens, unite in a point located on the side of the rear surface of the spectacle lens and spaced therefrom.The cutting plane is the plane in which a front connecting line lies, running at a specific azimuth angle in the front surface of the lens, which connects the geometric center of gravity of the enclosed front surface area by the shortest path to a point on the front cutting line of one of the interfaces, and in which a rear connecting line also lies, running at the same specific azimuth angle in the rear surface of the lens, which connects the geometric center of gravity of the enclosed rear surface area by the shortest path to a point on one of the rear cutting lines of the same interface. In particular, this point, located on the side of the rear surface of the lens and spaced from it, can be the same for all azimuth angles, whereby the rays then run along a conical surface.In this way, the spectacle lens can be designed so that all rays traveling along an interface, after exiting the rear surface of the lens, converge at the pupil center, the eye rotation point, or at a point located on a straight line passing through the pupil center and the eye rotation point in the zero gaze direction. For the purposes of the invention, the zero gaze direction is the fixation line, assumed to be horizontal, which, when looking straight ahead without correction and with a habitual head and body posture, leads to an object located at infinity (cf. DIN EN ISO 13666:2019-12, Section 3.2.25).In the sense of the invention, a conical surface is to be understood as a surface which is obtained when the points of a rear section line are connected with a point which is spaced from the rear surface of the spectacle lens in a coordinate along the surface normal in the geometric center of gravity of the enclosed rear surface area.

[0022] In alternative embodiments, the distance of the point located on the side of the back surface of the lens and spaced from it from the back surface of the lens can also depend on the azimuth angle. This makes it possible, for example, to provide a different point for an azimuthal orientation of the cutting plane that corresponds to the wearer's horizontal viewing directions than for an azimuthal orientation of the cutting plane that corresponds to the wearer's vertical viewing directions. This makes it possible, for example, to take into account the fact that the eye rolls more horizontally than vertically. For example, for a horizontal viewing direction, the rays can converge at the eye's center of rotation, and for vertical viewing directions, which are usually less varied, the rays can converge at the pupil center.In other words, the Fresnel structure can be optimized for horizontal viewing directions for a moving eye and for vertical viewing directions for a stationary eye.

[0023] In the spectacle lens according to the invention, at least two of the interfaces, and in particular all interfaces, can be aligned such that, for the respective interface, all rays running within the sectional plane along these interfaces converge, after exiting the rear surface of the lens, at a point located on the side of the rear surface of the lens and spaced from it, and the point located on the side of the rear surface of the lens and spaced from it is the same for the at least two interfaces. For example, if the spectacles are primarily intended to be used with one eye at rest, it is advantageous to align at least two of the interfaces, and preferably all of the interfaces, such that the rays converge at the pupil center.

[0024] However, it is also possible for at least two of the interfaces, and in particular all interfaces, to be aligned such that, for the respective interface, all rays running within the sectional plane along this interface converge, after exiting the rear surface of the lens, at a point located on the side of the rear surface of the lens and spaced from it, and for the distance of the point located on the side of the rear surface of the lens and spaced from it to the rear surface of the lens to be different for the at least two interfaces. For example, the innermost interface or interfaces can be aligned such that the rays converge at the pupil center, whereas the outermost interface or interfaces are aligned such that the rays converge at the eye's rotation point.In this way, the eye can be treated like a resting eye for small eye movements and like a rolling eye for large eye movements. Furthermore, it is possible to design the distance of the point on the side of the back of the lens and the point of objection to it differently for all interfaces. For example, the innermost interface can be aligned so that the rays converge at the pupil center, and the outermost interface so that the rays converge at the eye rotation point. The interfaces in between can then be aligned so that the rays each converge at different points that lie on a straight line running through the pupil center and the eye rotation point in the zero-gaze direction.A lens equipped in this way is optimized for small viewing angles with a resting eye in mind, and its optimization gradually changes with increasing viewing angle, from a resting eye to a rolling eye. By appropriately selecting the point where the rays converge, or the points where rays traveling along different interfaces converge after exiting the back surface of the lens, the lens can be particularly well adapted to the wearer and the intended use of the glasses.

[0025] The spectacle lens according to the invention can be manufactured particularly easily if at least one of the interfaces, and in particular all interfaces, runs along a straight line within the section plane. Alternatively, at least one of the interfaces can run along a curved line within the section plane.The curvature of the curved line is: a curvature that follows the path of a light ray that emanates from the point spaced from the rear surface of the lens and enters the spectacle lens at the boundary between the high refractive index of one Fresnel zone and the low refractive index of the adjacent Fresnel zone through the rear surface of the lens immediately adjacent to the interface (5a to 5e) on the side of the high refractive index; a curvature that follows the path of a light ray that emanates from the point spaced from the rear surface of the lens and enters the spectacle lens at the boundary between the high refractive index of one Fresnel zone and the low refractive index of the adjacent Fresnel zone through the rear surface of the lens immediately adjacent to the interface on the side of the low refractive index; or a curvature whose path lies between the paths of the said light rays.

[0026] The point from which the light beam emanates, i.e. the point at which the rays converge, can be the pupil center, the eye pivot point, or a point on a straight line running through the pupil center and the eye pivot point in the zero viewing direction. By designing the interface as a curved surface, shadows and reflections can be particularly well avoided. Here, too, the spectacle lens can be particularly well adapted to the wearer and their use of the spectacles by appropriately choosing the point or points from which the light beam emanates. The point from which the light beam emanates can be the same point for at least two interfaces, in particular for all interfaces. However, there can be at least two interfaces for which different points at a distance from the back surface of the lens exist.

[0027] When designed as a negative lens, the spectacle lens typically has a dead zone for each interface. The dead zones are each delimited by the path of a set of first light rays in the spectacle lens, by the path of a set of second light rays in the spectacle lens, and by an annular region of the front surface of the spectacle lens resulting from the path of the first set of light rays and the path of the second set of light rays. For the respective interface, the first light rays are those light rays that emanate from the point spaced from the rear surface of the spectacle lens or are united at this point and enter through the rear surface of the spectacle lens immediately adjacent to the corresponding interface into the Fresnel zone with the high refractive index adjacent to the interface, and the second light rays are those light rays that emanate from the point spaced from the rear surface of the spectacle lens or are united at this point.are united at this point and enter the Fresnel zone with the low refractive index adjacent to the interface through the rear surface of the spectacle lens, immediately adjacent to the corresponding interface. Due to the different refractive indices on both sides of the interfaces, the light rays incident on the different sides of the respective interface are refracted differently, which in turn leads to the dead zones described. Although these dead zones do not contribute to the image, the interface located in the dead zone can still lead to stray light and reflections. To reduce stray light and reflections, in an advantageous embodiment of the spectacle lens according to the invention, the dead zones are each provided with at least one light-absorbing layer.In this case, a light-absorbing layer may be present along the path of the set of first rays and / or a light-absorbing layer may be present along the path of the set of second rays and / or a light-absorbing layer may be present in the annular region of the front surface of the spectacle lens.

[0028] If at least one of the interfaces, and in particular all interfaces, runs along a straight line within the section plane described above, it is advantageous if these straight lines are aligned such that they run within the dead zone. Such a design of the spectacle lens also makes it possible to reduce stray light and reflections.

[0029] To reduce stray light and reflections, the dead zones of the lens can also have a different refractive index than the high refractive index and the low refractive index of the Fresnel zones adjacent to the respective dead zones. This can be achieved, for example, by doping the corresponding parts of the lens or by using a different material for the manufacture of the corresponding parts of the lens. Furthermore, the dead zone can be used for a continuous transition of the refractive index, which may be preferable to a sharp jump to reduce reflections, etc.

[0030] The aforementioned measures for reducing stray light and reflections can be applied alternatively or cumulatively. The spectacle lens according to the invention can have a central region without a Fresnel structure and with a curved surface. This central region can have a diameter of up to 20 mm. In particular, the central region can have a diameter between 5 mm and 20 mm, in particular between 10 mm and 15 mm. In this case, the Fresnel structure is only present in an area outside the central region. The spectacle lens then provides a focusing effect in the center due to the curved surface and in the edge region due to the Fresnel structure.With this type of lens design, a good compromise between thickness / weight on the one hand and image quality on the other can be achieved, without causing image distortion near the edge of the lens, as is otherwise common with surface shapes of this type. At the same time, chromatic aberration can be significantly improved compared to a lens in which the refractive effect is based solely on a curved surface up to the edge, if there is low dispersion at the high refractive index and high dispersion at the low refractive index. In lenses designed as positive lenses, the Fresnel structure can be designed as a flat plate or meniscus of constant thickness if its focusing effect is based exclusively on a gradient of the refractive index within the Fresnel zones. In lenses designed as negative lenses, the thickness can also decrease again towards the edge.Due to the decoupling of surface shape and focusing effect possible with the Fresnel structure, many variants are conceivable.

[0031] The resolution of a Fresnel structure for ophthalmic applications is limited by the structure width, which should ideally be larger than a certain fraction of the eye pupil (e.g., > 1 mm or at least > 0.5 mm). A strong focusing effect results in thick elements in Fresnel structures whose focusing effect is based on a refractive index gradient within the Fresnel zones, and in large jumps in the sagittal angles in Fresnel structures whose focusing effect is based on curved or inclined surfaces of the Fresnel zones. It can therefore be advantageous to combine a Fresnel structure whose focusing effect is based on a refractive index gradient within the Fresnel zones with a Fresnel structure whose focusing effect is based on curved or inclined surfaces of the Fresnel zones.It is therefore advantageous if the spectacle lens according to the invention, in addition to a Fresnel structure whose focusing effect is based at least partially on a gradient of the refractive index within the Fresnel zones, includes an additional Fresnel structure which has Fresnel facets with curved and / or inclined surfaces and in which jumps in the sagittal height are present at the boundaries between adjacent Fresnel facets, i.e. a Fresnel structure in which the focusing effect is based on the curvature and in particular inclination of the surfaces of the Fresnel facets.In such a combined Fresnel structure, the thickness of the Fresnel structure, whose focusing effect is based on a refractive index gradient within the Fresnel zones, can be reduced while maintaining the strong focusing effect compared to a non-combined Fresnel structure—that is, compared to a Fresnel structure whose focusing effect is based solely on a refractive index gradient within the Fresnel zones. At the same time, the jumps in the sagittal angles of the Fresnel structure, whose focusing effect is based on the curved surfaces of the Fresnel zones, can be reduced in the combined Fresnel structure, compared to a non-combined Fresnel structure—that is, compared to a Fresnel structure whose focusing effect is based solely on the curved surfaces of the Fresnel zones.

[0032] To combine a Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones with a Fresnel structure whose focusing effect is based on curved and / or inclined surfaces of the Fresnel zones, a Fresnel structure whose focusing effect is based on curved and / or inclined surfaces of the Fresnel zones can, for example, be additionally provided with variations in the refractive index within the Fresnel zones. This approach offers the advantage that the jumps in the sagittal angle coincide with the interfaces between a high refractive index of one Fresnel zone and a low refractive index of an adjacent Fresnel zone. However, this is not necessary within the scope of the present invention.

[0033] In the combined Fresnel structure, the refractive index variations can be limited to the section of the Fresnel structure over which the curved and / or inclined surfaces of the Fresnel zones with the jumps in the sagittal angles extend. If the refractive index variations also extend into the section of the Fresnel structure that has the curved and / or inclined surfaces and the jumps in the sagittal angles, the curvatures and / or inclinations of the Fresnel zone surfaces must be adapted to the refractive index variation within the Fresnel zone.

[0034] In the combined Fresnel structure, the jumps in the sagittal heights can be formed by flanks of the Fresnel facets, which may continue the course of the interfaces except for a kink caused by the law of refraction at the interface between the Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones and the Fresnel structure whose focusing effect is based on curved and / or inclined surfaces of the Fresnel zones.

[0035] The gradient of the refractive index within the Fresnel zones is, in particular, non-linear in the context of the spectacle lens according to the invention, meaning that the refractive index increases in the radial direction according to a spherical or aspherical profile. A parabolic or hyperbolic profile, for example, can be considered as an aspherical profile. However, other aspherical profiles are also possible. Furthermore, the radii of curvature do not need to be the same in all radial directions, for example, if astigmatism is to be corrected.

[0036] However, in the context of the spectacle lens according to the invention, the gradient of the refractive index within the Fresnel zones can also have a linear increase in the radial direction. Linear increases offer the advantage that they can be easier to produce than non-linear refractive index gradients. In the case of a linear refractive index gradient, however, an adaptation of the surface of the spectacle lens is necessary. The adaptation can be achieved, for example, by the described combination with a Fresnel structure whose focusing effect is based on curved and / or inclined surfaces of the Fresnel zones. In the spectacle lens according to the invention, the adaptation can also be achieved by a spectacle lens surface without jumps in the sagittal angles. In this case, the spectacle lens has a front surface and / or a back surface, each of which has a kink at the boundaries between two Fresnel zones.In this case, a surface would be created that locally generates the curvature of the wavefront, while the refractive index gradient is responsible for beam deflection according to the desired focusing effect. Compared to a combination with a Fresnel structure, whose focusing effect is based on curved and / or inclined surfaces of the Fresnel zones, this approach offers the advantage that fewer complex measures are required to prevent contamination of the lens surface, and the lens surface is also easier to clean.

[0037] In order to design the spectacle lens according to the invention as an achromatic spectacle lens, two materials can be combined in the spectacle lens in such a way that chromatic aberrations are at least partially compensated and / or a low dispersion with the high refractive index and a high dispersion with the low refractive index can be combined.

[0038] According to a second aspect of the invention, a computer-implemented method for designing a spectacle lens according to the invention is provided. The computer-implemented method comprises the steps:

[0039] Acquiring at least correction data, which represent at least the correction to be achieved with the spectacle lens, and distance data, which represent at least the distance of the pupil center or the eye rotation point from the vertex of the rear surface of the spectacle lens, or from which at least the distance of the pupil center or the eye rotation point from the vertex of the rear surface of the spectacle lens can be derived; determining the Fresnel structure on the basis of the correction data and the distance data.

[0040] The recorded correction data and the recorded distance data can be standardized data, which, particularly in the case of distance data, have been statistically derived from a sufficiently large group of test subjects. Alternatively, they can also be individualized data, i.e., data measured for a specific spectacle wearer. The latter offers the advantage that the spectacle lens can be individually adjusted to the wearer. However, it is also possible, for example, to individually determine the correction data and use standardized distance data for this purpose. If both the correction data and the distance data are standardized data, stock spectacle lenses can be generated for a number of combinations of correction data and distance data.

[0041] The method can, in particular, also include measuring the corneal-vertex distance, i.e., the distance between the vertex of the back surface of the lens and the apex of the wearer's cornea. The distance of the pupil center from the vertex of the back surface of the lens can then be determined based on the corneal-vertex distance and the distance of the pupil center from the apex of the wearer's cornea. Similarly, the distance of the ocular rotation center from the vertex of the back surface of the lens can be determined based on the corneal-vertex distance and the distance of the ocular rotation center from the apex of the wearer's cornea. A statistically averaged standardized distance of the ocular rotation center from the apex of the cornea is 13.5±2.5 mm.

[0042] In particular, the computer-implemented method may also include a step of outputting a numerical representation of the designed spectacle lens for use in the manufacture of an actual spectacle lens corresponding to the numerical representation of the spectacle lens by means of a computer-aided numerically controlled (CNC) manufacturing process. According to the second aspect of the invention, a non-transitory computer-readable storage medium with a numerical representation of the spectacle lens according to the invention is also provided for use in the manufacture of an actual spectacle lens corresponding to the numerical representation of the spectacle lens by means of a computer-aided numerically controlled (CNC) manufacturing process.

[0043] Furthermore, according to the second aspect of the invention, a computer system is provided with data retrievable via a network, which provides a numerical representation of the ophthalmic lens according to the invention for use in the manufacture of an actual ophthalmic lens corresponding to the numerical representation of the ophthalmic lens by means of a computer-aided numerically controlled (CNC) manufacturing process for retrieval.

[0044] Furthermore, according to the second aspect of the invention, a computer program is provided with instructions that cause a computer to carry out the computer-implemented method according to the invention when the instructions are executed by the computer.

[0045] Finally, according to the second aspect of the invention, a data processing system is provided having a memory storing instructions that cause the data processing system to perform the computer-implemented method, and a processor for executing the instructions stored in the memory.

[0046] According to a third aspect of the invention, a method for producing a spectacle lens is provided. In this method, a physical spectacle lens corresponding to the numerical representation of the spectacle lens is produced by means of a computer-aided, numerically controlled production process on the basis of a numerical representation of the spectacle lens according to the invention. The computer-aided, numerically controlled production process can in particular be an additive manufacturing process such as, for example, 3D printing. Alternatively, the computer-aided, numerically controlled production process can be a production process in which a photosensitive material is selectively exposed by means of structured illumination and / or by means of suitable masks. In addition, methods are conceivable in which, in a first step, for exampleBy winding or stacking thin polymer films, such as those already used for GRIN lenses, a cylindrical or cubic blank is first produced. After forming, this blank may have a Fresnel structure with a gradient of the refractive index within the Fresnel zones, and its diameter corresponds to the diameter of the subsequent unprocessed round ophthalmic lens. In a next step, unprocessed round ophthalmic lenses can be cut from the cylindrical blank.

[0047] A pair of spectacles according to the invention is equipped with at least one spectacle lens according to the invention. The advantages associated with the spectacles according to the invention arise directly from the advantages described with reference to the spectacle lens according to the invention.

[0048] The spectacles according to the invention can also comprise a display, a light guide, a coupling element for coupling a beam of rays emanating from the display into the light guide, and a coupling-out structure for coupling the beam of rays out of the light guide toward the eye of a wearer of the spectacles. For example, an air gap can be present between the light guide and the spectacle lens, enabling the beam of rays to be guided inside the light guide by means of total internal resection. Instead of an air gap between the light guide and the spectacle lens, a layer of a material with a lower refractive index than that of the light guide can also be present between the light guide and the spectacle lens. In this embodiment, the beam of rays to be guided inside the light guide by means of total internal resection is also possible.

[0049] Due to the fact that the Fresnel structure of the spectacle lens provides a focusing effect which is based in at least one of the Fresnel zones, in particular in a plurality of the Fresnel zones or in all Fresnel zones, at least partially, but in particular completely, on a gradient of the refractive index within the corresponding Fresnel zone, the thickness of the spectacle lens can be kept low, even if the spectacle lens is designed to correct severe ametropia, so that the combination of the spectacle lens with a light guide can also have a relatively low thickness.

[0050] The display can be designed as an LED display, an LCD display, an OLED display, or another suitable display. A prism, for example, can be used as the input coupling element, the prism surfaces of which are shaped and inclined in such a way that a beam of light emanating from the display is guided into the light guide in such a way that it is guided to the output coupling structure via reflections at the light guide surfaces, in particular via total internal reflection at the light guide surfaces. The output coupling structure can be designed as a diffraction grating, as a partially transparent, inclined mirror, or in the form of partially transparent Fresnel elements. In the case of a diffraction grating, the beam of light is coupled out of the spectacle lens via the 1st order diffraction maximum, for example, while the observation light can pass through the output coupling structure as unaffected as possible via the 0th order diffraction maximum.

[0051] Further features, properties, and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. Features of the individual exemplary embodiments can also be combined with one another.

[0052] Figure 1 shows the general structure of a Fresnel structure in which the focusing effect is based on a gradient in the refractive index within the Fresnel zones.

[0053] Figure 2 schematically shows a first embodiment of a spectacle lens with a Fresnel structure whose focusing effect is based on a refractive index gradient within the Fresnel zones. Figure 3 schematically shows a second embodiment of a spectacle lens with a Fresnel structure whose focusing effect is based on a refractive index gradient within the Fresnel zones.

[0054] Figure 4 shows a schematic representation of a third embodiment of a spectacle lens with a Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones.

[0055] Figure 5 shows a schematic representation of a fourth embodiment of a spectacle lens with a Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones.

[0056] Figure 6 shows a schematic representation of a fifth embodiment of a spectacle lens with a Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones.

[0057] Figure ? shows schematically a sixth embodiment of a spectacle lens with a Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones.

[0058] Figure 8 schematically shows a seventh embodiment of a spectacle lens with a Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones.

[0059] Figure 9 shows schematically an eighth embodiment of a spectacle lens with a Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones.

[0060] Figure 10 shows an exemplary embodiment of a computer-implemented method for designing a spectacle lens with a Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones, using a flow chart.

[0061] Figure 11 shows a schematic representation of spectacles with lenses having a Fresnel structure whose focusing effect is based on a gradient of the refractive index within the Fresnel zones.

[0062] The basic structure of a Fresnel structure, in which the focusing effect is based on a gradient in the refractive index within the Fresnel zones, is described below with reference to Figure 1. Various embodiments of a spectacle lens with a Fresnel structure, whose focusing effect is based on a gradient in the refractive index within the Fresnel zones, are described with reference to Figures 2 to 9. The focusing effect can be positive or negative. Furthermore, it can comprise a spherical effect and / or an astigmatic effect.

[0063] Figure 1 schematically shows an example of a spectacle lens 1 with a Fresnel structure 3, with six Fresnel zones 3-1 to 3-6, in which the focusing effect is based on a gradient in the refractive index within the Fresnel zones 3-1 to 3-6. These gradients in the refractive index are symbolized by the point densities within the individual Fresnel zones 3-1 to 3-6, with a higher point density symbolizing a higher refractive index. It can be seen that in the present example, the refractive index in each Fresnel zone 3-1 to 3-6 increases from radially inside to radially outside.

[0064] The spectacle lens 1 shown as an example is an unmounted round spectacle lens with a diameter of 40 mm. It should be noted, however, that the diameter of unmounted round spectacle lenses can also be larger or smaller than 40 mm and typically ranges between 30 and 60 mm. The central Fresnel zone 3-1 has a diameter of 12.6 mm in the present example. The widths of the annular Fresnel zones 3-2 to 3-6 adjoining the central Fresnel zone 3-1 decrease progressively towards the outside, and the outermost Fresnel zone 3-6 has a width of 1 mm in the present example.

[0065] Due to the decreasing width of the Fresnel zones, the refractive index gradient becomes increasingly steeper from the central Fresnel zone 3-1 to the outer Fresnel zone 3-6. However, it would also be possible to make the refractive index gradient less steep in the outer Fresnel zones and instead make the surface of the Fresnel zones curved and / or inclined, so that the focusing effect of the Fresnel zones is determined partly by the refractive index gradient and partly by the shape of the surface of the Fresnel zones.

[0066] The local beam deflection achieved by Fresnel structure 1 is determined by the gradient in the refractive index of the individual Fresnel zones 3-1 to 3-6 and the thickness of the lens 1. With a thickness of, for example, 1 mm and a maximum refractive index difference of 0.1 within a Fresnel zone, path length differences of 100 pm can be achieved in the Fresnel structure. A lens with a focusing power of 5 dpt thus has a central Fresnel zone diameter of 12.6 mm. At a distance of 20 mm from the lens center, the structure size is 1 mm, which is still acceptable for image quality in terms of an effective pupil diameter.

[0067] In the approximation of vertical passage of the light rays through the spectacle lens 1, the path length difference AOPD (OPD: optical path difference) introduced by a spectacle lens with local thickness d(x,y) is given by the equation

[0068] AOPD = (n(x,y) - 1 ) ■ d(x,y) is given, where n(x,y) denotes the refractive index at location (x,y). The y-direction of the coordinate system shown in Figure 1 runs perpendicular to the plane of the page away from the observer. Within the framework of the limits of the refractive index nmin and nmax that are possible in materials with refractive index gradients and possibly a predetermined minimum and maximum thickness dmin and dmax of the spectacle lens 1, starting from a predetermined target path length difference (target OPD), which for example for a focusing spectacle lens increases or decreases approximately quadratically with the distance from the axis, a sectionally continuously varying path length difference can be realized, with the jumps in the refractive index preferably taking place from the maximum to the minimum refractive index in order to reduce the number of jumps. In addition, jumps in the surface can also be permitted, but this is not absolutely necessary.For example, a continuous surface can be specified as a boundary condition. The distribution of the refractive index inside the lens 1—including the discontinuities in the refractive index—can then be determined based on the specified target OPD and / or on the basis of specified target imaging properties for the continuous surface. Alternatively, the locations of the discontinuities in the refractive index can be specified, and the surface determined accordingly, so that, for example, as much of the focusing effect as possible is realized via the gradient in the refractive index, e.g., to minimize the overall thickness or mass of the element.

[0069] In particular, the described procedures can also be iterated, or the position of the jumps in the refractive index and / or the distribution of the refractive index and / or the surface shape can be optimized using a suitable objective function.

[0070] For optimization purposes, a numerical model of the spectacle lens is typically specified with a specific initial position of the jumps in the refractive index and / or a specific initial distribution of the refractive index and / or an initial surface shape. Based on this numerical model of the spectacle lens, the path length difference and / or the imaging properties to be achieved with the spectacle lens are simulated using ray tracing. The deviation of the path length difference determined from the simulation or the imaging properties determined from the simulation from the target path length difference and / or the target imaging properties is then determined. The position of the jumps in the refractive index and / or distribution of the refractive index and / or the surface shape in the numerical model of the spectacle lens is / areare then varied iteratively until the deviation of the path length difference determined from the simulation from the target path length difference and / or the mapping properties determined from the simulation from the target mapping properties meets a termination criterion. This termination criterion can be, for example, that the value of an objective function dependent on the deviation no longer exceeds a specified limit, or the fact that the value of the objective function no longer changes significantly during the iteration steps.

[0071] In the optimized lens, the distribution of the jumps in the refractive index does not have to be uniform (e.g., concentric for a rotationally symmetric optic). Furthermore, the jumps in the refractive index do not have to be between the minimum value nmin and the maximum value n max of the refractive index if this is advantageous for the imaging properties or aesthetics. For example, for spectacles with an astigmatic power, the contour lines could still be chosen concentrically for aesthetic reasons (then with different refractive index distributions at different azimuths). This offers advantages in terms of aesthetic appearance, particularly in cases of oblique astigmatism or when astigmatism differs between the two eyes.

[0072] For non-vertical passage of rays through the spectacle lens 1, an analogous consideration or optimization is possible.

[0073] A first exemplary embodiment of a spectacle lens 1 designed according to the invention is described below with reference to Figure 2. In the spectacle lens 1 of Figure 2, interfaces 5a to 5e are present, at which a high refractive index of one Fresnel zone and a low refractive index of an adjacent Fresnel zone adjoin one another. The interfaces 5a to 5e each have an intersection line 4a to 4e with the rear surface 11 of the spectacle lens and an intersection line 6a to 6e with the front surface 13 of the spectacle lens. The figure shows a section through the spectacle lens 1, which runs along a line extending in the x-direction of the coordinate system shown in Figure 2, wherein the origin of the coordinate system is located in the geometric center of gravity VS of the front surface region of the front surface 11 of the spectacle lens enclosed by the front-side intersection line 6a.In Figure 2, the axes are shown above the front surface 11 of the lens only for the sake of clarity.

[0074] In the present exemplary embodiment, the x-direction of the coordinate system corresponds to an azimuth angle of 0 degrees, where the azimuth angle represents the angle formed by a straight line running clockwise in the xy plane with the x-axis. The x-axis thus represents a reference line for determining the azimuth angle. The y-direction of the coordinate system shown in Figure 1 runs perpendicular to the plane of the page, away from the observer.

[0075] In the spectacle lens 1 shown in Figure 2, the front surface 13 and the rear surface 11 of the lens each run parallel to the xy plane. The azimuth angle can thus be determined directly using a straight line running in the front surface 13, which line runs from the geometric center of gravity VS of the front surface region to a point on one of the front section lines 6a to 6e. The point to which this straight line runs then has the same azimuth angle as the straight line. In a corresponding manner, an azimuth angle can be specified for the line running from the geometric center of gravity RS of the rear surface region to a point on one of the rear section lines 4a to 4e, as well as for the point on one of the rear section lines 4a to 4e that this straight line connects to the geometric center of gravity RS of the rear surface region.

[0076] If the spectacle lens has a curvature other than that shown in Figure 2, the azimuth angle of a connecting line running on the front surface 13 of the spectacle lens, which line connects the geometric center of gravity VS of the front surface area with a point on a front section line 6a to 6e by the shortest route, is equal to the azimuth angle between the projection of this connecting line onto a tangential plane which runs tangential to the geometric center of gravity VS of the front surface area enclosed by the front section line 6a and the x-axis running in the tangential plane, wherein the projection takes place along the normal direction of the tangential plane.Accordingly, the azimuth angle of a connecting line running on the rear surface 11 of the lens, which connects the geometric center of gravity RS of the rear surface region with a point on a rear section line 4a to 4e by the shortest route, is the azimuth angle between the projection of this connecting line onto the aforementioned tangential plane and the x-axis running in the tangential plane, with the projection occurring along the normal direction of the tangential plane. Instead of a projection onto a tangential plane running tangential to the geometric center of gravity VS of the front surface region, a projection onto a tangential plane running tangential to the geometric center of gravity RS of the rear surface region can alternatively be used, with the projection occurring along the normal direction of the tangential plane.

[0077] In the section shown in Figure 2 along a line with an azimuth angle of 0 degrees, the radially innermost interface 5a, i.e. the interface between the high refractive index of the Fresnel zone 3-1 and the lower refractive index of the Fresnel zone 3-2, is represented by two straight lines. These straight lines are aligned such that light rays 9-1 traveling along these lines inside the lens 1 converge outside the rear surface of the lens at the pupil center PM of the wearer's eye 7 when the spectacles are worn according to their intended use position. The term "use position" refers to the position and orientation of the spectacles in relation to the wearer's eyes and face while wearing the spectacles (cf. DIN EN ISO 13666:2019-12, Section 3.2.36).

[0078] The remaining boundary surfaces 5b to 5e are each represented in the section shown in Figure 2 by two straight lines that are aligned such that light rays 9-2 to 9-5 traveling along these lines inside the spectacle lens 1 converge outside the rear surface of the lens at the ocular rotation point AD of the wearer's eye 7. By inclining the lines representing the boundary surfaces 5a to 5e, shadows and reflections for the wearer can be significantly reduced. In the exemplary embodiment shown in Figure 2, the boundary surfaces 5b to 5e are particularly well adapted to the rolling eye when looking through an edge region of the spectacle lens 1. Only for the central Fresnel zone 3-1 is the boundary surface 5a to the second Fresnel zone 3-2 adapted to the static eye in the zero viewing direction.

[0079] It should be noted that it is not necessary for the radially innermost interface 5a to be oriented such that light rays 9-1 running along it are directed outside the spectacle lens 1 toward the pupil center, whereas the remaining interfaces 5b to 5e are oriented such that light rays 9-2 to 9-5 running along these interfaces are directed outside the spectacle lens 1 toward the eye rotation point AP. Rather, it is also possible to orient all interfaces 5a to 5e either such that light rays running along the interfaces are directed outside the spectacle lens 1 toward the pupil center PM or toward the eye rotation point AD.It is also possible to orient several interfaces in such a way that light rays running along these interfaces are directed outside the spectacle lens 1 to the pupil center PM and to orient several other interfaces in such a way that light rays running along these other interfaces are directed outside the spectacle lens 1 to the eye rotation point AD, for example the light rays 9-1 and 9-2 running along the interfaces 5a and 5b to the pupil center PM and the light rays 9-3 to 9-5 running along the interfaces 5c to 5e to the eye rotation point AD.Furthermore, it is possible to orient the interface 5a such that light rays 9-1 running along it outside the spectacle lens 1 are directed to the pill center PM, and to orient the interface 5e such that light rays 9-5 running along it outside the spectacle lens 1 are directed to the eye rotation point AD, whereas the remaining interfaces 5b to 5d are oriented such that light rays 9-1 running along these interfaces outside the spectacle lens 1 are directed to one or more points which, in the zero viewing direction shown in Figure 2, lie on a straight line 8 running through the pupil center PM and the eye rotation point AD between the pupil center PM and the eye rotation point AD.The interfaces 5b to 5d can, for example, be oriented such that light rays 9-2 to 9-4 running along these interfaces are directed to the same point outside the spectacle lens 1 or to different points, for example such that the points to which the light rays 9-2 to 9-4 running along the interfaces 5b to 5d are directed outside the spectacle lens 1 are located, the closer to the eye rotation point AD, the further the corresponding interface is located radially outside in the spectacle lens 1.

[0080] When exiting the spectacle lens 1, the orientation of the light rays changes due to refraction upon passing through the rear surface 11 of the lens, so that the rays outside the spectacle lens 1 form an angle to the rays inside the spectacle lens 1. Since the refractive index of the spectacle lens 1 is always greater than 1 (refractive index of air) and is typically in the range from 1.50 to 1.75, the rays exiting the rear surface of the spectacle lens form a larger angle to the surface normal than they did inside the spectacle lens.Since a low refractive index and a high refractive index border on each other at the interface between the Fresnel zones, with the difference between the low refractive index and the high refractive index generally not being more than 10%, the refractive index of the spectacle lens can be assumed to be either the high refractive index, the low refractive index, or any refractive index lying between the high refractive index and the low refractive index. This refractive index lying between the high refractive index and the low refractive index can, in particular (but does not have to be), be the mean value between the high refractive index and the low refractive index. The different distances of the point at which the rays converge from the back surface of the lens resulting from the different refractive indices do mean that the pupil center or the pupil aperture is different.The eye rotation point may not be hit exactly, but this only slightly limits the usability of the lens.

[0081] The alignment of the lines that represent the boundary surfaces 5a to 5e in a section through the spectacle lens 1 can be to the same point regardless of the azimuth angle of the section. In this case, the rays emanating from a rear section surface 4a to 4e each represent the surface area of ​​a cone, the tip of which lies at the pupil center PM or the eye rotation point AD. However, the rays do not necessarily have to represent the surface areas of cones. For example, it is possible for the alignment of the lines representing the boundary surfaces 5a to 5e to change with the azimuth angle in the direction of the section. This can, for example,It must be taken into account that the eye rolls horizontally rather than vertically, for example by aligning the lines representing the boundary surfaces 5a to 5e in a section whose azimuth corresponds to the horizontally rolling eye 7 of the spectacle wearer, in such a way that light rays 9-1 to 9-5 running along these lines inside the spectacle lens 1 intersect outside the rear surface 11 of the spectacle lens at the eye rotation point AD, whereas the lines in a section whose azimuth corresponds to the vertically rolling eye 7 of the spectacle wearer are aligned in such a way that light rays 9-1 to 9-5 running along these lines inside the spectacle lens 1 intersect outside the rear surface 11 of the spectacle lens at the pupil center PM.In sections whose azimuthal orientation lies between these two azimuthal orientations, the lines representing the boundary surfaces 5a to 5e can be aligned such that light rays 9-1 to 9-5 running along these lines inside the spectacle lens 1 intersect outside the rear surface of the spectacle lens at a point located between the eye rotation point AD and the pupil center PM.

[0082] Due to the described alignments of the interfaces 5a to 5e, each interface 5a to 5e has an intersection line 4a to 4e with the rear surface 11 of the spectacle lens, which has a smaller distance from the geometric center of gravity RS of the rear surface region RB of the rear surface 11 of the spectacle lens, which is enclosed by the innermost rear intersection line 4a, than the distance that the front intersection line 6a to 6e of this interface 5a to 5e with the front surface 13 of the spectacle lens has from the geometric center of gravity VS of the front surface region VB of the front surface 13 of the spectacle lens, which is enclosed by the innermost front intersection line 6a.The geometric center of gravity RS of the rear surface area enclosed by the innermost rear intersection line 4a is hereinafter referred to as the rear geometric center of gravity RS, and the geometric center of gravity VS of the rear surface area enclosed by the innermost front intersection line 6a is referred to as the front geometric center of gravity VS. In the present exemplary embodiment, each boundary surface 5a to 5e has an intersection line 4a to 4e with the lens rear surface 11, which, for any arbitrarily specified azimuth angle, has a smaller distance from the rear geometric center of gravity RS than the distance that the intersection line 6a to 6e of this boundary surface 5a to 5e with the lens front surface 13 has from the front geometric center of gravity VS.In alternative embodiments, each boundary surface 5a to 5e can each have an intersection line 4a to 4e with the lens rear surface 11, which has a smaller distance from the rear geometric center of gravity RS for only a portion of all azimuth angles than the distance that the intersection line 6a to 6e of this boundary surface 5a to 5e with the lens front surface 13 has from the front geometric center of gravity VS. This portion of all azimuth angles comprises at least 25% of all azimuth angles, preferably at least 50% of all azimuth angles, and in particular at least 90% of all azimuth angles.

[0083] In order to further reduce shadows and reflections, it is possible to arrange reflection-reducing layers at the interfaces in addition to the inclination of the interfaces 5a to 5e.

[0084] The interfaces 5a to 5e between a high refractive index of a Fresnel zone and a lower refractive index of an adjacent Fresnel zone do not necessarily have to be represented by straight lines in an azimuthal section, as is the case in the first exemplary embodiment. Instead, they can be curved such that they follow the path of a light ray emanating from the pupil center PM, the eye rotation point AD, or an intermediate point. In this case, too, each interface 5a to 5e has an intersection line 4a to 4e with the rear lens surface 11, which is at a smaller distance from the rear geometric center of gravity RS than the distance that the intersection line 6a to 6e of this interface 5a to 5e with the front lens surface 13 has from the front geometric center of gravity VS. A corresponding second exemplary embodiment is shown in Figure 3.

[0085] Figure 3 shows, by way of example, the interface 5a between the high refractive index of the central Fresnel zone 3-1 and the adjacent Fresnel zone 3-2 in a section along an azimuthally oriented line. Furthermore, the figure shows a light beam 9 emanating from the pupil center PM and entering the lens 1 through the rear lens surface 11 at the interface 5a between the high refractive index and the lower refractive index. Due to the gradient in the refractive index, the light beam 9 has a curved path inside the lens 1. In the exemplary embodiment shown in Figure 3, the line representing the interface 5a has a curvature in each section along an azimuthal line that is adapted to the path of the light beam 9. This measure helps to further reduce shadows and reflections.

[0086] The different refractive indices to the left and right of an interface 5 also result in a light beam 9 entering the lens 1 at the interface 5a through the rear surface 11 of the lens being deflected slightly differently, depending on whether it enters the lens 1 immediately to the left or immediately to the right of the interface 5a. Therefore, depending on whether it enters the lens 1 immediately to the left or immediately to the right of the interface 5a, it exits the lens 1 at different points through the front surface 13 of the lens, as shown in Figure 4 using the light beams 9a and 9b.If one now considers a set of light rays which, in the present exemplary embodiment, emanate from the pupil center PM and which enter the region of the Fresnel zone 3-1 with the high refractive index at the intersection line 4a immediately adjacent to the interface 5a, these light rays exit the spectacle lens 1 as light rays 9a through the front surface 13 of the lens. These light rays are hereinafter referred to as first light rays. If one correspondingly considers a set of light rays which, in the present exemplary embodiment, emanate from the pupil center PM and which, in the present exemplary embodiment, enter the region of the Fresnel zone 3-2 with the low refractive index at the intersection line 4a immediately adjacent to the interface 5a, these light rays exit the spectacle lens 1 as light rays 9b through the front surface 13 of the lens. These light rays are hereinafter referred to as second light rays.In the case of negative lenses, the distance between the first light rays 9a emerging along the interface 5a and the second light rays 9b emerging along the interface 5a results in an annular region 14 on the front surface 13 of the spectacle lens from which no light rays emerge. The area in the spectacle lens 1 delimited by this annular region 14 and the path of the light rays 9a and 9b inside the spectacle lens 1 is referred to in the context of the present invention as the dead zone 15, since no beam emanating from the pupil center PM passes through this zone. Corresponding dead zones arise at all interfaces 5a to 5b. Light entering these dead zones from outside can lead to reflections and scattered light.In a third exemplary embodiment, shown in Figure 4, the annular region 14 on the front surface 13 of the spectacle lens is therefore provided with a coating 17 to prevent reflections and scattered light, which coating can in particular be a light-absorbing coating. Additionally or alternatively, it is possible to provide the dead zones 15 with a different refractive index than the adjacent refractive indices. A different refractive index can be achieved, for example, by using a different material in the dead zones 15 or by doping the dead zones 15. Furthermore, additionally or alternatively, to prevent reflections and scattered light, the surfaces represented by the path of the rays 9a and 9b in the interior of the spectacle lens 1 can be provided with anti-reflective layers. The anti-reflective layers can in particular be light-absorbing layers.

[0087] Although the interface 5a in Figure 4 has a curvature that is adapted to the beam path inside the spectacle lens, it is alternatively possible to provide an interface that is represented in the sections along an azimuthal line by a straight line that extends from the entry point of the beam 9 located on the rear surface 11 of the spectacle lens to a point that lies in the annular region 14 of the front surface 13 of the spectacle lens.

[0088] The resolution of a Fresnel structure for ophthalmic applications is limited by the structure width, which should ideally be larger than a certain fraction of the eye pupil, for example, larger than 0.5 mm, in particular larger than 1 mm. With a strong focusing effect, this leads to thick Fresnel structures in the case of Fresnel structures based on a gradient in the refractive index and to large jumps in the sagittal angle in the case of Fresnel structures based on a curvature and / or inclination of the surface. In a fourth exemplary embodiment, shown in Figure 5, the spectacle lens 1 has a combined Fresnel structure comprising a first Fresnel structure 3 based on a gradient in the refractive index and a second Fresnel structure 19 based on Fresnel facets 20-1 to 20-6, i.e., a Fresnel structure in which the focusing effect is based on a curvature and / or inclination of the surface of the Fresnel facets.By combining the two Fresnel structures, the thickness of the spectacle lens 1, on the one hand, and the maximum sagittal height h of the Fresnel facets 20-1 to 20-6, and the associated jumps in sagittal height, on the other hand, can be kept relatively low. It is advantageous if, as in the present exemplary embodiment, the boundary surfaces 5a to 5e spatially coincide with the rear flanks 21a to 21f of the Fresnel facets 20-1 to 20-6. However, this is not absolutely necessary within the scope of the invention.

[0089] In the exemplary embodiment shown in Figure 5, the gradients in the refractive index are limited to the part of the combined Fresnel structure shown at the top in the figure, i.e. they do not extend into the Fresnel facets 20-1 to 20-6. In alternative embodiments, however, the gradients can also extend into the Fresnel facets 20-1 to 20-6. In this case, however, the curvatures of the surfaces of the Fresnel facets 20-1 to 20-6 differ from the curvature of the surfaces of Fresnel facets into which the gradients in the refractive index do not extend. Additionally or alternatively, in further embodiments, the trailing flanks 21a to 21e of the Fresnel facets 20-1 to 20-5 can have the same orientation as the interfaces 5a to 5e. Otherwise, the spectacle lens 1 of the fourth exemplary embodiment does not differ from the spectacle lens of the first exemplary embodiment.

[0090] A fifth exemplary embodiment of a spectacle lens 1 according to the invention is shown in Figure 6. Elements which do not differ in their function from elements of the preceding exemplary embodiments are designated in Figure 6 with the same reference numerals as in the preceding exemplary embodiments and are not explained again in detail.

[0091] The spectacle lens 1 of the fifth exemplary embodiment shown in Figure 6 differs from the spectacle lens of the first exemplary embodiment shown in Figure 2 in that the front surface 13 has a concave curvature. This offers the advantage that in the edge region, where a greater deflection of the light rays is required to achieve the focusing effect, the spectacle lens 1 is thicker, thus enabling a larger structural width of the Fresnel structure 3 based on the gradient in the refractive index. Instead of the concave curvature shown in Figure 6, the spectacle lens front surface 13 can alternatively have a convex curvature. Furthermore, instead of the spectacle lens front surface 13 or in addition to the spectacle lens front surface 13, the spectacle lens rear surface 11 can also have a concave or convex curvature.The combination of a concave or convex curvature of the front surface 13 of the spectacle lens and / or a concave or convex curvature of the rear surface 11 of the spectacle lens with a Fresnel structure 3 based on a gradient in the refractive index generally offers the possibility of decoupling the surface geometry of the spectacle lens 1 from the desired focusing effect. Otherwise, the spectacle lens 1 of the fifth exemplary embodiment does not differ from the spectacle lens of the first exemplary embodiment.

[0092] A sixth exemplary embodiment of the spectacle lens 1 according to the invention is shown in Figure ?. Elements which do not differ in their function from elements of the preceding exemplary embodiments are designated in Figure 7 with the same reference numerals as in the preceding exemplary embodiments and will not be explained again in detail.

[0093] In contrast to the first exemplary embodiment shown in Figure 2, the spectacle lens front surface 13 according to the sixth exemplary embodiment shown in Figure 7 has facets that are formed by the spectacle lens front surface 13 having curved surface sections 13-1 to 13-6 in the region of the respective Fresnel zones 3-1 to 3-6. The spectacle lens front surface 13 itself is continuous; however, at the boundaries between the individual Fresnel zones 3-1 to 3-6, there are kinks 18a to 18e in the spectacle lens front surface 13, so that the first derivative of the spectacle lens front surface 13 is not continuous. This configuration offers the possibility of the gradients in the refractive index increasing linearly within the respective Fresnel zones 3-1 to 3-6.Linear increases in the refractive index are generally easier to produce than gradients in the refractive index that follow a nonlinear function, such as a spherical, parabolic, or hyperbolic function. In the case of linear gradients, the beam deflection required for the focusing effect is brought about by the gradients in the refractive index, while the shape of the wavefront is determined by the curvatures of the front surface 13 of the lens in the surface sections 13-1 to 13-6. Because the kinks 18a to 18e in the front surface 13 of the lens coincide with the jumps in the refractive index, such a spectacle lens 1 can be realized without disruptive optical properties. Instead of the concave facets shown in Figure 7, the front surface 13 of the lens can alternatively have convex facets.In addition, instead of the front surface 13 of the lens or in addition to the front surface 13 of the lens, the rear surface 11 of the lens can also have concave or convex facets.

[0094] A seventh exemplary embodiment of the spectacle lens according to the invention is shown in Figure 8. Elements which do not differ in their function from elements of the preceding exemplary embodiments are designated in Figure 8 with the same reference numerals as in the preceding exemplary embodiments and are not explained again in detail.

[0095] In the exemplary embodiment shown in Figure 8, the spectacle lens 1 has a central region 23 without a gradient in the refractive index. In this region, the focusing effect of the spectacle lens 1 is brought about solely by the curved shape of the front surface 13 of the lens. This central region 23 without a gradient in the refractive index is adjoined by Fresnel zones 3-2 to 3-6, as described with reference to the spectacle lens 1 of the first exemplary embodiment. The focusing effect of the spectacle lens 1 shown in Figure 8 is therefore brought about outside the central region 23 by the Fresnel structure 3 based on a gradient in the refractive index.In contrast to the preceding exemplary embodiments, the first interface 5a is not an interface where a low refractive index and a high refractive index adjoin one another, but rather an interface between a region without a gradient in the refractive index (namely, the central region 23) and a region with a gradient in the refractive index (namely, the first Fresnel zone 3-2). With the spectacle lens 1 shown in Figure 8, a good compromise between thickness / weight on the one hand and the image quality of the spectacle lens 1 on the other hand can be achieved, without image distortions occurring in the edge region, as would otherwise be common with surface shapes of this type.

[0096] The spectacle lens 1 shown in Figure 8 is a positive lens which has its greatest thickness in the center of the spectacle lens 1 and which has a flat geometry in its edge region. In contrast, with negative lenses, the thickness increases starting from the central part 23 of the spectacle lens 1 and can decrease again towards the edge of the spectacle lens 1, as is illustrated in Figure 9 using an eighth exemplary embodiment of the spectacle lens 1 according to the invention designed as a negative lens. Apart from the shape of its front surface 13, the spectacle lens shown in Figure 9 also differs from the spectacle lens shown in Figure 8 in that the gradient in the refractive index is designed such that it increases from radially inward to radially outward, whereas in the spectacle lens from Figure 8 it is designed such that it decreases from radially inward to radially outward.Furthermore, the lenses shown in Figure 8 and Figure 9 do not differ from each other.

[0097] The gradients in the refractive index in the spectacle lenses according to exemplary embodiments 2 to 6 and 8 are selected such that the refractive index increases from the radial inside to the radial outside. Therefore, the spectacle lenses of exemplary embodiments 2 to 6 and 8 represent negative lenses. However, the spectacle lenses of exemplary embodiments 2 to 6 and 8 can also be configured as positive lenses if the gradient in the refractive index is selected such that the refractive index decreases from the radial inside to the radial outside. Due to the Fresnel structure based on a gradient in the refractive index, a decoupling of the surface shape of the spectacle lens from its focusing effect is possible, so that a specific focusing effect can be realized with different combinations of surface shapes and gradients in the refractive index. This significantly expands the design possibilities for spectacle lenses.

[0098] In the ophthalmic lenses according to the invention, chromatic aberrations of the Fresnel structures based on the gradient in the refractive index can be minimized or completely avoided by suitable combinations of two or more materials. This is described, for example, in Buczinsky et al., "Achromatic nanostructured gradient index microlenses," Opt. Exp. 27 (2019), pp. 9588-9599, and the references cited therein. The classic analogue to this is an achromatic doublet, in which the refractive index is (notionally) averaged along the optical axis. For a flat Fresnel structure based on a gradient in the refractive index, materials must be selected in this analogous consideration that allow the desired refractive power of a doublet with flat surfaces on both sides to be realized. This is in principle possible with a neoachromat (low dispersion with a high refractive index or high dispersion with a low refractive index).Also interesting is the case of a doublet, which still requires a certain curvature of a surface for color correction. Applied to a Fresnel structure based on a gradient in the refractive index, this means that a certain basic curvature of the front and / or rear surface of the lens, as shown in Figure 6, or a faceting of the front and / or rear surface of the lens, as shown in Figure 7, is required to achieve the desired color correction.

[0099] With reference to Figure 10, an exemplary embodiment of a computer-implemented method for designing a spectacle lens according to the invention is described below using a flowchart. The method is executed on a computer in which a computer program with instructions for carrying out the method is stored in a memory. Based on the instructions, the computer processor then executes the computer-implemented method. For reading the computer program into the memory, a non-volatile computer-readable storage medium on which the computer program is stored can be used, for example. Alternatively, the computer program can also be retrieved from a computer system via a network.

[0100] In a first step S1 of the method, the required user-specific data are read into the computer. The user-specific data includes at least correction data representing the correction to be achieved with the spectacle lens, as well as distance data representing at least the distance of the pupil center and / or the eye rotation point from the vertex of the rear lens surface, or from which at least the distance of the pupil center and / or the eye rotation point from the vertex of the rear lens surface can be derived.

[0101] The correction data can specify the correction to be achieved with the spectacle lens, for example, in the form of a spherical vertex power for near or distance vision if the spectacle lens is to be a single-vision lens. Alternatively, they can also specify the correction to be achieved in the form of several spherical vertex powers if the spectacle lens is to be a multifocal lens, such as a progressive lens. In the case of a progressive lens, the spherical vertex power for near vision can be specified by adding the spherical vertex power for distance vision in accordance with DIN EN ISO 13666:2019-12, Section 3.16.3. If the correction to be achieved with the spectacle lens is also to correct astigmatism, the correction data can specify at least one astigmatic vertex power in addition to at least one spherical vertex power.

[0102] Optionally, the user-specific data may also include data indicating the wearing position of the spectacle lens (DIN EN ISO 13666:2019-12, Section 3.2.36). This data may include, in particular, the forward tilt angle (DIN EN ISO 13666:2019-12, Section 3.2.37), the frame lens angle (DIN EN ISO 13666:2019-12, Section 3.2.8), and the corneal vertex distance (DIN EN ISO 13666:2019-12, Section 3.2.40).

[0103] The user-specific data may be individualized for the respective user, or it may be general data determined from a statistical ensemble of users.

[0104] Based on the acquired data, the locally required beam deflection is determined in a second step S2. In the case of a multifocal lens or a progressive lens, an object-distance model is also used, which specifies the object distance for which the lens is to be optimized for the respective viewing direction.

[0105] In the next step S3, a surface shape of the spectacle lens is then specified. If the spectacle lens is to have a central region without a gradient in the refractive index, as described with reference to Figures 8 and 9, step S3 can also include optimizing the surface shape in the central region with regard to the beam deflection to be achieved, so that the surface shape in the central region specified in step S3 is already optimized with regard to the focusing effect.

[0106] In step S4, the gradients of the refractive index and / or the locations of the jumps in the refractive index are then optimized, as described with reference to Figure 1. Furthermore, as part of the optimization carried out in step S4, the inclination of the interfaces between the Fresnel zones or the course of these interfaces is determined, whereby the point from which a ray runs to the respective interface is determined based on the distance data. In the case of conical interfaces, as described, for example, with reference to Figure 2, the inclination of the respective interface can be determined based on the geometric conditions resulting from the wearing position of the spectacle lens and the distance data. In the case of curved interfaces, as described with reference to Figures 3 and 4, the course of this interface is determined based on the ray tracing carried out as part of the optimization.

[0107] If the central region is not to have a gradient in the refractive index and a surface shape has already been optimized in step S3 with regard to the focusing effect, only the edge region of the spectacle lens adjoining the central region needs to be optimized in step S4.

[0108] In an alternative embodiment of the method, it is possible to specify the locations of the refractive index jumps instead of the surface shape and then optimize the surface shape and the refractive index gradients. Another alternative is to optimize both the surface shape and the locations of the refractive index jumps, as well as the refractive index gradients, together.

[0109] At the end of the process, the optimized ophthalmic lens is then output by the computer in step S5 in the form of a numerical representation of the ophthalmic lens. Based on this numerical representation, a computer-controlled manufacturing machine can then be controlled to produce an actual ophthalmic lens, for example, using an additive manufacturing process. For example, the computer-controlled manufacturing machine can be a 3D printer that prints a ophthalmic lens corresponding to this numerical representation based on the numerical representation of the ophthalmic lens. The gradients in the refractive index can be realized by varying the material feed depending on the current location of the print head. A continuous variation of the refractive index can be achieved by suitably mixing two materials.

[0110] A pair of spectacles 30 equipped with at least one spectacle lens 1 according to the invention is schematically illustrated in Figure 11. The illustration in Figure 11 is essentially limited to the right spectacle lens 1L and the right temple 33. The left spectacle lens 1L is only partially illustrated, and the left temple is not illustrated at all.

[0111] The glasses 30 shown in Figure 11 are designed as AR glasses (AR: Augmented Reality), with which a wearer can be presented with images superimposed on the surroundings. The right-hand spectacle lens 1R is assigned a light guide 31, which in the present exemplary embodiment extends from the right edge of the spectacle lens 1R to approximately the middle of the spectacle lens 1R. The light guide 31 is arranged with an air gap 32 to the spectacle lens 1R, so that a beam of rays can be guided through the interior of the light guide 31 by means of total internal reflection. Instead of an air gap 32 between the spectacle lens 1R and the light guide 31, an intermediate layer can also be present, the refractive index of which is lower than the refractive index of the material from which the light guide 31 is made. Such an intermediate layer offers the advantage over an air gap that it can simultaneously serve to attach the light guide 31 to the spectacle lens 30.The intermediate layer can be formed, for example, by an optical kit. Alternatively, the production of the intermediate layer can be integrated into the 3D printing process of the spectacle lens by first printing a suitable low-refractive-index material as a layer before the spectacle lens 1 R is manufactured. The low-refractive-index material of the intermediate layer can, for example, be printed onto the light guide 31 before the spectacle lens is printed onto the intermediate layer. Furthermore, additional layers for further functions can be applied in a final outer layer of the spectacle lens 1 R, for example, to integrate scratch protection or tints.

[0112] In the area of ​​the temple 33 there is a display 34, such as an LED display, an LCD display, an OLED display, etc. In addition, in the area of ​​the temple 33 there is a control device 35 for controlling the display 34. The control device 35 controls the display 34 such that images that are to be displayed on the wearer's field of vision in order to superimpose them on the surroundings are shown on the display 34. The control device 35 can generate the images to be displayed on the display 34 itself or receive them via a cable or, preferably, wirelessly from another device not shown. A beam of rays emanating from the display 34 and representing the image to be displayed is coupled into the light guide 31 via a coupling element 36 arranged on the right edge of the light guide 31 via a circumferential surface of the light guide 31. In the present exemplary embodiment, the coupling element 36 is designed as a prism.The prism surfaces of the prism 36 are designed such that a beam emanating from the display 34 is coupled into the light guide 31 at such an angle across the peripheral surface toward an outer surface of the light guide 31 that it is totally reflected by the outer surface at an angle that, upon impinging on the opposite outer surface of the light guide 31, again leads to total reflection. In this way, the beam can be guided via total reflections from the input coupling element 36 to an output coupling structure 37, which couples the beam out of the light guide 31 in the direction of the eye. It should be noted at this point that the guidance of the beam in the light guide does not necessarily have to occur by means of total reflection.Instead, the outer surfaces of the light guide can be provided with partially transparent reflective coatings which allow the passage of ambient light through the light guide 31 and at the same time guide the beam of rays coupled in via the coupling element 36 at least partially to the coupling-out structure 37 by means of reflections.

[0113] In the present embodiment, the surfaces of prism 36 also have an imaging function, which gives the wearer of the glasses the impression that the image shown on display 34 is floating in the surroundings at a certain distance in front of the eye. Alternatively, this imaging function can be performed entirely or partially by one or more other structures, for example, an imaging optics system (not shown) arranged between display 34 and prism 36, instead of by prism 36.

[0114] In the present exemplary embodiment, the output coupling structure 37 is designed in the form of partially transparent Fresnel elements, so that in addition to the image superimposed into the wearer's field of vision, the surroundings can also be perceived. However, it can also be designed as a partially transparent, inclined mirror. In a further alternative, the output coupling structure 37 can be designed as a diffraction grating. In this case, the beam is coupled out of the light guide 31, for example, via the 1st order diffraction maximum, while the observation light can pass through the output coupling structure 31 as unaffected as possible via the 0th order diffraction maximum. Furthermore, the output coupling structure 37 can also be designed such that it contributes to the imaging, for example by providing the partially transparent Fresnel elements with a suitable curvature.

[0115] Because the Fresnel structure of the spectacle lens 1R of the spectacles 30 provides a focusing effect that is based, at least partially, but especially completely, on a gradient of the refractive index within the corresponding Fresnel zone in at least one of the Fresnel zones, in particular in a plurality of the Fresnel zones or in all Fresnel zones, the thickness of the spectacle lens 1R can be kept small, even if the spectacle lens 1R is designed to correct severe ametropia. As a result, the combination of the spectacle lens 1R with the light guide 31 can be realized with a relatively small thickness.

[0116] The left spectacle lens 1 L, which is only partially shown in Figure 11, can either be designed analogously to the right spectacle lens 1 R, or it can be a spectacle lens without a light guide. Of course, it is also possible for the left spectacle lens 1 L to be equipped with a light guide and the right spectacle lens 1 R not.

[0117] The present invention has been described in detail for illustrative purposes using exemplary embodiments. However, one skilled in the art will recognize that, within the scope of the invention, deviations from the individual exemplary embodiments may be made, and in particular, features of the individual exemplary embodiments may also be combined with one another. Therefore, the present invention is not intended to be limited by the exemplary embodiments, but only by the appended claims.

[0118] Reference symbols

[0119] 1 lens

[0120] 3 Fresnel structure

[0121] 3-1 - 3-6 Fresnel zones

[0122] 4a-e section line

[0123] 5a-e Interfaces

[0124] 6a-e section line

[0125] 7 Eye

[0126] 8 straight

[0127] 9-1 - 9-5 Light rays

[0128] 9, 9a, 9b Light rays

[0129] 11 Back surface of the lens

[0130] 13 Front surface of the lens

[0131] 14 annular area

[0132] 15 Dead zone

[0133] 17 Coating

[0134] 18a-e kinks

[0135] 19 Fresnel structure

[0136] 20-1 - 20-6 Fresnel facets

[0137] 21a-f trailing edges

[0138] 23 central area

[0139] 30 lenses

[0140] 31 light guides

[0141] 32 air gap

[0142] 33 temples

[0143] 34 Advertisement

[0144] 35 Control device

[0145] 36 coupling element

[0146] 37 Decoupling structure

[0147] AD eye pivot point

[0148] PM Pupil center

[0149] RS geometric center of gravity

[0150] VS geometric center of gravity

[0151] RB Rear surface area VB Front surface area

Claims

Patent claims 1. Spectacle lens (1) with a rear lens surface (11) facing the eye; a front lens surface (13) facing away from the eye; a Fresnel structure (3) comprising at least two Fresnel zones (3-1 to 3-6) providing a focusing effect, wherein the focusing effect of the Fresnel structure (3) in at least one of the Fresnel zones (3-1 to 3-6) is based at least partially on a gradient of the refractive index within, and the Fresnel structure (3) has interfaces (5a to 5e) at which a high refractive index of a Fresnel zone (3-1 to 3-6) and a low refractive index of an adjacent Fresnel zone (3-1 to 3-6) adjoin one another, wherein the at least one interface (5a to 5e) has a rear-side intersection line (4a to 4e) with the rear surface (11) of the spectacle lens and a front-side intersection line (6a to 6e) with the front surface (13) of the spectacle lens;the rear surface region of the lens rear surface (11) enclosed by the innermost rear cutting line (4a) has a rear geometric center of gravity (RS), and the front surface region of the lens front surface (11) enclosed by the innermost front cutting line (6a) has a front geometric center of gravity (VS); characterized in that the rear cutting line (4a to 4e) has a smaller distance from the rear geometric center of gravity (RS) than the front cutting line (6a to 6e) from the front geometric center of gravity (VS) for at least 25% of the azimuth angles.

2. Spectacle lens (1) according to claim 1, characterized in that at least one boundary surface (5a to 5e) is aligned such that those rays (9-1 to 9-5) which run within a cutting plane along this boundary surface (5a to 5e) unite, after exiting the rear surface of the lens (11), at a point (PM, AD) located on the side of the rear surface of the lens (11) and spaced therefrom, wherein the cutting plane is a plane in which a front connecting line lies which runs at a specific azimuth angle in the front surface of the lens (13), which connects the geometric center of gravity (VS) of the enclosed front surface area by the shortest path to a point on the front cutting line (6a to 6e) of one of the boundary surfaces (5a to 5e), and in which a rear connecting line also runs at the same specific azimuth angle in the rear surface of the lens (11),which connects the geometric center of gravity (RS) of the enclosed back surface area by the shortest path with a point on one of the back intersection lines (4a to 4e) of the same boundary surfaces (5a to 5e).

3. Spectacle lens (1) according to claim 2, characterized in that the point (PM, AD) lying on the side of the rear surface of the spectacle lens (11) and spaced therefrom is the same for all azimuth angles.

4. Spectacle lens (1) according to claim 2, characterized in that the distance of the point (PM, AD) lying on the side of the spectacle lens rear surface (11) and spaced therefrom from the spectacle lens rear surface (11) depends on the azimuth angle.

5. Spectacle lens (1) according to one of claims 2 to 4, characterized in that at least two of the boundary surfaces (5a to 5e) are aligned in such a way that, for the respective boundary surface (5a to 5e), all rays (9-1 to 9-5) extending within the cutting plane along this boundary surface (5a to 5e) after exiting from the spectacle lens rear surface (11) are directed into a beam path located on the side of the spectacle lens rear surface (11) and spaced apart from this point (PM, AD), and the point (PM, AD) lying on the side of the rear surface of the spectacle lens (11) and spaced therefrom is the same for the at least two boundary surfaces (5a to 5e).

6. Spectacle lens (1) according to one of claims 2 to 5, characterized in that at least two of the boundary surfaces (5a to 5e) are aligned such that, for the respective boundary surface (5a to 5e), all rays (9-1 to 9-5) running within the sectional plane along this boundary surface (5a to 5e) converge, after exiting the spectacle lens rear surface (11), into a point (PM, AD) located on the side of the spectacle lens rear surface (11) and spaced therefrom, and the distance of the point (PM, AD) located on the side of the spectacle lens rear surface (11) and spaced therefrom from the spectacle lens rear surface (11) is different for the at least two boundary surfaces (5a to 5e).

7. Spectacle lens according to one of claims 2 to 6, characterized in that at least one of the boundary surfaces (5a to 5e) runs along a straight line within the cutting plane.

8. Spectacle lens (1) according to one of claims 2 to 7, characterized in that at least one of the boundary surfaces (5a to 5e) extends within the section plane along a curved line, the curvature of which is a curvature that follows the path of a light ray (9a) that emanates from the point (PM, AD) spaced from the spectacle lens rear surface (13) and enters the spectacle lens (1) at the boundary between the high refractive index of one Fresnel zone (3-1 to 3-6) and the low refractive index of the adjacent Fresnel zone (3-1 to 3-6) through the spectacle lens rear surface (11) immediately adjacent to the boundary surface (5a to 5e) on the side of the high refractive index; or is a curvature that follows the path of a light ray (9b) that emanates from the point spaced from the spectacle lens rear surface (13) (PM, AD) and enters the spectacle lens (1) at the boundary between the high refractive index of one Fresnel zone (3-1 to 3-6) and the low refractive index of the adjacent Fresnel zone (3-1 to 3-6) through the rear surface (11) of the spectacle lens immediately adjacent to the boundary surface (5a to 5e) on the side of the low refractive index; or a curvature whose course lies between the courses of the said light rays (9a, 9b).

9. Spectacle lens (1) according to one of claims 2 to 8, characterized in that the spectacle lens (1) is designed as a negative lens and has a dead zone (15) for each boundary surface (5a to 5e), which dead zone is delimited by the path of a set of first light rays (9a) in the spectacle lens (1), by the path of a set of second light rays (9b) in the spectacle lens (1) and by an annular region (14) of the spectacle lens front surface (13) resulting from the path of the first set of light rays (9a) and the path of the second set of light rays (9b), wherein the first light rays (9a) are those light rays (9) which emanate from the point (PM, AD) spaced from the spectacle lens rear surface (11) and pass through the spectacle lens rear surface (11) immediately adjacent to the corresponding boundary surface (5a to 5e) into the Fresnel zone (3-1 to 3-6) with the light beam directed to the boundary surface (5a to 5e) adjacent high refractive index,and the second light rays (9b) are those light rays (9) which emanate from the point (PM, AD) spaced from the rear surface of the spectacle lens (11) and enter the Fresnel zone (3-1 to 3-6) with the low refractive index adjacent to the rear surface (5a to 5e) through the rear surface of the spectacle lens (11) immediately adjacent to the corresponding interface (5a to 5e), and the respective dead zones (15) are each provided with at least one light-absorbing layer (17).

10. Spectacle lens (1) according to claim 7 and claim 9, characterized in that at least one of the boundary surfaces (5a to 5e) runs along a straight line within the cutting plane and this straight line is aligned such that it runs at least partially within the dead zone (15).

11. Spectacle lens (1) according to claim 9 or claim 10, characterized in that the dead zones (15) of the spectacle lens (1) have a different refractive index than the high refractive index and the low refractive index of the Fresnel zones (3-1 to 3-6) adjacent to the respective dead zone (15).

12. Spectacle lens (1) according to one of claims 1 to 11, characterized in that it has a central region (23) without a Fresnel structure (3) and with a curved surface and the Fresnel structure (3) is only present in a region outside the central region (23), wherein the spectacle lens (1) provides a focusing effect in the central region (23) due to the curved surface and in the edge region due to the Fresnel structure (3).

13. Spectacle lens (1) according to one of claims 1 to 12, characterized in that an additional Fresnel structure (20) with Fresnel facets (20-1 to 20-6) having curved surfaces is formed on the spectacle lens front surface (13) or the spectacle lens rear surface (11) and has jumps in the sagittal height at the front cutting lines (6a to 6e) or the rear cutting lines (6a to 6e).

14. Spectacle lens (1) according to claim 2 and claim 13, characterized in that the jumps in the sagittal heights are formed by flanks (21 a to 21 e) of the Fresnel facets (20-1 to 20-6) which continue the course of the boundary surfaces (5a to 5e).

15. Spectacle lens (1) according to one of claims 1 to 14, characterized in that it has a spectacle lens front surface (13) and / or a spectacle lens rear surface (11) which has a bend (18a to 18e) at the boundaries between two Fresnel zones (3-1 to 3-6).

16. Spectacle lens (1) according to one of claims 1 to 15, characterized in that at least two materials are combined in such a way that color errors are at least partially compensated.

17. Spectacle lens (1) according to one of claims 1 to 16, characterized in that at the high refractive index there is a low dispersion and at the low refractive index there is a high dispersion 18. Computer-implemented method for designing a spectacle lens according to one of claims 1 to 17, characterized by Acquiring at least correction data which represent the correction to be achieved with the spectacle lens (1 ) and distance data which represent at least the distance of the pupil center (PM) or the eye rotation point (AD) from the vertex of the rear surface of the spectacle lens (11 ) or from which at least the distance of the pupil center (PM) or the eye rotation point (AD) from the vertex of the rear surface of the spectacle lens (11 ) can be derived; Determining the Fresnel structure (3) on the basis of at least the correction data and the distance data.

19. A computer-implemented method according to claim 18, characterized by a step of detecting the corneal-vertex distance.

20. Computer-implemented method according to claim 18 or 19, characterized by a step of outputting a numerical Representation of the designed spectacle lens (1) for use in the manufacture of an actual spectacle lens (1) corresponding to the numerical representation of the spectacle lens (1) by means of a computer-aided numerically controlled manufacturing process.

21. A non-volatile computer-readable storage medium having a numerical representation of a spectacle lens (1) according to any one of claims 1 to 17 for use in the manufacture of an actual spectacle lens (1) corresponding to the numerical representation of the spectacle lens (1) by means of a computer-aided numerically controlled manufacturing process.

22. A computer system having data retrievable via a network, which provides a numerical representation of a spectacle lens according to one of claims 1 to 17 for use in the manufacture of an objective spectacle lens corresponding to the numerical representation of the spectacle lens (1) by means of a computer-controlled manufacturing process.

23. A computer program comprising instructions which, when executed by the computer, cause a computer to perform the computer-implemented method according to any one of claims 18 to 20.

24. A computer comprising a memory storing instructions for causing a computer to perform the computer-implemented method of any one of claims 18 to 20, and a processor for executing the instructions stored in the memory.

25. A method for producing a spectacle lens (1 ), in which by means of a computer-aided numerically controlled manufacturing process on the basis of a numerical representation of a spectacle lens (1 ) according to one of claims 1 to 17, an actual spectacle lens (1) corresponding to the numerical representation of the spectacle lens is produced.

26. Spectacles (30) with at least one spectacle lens (1) according to one of claims 1 to 18.

27. Spectacles (30) according to claim 26, further comprising a display (34), a light guide (31), a coupling element (36) for coupling a beam of rays emanating from the display (34) into the light guide (31), and a coupling-out structure (37) for coupling the beam of rays out of the light guide (31) in the direction of the eye of a wearer of the spectacles (30).

28. Spectacles according to claim 27, in which an air gap (32) is present between the light guide (31) and the spectacle lens (1).

29. Spectacles according to claim 27, in which a layer is present between the light guide (31) and the spectacle lens (30) whose refractive index is lower than the refractive index of the light guide (31).

Images