Multifocal lenses for eyes

Abstract

A new generation of multifocal ophthalmic lenses and a method for manufacturing the same. The lens provides at least focal points for myopia, intermediate vision, and hyperopia. The lens body provides a refractive focus for intermediate vision. The lens body includes a diffraction grating (91) that operates as a light wave beam splitter, providing a diffraction focus for myopia and a diffraction focus for hyperopia. The lens body includes a single focus central region (92) that extends at a distance from the optical axis of the lens body and provides a focus that coincides with one of the diffraction focuses. The diffraction grating (91) is arranged at a radial position from a transition point (93) where the single focus central region (92) of the lens body ends. At the transition point (93), the diffraction grating (91) and the single focus central region (92) have overlapping amplitude values.

Description

Technical Field

[0001] The present disclosure relates generally to ophthalmic lenses, and more particularly to ophthalmic spectacles, ophthalmic contacts, and intraocular multifocal diffractive lenses that provide diffraction orders with adjusted light distribution for different pupil sizes. Background Art

[0002] Ophthalmology is the field of medicine that deals with the anatomy, physiology, and diseases of the human eye.

[0003] The anatomy of the human eye is complex. The main structures of the eye include the cornea, a spherical, clear tissue located at the outer front of the eye; the iris, which is the colored part of the eye; the pupil, an adjustable hole in the iris that controls the amount of light entering the eye; and the lens, a small, clear disk inside the eye that focuses light onto the retina. The retina forms the back, or back, of the eye and converts incoming light into electrical impulses that travel through the optic nerve to the brain. The posterior cavity (the space between the retina and the lens) is filled with vitreous humor, a clear, jelly-like substance. The anterior and posterior chambers, the spaces between the lens and the cornea, are filled with aqueous humor, a clear, watery fluid.

[0004] The natural lens has a flexible, transparent, biconvex structure and works with the cornea to focus refracted light on the retina. The front of the lens is flatter than the back, and its curvature is controlled by the ciliary muscle, to which the lens is connected by cantilever ligaments (called zonules). By changing the curvature of the lens, the focal length of the eye is changed so that objects at various distances can be focused. In order to view objects at a short distance from the eye, the ciliary muscle contracts and the lens thickens, resulting in a more rounded shape and, therefore, a high refractive power. Changing the focus to objects at a greater distance requires relaxing the lens and, thereby, increasing the focal length. This process of changing the curvature and adjusting the focus of the eye to form a clear image of an object on the retina is called accommodation.

[0005] In humans, the lens in its natural setting has a refractive power of about 18 to 20 diopters, roughly one-third of the eye's total optical power. The cornea provides the remaining 40 diopters of the eye's total optical power.

[0006] As eyes age, the lens becomes increasingly opaque due to clouding of the eye, called cataracts. Certain medical conditions, such as diabetes and trauma, as well as some medications and excessive ultraviolet light exposure, can also cause cataracts. Cataracts are painless and cause cloudy, blurred vision. Treatment for cataracts involves surgery to remove the cloudy lens and replace it with an artificial lens, commonly known as an intraocular lens (IOL).

[0007] Another age-related effect is called presbyopia, which manifests as difficulty reading small print or seeing nearby images clearly. Presbyopia is generally believed to be caused by thickening and loss of flexibility in the natural lens within the eye. Age-related changes also occur in the ciliary muscle surrounding the lens. When it becomes less flexible, it becomes difficult to focus on objects close to the eye.

[0008] A variety of intraocular lenses can also be used to correct other visual impairments such as myopia or nearsightedness, which occurs when the eye cannot see distant objects, for example, due to a cornea that is too curved. Myopia causes distant light rays to focus on a point in front of the retina, rather than directly on the retina's surface. Hyperopia or farsightedness, caused by an abnormally flat cornea, causes light rays entering the eye to focus behind the retina, preventing close objects from being focused, and astigmatism, where images are blurred due to an irregularly shaped cornea, is another common cause of visual difficulties.

[0009] In most cases, an intraocular lens is implanted in the patient's eye during cataract surgery to compensate for the loss of optical power of the removed lens. Conventional IOLs are monofocal and usually only provide a far (long distance) focus, requiring the user to use additional ophthalmic lenses (such as glasses or contact lenses) for reading, for example. Some modern IOL lenses solve this problem by having a multifocal optical design, providing near and / or intermediate vision in addition to a far focus. The multifocal intraocular lenses MIOL currently available on the market are either bifocal or trifocal. In fact, multifocal ophthalmic lenses with four target focal points, so-called quadfocal lenses, or even multifocal ophthalmic lenses with five target focal points, so-called pentafocal lenses, have been proposed.

[0010] Multifocal ophthalmic lenses utilize two optical principles: refraction and diffraction. Multifocal contact lenses also utilize these principles. Presbyopia is corrected with glasses or contact lenses, and multifocal optics are also an option.

[0011] To illustrate the physical differences between these principles, this specification uses a wave model of light, in which electromagnetic waves propagate at a specific speed in a specific direction and have a specific wavelength, amplitude, and phase.

[0012] Refraction is the deflection that light waves experience when traveling from one medium (such as air or liquid) to another medium with a different speed of propagation (such as glass or plastic).

[0013] The most basic form of diffraction is based on the physical effect that when a light wave strikes an irregularity in an object, it becomes a source of secondary light waves. These secondary waves can interfere with each other in both constructive and destructive ways. Constructive interference occurs when the optical path length difference between the waves arriving at a particular point is an integer multiple of their wavelengths, causing their amplitudes to add in an amplifying manner. This is also known as the waves being in phase. Destructive interference occurs when the optical path length difference between the waves being interfered with is an odd multiple of half the wavelength, causing the peaks of one wave to meet the troughs of the other wave, and the waves partially or completely extinguish each other. This is also known as the waves being out of phase.

[0014] Multifocal ophthalmic lenses typically have a lens body that is biconvex or plano-convex or biconcave or plano-concave, with a curvature and thickness suitable for providing a first focus on its optical axis by refraction. On one or both of the front and back surfaces of the lens body, a transmissive surface relief or diffraction grating can be provided, which consists of regularly or periodically spaced ridges and / or grooves designed to diffract transmitted light and arranged in concentric rings or areas at the corresponding surfaces of the lens body. The periodic spacing or spacing of the ridges and / or grooves essentially determines the destructive and constructive interference points at the optical axis of the lens. The shape and height of the ridges and / or grooves control the amount of incident light provided at the constructive interference points by diffraction. The constructive interference points are often referred to as diffraction orders or focal points. The diffraction relief can be designed to provide, for example, second and third focal points of a trifocal lens that are different from the refractive focal points.

[0015] A common type of multifocal ophthalmic lens includes sawtooth or binary gratings or reliefs. In this specification, the term sawtooth or staggered refers to a type of transmissive diffraction grating or relief that consists of a plurality of repeating, continuously arranged prismatic transparent diffractive optical elements (DOEs) with monotonically tilted light-receiving surfaces (such as linear or curved monotonically tilted light-receiving surfaces). For the purposes of this specification, the term binary relief refers to a type of transmissive diffraction relief that consists of a plurality of repeating, spaced-apart rectangular or prismatic transparent DOEs.

[0016] In order to operate as a lens, the repetition period or pitch of the sawtooth grating must decrease monotonically in the radial direction r from the center or optical axis of the lens. Or more specifically, if the first period starts at the center of the lens and the second period starts at (1*k) 0.5 Start, where k is a positive constant, then the third period is (2*k) 0.5 Start, the fourth cycle is at (3*k) 0.5 So, in diffraction optics, in the so-called r 2 It is advantageous to represent the grating in space. That is, the parameters along the horizontal axis vary with r 2 changes so that the cycle repeats at equal intervals.

[0017] r 2 The period in space can be written as |2λf|, where λ is the design wavelength and f is the inverse of the optical power of the first diffraction order. Although the periods of diffractive lenses are not equidistant, they are periodic in physical space. One way to see this is to look at the r 2 space. A different way to look at it is that within each period, the difference in the optical path length to the focus increases with exactly one wavelength, λ. The source of the periodicity is this same increase in the optical path length within each period.

[0018] The calculation of the focal points (i.e. diffraction orders) of such elementary reliefs is well known and straightforward to those skilled in the art of diffractive optical lenses. Typically, in order to operate as an ophthalmic lens, the period or spacing of the elementary reliefs or gratings is selected so as to have first and / or second diffraction orders to provide the target focal point. Here, because of these elementary reliefs, most of the light is diffracted in the lower diffraction orders. During the design process, the reliefs are constructed with an amplitude profile to achieve the desired intensity profile of the light coupled onto these elementary gratings or reliefs at the refractive focal points and diffracted in the first and / or second diffraction orders. However, this approach does not automatically lead to an optimal distribution of the light incident on the lens, since an amount of light is also allocated to unused higher diffraction orders, which makes it difficult to adjust or control the relative light distribution between the focal points of the lens for different pupil sizes and which can significantly reduce the overall efficiency of the multifocal lens.

[0019] Sharp transitions in diffraction reliefs or gratings cause processing difficulties and, in the finished lens, lead to light scattering and other related undesirable optical phenomena, such as stray light, chromatic aberration, glare (i.e., difficulty seeing in the presence of bright light, such as direct or reflected sunlight, or artificial light, such as car headlights at night), and halo effects (i.e., white or colored rings or spots of light seen in dim light, i.e., under mesopic conditions). To mitigate these undesirable optical effects, it has been proposed to smooth the sharp edges of stepped diffraction reliefs or gratings by using any of a distributed approximation of sine and cosine functions, a polynomial expression, filtering using a super-Gaussian function, or a convolution integral. This smoothing of sharp edges or steps with sawtooth-type or binary DOEs, for example, results in the effect of stretching or expanding in the radial direction of the lens.

[0020] When comparing diffractive surfaces, an important factor is diffraction efficiency. Diffraction efficiency is a measure of how much optical power is directed into the desired diffraction order, or when referring specifically to diffractive lenses, how much optical power is directed into the desired focus. For bifocal lenses, in which the surface of the lens body is optimized to provide the best possible vision at two different distances, the highest possible diffraction efficiency is achieved by using the principle of a phase-matched Fresnel lens, which utilizes a sawtooth or staggered type diffraction pattern. Reference is made to the disclosure by M. Rossi et al., "Refractive and diffractive properties of planar micro-optical elements," Applied Optics, Vol. 34, No. 26 (1995), pp. 5996-6007, which is incorporated herein by reference.

[0021] Due to the sharp edges of the sawtooth or staggered diffraction pattern, which results from discontinuities in the diffraction profile, Fresnel lenses suffer from all the aforementioned disadvantages, particularly with regard to glare and haloing. Furthermore, they are difficult to manufacture accurately. However, for trifocal lenses, i.e. lenses designed to provide the best possible vision at three different focal points, the optimal grating is one without any sharp edges.

[0022] For the case of a trifocal linear grating with equal intensity distribution per stage, this is proposed by F. Gori et al. in the publication entitled "Analytical derivation of the optimal triplicator", specifically illustrated in Optics Communication 157 (1998), pp. 13-16, which disclosure is incorporated herein by reference.

[0023] This is more generally disclosed in the publication "Theory of optimal beam splitting by phase gratings. I. One-dimensional gratings" by Laromero and Dickey in the Journal of the Optical Society of America, Vol. 24, No. 8 (2007), pp. 2280-2295, incorporated herein by reference, showing that the optimal grating for equally splitting into odd orders has at least a continuous profile. This latter article provides mathematical tools for finding the optimal linear phase grating for any given set of target orders and any given intensity distribution between these target orders. The optimal grating is defined as the linear diffraction grating with the highest diffraction efficiency for a specific intensity distribution.

[0024] Note that the publications by Gori et al. and Romero et al. discuss linear phase gratings for creating beam splitters only.

[0025] As disclosed in the applicant's international patent application WO2019 / 020435, the trifocal grating from Gori et al. can be used to design multifocal ophthalmic lenses.

[0026] As will be explained below, the approach disclosed in WO 2019 / 020435 is generally applicable to linear gratings. 2 If the shape of the lens profile in space is the same, then the linear grating can be converted to a lens. A linear grating can be converted in this way by changing the independent variable to the square of the radius of the lens to be constructed.

[0027] WO2019 / 020435A discloses a general method for designing a multifocal ophthalmic lens comprising a diffractive relief or grating, the diffraction profile of the multifocal ophthalmic lens being mathematically specified by a single continuous closed-form expression or function along the radial direction of the lens body.

[0028] This mathematical expression can represent the phase profile and / or height profile or amplitude profile of a diffraction grating capable of splitting an incident light beam with the highest conceivable efficiency for a given intensity distribution into the amount of light distributed in the target focus in (-m, +m) diffraction orders, where m is a positive integer. Such a grating includes the 0th order (creating the refractive focus) as the central order. If m = 1, a trifocal lens is created, if m = 2, a pentafocal lens is provided, and so on.

[0029] An advantageous way to design such a grating is to first determine the desired target levels and the desired light distribution between these levels, and then design an optimal grating that provides these characteristics.

[0030] An ophthalmic lens having a continuous periodic phase profile function extending in the radial direction of the lens body causes less visual discomfort and obstruction than a lens having a discontinuous or staggered type of phase profile function. A function is said to be continuous when, at every point or value of its argument (i.e., the variable, term, or expression on which the function operates), (i) the function is defined at that point, (ii) the limits of the function as the argument approaches the point from the right and left hands exist and are equal, and (iii) the limits of the function as the argument approaches the point are equal to the value of the function at that point.

[0031] Lenses with a continuous, periodic phase profile function are particularly susceptible to miscalculations of diopter power. This refers to miscalculations of the desired optical power correction required for a particular user, for example, due to poorly accurate measurement equipment used by a doctor or physician in the case of intraocular lenses, or by an optometrist in the case of contact lenses. Furthermore, lenses with a continuous, periodic phase profile function are reported to exhibit negligible sensitivity to lens displacement (decentering), which can occur after lens installation due to tilt and misalignment in the case of intraocular lenses. It has also been observed that such lenses are less likely to produce glare, a scattering of incident light along its path through the lens caused by non-uniformities, and also produce less halo.

[0032] For example, compared to sawtooth or binary gratings or reliefs, lenses with a continuous periodic phase profile function, especially when constructed from smooth curves, have the advantage of being easily manufactured from a calculated profile.

[0033] The above advantages are largely due to the absence of concentric rings or regions with sharp edges in diffraction gratings with a continuously periodic phase profile function.

[0034] A lens having a diffraction grating whose optical transfer function or light transmission function is specified by a continuously periodic phase profile function not only provides freedom in selecting target focal points but also provides control over the light distribution at each selected target focal point. By modulating the argument of the phase profile function as a function of radius or radial distance from the optical axis of the lens body, the relative light distribution at the diffractive and / or refractive focal points of such a lens can be adjusted, thereby allowing the light distribution at the target focal points to be adjusted individually and, for example, differently for different pupil sizes. In other words, the lens surface as a whole can be optimized for multifocality.

[0035] After an IOL is implanted in a person's eye, the new focusing properties of the eye as a whole must be measured. That is, the complete visual system, consisting of the new lens and the rest of the user's eye, is measured as a whole, providing a first objective indication of the outcome of the IOL implant. In practice, most doctors rely on simple measurements, such as those from an autorefractor. An autorefractometer, or autorefractometer, is a computer-controlled device used during an eye exam to provide an objective measurement of a person's refractive error and a prescription for, for example, glasses or contact lenses. This is achieved by measuring how light changes when it enters the eye. An autorefractometer can determine when a patient's eye is correctly focusing an image.

[0036] After implantation of a multifocal intraocular lens, there is always an adaptation period before the user fully appreciates the lens's benefits. This is due to the adaptation process in the user's eyes and brain. Clinical observations show that after implantation, users initially adopt far focus and, with multifocal lenses, eventually adopt two additional focal points—near and intermediate—over a few days or weeks. However, even with lenses fully optimized for multifocality, the adaptation time to far focus will increase for all pupil sizes. This can be unpleasant and uncomfortable for the user.

[0037] Although protocols exist for correctly measuring all focal points of an IOL, fully applying such protocols is often considered too time-consuming, resulting in the measurement returning only one optical power for a multifocal IOL. Because the measurement is often not even performed by a medical doctor, ophthalmologist, or optometrist, for example, medical professionals often believe that the measurement returns the diffraction far focus, which can lead to a false judgment of whether the operation was successful.

[0038] For example, for sawtooth IOLs, measurements typically return the far focus. However, for lenses produced according to the teachings of WO2019020435, when optimized for multifocality, providing three or more focal points for the user's different pupil sizes, the single focal point measured for these types of IOLs is typically the intermediate focus, as this is the refractive strength of the lens. It has proven difficult to convince those involved in the measurement that the focal point actually measured with an autorefractor is not one of the diffraction focal points, but is most often the intermediate or refractive focus.

[0039] WO2019020435 discloses that the multifocal properties of an ophthalmic lens can be limited to a first radial region of the surface of the lens body adjacent to the optical axis, while radially outwardly beyond the first region and toward the peripheral edge of the lens body, the lens can include a second region with bifocal properties, for example, providing focal points for intermediate and distant vision. However, when measuring this type of lens, an automatic refractometer will often only return the midpoint, i.e., the refracted focal point.

[0040] Therefore, there is a need for an improved ophthalmic lens design that provides the freedom to target three or more diffraction orders or focal points, adjust or control the relative light intensity in all target focal points, especially for different pupil sizes, improve the adaptation time of the user or patient, and provide the possibility to easily measure the diffraction focus (either far focus or near focus). Summary of the Invention

[0041] In a first aspect, a multifocal ophthalmic lens is provided that includes at least focal points for near vision, intermediate vision, and far vision. The lens has a translucent lens body that includes a diffraction grating extending concentrically in a radial direction r from the optical axis of the lens body across a portion of a surface of the lens body. The lens body is designed to provide a refractive focus for intermediate vision, and the periodic diffraction grating has a phase distribution φ(r) represented by a single continuous periodic function arranged to change the phase of incident light at the lens body and operates as a lightwave beam splitter, providing at least a diffraction focus for near vision at diffraction order +m and a diffraction focus for far vision at diffraction order -m, where m is a positive integer value.

[0042] A lens body according to the present disclosure includes a monofocal central region extending a distance r from the optical axis of the lens body across a portion of the surface of the lens body and having a continuous phase profile function Continuous Phase Profile Function The invention relates to a lens body configured to modify the phase of incident light at the lens body, the lens body providing a focal point that coincides with one of the diffraction focal points, wherein the diffraction grating provides a transition point at a radial position from where the monofocal central region of the lens body ends. At the transition point, the diffraction grating and the monofocal central region have coinciding amplitude values.

[0043] The present invention is based on the recognition that by providing a monofocal portion at the center of an ophthalmic lens (having a focus that coincides with one of the diffraction foci provided by a diffraction grating), after implantation of the IOL, for relatively small pupil sizes, one of the target diffraction foci of the patient's entire visual system (i.e. the combination of lens and eye) can be accurately measured if the focus of the monofocal portion coincides with one of the target diffraction foci.

[0044] Assume that a lens is designed to provide a target focus for near vision of diffraction order +1, a target focus for far vision of diffraction order -1, and a target intermediate refractive focus, also indicated as 0 (zero) order. For example, when the focus of the monofocal central area coincides with the target focus for far vision, the adaptability of the patient's visual system (i.e., the combination of the lens and eye for target far vision) can be measured for pupil sizes within the size range of the monofocal central area. Similarly, for the monofocal central area, a focus that coincides with the diffraction focus for near vision is provided.

[0045] A typical autorefractometer will measure at the periphery of a patient's pupil. However, doctors often measure under lighting conditions that result in a pupil diameter of approximately 3 mm or less. Typical pupil dimensions when measuring lenses manufactured according to the present disclosure have a diameter of approximately 1-2 mm. Therefore, using these dimensions, the person performing the measurement knows that the measurement will return a result based on the focus of the central region of a single focal point.

[0046] Furthermore, through the present disclosure, the strong far or near focus provided by the single focal center area can be used for a wide range of pupil sizes. Depending on the ambient environment and / or daytime conditions, the far or near focus will prevail. Compared to prior art multifocal lenses such as those disclosed in WO2019020435, this results in a faster adaptation time to the focus provided by the single focal center area and a more comfortable experience until all the focuses are accepted by the user's visual system.

[0047] As described above, lenses having a continuous periodic phase profile function offer the advantages of being less likely to produce glare or scatter due to non-uniformities in the path of incident light through the lens, and also producing less halo, due to the absence of concentric rings or areas with sharp edges, while being easier to manufacture according to the calculated profile than, for example, sawtooth or binary gratings or relief.

[0048] These advantages are maintained by the present disclosure because, at the transition point in the radial position of the lens body where the monofocal central region ends and the diffraction grating begins, the height profile or amplitude profile of the monofocal central region and the height profile or amplitude profile of the diffraction grating have overlapping amplitude values. That is, at the transition point, jumps in amplitude or height of the overall optical profile of the lens body transverse to the surface of the lens body are effectively avoided, thereby avoiding non-uniformities in the path of incident light traveling through the lens.

[0049] For example, a crucial step in manufacturing ophthalmic lenses through micromachining or diamond turning is mechanical polishing to remove cutting marks. All visible cut marks must be removed to meet quality requirements and medical regulations for intraocular lenses. However, achieving extremely low levels of cut marks requires expensive machinery and slow cutting. Polishing the lens after cutting allows the machine to work more quickly.

[0050] The sharp angles in the height profile of a diffractive lens complicate mechanical polishing. If mechanical polishing is impossible due to the lens's height profile, either chemical polishing, which requires hazardous chemicals, or the lens must be manufactured without polishing. The latter option results in significantly increased manufacturing costs due to either lower yields and more expensive machinery, or both.

[0051] The smooth diffractive geometry according to the invention allows for polishing and therefore leads to a significant increase in yield compared to lenses with sharp transitions in their height profile.

[0052] In an embodiment of an ophthalmic multifocal lens according to the present disclosure, wherein the diffraction grating comprises a wave-type diffraction pattern, i.e., the phase profile φ(r) of the periodic diffraction grating comprises a wave-type diffraction pattern having alternating peak amplitude values and trough amplitude values, the transition points are positioned closer to the peak amplitude values of the diffraction grating than to the trough amplitude values.

[0053] It has been observed that the diffraction efficiency of a lens increases when the transition point occurs closer to the peaks of the diffraction grating than to the valleys, that is, when the transition point is close to the peaks of the diffraction grating near the surface of the lens body.

[0054] In another embodiment of the ophthalmic multifocal lens according to the present invention, when 2 When observed in space, the distance between the peak amplitude and the transition point measured in the radial direction r of the lens body is less than the distance between the peak amplitude and the transition point measured in the radial direction r 2 0.25 times the period or pitch of the diffraction grating in space, preferably less than the period or pitch of the diffraction grating in r 2 0.2 times the period or pitch of the diffraction grating in space.

[0055] The period of a diffraction grating can be most easily determined by measuring the diffraction profile of the diffraction grating and by displaying the measurement using a squared r-axis.

[0056] Therefore, by positioning the transition point at the rising or falling edge of the amplitude profile of the diffraction grating next to the peak amplitude value, a relatively smooth transition from the amplitude profile of the single focus central area to the amplitude profile of the diffraction grating and improved diffraction efficiency are obtained.

[0057] That is, the monofocal central region and the diffraction grating merge at one of the leading or rising edge and the falling or trailing edge of a particular peak amplitude value of the diffraction grating, i.e., such an edge of the wave-type periodic diffraction profile whose distance from the surface of the lens body decreases as the radial distance in either direction toward that peak amplitude value decreases.

[0058] In an embodiment of the present disclosure, the transition point is set by at least one of: adapting the radius of the central region of the single focus, the independent variable and the amplitude of the amplitude profile H(r) of the diffraction grating based on the phase profile function φ(r) of the diffraction grating, and adapting the phase profile function φ(r) of the central region of the single focus to the phase profile function H(r) of the diffraction grating. To adapt the independent variable and amplitude of the amplitude profile h(r) in the central area of the single focus.

[0059] The diffraction grating and monofocal central region of an ophthalmic multifocal lens according to the present disclosure can extend in a radial direction r across portions of the surface of the lens body symmetrically and asymmetrically relative to the optical axis of the lens body. In asymmetrical embodiments, the optical axis can include a point on the surface of the lens body that is displaced in the radial direction r from the center of the lens body. Symmetrical embodiments are most commonly used in practice.

[0060] In embodiments of the ophthalmic multifocal lens according to the present disclosure, one or both of the argument and the amplitude of the periodic phase profile φ(r) of the diffraction grating are variable as a function of the distance in the radial direction r from the optical axis of the lens body.

[0061] It is known from W02019020435 that the light distribution in the focus of an ophthalmic lens comprising a diffraction grating having a continuously periodic phase profile function can be extremely well adjusted over a relatively large intensity range by modulating one or both of the independent variable and the amplitude of the phase profile function as a function of the radius or the radial distance to the optical axis of the lens body.

[0062] In this way, for various pupil sizes, the desired relative light distribution in each focus of the lens can be effectively established despite or due to the contribution of the monofocal central region to the amount of light in one of the diffraction foci according to the present disclosure, and any influence on the target light distribution in the focus of the lens can be corrected by setting the transition point by any of the above-mentioned measures, such as adapting the radius of the central region and / or adapting the amplitude of the amplitude profile h(r) of the central region and / or adapting the independent variable and / or amplitude of the amplitude profile H(r) of the diffraction grating.

[0063] In an embodiment of an ophthalmic multifocal lens according to the present disclosure, the lens body, the diffraction grating and the monofocal central region are arranged for:

[0064] providing a monofocal property at a first zone of the lens body including the optical axis, the focus of the first zone coinciding with one of the diffraction foci provided by the diffraction grating,

[0065] providing multifocal properties at a second region of the lens body extending radially beyond the first region of the lens, and

[0066] The bifocal property is provided at a third region of the lens body extending beyond the second region radially toward the peripheral edge of the lens body.

[0067] With this embodiment, the multifocal property of the ophthalmic lens is limited to a second zone in the radial direction of the surface of the lens body, which is located between the monofocal central zone (i.e., the first zone of the lens) and the peripheral edge of the lens body. Furthermore, the lens includes a third zone having bifocal properties, radially outwardly beyond the second zone and toward the peripheral edge of the lens body.

[0068] This type of lens provides an optimized diffraction efficiency that is best adjusted to the user's pupil size. The sizes of the first, second and third zones are arranged so that for strong or relatively strong ambient light conditions, such as when reading, the pupil size of the human eye mainly covers the first and second zones of the lens, so that most of the optical power should be directed to the focus points for near and intermediate vision. In low light conditions, for example, such as when driving a vehicle at night, the pupil size is relatively large, covering almost the entire surface area of the lens, so that most of the optical power should be directed to the focus points for intermediate and far vision. Those skilled in the art will understand that in actual embodiments, the ratio of the optical powers between the focal points at the respective surface areas depends on whether the monofocal first zone of the lens contributes to either of the focal points for near or far vision.

[0069] In embodiments of ophthalmic multifocal lenses according to the present disclosure, the monofocal central zone produces a focal point that coincides with the diffraction focal point for distance vision.

[0070] It has been observed that, after implantation of an IOL, for example, patients can adapt to farsightedness more quickly than to either or both of nearsightedness and intermediate vision. The above-described embodiment will provide the patient with a clearly defined single focal point (i.e., the focal point for farsightedness) to which the patient quickly adapts and which will enable the patient to perform most daily activities very well in the early post-implantation period. Furthermore, this embodiment makes it easier for the physician to evaluate the lens, since they know that the specific monofocal central area provides only far focus. When measuring the visual system using an (auto)refractor and the size of the patient's pupil is smaller than the size of the monofocal central area, it is ensured that the far focus is measured.

[0071] An ophthalmic lens according to the present disclosure has a transition point at a radial position such that the monofocal central region or first region has a diameter in the range of 0.8-1.3 mm, and has a phase profile function of the monofocal central region designed such that the ratio of the intensity of incident light distributed in the target focal points for far and near vision is in the far / near ratio range of 0.8-2.0 and the phase profile function φ(r) of the diffraction grating, the ophthalmic lens actually covers the majority of the lenses to be implanted.

[0072] The shape or height profile of the monofocal area may be selected from a plurality of continuous refractive profiles known for monofocal lenses. Asphericity is one of the most common known shapes of monofocal lenses known in practice.

[0073] In an embodiment of a multifocal ophthalmic lens according to the present disclosure, the monofocal central region comprises a continuous phase profile function Continuous Phase Profile Function Defined by:

[0074]

[0075] Where: r is the radial distance from the optical axis of the lens body, [mm],

[0076] f is the focal length of the central area of the single focus, [mm], and

[0077] λ is the design wavelength, [mm].

[0078] In the paraxial approximation, using geometric or ray optics where the angle θ between these rays and the optical axis of the lens is kept small, i.e. << 1 rad, so that one can assume tanθ ≈ sinθ ≈ θ, the above phase profile function (1) for the central region of the monofocal point reduces to:

[0079]

[0080] An alternative refractive profile for the central region of the monofocal point is defined by:

[0081]

[0082] Where: z(r) is the sag at distance r from the optical axis,

[0083] r is the radial distance from the optical axis of the lens body, [mm],

[0084] R is the radius of curvature, [mm],

[0085] k is the quadratic constant that defines the shape of the lens,

[0086] h is the radial coordinate (from the optical axis), and

[0087] A 2n are the coefficients of the correction polynomial (allowing for higher order aspheric optics).

[0088] The term "sag" can be thought of as starting from a cylinder, then cutting the aspheric lens from one of the ends z(r) provides a cutting depth to each distance h from the central optical axis, where R is the radius of curvature of the cylinder.

[0089] As mentioned previously, it is often advantageous to provide the desired multifocal grating calculated for a linear phase grating and then convert this grating into a diffraction optic or portion of a diffraction optic. For example, Gori et al. demonstrated that the best way to create an optical tripler (i.e., a beam splitter that splits the incident light into three levels of equal intensity) is provided by:

[0090] φ lin (x) = tan -1 [2.65718...*sin2πx] (4)

[0091] Where: φ lin (x) is the phase profile of the linear phase grating,

[0092] x is the axis or distance that the grating extends, in [mm]. Using this definition, one period is exactly 1 unit long.

[0093] In one embodiment of the multifocal ophthalmic lens according to the present disclosure, the diffraction grating is arranged for operating as a wave beam splitter and comprises two diffraction foci at diffraction orders +1 and -1, and wherein the phase profile function is expressed by a single continuous periodic closed form or function as disclosed by WO2019020435, namely:

[0094]

[0095] Where: r is the radial distance or radius outward from the optical axis of the lens body, [mm],

[0096] A(r) is the amplitude modulation function of the phase profile function in the radial direction of the lens body,

[0097] F[a*G] is a function of the radial direction of the lens body providing the beam splitter,

[0098] G(r) is r 2 A continuous periodic function in space,

[0099] α(r) is the independent variable amplitude modulation function of G(r),

[0100] S(r) is G(r) at r 2 The independent variable angular modulation function in space, [mm 2 ],

[0101] T is the diffraction grating at r 2 Period or spacing in space, [mm 2 ],and

[0102] B(r) is the amplitude modulation function of the continuous periodic phase profile function,

[0103] Therein, at least one of the argument amplitude modulation function A(r) and the argument angle modulation function S(r) comprises an argument modulated as a function of radial distance from the optical axis of the lens body.

[0104] In equation (4), the linear phase grating with the highest diffraction efficiency for a trifocal beam splitter with equal intensity distribution is defined. If the independent variable changes from x to x 2, then a phase distribution with the correct zone distance for the lens is provided. If this is applied to the phase profile function φ(r) in equation (5) F[α*G], it is an inverse tangent function, and G(r) is a sine function. In the case of S(r) = 0, A(r) = 1 and B(r) = 0, a diffraction grating is obtained, when at r 2 When viewed in space, this diffraction grating looks identical to a linear phase grating. As a lens, it is a continuous periodic phase profile function of a planar diffraction grating that separates the incident light beam with maximum efficiency at the focal points of the ±1st and 0th diffraction orders.

[0105] Both α(r) and S(r) can be independently selected to modulate the arguments of the above continuous periodic phase profile function (4) to adjust the light distribution in the target focus for different pupil sizes.

[0106] The constant value of the independent variable angle modulation function S(r) represents the phase shift of the continuous periodic phase profile function, and determines the starting point of the slope of the phase profile function, thereby determining whether more light is diffracted in the +1 diffraction order or whether more light is diffracted in the -1 diffraction order, depending on the sign and value of the phase shift, respectively.

[0107] It is advantageous to express the phase shift S(r) as a fraction of the period T of the grating, for example S = ±0.25*T. Those skilled in the art will appreciate that a particular phase shift comprising an integer value of the period T of the diffraction grating will achieve the same effect as a corresponding phase shift within a single period T.

[0108] According to the present disclosure, the light distribution in the diffraction focus and the refraction focus can be further adjusted by adapting at least one of the amplitude modulation function A(r) and the amplitude modulation function B(r) of the continuous periodic phase profile function (5).

[0109] The amplitude modulation functions A(r) and B(r) provide further control over the amount of light distributed between the ±1st diffraction order and the 0th order depending on the pupil size. In general, if the maximum phase retardation in the phase profile is below the design wavelength, an increase in either or both of the amplitude modulation functions will increase the amount of light diffracted in the ±1st diffraction order (i.e., the diffraction focus) compared to the 0th order or the refracted focus, while a decrease in either or both of the amplitude modulation functions will increase the amount of light provided in the refracted focus compared to the diffraction focus.

[0110] For apodization purposes, the amplitude modulation function can vary as a function of radial distance from the center or optical axis of the lens. Varying the amplitude is a way to control the relative light intensity in the intermediate (i.e., refractive) focus. In practical embodiments, in accordance with the present disclosure, the amplitude modulation functions A(r) and B(r) can be constant over a portion of the lens body.

[0111] The amount of light distributed at zero order, i.e., the intermediate focus in the present disclosure, can be adjusted by using an independent variable amplitude modulation function or light distribution parameter α(r). According to the present disclosure, α(r) can have a constant value over a portion of the lens body. In practice, the value of α(r) can range from, for example, 2 to 3.

[0112] Therefore, in an embodiment of an ophthalmic lens according to the present disclosure, the phase profile function (4) of the diffraction grating is simplified to:

[0113]

[0114] Where: S(r) at r 2 has a constant value in the range between -0.5*T and 0.5*T in space, A(r) has a constant value, and

[0115] α(r) has a constant value in the range between 2.5 and 3.

[0116] The value of the amplitude modulation function A(r) may be constant over the lens surface, for example between 1.05 and 1.15, in order to take into account the reduction of the height of the diffraction grating by a finishing operation of the lens (for example by polishing). For lens bodies that do not require such finishing operations, the value of A(r) may be 1.

[0117] Although the phase profile function of the central region of a single focal point and / or the phase profile function of the diffraction grating can be calculated using mathematical analysis, according to the present disclosure, either or both of the phase profile functions can be provided by computer calculation, wherein the phase profile function is represented by a Fourier series, and each diffraction order is represented by a corresponding Fourier coefficient. The phase profile function can be calculated so that the sum of the squared absolute values or the weighted squared absolute value of the Fourier coefficients of the diffraction orders associated with the target focal point is maximized.

[0118] In equation (4), the optimal linear phase grating for a three-focal grating with equal intensity distribution is shown. It is often advantageous to design a specific grating with the desired characteristics. In the already mentioned paper by Romero et al., a method for finding the optimal linear phase grating for a set of desired target foci and a specific intensity distribution in these foci is disclosed. For the case of a three-focal grating, the linear phase grating φ based on the formula of Romero et al. is lin The complete non-simplified formula for (x) is:

[0119]

[0120] Where: γ1, γ2, γ3 represent the relative intensities of the corresponding diffraction orders -1, 0, and 1, respectively.

[0121] α1, α2, α3 represent the phases of the corresponding Fourier coefficients of the phase profile function,

[0122] μ1, μ2, μ3 are constants to be optimized, and

[0123] |a k | / γ k =N, where N is a positive constant, and for k=1, 2, 3, |a k | represents the Fourier coefficient a of the diffraction grating k The amplitude of

[0124] x is the axis along which the grating extends.

[0125] Using this definition, a period is exactly 1 unit long.

[0126] The grating in equation (7) can be used for the trifocal portion of the lens by replacing x with the square of the lens radius r. More precisely, to achieve the equivalence of equation (5), x should be 1 / T{r 2 -S(r)} instead.

[0127] A lens equation equivalent to equation (5) above can now be formed from the linear grating in equation (7).

[0128] Using the phase profile φ defined in (7) lin (x) Arrival:

[0129]

[0130] in:

[0131] φ(r) is the continuous periodic phase profile function of the lens diffraction grating,

[0132] r is the radial distance or radius outward from the optical axis of the lens body, [mm],

[0133] A(r) is the amplitude modulation function of the continuous periodic phase profile function,

[0134] B(r) is the amplitude modulation function of the continuous periodic phase profile function,

[0135] S(r) in r 2 The independent variable angular modulation function in space, [mm 2 ],and

[0136] T is the diffraction grating at r 2 Period or spacing in space, [mm 2 ].

[0137] Note that due to the way the theory of Romero et al. is applied here, the focal points for far and near vision correspond to positive and negative diffraction orders, respectively. This is the opposite of what is used in the description of this application. From a theoretical point of view, this reversal of the order and the focal points is irrelevant.

[0138] From the mathematical approach of Romero et al., to find the optimal trifocal grating with equal splitting on the levels (-1, 0, +1), the following equation is obtained:

[0139] φ lin (x) = tan -1 (2.65718...*cos2πx) (9)

[0140] This definition is the same as equation (4) above, except that it is offset by 90 degrees (0.25*T). This offset needs to be taken into account when manufacturing the lens by changing S(r) appropriately.

[0141] If, instead of providing an equal intensity distribution, a diffraction grating with a (near, middle, far) division of (1.2, 1, 1) is provided, for example, a way to express the best diffraction grating that meets these requirements is by applying the teaching of Romero et al. regarding equation (7), with the constants set as follows:

[0142]

[0143] In another embodiment of a multifocal ophthalmic lens according to the present disclosure, the diffraction grating is arranged to operate as a symmetric optical wave splitter comprising diffraction foci at diffraction orders +1, 0, and -1, and wherein the single continuous periodic phase profile function φ(r) of the lens diffraction grating is defined by equations (8) and (7) above. In a specific embodiment, constants according to equation (10) are applied in equations (7) and (8).

[0144] The surface of the lens body can also be modified by applying Fourier filtering or convolution with a kernel, or other known signal processing methods can be applied to smooth or slightly reshape the lens profile to change the energy distribution between diffraction orders or to remove unwanted stray light. Such modifications are generally easier to apply to r 2 space.

[0145] It should also be noted that the teachings according to the present disclosure are equally applicable to designing and adjusting the light distribution of multifocal ophthalmic lenses with four target focal points (i.e., so-called quadfocal lenses) or even multifocal ophthalmic lenses with five target focal points (i.e., so-called pentafocal lenses).

[0146] Numerical methods may be needed to calculate the phase function or phase profile function to provide the desired light distribution in the refractive and diffraction foci of a symmetric or asymmetric beam splitter having at least foci for near and far vision that are different from the first diffraction order ±1 as described above.

[0147] In a second aspect, the present disclosure provides a method of manufacturing an ophthalmic multifocal lens, the ophthalmic multifocal lens including at least focal points for near vision, intermediate vision, and far vision, the lens having a light-transmitting lens body, the light-transmitting lens body including a diffraction grating extending concentrically in a radial direction r from an optical axis of the lens body across a portion of a surface of the lens body, the lens body being designed to provide a refractive focus for intermediate vision, the diffraction grating having a phase profile φ(r) represented as a single continuous periodic function arranged to change the phase of incident light at the lens body and operating as an optical wave beam splitter, which provides at least a diffraction focus for near vision at diffraction order +m and a diffraction focus for far vision at diffraction order -m, where m is a positive integer value, the method comprising the steps of:

[0148] - determine the target focus for near, intermediate and far vision for multifocal lenses,

[0149] - providing a light-transmitting lens body having a target focus for intermediate vision, and

[0150] - providing a diffraction grating with target focus for near and far vision,

[0151] Characterized by the following further steps:

[0152] - providing a monofocal central zone extending a distance r from the optical axis of the lens body across a portion of the surface of the lens body and having a continuous phase profile function Continuous Phase Profile Function is arranged to change the phase of incident light at the lens body to provide a focus that coincides with one of the target focal points for far vision and near vision,

[0153] - Determine the amplitude profile H(r) of the diffraction grating based on the phase profile function φ(r) of the diffraction grating, and the phase profile function of the central area of the single focus To determine the amplitude profile h(r) of the central region of the single focus,

[0154] - determining a transition point at the radial position where the monofocal central region of the lens body ends, at which transition point the diffraction grating and the monofocal central region have coincident amplitude values, and

[0155] - Application of a single focus central area and a diffraction grating according to the determined transition point.

[0156] The monofocal central region of the lens and the amplitude profile or height profile of the diffraction grating (which specifies the height and position of the varying DOE extending as an annular, elliptical, or other rotationally shaped region concentric with the optical axis or center of the lens on the lens surface) can be applied to the lens body by, for example, laser micromachining, diamond turning, 3D printing, or any other machining or lithographic surface treatment technique. Lenses with the same optical effect can also be produced by holographic devices, using holographic optical elements to propagate light to the desired focus.

[0157] In one embodiment of a method of manufacturing an ophthalmic multifocal lens according to the present disclosure, wherein the diffraction grating includes a wave-type diffraction pattern having alternating peak amplitude values and trough amplitude values, the transition point is determined to be closer to the peak amplitude values of the diffraction grating than to the trough amplitude values.

[0158] In particular, the transition point is positioned so that when r 2 When observed in space, the distance between the peak amplitude value and the transition point measured in the radial direction r of the lens body is less than the distance between the peak amplitude value and the transition point measured in the radial direction r 2 0.25 times the period or pitch of the diffraction grating in space, preferably less than the period or pitch of the diffraction grating in r 2 0.2 times the period or pitch of the diffraction grating in space.

[0159] In another embodiment of the method of manufacturing an ophthalmic multifocal lens according to the present disclosure, at least one of the amplitude profile h(r) of the monofocal central area and the amplitude profile H(r) of the diffraction grating is adapted to provide amplitude values that coincide with the monofocal central area and the diffraction grating at the transition point.

[0160] In another embodiment of the method of manufacturing an ophthalmic multifocal lens according to the present disclosure, the transition point and the radial shift of the diffraction grating are determined based on the distribution of light incident on the lens in the target focus, so that for a given aperture size:

[0161] - the intensity of the light distributed at each of the target foci is within a predetermined intensity range for each individual target focus, and

[0162] - the total intensity of the light distributed in the target focus is within a predetermined sum range, and

[0163] - A ratio of the intensities of light distributed in the target focus for farsightedness and nearsightedness is within a predetermined ratio range.

[0164] The lens body may include any one of hydrophobic acrylic, hydrophilic acrylic, silicone material, or any other suitable light-transmitting material.

[0165] The continuous phase profile function and height profile of the lens in the method according to the present disclosure can be provided remotely from the equipment used to manufacture the lens. The specific characteristics of the height profile of the diffraction grating of the lens can be forwarded to the manufacturing site or equipment by data transmission over a practically available telecommunication network (such as the Internet).

[0166] Adjustment and smoothing of optical properties and light distribution in targeted refractive and diffractive focuses can be applied so that the amount of light diffracted at a particular focus or focus order is spread or smeared out over a portion of the optical axis to provide an ophthalmic lens with enhanced depth of focus (ED) characteristics.

[0167] In a third aspect, the present disclosure provides an ophthalmic multifocal lens as described above, configured as one of a contact lens, an intraocular lens, an aphakic contact lens, an aphakic intraocular lens, and a spectacle lens. It is noted that in the case of an intraocular lens, the lens body typically takes the form of a biconvex or plano-convex optically transparent disk. In the case of a contact lens, or a spectacle lens, or a spectacle lens, the lens body may take any of a biconvex or plano-convex and a biconcave or plano-concave shape, or a combination thereof, whether or not enhanced by further optical correction disposed within or within the optically transparent body.

[0168] These and other aspects of the disclosure will be apparent from and elucidated with reference to the examples described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0169] Figure 1 The focusing of light beams from several distances at the human eye is illustrated in a schematic manner.

[0170] Figure 2a A top view of a typical prior art multifocal aphakic intraocular lens is illustrated in a schematic manner.

[0171] Figure 2b Schematically illustrated Figure 2a A side view of a multifocal aphakic intraocular lens is shown.

[0172] Figure 3 The optical operation of a prior art diffractive lens comprising a biconvex light-transmitting body and a staggered or sawtooth type light-transmitting diffraction grating is shown in a schematic manner in cross-section.

[0173] Figures 4a-4c Schematically and graphically illustrated are examples of height profiles and computer simulated light distributions of a continuous periodic diffraction grating on a biconvex lens body of an embodiment of a prior art multifocal aphakic lens as disclosed by WO2019020435.

[0174] Figures 5a-5dExamples of height profiles and computer simulated light distributions for various pupil sizes of a continuous periodic diffraction grating on a biconvex lens body of an embodiment of a prior art multifocal aphakic lens as disclosed by WO2019020435 are schematically and graphically illustrated.

[0175] Figures 6a-16c Examples of height profiles, independent variable modulation parameters, and independent variable modulation functions for illustrating a monofocal central region and a diffraction grating on a lenticular lens body of the present disclosure, and corresponding computer simulated light intensity distributions are schematically illustrated graphically.

[0176] Figure 17 The steps of a method for manufacturing an ophthalmic multifocal lens according to the present disclosure are shown in a simplified flow chart. DETAILED DESCRIPTION

[0177] To illustrate the present disclosure, Figure 1 The anatomy of the human eye 10 is shown in a simplified form. The front of the eye 10 is formed by the cornea 11, a spherical, transparent tissue covering the pupil 12. The pupil 12 is the adaptive, light-receiving part of the eye 10 that controls the amount of light received by the eye 10. Light passing through the pupil 12 is received at the natural lens 13, a small, transparent disk within the eye 10, which focuses the light onto the retina 14 at the back of the eye 10. The retina 14 contributes to the image formed by the eye 10. The posterior cavity 15, the space between the retina 14 and the lens 13, is filled with vitreous humor, a clear, jelly-like substance. The anterior and posterior chambers 16, the spaces between the lens 13 and the cornea 11, are filled with aqueous humor, a clear, watery fluid. Reference numeral 20 denotes the optical axis of the eye 10.

[0178] For sharp, far vision of the eye 10, the lens 13 should be relatively flat, while for sharp, near vision, the lens 13 should be relatively curved. The curvature of the lens 13 is controlled by the ciliary muscle (not shown), which is in turn controlled by the brain. A healthy eye 10 is able to accommodate (i.e., control) the lens 13 in a manner that provides sharp, clear images at any distance in front of the cornea 11 between the far and near fields of vision.

[0179] Ophthalmic or intraocular lenses are used to correct the vision of the eye 10 in combination with the crystalline lens 13, in which case the ophthalmic lens is located in front of the cornea 11, or replaces the crystalline lens 13. In the latter case, it is also indicated as an aphakic intraocular lens.

[0180] Multifocal ophthalmic lenses are used to enhance or correct vision for various distances of the eye 10. For example, in the case of a trifocal ophthalmic lens, the ophthalmic lens is arranged for sharp, clear vision at three more or less discrete distances or focal points (commonly referred to as farsightedness, intermediate vision, and nearsightedness). Figure 1 The focal points 17, 18, and 19 are designated by reference numerals 17, 18, and 19, respectively. Light rays emitted from objects located at or near these distances or focal points 17, 18, and 19 are correctly focused on the retina 14, i.e., a sharp image of these objects is projected. In practice, focal points 17, 18, and 19 can each correspond to a focal length ranging from a few meters to tens of centimeters to a few centimeters. Doctors typically select lenses for their patients so that the far focal point allows the patient to focus on parallel light. In common optical terminology, the far focal point is focused at infinity.

[0181] The amount of correction provided by an ophthalmic lens is called the optical power OP and is expressed in diopters (D). The optical power OP is calculated as the inverse of the focal length f, measured in meters. That is, OP = 1 / f, where f is the focal length from the lens to the respective focal point for farsightedness 17, intermediate vision 18, or nearsightedness 19. The optical power of a cascade lens is calculated by, for example, adding the optical powers of the constituent lenses. The optical power of a healthy human lens 13 is approximately 20 diopters.

[0182] Figure 2a 1 shows a top view of a typical ophthalmic multifocal aphakic intraocular lens 30, Figure 2b A side view of a lens 30 is shown. The lens 30 includes a light-transmissive, disc-shaped lens body 31 and a pair of haptics 32 extending outwardly from the lens body 31 to support the lens 30 within the eye. The lens body 31 has a biconvex shape and includes a central portion 33, an anterior surface 34, and a posterior surface 35. The lens body 31 also includes an optical axis 29 extending transversely to the anterior and posterior surfaces 34, 35 and through the center of the central portion 33. Those skilled in the art will appreciate that the optical axis 29 is a virtual axis used for purposes of reference regarding the optical properties of the lens 30. In a practical embodiment, the convex lens body 31 provides approximately 20D of optical power.

[0183] In the illustrated embodiment, a periodic light-transmitting diffraction grating or relief 36 is disposed on the front surface 34 of the lens body 31 and comprises rings or zones extending concentrically with respect to the optical axis 29 through the central portion 33 on at least a portion of the front surface 34 of the lens body 31. The diffraction grating or relief 36 provides a set of diffraction foci. Although not illustrated, the diffraction grating or relief 36 may also be disposed on the back surface 35 of the lens body 31, or on both surfaces 34, 35. In practice, the diffraction grating 36 is not limited to concentric circular or annular shaped zones, but includes concentric elliptical or oval shaped zones, for example, or more generally includes any type of concentrically rotated zone shape.

[0184] In practice, the optical diameter 37 of the lens body 31 is approximately 5-7 mm, while the total outer diameter 38 of the lens 30, including the haptics 31, is approximately 12-14 mm. The lens 30 may have a center thickness 39 of approximately 1 mm. In the case of multifocal ophthalmic contact lenses and eyeglasses or spectacle lenses, the haptics 32 are not provided on the lens body 31, and the lens body 31 may have a plano-convex, biconcave, or plano-concave shape, or a combination of concave-convex shapes. In the case of aphakic intraocular lenses, the lens body may include any of a hydrophobic acrylic, a hydrophilic acrylic, a silicone material, or any other suitable light-transmitting material for use in the human eye.

[0185] Figure 3 The optical operation of a known periodic light-transmitting diffraction grating or relief 42 of a lens 40 is schematically shown, which comprises a biconvex light-transmitting disc-shaped lens body 41. The lens 40 is shown in a cross-sectional view in the radial direction of the lens body. The diffraction grating or relief 42 comprises a plurality of repeated, continuously arranged transparent diffractive optical elements DOE 43 in the shape of prisms. The DOE 43 is arranged in a manner similar to Figure 2a The pattern of rings or zones of grating or relief 36 shown extends in concentric regions around a central portion 45 of lens body 41. For illustrative purposes, DOEs 43 of diffraction grating 42 are shown as well-known staggered or sawtooth-shaped elements comprising a continuous series of inclined light-receiving surfaces 44, such as linear or curved inclined light-receiving surfaces 44. A grating or relief in which DOEs 43 are spaced apart in the radial direction of lens body 41 is referred to as a binary relief (not shown). The repetition period or pitch of DOEs 43 decreases monotonically in the radial direction from the center or optical axis of the lens and varies as the square of the radial distance.

[0186] An incident light beam, or primary beam 46, passing through the grating 42 and the lens body 41 is diffracted and refracted, respectively, to produce an output light beam, or secondary beam 47. The refracted and diffracted light waves 47 form multiple focal points on the optical axis 48 of the lens 40 due to constructive interference of the light waves 47. Constructive interference occurs when the optical path length difference between the light waves 47 arriving from the lens body 41 at a particular focal point is an integer multiple of their wavelengths, i.e., the light waves are in phase, causing their amplitudes to add in an amplifying manner. When the optical path length difference between the interfering light waves 47 from the lens body 41 is an odd multiple of half the wavelength, such that the crest of one wave meets the trough of another wave, the light waves 47 partially or completely extinguish each other, i.e., the light waves are out of phase, and no focal point is produced on the optical axis 48 of the lens body 41.

[0187] The points of constructive interference at various distances from the lens body 41 are usually assigned diffraction orders. The focal point corresponding to the focal point produced by the refractive operation due to the curvature of the lens 40 is indicated by the 0th order. The other focal points are designated by the +m and -m orders, where m is a positive integer. That is, m = +1, +2, +3, etc. If the corresponding focal point appears to the left of the 0th order when viewed in the plane of the figure, that is, at a certain distance in the direction towards the lens body 41, the other focal points are designated by the m = -1, -2, -3 orders, etc. If the corresponding focal point appears to the right of the 0th order when viewed in the plane of the figure, that is, at a certain distance in the direction away from the lens body 41. Such as Figure 3 shown.

[0188] Note that in some publications and handbooks the above assignment of positive and negative diffraction orders may be reversed with respect to their position relative to the zero order. This becomes the case, for example, when the theory in the publication by Romero et al. is directly applied as is done here. If not otherwise stated, this description follows the Figure 3 Convention shown.

[0189] The diffraction reliefs 42 can be designed to provide focal points at different distances from the lens body 41. The periodic spacing or pitch of the DOEs 43 substantially determines the locations of the points on the optical axis 48 of the lens where destructive and constructive interference occur, i.e., the locations of the diffraction orders on the optical axis 48. The amount of incident light provided at the points of constructive interference (i.e., at or in a particular diffraction order) is controlled by the shape and height of the DOEs 43.

[0190] In case the diffraction grating or relief 42 provides diffraction orders regularly spaced on either side of the 0th order, the grating or relief is called a symmetric beam splitter, because the incident light beam 45 is diffracted or split symmetrically with respect to the 0th order. A grating or relief that produces irregular spacing of diffraction orders (such as +1, +2, -3, -5) is called an asymmetric beam splitter.

[0191] Light energy in light waves 47 that are focused or diffracted at focal points or orders that do not contribute to image formation at the retina 14 of the human eye 10 is lost and reduces the overall efficiency of the lens 40 and, therefore, the quality of the image perceived by a person using such a lens. In practice, to optimally design a lens, it would be advantageous if, for example, focal points for providing or correcting far, intermediate, and near vision to the human eye could be pre-set, such as Figure 1 As shown, it is advantageous to provide a diffraction grating 42 that is optimized to maximize the overall efficiency of the light energy received from the incident light beam 46 at these predetermined focal points.

[0192] In the scientific literature, diffraction gratings that optimize the overall efficiency of light distribution in preset or target diffraction orders can be obtained by determining only the linear phase function or phase profile that produces the target diffraction order with the maximum overall efficiency η or a figure of merit defined as the sum of the normalized light energy of all these target orders. Then, by adjusting the independent variables, these diffraction gratings can be shaped into lenses so that they have a maximum overall efficiency η in r 2 There are equidistant periods in space.

[0193] Those skilled in the art will appreciate that the lens body 41 can include plano-convex, bi-concave, or plano-concave shapes, as well as combinations of convex and concave shapes or curvatures (not shown).

[0194] Figure 4a Reference numeral 50 in FIG. 5 shows the diameter of the axially spaced ... 2 Represented by r 2 An example of a height profile or amplitude profile H(r) of a continuous periodic diffraction profile in space, and Figure 4b The same height function along a linear scale is shown based on the phase profile function φ(r) as a function of radial distance r according to equation (5), namely:

[0195]

[0196] Where: H(r) is the height profile of the lens, [nm],

[0197] A(r) is the amplitude modulation function of the phase profile function in the radial direction of the lens body,

[0198] λ is the design wavelength of the lens, [nm],

[0199] n is the refractive index of the lens body,

[0200] n m is the refractive index of the medium surrounding the lens body.

[0201] The amplitude of the height profile H(r) is depicted in μm along the vertical axis. The radial distance r measured in outward direction from the optical axis is represented in mm along the vertical axis assuming the optical axis passing through the center of the lens body is at radial position r=0.

[0202] In this embodiment, it is assumed that the design wavelength λ of the lens is 550 nm, the refractive index n of the lens body is set to 1.4618, and the refractive index n of the medium surrounding the lens body is m The amplitude modulation function A(r) is a constant at 1.07, and the independent variable amplitude modulation function α(r) is a constant at α=2.65718. 2 Period in space T = 0.733 mm2 , and the independent variable angle modulation function S(r)=0, that is, there is no phase shift or independent variable angle modulation.

[0203] Reference numeral 50 refers to the peripheral or baseline curvature of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 including a diffraction profile function H(r) 51, see Figure 2a and 2b .

[0204] As from Figure 4a It can be observed that in r 2 Each period T of the height profile H(r)51 is depicted in space at equal or equidistant lengths. The height profile, or height function H(r)51, is a single, closed-form, continuous geometric function that defines concentrically arranged DOEs, starting at the optical axis, i.e., r=0, and extending outward from the optical axis on the lens body. The diffraction profile lacks sharp transitions that are difficult to manufacture in the lens body. Therefore, the height profile H(r)51 of the diffraction grating allows for precise lens manufacturing.

[0205] The amount of light diffracted by a lens having a height profile H(r)51 is given by Figure 4c A computer-simulated light intensity distribution is shown in FIG. Reference numeral 54 designates diffraction order 0, which provides focus for intermediate vision; reference numeral 52 designates diffraction order -1, which provides focus for far vision; and reference numeral 53 designates diffraction order +1, which provides focus for near vision. In the intensity distribution, the intensity I of the diffracted light is plotted in arbitrary units along the vertical axis as a function of optical power in diopters D, which is plotted along the horizontal axis.

[0206] Assumptions of light intensity distribution in computer simulations Figure 2a 、 2b , which is designed to aim the zero order focus at 20 diopters D, and the first order focus at 21.5D and 18.5D located symmetrically with respect to the zero order. That is, for the zero order focus, the focus for intermediate vision is provided at 20D, for the diffraction order -1, the focus for far vision is provided at 18.5D, and for the diffraction order +1, the focus for near vision is provided at 21.5D. It will be understood by those skilled in the art that these optical powers or focal points may be different for the actual lens depending on the target focus. The example uses a MATLAB based TM The simulation software was used to calculate the pupil size, assuming a 6 mm diameter.

[0207] from Figure 4cIt can be seen that, unlike the lens phase profile calculated by Gori et al. for the linear optimal triplex lens, the amount of light incident on the curved lens body for a(r) = 2.65718 is not uniformly distributed at the target focus. This is because the periodic phase distribution function of the optimal triplex lens calculated by Gori et al. for a linear or planar phase grating exhibits a linear dependence in the distance between periods, while by converting it to a lens, the distance between periods of the phase profile function includes a square root dependence.

[0208] Figure 5a The height profile or height function H(r) 56 according to equation (11) above is shown as a function of the radial distance r of the diffraction grating in an embodiment of a trifocal intraocular lens. For this embodiment, the design wavelength λ, the refractive index n of the lens body, the refractive index n of the medium surrounding the lens body, m , amplitude modulation function A(r), independent variable amplitude modulation function α(r) and r 2 The period T in space is related to Figures 4a-4c The parameters of the embodiment shown are the same. Figures 4a to 4c The embodiments are different, Figure 5a The argument angle of the height profile H(r) 56 of the illustrated diffraction grating is modulated by a modulation function S(r) having a fixed value S=0.42*T. Reference numeral 55 refers to the peripheral or baseline curvature of the front surface 34 of the lens body 30 having the diffraction grating or relief 36 extending from the optical axis, including the diffraction profile function H(r) 56.

[0209] The height profile or height function H(r) 56 is a single closed-form continuous geometric function that defines concentrically arranged DOEs starting from the optical axis, ie, r=0, and extending in an outward direction from the optical axis on the lens body.

[0210] Figure 5b 、 5c and 5d show the results for different pupil sizes. Figure 5a Computer simulation of the light intensity distribution of the lens. Figure 5b 、 5c The vertical axis of the graph in 5d, the relative intensity rel.I of the refracted and diffracted light relative to the maximum intensity at a focus, is depicted as a function of the optical power in diopters D plotted along the horizontal axis. The example again uses a MATLAB-based TM simulation software to calculate.

[0211] The computer-simulated light intensity distribution assumes a biconvex lens body designed to aim the zero-order focus at 20 diopters D, and the first-order focuses at 21.5 D and 18.5 D, which are symmetrically located relative to the zero-order. That is, for the zero-order focus, the focus for intermediate vision is provided at 20 D, for the diffraction order -1, the focus for distance vision is provided at 18.5 D, and for the diffraction order +1, the focus for near vision is provided at 21.5 D.

[0212] Figure 5b The light intensity distribution 57 is shown for a pupil size of 1 mm in diameter. Figure 5b It can be seen that almost all the light incident on the lens is concentrated at the focal point of the intermediate vision at 20D. That is, when using an automatic refractometer and light intensity to measure the Figure 5a In an embodiment of the intraocular lens, when the optical system of the user is such that the diameter of the user's pupil size is approximately 1 mm, the focus actually measured by the autorefractor is not one of the diffraction focuses, but rather an intermediate or refractive focus.

[0213] Figure 5c The light intensity distribution is shown for a pupil size of 3 mm in diameter. A pupil of this size covers the Figure 5b The diffraction profile for a 1 mm pupil size is shown and the larger portion of the convex surface of the lens. Reference numeral 57 again refers to diffraction order 0, providing focus for intermediate vision. Reference numeral 58 refers to diffraction order -1, providing focus for far vision, and reference numeral 59 refers to diffraction order +1, providing focus for near vision. Figure 5b From the intensity profile, it can be seen that a greater portion of the incident light is distributed in the focal point of the near vision 59 than in the focal points of the intermediate vision 57 and the distant vision 64.

[0214] Figure 5d The light intensity distribution for a pupil size of 6 mm in diameter is shown. A pupil of this size typically covers the entire optical system of an ophthalmic lens. Reference numeral 57 again refers to diffraction order 0, which provides the focus for intermediate vision, reference numeral 58 refers to diffraction order -1, which provides the focus for far vision, and reference numeral 59 refers to diffraction order +1, which provides the focus for near vision.

[0215] Figure 6a The amplitude profile or height profile of an embodiment of a trifocal ophthalmic lens according to the present disclosure is shown, including a central region (ie, a region indicated by reference numeral 62) having a continuous amplitude profile h(r). Figure 2a ) and a diffractive profile 61 having an amplitude function H(r) extending across a surface 60 of the lens body over a radial distance of the lens body, thereby providing diffractive focus for both far and near vision.

[0216] The amplitudes of the height profiles h(r) and H(r) are along Figure 6a The longitudinal axis of is depicted in μm scale. The optical axis passing through the center of the lens body is assumed to be at radial position r=0, while the radial distance r measured in outward direction from the optical axis is represented along the longitudinal axis in mm.

[0217] The central region extends a distance r from the optical axis in the radial direction, spanning a portion of the surface 60 of the lens body, and its continuous amplitude profile h(r) 62 is designed to provide a single focus that coincides with one of the diffraction foci of the diffraction profile 61, thereby providing a monofocal central region.

[0218] exist Figure 6a In FIG. 6 , reference numeral 60 refers to the perimeter or baseline curvature of the front surface 34 of the lens body 30, as shown in FIG. Figure 2a and 2b At a transition point 63, at a radial position of the lens body at a distance from the optical axis, the continuous amplitude profile h(r) of the monofocal central area ends and is continuous in the amplitude profile H(r) 61.

[0219] exist Figure 6a In the embodiment, the single focus center region 62 includes a phase profile function according to the above equation (2) Right now:

[0220]

[0221] f is the focal point of the central region. It differs from the focal point of the lens as a whole. In a typical example, an IOL might have an intermediate focal point of 20D, with far and near focal points at 18.5D and 21.5D, respectively. The absolute value of f is (1 / 1.5)m = 0.67m.

[0222] To obtain the actual physical shape or amplitude profile on the lens, the following steps are applied.

[0223] It is assumed that the monofocal central area 62 should contribute to the focus of farsightedness, that is, the focus of the monofocal central area 62 should coincide with the focus of farsightedness provided by the diffraction grating 61. Figure 2b The lenticular lens sheet main body 31 shown in FIG contributes to the intermediate vision provided.

[0224] Adding a distance vision zone to the lens requires providing a negative lens component. To achieve this, change the sign of equation (2), i.e.:

[0225]

[0226] Then, to convert this expression into distance, the shape of the single focus area is expressed in terms of wavelength, i.e. Next, the refractive indices of the lens and the surrounding medium must be established to find the distance that corresponds to a complete phase shift, or 2π phase shift. This can be written as λ / (nn m ), where λ is the design wavelength of the lens, [nm], n is the refractive index of the lens body, and n m is the refractive index of the medium surrounding the lens body. Multiplied by the lens profile expressed in wavelength, the amplitude profile or height profile h(r) of the monofocal central area 62 is obtained, that is:

[0227]

[0228] Note that the design wavelength λ disappears from equation (13).

[0229] If a spherical monofocal central region is chosen, the radius of curvature can be obtained using the well-known Lensmaker formula. Assuming that the thin lens approximation can be applied, this leads to:

[0230]

[0231] Where: R represents the radius of curvature of the central area of the single focus [m].

[0232] Using the knowledge that the concave center region is to be provided, the amplitude profile of the single focus center region can be calculated according to equations (13) and (14):

[0233]

[0234] exist Figure 6a In the embodiment of the present invention, the amplitude profile of the diffraction grating 61 corresponds to the above reference Figure 4a The amplitude profile of the disclosed diffraction grating (11) is:

[0235]

[0236] According to the present invention, at the transition point 63, the amplitude profiles of the diffraction grating 61 and the monofocal central region 62 have coincident amplitude values. That is, at the transition point 63, the amplitude values of the two amplitude profiles are equal or substantially equal, so that at the transition point, jumps in amplitude or height of the overall optical profile of the lens transverse to the surface 60 of the lens body are effectively avoided, which would cause non-uniformity in the path of incident light traveling through the lens.

[0237] In this embodiment, it is assumed that the design wavelength λ of the lens is 550 nm, the refractive index n of the lens body is set to 1.492, and the refractive index n of the medium surrounding the lens body is m The amplitude modulation function A(r) is a constant of 1.06, and the independent variable amplitude modulation function α(r) is a constant, α=2.65718, r 2Period in space T = 0.66 mm 2 , the independent variable angle modulation function S(r) represents a constant phase shift S=0.31*T.

[0238] Figure 6b 、 6c and 6d show the Figure 5b 、 5c and the changes in pupil size in 5d Figure 6a Computer simulation of the light intensity distribution of the lens. Figure 6b 、 6c The vertical axis of the graph in 6d, the relative intensity rel.I of the refracted and diffracted light relative to the maximum intensity at a focus, is depicted as a function of the optical power in diopters D plotted along the horizontal axis. The example again uses a MATLAB-based TM simulation software to calculate.

[0239] The computer-simulated light intensity distribution assumes a biconvex lens body designed to aim the zero-order focus at 20 diopters D, and the first-order focuses at 21.5 D and 18.5 D, which are symmetrically located relative to the zero-order. That is, for the zero-order focus, the focus for intermediate vision is provided at 20 D, for the diffraction order -1, the focus for distance vision is provided at 18.325 D, and for the diffraction order +1, the focus for near vision is provided at 21.675 D.

[0240] Figure 6b The light intensity 64 is shown for a pupil size of 1 mm in diameter. Figure 6b It can be seen that almost all the light incident on the lens is concentrated on the focus of 18.5D hyperopia. This is consistent with the design goal of the lens according to this embodiment of the present invention, that is, to provide a single focal center area that coincides with the target focus of the hyperopia of the diffraction grating. Figure 6a From the amplitude profile, it can be seen that the radius of the monofocal central region 62 ends at a distance of approximately 0.5 mm, so that a pupil size of 1 mm diameter almost completely covers the monofocal central region.

[0241] Figure 6c The light intensity is shown for a pupil size of 3 mm in diameter. This size pupil covers the monofocal central area and a portion of the diffraction distribution and convex surface of the lens. Reference numeral 66 refers to diffraction order 0, providing focus for intermediate vision. Reference numeral 65 refers to diffraction order +1, providing focus for near vision. As can be seen from Figure 6c As can be seen from the intensity profile, most of the incident light is distributed at the far-sighted focus 64.

[0242] Figure 6dThe light intensity is shown for a pupil size of 6 mm in diameter. A pupil of this size generally covers the entire optical system of an ophthalmic lens. Reference numeral 66 refers to diffraction order 0, providing focus for intermediate vision, reference numeral 64 refers to diffraction order -1, providing focus for far vision, and reference numeral 65 refers to diffraction order +1, providing focus for near vision. Figure 6d As can be seen from the intensity profile, the amount of light distributed in each focus 64, 65, 66 is almost equal. Therefore, the additional contribution of light distributed in the focus for far vision due to the monofocal central region according to the present disclosure can be compensated by appropriate design of the diffraction profile to provide multifocal characteristics for pupil sizes larger than the monofocal central region.

[0243] Figure 7 Examples are shown of a continuous height or amplitude profile h(r) 72 of a single focal center region of a phase profile according to equations (11) and (15) above extending across the lens surface 70 and a continuous periodic height or amplitude profile H(r) 71 of a diffraction grating.

[0244] In this embodiment, it is assumed that the design wavelength λ of the lens is 550 nm, the refractive index n of the lens body is set to 1.492, and the refractive index n of the medium surrounding the lens body is m The amplitude modulation function A(r) is a constant at 1.06, and the independent variable amplitude modulation function α(r) is a constant, α=2.65718, at r 2 Period in space T = 0.67 mm 2 , and the independent variable angular modulation function S(r) represents a constant phase shift S = 0.34*T. The computer simulated light intensity distribution assumes a biconvex lens body designed to aim the zeroth order focus at 20 diopters D, and the first order focuses at 21.675D and 18.325D located symmetrically with respect to the zeroth order.

[0245] In accordance with the present disclosure, at the transition point 73 where the monofocal central region ends, i.e., at a radial distance of approximately 0.3 mm from the optical axis, the amplitudes of the amplitude profiles 71 and 72 are unequal or substantially equal, such that a relatively sharp edge appears in the optical system of the lens at the transition point 72.

[0246] Figure 8 Pictured Figure 7 The sharp edges of the height or amplitude profile of the optical system of the lens of the illustrated embodiment can be smoothed by increasing the size of the monofocal central region and terminating the monofocal central region at a transition point 83 where the amplitude value h(r) 82 of the monofocal central region is equal to the amplitude value H(r) 81 of the diffraction grating. In this example, the monofocal central region terminates at a radial distance of approximately 0.5 mm from the optical axis.

[0247] The continuous height or amplitude profile H(r) 82 of the single focus central region and the continuous periodic height or amplitude profile H(r) 81 of the diffraction grating also conform to the phase profile extending across the lens surface 80 according to the above equations (15) and (11).

[0248] It has been observed that by positioning the transition point 83 closer to the valleys 85 of the diffraction grating 81 than to the peaks 84, the diffraction efficiency of the lens is not optimal.

[0249] In this embodiment, it is assumed that the design wavelength λ of the lens is 550 nm, the refractive index n of the lens body is set to 1.492, and the refractive index n of the medium surrounding the lens body is m The amplitude modulation function A(r) is a constant at 1.06, and the independent variable amplitude modulation function α(r) is a constant, α=2.65718, at r 2 Period in space T = 0.67 mm 2 , and the independent variable angular modulation function S(r) represents a constant phase shift S = 0.50*T. The computer simulated light intensity distribution assumes a biconvex lens body designed to aim the zeroth order focus at 20 diopters D, and the first order focuses at 21.675D and 18.325D located symmetrically with respect to the zeroth order.

[0250] Figure 9a It is shown that for an ophthalmic lens according to the present disclosure, having a phase profile of equations (15) and (11) or a phase profile having a similar shape, i.e., a periodic sinusoidal or continuous wave type diffraction grating 91 having alternating peak 98 and trough 99 amplitude values and a continuously curved monofocal central region 92, improved diffraction efficiency and a relatively smooth transition of the height profile from the central region 92 to the diffraction grating 91 are achieved when the transition point 93 where the monofocal central region ends and the diffraction grating begins is located closer to the peaks 98 of the diffraction grating 91 than to the troughs 99.

[0251] exist Figure 9a , the transition point 93 is shown on one side of the peak 100 adjacent to the optical axis of the lens at r = 0. However, the transition point can also be located on the other side of the peak 100, i.e., adjacent to the periphery of the lens, as shown by the dotted line 94. Note that in the latter case, the position of the transition point 94 is still related to the position of the peak amplitude value 100.

[0252] Figure 9b Shows r 2 In space Figure 9a In particular, when the transition point 93 occurs, a relatively smooth transition is obtained from the amplitude profile of the single focus central region to the amplitude profile of the periodic diffraction grating, so that at r 2The distance 95 between the nearest peak amplitude value 100 measured in space and the transition point 93 or the transition point 94 is less than 0.25*T, that is, less than r 2 The period or pitch of the diffraction grating in space is 0.25 times T, preferably less than 0.2*T, such as Figure 9b Note again that in the case of the transition point 94, this distance is still related to the location of the peak amplitude value 100, which, although not directly visible in the final lens profile, can be easily reconstructed from measurements at the lens profile.

[0253] That is, the transition point 93 or 94 is close to the peak 100 of the amplitude profile 91 of the periodic diffraction grating near the surface 90 of the lens body, where the amplitude profile h(r) of the monofocal central area 92 and the amplitude profile H(r) of the periodic diffraction grating merge at the leading edge or rising edge of the amplitude profile H(r) of the diffraction grating, as shown by the dotted circle 97 in Figure 9.

[0254] Alternatively expressed, a smooth transition of the amplitude profiles h(r) and H(r) and improved diffraction efficiency are obtained when the transition point 93 or 94 is positioned in the surrounding area 97 at the rising or falling edge of the periodic diffraction profile 91, so that the edge of the periodic diffraction profile 91 goes from the trough 99 to the peak 98 of the profile or from the peak 99 to the trough 98.

[0255] The surrounding region 97 may cover an extent measured transversely to and from the surface 90 of the lens body that is approximately 10% to 30% of the maximum amplitude 96 of the amplitude profile 91 of the periodic diffraction grating, ie, half the top-to-top amplitude.

[0256] Figure 9a and 9b The diameter of the central area is 1.04 mm, the design wavelength I of the lens is assumed to be 550 nm, the refractive index n of the lens body is set to 1.492, and the refractive index n of the medium surrounding the lens body is set to 1.492. m Assume that is 1.336, the amplitude modulation function A(r) is a constant of 1.02, the independent variable amplitude modulation function α(r) is a constant, α=2.65718, r 2 Period in space T = 0.67 mm 2 , and the independent variable angular modulation function S(r) represents a constant phase shift S=0.32*T. Calculated to provide 20D+ / -1.625D focal points, ie, 18.375D, 20.0D, and 21.625D, and an adjusted height of a single focal center area.

[0257] At the transition point, the angle β between the tangent to the amplitude profile h(r) of the monofocal central area and the tangent to the amplitude profile H(r), as viewed from the edge of the periodic diffraction profile from its troughs to its peaks, is less than approximately 1 degree. This angle β also provides for a relatively smooth transition from the amplitude profile of the monofocal central area to the amplitude profile of the periodic diffraction grating. If the smooth profile shown here is used, the angle β at the transition point will rarely exceed 1 degree for a central area of approximately 1 mm, but can be higher for different profiles. The angle will also be higher for larger central areas. Note that in the profile diagrams, the angle at the transition point often appears large due to the asymmetric scaling of the horizontal and vertical axes.

[0258] Instead of or in addition to the above references Figure 7 In addition to adapting the size of the single focus center area, i.e., the radius or distance to the optical axis, the position of the transition point where the single focus center area ends and the diffraction grating begins can also be set by adapting either or both of the independent variable angle of the phase profile function of the diffraction grating and the amplitude modulation function of the phase profile function.

[0259] Assume that the phase profile function φ(r) of the diffraction grating conforms to equation (5), where F[α*G] is the inverse tangent function and G(r) is the sine function:

[0260]

[0261] Generate an amplitude or height profile H(r):

[0262]

[0263] By adapting or setting any one of the independent variable angular modulation function S(r) and / or the light distribution parameter α(r), the periodic diffraction profile is radially shifted on the lens surface in its phase or position so as to establish a smooth transition between the coincidence amplitude profile h(r) of the monofocal area and the coincidence amplitude profile H(r) of the diffraction grating at the transition point according to the present disclosure.

[0264] The smooth transition of the coincidence amplitude profile h(r) of the single focus area and the coincidence amplitude profile H(r) of the diffraction grating at the transition point according to the present disclosure may be separate from or in addition to the above measures, and may also require adapting either or both of the amplitude modulation functions A(r) and B(r) of the phase profile function according to the above equation (17).

[0265] As disclosed in WO2019020435, the teachings of which are incorporated herein by reference, the diffraction efficiency, i.e., the amount of optical power directed to a target diffraction order or target focus, can be effectively adjusted by shifting and amplitude modulating the phase profile of a diffraction grating depending on the radial distance from the optical axis of the lens, for achieving a corresponding target light distribution or focus enhancement, in particular providing a pupil-dependent light distribution in the focus. In this way, the effect of the desired light distribution in the target focus can be effectively reduced or compensated for several pupil sizes by adapting the diffraction grating to obtain a single focal center region and a smooth transition of the diffraction grating's amplitude profile.

[0266] Figure 10 Graphically illustrated are computer simulations of ophthalmic lenses designed according to the present disclosure based on the phase profile of a diffraction grating and the hyperopic monofocal central area according to equations (11) and (15) above, respectively, as a function of the independent variable modulation function or parameter S(r). Figure 10 The lenses simulated in Figure 1 all have a hyperopic monofocal central region with a diameter of 1.1 mm. The intensity values of the focal point are sampled at a 3 mm aperture, simulating an eye with a pupil of 3 mm in diameter. The trifocal grating S(r) in each lens is static across all diameters, with the values indicated by the horizontal axis.

[0267] Each lens is automatically constructed in a computer program as follows: 1) a monofocal central region is constructed with the desired optical power, 2) a diffraction grating is created according to any number of techniques, including applying S(r), and 3) the height difference between the central region and the diffraction grating at the desired transition point is calculated and then compensated so that there is no vertical jump.

[0268] Figure 10 The top portion of the graph illustrates, along the vertical axis and in arbitrary units, the calculated absolute intensity of light coupled into the intermediate focus 103, the calculated absolute intensity of light coupled into the far focus 101, and the calculated absolute intensity of light coupled into the near focus 102 as a function of a parameter S, expressed as a period along the horizontal axis. That is, S(r) is the constant phase shift provided by S*T. Figure 10 The middle part of shows the sum 104 of the absolute intensities 101, 102 and 103 as a function of S, and Figure 10 The lower part of Graph 1 illustrates the ratio of the amount of light coupled into the far focus to the amount of light in the near focus, ie the far / near ratio 105, also as a function of S. The intensity of the central area of the hyperopic monofocal point with a diameter of 1.1 mm is calculated.

[0269] Figure 11 With Figure 10 In a similar manner, computer simulated intensity profiles for different values of parameter S for an ophthalmic lens designed according to the present disclosure based on a pupil size or aperture size of 3 mm in diameter are illustrated.

[0270] Figure 11 The upper portion of illustrates the calculated absolute intensity 110 of light coupled to the intermediate focus, the calculated absolute intensity 111 of light coupled to the far focus, and the calculated absolute intensity 112 of light coupled to the near focus as a function of S, expressed as periods along the horizontal axis. Figure 11 The middle part of Graph 1 illustrates the sum 113 of the absolute intensities 110 , 111 and 112 as a function of S. Figure 11 The lower part of Graph 114 illustrates the far / near ratio 114 also as a function of S. The intensity of the central area of the hyperopic monofocal focus with a diameter of 0.98 mm is calculated.

[0271] from Figure 10 and 11 In the figures, as indicated by the vertical dotted lines 106, 107 and 115, 116, respectively, it can be seen that for single focal center regions having diameters of 1.1 mm and 0.98 mm, respectively, relatively high total intensity values, both individually and additively, are provided for S values between about 0.1 and 0.3, as well as relatively stable, i.e., less volatile, far / near intensity ratios between acceptable levels of about 2-3.

[0272] Figure 12 The three-dimensional graphic view 120 shows the Figure 6a 、 10 The total intensity of light at the three focal points of the ophthalmic lens designs 11 and 11 is plotted in arbitrary units along the vertical or z-axis as a function of both the radius of the central region, plotted in μm, along the y-axis, and the S parameter, plotted along the x-axis. Each raster point 121 in the xy plane represents one lens design, sampling the intensity at the three focal points in the model at an aperture of 3 mm.

[0273] To evaluate the design from this drawing, the two main concepts to judge from are theoretical performance and manufacturability. High and strong indicate high performance. Figure 12 For a specific choice of the parameters of the central region and the grating used in , the highest possible overall performance can be found for a central region radius of about 0.550 mm and an S value of about 0.1 to 0.35. Figure 12 A plateau can be seen in FIG. 1 , ie the circled area 122 , whereby the summed intensities are quite similar within the indicated range of S values.

[0274] Even when the sum is the same, the potential distribution will differ between different focal points. However, some degree of error always exists in manufacturing. As can be seen in the figure, the combination of a central region radius of 0.550 mm and an S value of 0.1 or 0.35 results in a designed lens very close to efficiency drop-off. Small deviations in S can cause the manufactured lens to behave like a lens with a smaller or larger S value. Therefore, it is generally advantageous to select a design from the central region of a high-performance platform, which has a positive impact on manufacturing yield.

[0275] Figure 13 The three-dimensional graphical view 130 shows the Figure 10 and 11 The far / near ratio of the light intensity in the far and near focuses of an eyeglass design, plotted along the vertical or z-axis in the figure, as a function of both the radius of the central area in μm plotted along the y-axis and the S parameter plotted along the z-axis.

[0276] This diagram can be used to Figure 12 The design is chosen in a specific way. The distance ratio determines the light distribution and, therefore, visual acuity at the corresponding distance. Therefore, the absolute value is important. However, manufacturability is also a crucial factor here. As can be seen from the figure, there are several very sharp ridges. Manufacturing a lens close to one of these ridges will generally reduce manufacturing yields, as small deviations can have very significant negative effects.

[0277] Figure 14 The three-dimensional graphical view 140 shows the Figure 10 and 11 The horizontal distance from the transition point to the peak amplitude along the dimensionless z-axis of the ophthalmic lens design, which is expressed in r 2 The period of the diffraction grating between the transition point and the highest point observed in space, also known as the peak amplitude or peak representation. The ± symbol refers to the distance on one side or the other of the peak amplitude value. See also Figure 9a and 9b For some lenses, this peak amplitude or highest peak may not be present in the resulting lens and the distance should be calculated assuming the peak in the original diffraction grating before replacing a portion of the original diffraction grating with the monofocal central area.

[0278] Figure 14 This distance is shown as a function of both the radius of the central region plotted in μm along the y-axis and the S parameter plotted along the z-axis. A value of zero on the z-axis represents a lens where the transition point is at the highest point (i.e., the peak) of the current cycle. Figure 14 The middle easy positioning represents the line of the lens created using the center area exactly at the peak of the current cycle.

[0279] By comparison Figure 14 and Figure 12 , you can see, Figure 14 The lines dividing the lens having the transition zone at the peak or peak amplitude value of the cycle also divide the Figure 12 The longitudinal center of the high performance plateau 122 found in the . This shows that a lens with good performance with high yield can be expected to have a transition region closer to the nearest peak than to the nearest through hole. It is particularly advantageous when the r 2 When viewed in space, the absolute distance between the transition region and the highest peak of the period is less than about 0.25*T and preferably less than 0.2*T.

[0280] from Figure 10-14 As can be seen from the graph in , the optimal design space for the lens according to the present disclosure occurs when the transition point is at a radial position such that the monofocal central area has a diameter in the range of 0.8-1.3 mm, and the ratio of the intensities of the incident light distributed in the target focal points for far vision and near vision is in the far / near ratio range of 0.8-2.0.

[0281] Figure 15a The height profile or amplitude profile of another embodiment of a trifocal ophthalmic lens according to the present disclosure is illustrated by way of example as a function of the radial distance r in mm along a linear scale.

[0282] Figure 15a The amplitude profile or height profile of the embodiment of the ophthalmic lens shown in includes a central region (i.e., Figure 2a ) and a diffraction grating 151 based on a continuous periodic phase profile function according to equation (6) provided above in the Summary of the Invention section.

[0283] The amplitudes of the height profiles h(r) 162 and H(r) 161 are along Figure 16a The longitudinal axis is depicted in μm. The optical axis passing through the center of the lens body is assumed to be at radial position r=0, while the radial distance r measured in the outward direction from the optical axis is expressed in mm along the longitudinal axis. Figure 2a and 2b As shown, reference numeral 160 refers to the periphery of the front surface 34 of the lens body 30 .

[0284] The central region extends a distance r from the optical axis in the radial direction, across a portion of the surface 150 of the lens body, and its continuous amplitude profile h(r) 152 is designed to provide a single focus that coincides with the diffraction focus for far vision of the diffraction profile 151, thereby providing a monofocal central region.

[0285] At a transition point 153, at a radial position of the lens body at a distance of approximately 0.5 mm from the optical axis, the continuous amplitude profile h(r) 152 of the monofocal central zone ends and becomes continuous in the amplitude profile H(r) 151 of the diffraction grating. In the embodiment shown, the transition point 153 is located at the surface 150 of the lens body.

[0286] In this embodiment, it is assumed that the design wavelength λ of the lens is 550 nm, the refractive index n of the lens body is set to 1.492, and the refractive index n of the medium surrounding the lens body is m =1.336. The diffraction grating 151 is optimized using equations (7) and (8) to provide relative intensities (γ1, γ2, γ3) of the corresponding diffraction orders -1, 0, and 1 of (1.2, 1, 1), respectively. The grating is optimized to provide more light to the near focus, thereby compensating to some extent for the light intensity provided by the monofocal central region to the far focus.

[0287] Based on a pupil size of 3 mm in diameter, Figure 15b The intensity simulation diagram shows the amount of light diffracted by a lens having a central area profile 152 and a diffraction profile 151. Intensity is plotted in arbitrary units along the vertical axis. The computer simulated light intensity distribution assumes Figure 2a 、 2b , which is designed to aim the zero-order focus at 20 diopters D, and the first-order focuses at 21.675D and 18.325D, respectively, located symmetrically with respect to the zero-order. Reference numeral 154 refers to diffraction order 0, providing the focus for intermediate vision, reference numeral 155 refers to the focus for distance vision at 18.325D, and reference numeral 156 refers to the focus for near vision at 21.675D.

[0288] Figure 16a By example, it is illustrated in r 2 In space in mm 2 The height profile or amplitude profile of the pentafocal lens according to the present disclosure is represented by Figure 16b The same height profile or amplitude profile in mm is shown as a function of the radial distance r along a linear scale.

[0289] Figure 16a The amplitude profile or height profile of the embodiment of the pentafocal ophthalmic lens shown in FIG. 1 includes a central region (i.e., Figure 2a ), and a diffraction grating 161 that produces five different focal points.

[0290] The diffractive part of the lens is based on the linear phase grating φlin (x) can be described by the following equations (18):

[0291] Q=μ1γ1sin(-2x*2π+α1)

[0292] +μ2γ2sin(-x*2π+α2)

[0293] +μ3γ3sin(α3)+μ4γ4sin(x*2π+α4)+μ5γ5sin(2x*2πa5)

[0294] P=μ1γ1cos(-2x*2π+α1)

[0295] +μ2γ2cos(-x*2π+α2)

[0296] +μ3γ3cos(α3)+μ4γ4cos(x*2π+α4)+μ5γ5cos(2x*2πa5)

[0297] φ lin (x)=atan2(Q,P) (18)

[0298] Among them: atan2 refers to the arc tangent of the 2 independent variables,

[0299] γ1,γ2,γ3,γ4,γ5 represent the relative intensities of the corresponding diffraction orders -1, 0, and 1, respectively.

[0300] α1, α2, α3, α4, α5 represent the phases of the corresponding Fourier coefficients of the phase profile function,

[0301] μ1,μ2,μ3,μ4,μ5 are constants to be optimized, and

[0302] |a k | / γ k =N, where N is a positive constant, and for k=1, 2, 3, |a k | represents the Fourier coefficient a of the diffraction grating k The amplitude of

[0303] x is the axis along which the grating extends.

[0304] According to this definition, a period is exactly 1 unit long.

[0305] A multifocal lens with five focal points can be achieved using the system of equations (18) by applying equation (8) above, similar to how a trifocal lens is created.

[0306] The linear phase grating (14) is based on the teachings of the present disclosure and the publication by Romero, Louis A. and Fred M. Dickey, "Theory of optimal beam splitting by phase gratings. II. Square and hexagonal gratings." JOSA A 24.8 (2007): 2296-2312. For example, the linear phase grating is optimized for five diffraction orders with an intensity distribution of (γ1, γ2, γ3, γ4, γ5) = (1.1, 0.9, 0.8, 0.9, 1.1).

[0307] The amplitudes of the height profiles h(r) 162 and H(r) 161 are along Figure 16a The longitudinal axis is depicted in μm. The optical axis passing through the center of the lens body is assumed to be at radial position r=0, while the radial distance r measured in the outward direction from the optical axis is expressed in mm along the longitudinal axis. Figure 2a and 2b As shown, reference numeral 160 refers to the periphery of the front surface 34 of the lens body 30 .

[0308] The central region extends a distance r from the optical axis in the radial direction, across a portion of the surface 160 of the lens body, and its continuous amplitude profile h(r) 162 is designed to provide a single focus that coincides with the diffraction focus for far vision of the diffraction profile 161, thereby providing a monofocal central region.

[0309] At a transition point 163, at a radial position of the lens body at a distance of approximately 0.6 mm from the optical axis, the continuous amplitude profile h(r) 162 of the monofocal central zone ends and becomes continuous in the amplitude profile H(r) 161 of the diffraction grating. In the embodiment shown, the transition point 163 is located at the surface 160 of the lens body.

[0310] In this embodiment, it is assumed that the design wavelength λ of the lens is 550 nm, the refractive index n of the lens body is set to 1.4618, and the refractive index n of the medium surrounding the lens body is m is 1.336. 2 In space, the period T = 0.733 mm 2 , the independent variable angle modulation function S(r) represents a constant phase shift S=0.80*T. A(r)=γ(r)=δ(r)=1.

[0311] Based on a pupil size of 3mm, Figure 16cThe intensity simulation diagram shows the amount of light diffracted by a lens having a central area profile 162 and a diffraction profile 161. Intensity is plotted in arbitrary units along the vertical axis. The computer simulated light intensity distribution assumes Figure 2a 、 2b , which is designed to aim the zero-order focus at 20 diopters D, and the first-order focuses at 21.675D and 18.325D, respectively, located symmetrically with respect to the zero-order. Reference numeral 164 refers to diffraction order 0, providing the focus for intermediate vision, reference numeral 165 refers to the focus for distance vision at 18.325D, and reference numeral 166 refers to the focus for near vision at 21.675D.

[0312] In the present design, two additional focal points are provided, a first additional focal point at 19D between the focal points for intermediate and distant vision, and a second additional focal point at 21D between the focal points for intermediate and near vision.

[0313] For the purposes of the present application, in addition to the above-described continuous periodic phase profile function according to equation (14), other continuous periodic phase profile functions for providing pentafocal lenses may be applied. As indicated, a quadrifocal lens may also be provided having a monofocal central area according to the present disclosure.

[0314] Figure 17 The simplified flow chart 170 in Figure 1 illustrates the steps of a method of manufacturing an ophthalmic multifocal lens according to the second aspect of the present disclosure. The direction of flow is from the top to the bottom of the figure.

[0315] In a first step, at least the target focus for near, intermediate and far vision of the lens is set, box 171 "Set target focus".

[0316] In a second step, a target relative light distribution between the different focal points for the user's different pupil sizes is determined (block 172, "Set Relative Light Distribution"). The selected pupil sizes may, for example, be within the range of diameter values of 0-3 mm, 0-4.5 mm, and 0-6 mm. Above 6 mm, the lens may, for example, exhibit bifocal properties, i.e., associated with intermediate and distant vision.

[0317] Next, a clear lens body is selected, having a refractive focus that provides the target focus for intermediate vision, block 173 "Select Lens Body".

[0318] In another step, block 174, "Provide Monofocal Central Region," a monofocal central region is provided that extends a distance r from the optical axis of the lens body in a radial direction across a portion of the surface of the lens body. This monofocal central region has a continuous phase profile function For providing a refractive focus that coincides with one of the target focal points for far vision and near vision set in the first step above.

[0319] To provide the diffraction focus, a continuously periodic phase profile function of the diffraction grating is calculated mathematically or digitally using a suitably programmed processor or computer. That is, step 175 "Calculate diffraction phase profile". A continuous periodic phase distribution function is calculated to establish the desired light distribution in the target refractive and diffractive focus across the lens for different pupil sizes, including the contribution of the monofocal central area.

[0320] In step 176, "Determine Transition Point," a transition point is determined at a radial distance from the optical axis at which the monofocal central region ends and the diffraction profile begins, wherein at this transition point the diffraction grating and the monofocal central region have coincident amplitude values, as taught above in the first aspect of the present disclosure. To this end, the amplitude of the height profile of the monofocal central region and / or the amplitude of the height profile of the diffraction grating may be adjusted.

[0321] In step 176, the transition point may be determined, for example based on the light distribution in the target focus of the light incident on the lens, as taught in the first aspect of the present disclosure, such that for a given aperture size:

[0322] - the intensity of the light distributed at each of the target foci is within a predetermined intensity range for each individual target focus, and

[0323] - the total intensity of the light distributed in the target focus is within a predetermined sum range, and

[0324] - A ratio of the intensities of light distributed in the target focus for farsightedness and nearsightedness is within a predetermined ratio range.

[0325] In the next step, the calculated phase profile function and transition points are adapted to fine-tune and / or smooth the desired or target optical properties of the lens, such as the desired relative light distribution between target focal points, i.e., step 177, "Intensity Adjustment." This intensity adjustment can similarly be processed by a suitably programmed processor or computer and can include modulation as taught and illustrated in the examples above. This is also used to account for optical deviations from the target focal points and profile due to, for example, tolerances in the machining or manufacturing of the lens.

[0326] Finally, the geometric height profile or amplitude profile of the monofocal central area and diffraction grating used to manufacture the lens is calculated, step 178 "Process Height Profile", again using a suitably programmed processor.

[0327] Finally, the height profile or height function applied at the lens body is machined and polished, for example, by laser micromachining, diamond turning, 3D printing, or any other machining or photolithographic surface processing technology. That is step 179 "machining".

[0328] The calculation in step 175 can be based on a power spectrum calculation from a Fourier series representation of the diffraction grating, such that the sum of the absolute values of the squares of the Fourier coefficients of the diffraction orders associated with the target focus is maximized. As described above, this calculation can be performed under the constraint of equal or weighted target light intensity in the target focus.

[0329] The calculations according to the present disclosure may be provided remotely from the equipment used to process the lens. The calculated specificities of the diffraction grating may be forwarded to the processing equipment by data transmission over a practically available telecommunication network, such as the Internet (not shown).

[0330] Those skilled in the art will understand that the monofocal central region and the diffraction grating may be applied to one or both of the front and back surfaces of the lens, and this applies to all embodiments disclosed and claimed in the appended claims.

[0331] It should also be noted that the teachings according to the present invention are equally applicable to designing and adjusting the light distribution of multifocal ophthalmic lenses having an apodization height or amplitude distribution.

[0332] By studying the drawings, the disclosure and the appended claims, those skilled in the art can understand and implement other variations of the disclosed examples and embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a / an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting their scope. The same reference signs refer to the same or equivalent elements or operations.

Claims

1. An ophthalmic multifocal lens comprising at least focal points for near, intermediate, and far vision, the lens having a light-transmitting lens body comprising a symmetrical diffraction grating extending concentrically in a radial direction r from the optical axis of the lens body across a portion of a surface of the lens body, the lens body being designed to provide a refractive focus for intermediate vision, the diffraction grating having a symmetrical diffraction grating arranged in a radial direction r 2 a phase profile φ(r) of a single continuous periodic function that is periodic in space and is used to change the phase of incident light at the lens body and operates as a symmetric optical wave splitter, providing at least a diffraction focus at diffraction order +m for near vision and a diffraction focus at diffraction order -m for far vision, wherein m is a positive integer value selected to be 1 or 2, characterized in that the lens body includes a refractive monofocal central region that extends a distance r in a radial direction from the optical axis of the lens body across a portion of the surface of the lens body and has a continuous phase profile function arranged to change the phase of incident light at the lens body Providing a focal point that coincides with one of the diffraction foci, wherein the diffraction grating is provided at a transition point at a radial position where the monofocal central region of the lens body ends, at which transition point the diffraction grating and the monofocal central region have coincident amplitude values such that a sharp edge at the transition point is avoided, wherein the diffraction grating comprises a wave-type diffraction pattern having alternating peaks and troughs without any sharp edges, the transition point being positioned closer to the peaks of the diffraction grating than to the troughs.

2. The ophthalmic multifocal lens according to claim 1, wherein: When in r 2 When viewed in space, the distance between the peak and the transition point measured in the radial direction r of the lens body is less than 2 0.2 times the period of the diffraction grating in space.

3. The ophthalmic multifocal lens according to claim 1 or 2, wherein: The diffraction grating and the monofocal central region extend in a radial direction r across a portion of the surface of the lens body symmetrically relative to the optical axis of the lens body.

4. The ophthalmic multifocal lens according to claim 1 or 2, wherein: The lens body, the diffraction grating and the monofocal central area are arranged to provide monofocal properties at a first area of the lens body including the optical axis, the focus of the first area coinciding with one of the diffraction foci provided by the diffraction grating, to provide multifocal properties at a second area of the lens body extending beyond the first area in the radial direction of the lens, and to provide bifocal properties at a third area of the lens body extending beyond the second area toward the peripheral edge of the lens body in the radial direction of the lens.

5. The ophthalmic multifocal lens according to claim 1 or 2, wherein: The monofocal central region includes a focal point that coincides with the diffraction focal point for distance vision.

6. The ophthalmic multifocal lens according to claim 1 or 2, wherein: The transition point is at a radial position such that the monofocal central region has a diameter in the range of 0.8 mm to 1.3 mm, and a ratio of intensities of incident light distributed in the diffraction focal points for far and near vision is in the far / near ratio range of 0.8 to 2.

0.

7. The ophthalmic multifocal lens according to claim 1 or 2, wherein: The phase profile function of the single focus central area Defined by: in: r is the distance from the optical axis of the lens body in the radial direction, [mm], f is the focal length of the central area of the single focus, [mm], In particular, the phase profile function of the central area of the single focus Defined by:

8. The ophthalmic multifocal lens according to claim 1 or 2, wherein: The phase profile function φ(r) of the diffraction grating is defined by: in: r is the distance from the optical axis of the lens body in the radial direction, [mm], A(r) is the amplitude modulation function of the phase profile function φ(r) in the radial direction of the lens body, F[α(r)*G(r)] is a function in the radial direction of the lens body that provides the operation of the beam splitter, G(r) is the 2 A continuous periodic function in space, α(r) is the independent variable amplitude modulation function of G(r), S(r) is the 2 The independent variable angle modulation function of G(r) in space, [mm 2 ], T is in r 2 The period or spacing of the diffraction grating in space, [mm 2 ],and B(r) is the amplitude modulation function of the continuous periodic phase profile function.

9. The ophthalmic multifocal lens according to claim 8, wherein: The phase profile function φ(r) of the diffraction grating is defined by: in: S(r) in r 2 has a constant value in the range between -0.5*T and 0.5*T in space, A(r) has a constant value in the range between 1.05 and 1.15, and α(r) has a constant value in the range between 2.5 and 3.

10. The ophthalmic multifocal lens according to claim 1 or 2, wherein: The diffraction grating is designed to operate as a symmetric optical wave splitter comprising diffraction foci at diffraction orders +1, 0, and -1, and the phase profile function φ(r) of the diffraction grating is defined by: in: r is the distance from the optical axis of the lens body in the radial direction, [mm], A(r) is the amplitude modulation function of the phase profile function φ(r) in the radial direction of the lens body, S(r) is the 2 The independent variable angular modulation function in space, [mm 2 ], T is in r 2 The period or spacing of the diffraction grating in space, [mm 2 ], B(r) is the amplitude modulation function of the continuous periodic phase profile function, and in: γ1, γ2, and γ3 represent the relative intensities of the corresponding diffraction orders -1, 0, and 1, respectively. α1, α2, α3 represent the phases of the corresponding Fourier coefficients of the phase profile function, μ1, μ2, μ3 are constants to be optimized, and |a k | / γ k =N, where N is a positive constant and for k=1, 2, 3, |a k | represents the Fourier coefficient a of the diffraction grating k The amplitude of x is φ lin (x) An axis along which an element extends.

11. A method of manufacturing an ophthalmic multifocal lens comprising at least focal points for near, intermediate, and far vision, the lens having a light-transmitting lens body comprising a symmetrical diffraction grating extending concentrically in a radial direction r from an optical axis of the lens body across a portion of a surface of the lens body, the lens body being designed to provide a refractive focus for intermediate vision, the diffraction grating having a refracted focal point indicated as being arranged at r 2 a phase profile φ(r) of a single continuous periodic function that is periodic in space and is used to change the phase of incident light at the lens body and operates as a symmetric optical wave splitter, providing at least a diffraction focus at diffraction order +m for near vision and a diffraction focus at diffraction order -m for far vision, wherein m is a positive integer value selected to be 1 or 2, and the method comprises the following steps: - determining the target focus of said multifocal lens for near vision, intermediate vision and far vision, - providing said light-transmitting lens body with said target focus for intermediate vision, and - providing said diffraction grating with said target focus for near and far vision, Characterized by the following further steps: providing a refractive monofocal central region extending a distance r in a radial direction from the optical axis of the lens body across a portion of the surface of the lens body and having a continuous phase profile function arranged to alter the phase of incident light at the lens body providing a focus that coincides with one of the target focal points for far vision and near vision, - determining the amplitude profile H(r) of the diffraction grating based on the phase profile function φ(r) of the diffraction grating, whereby the diffraction grating comprises a wave-shaped diffraction pattern having alternating peaks and troughs without any sharp edges, and based on the phase profile function φ(r) of the monofocal central region To determine the amplitude profile h(r) of the central region of the single focus, - determining a transition point at the radial position of the lens body where the monofocal central region ends, at which transition point the diffraction grating and the monofocal central region have coincident amplitude values, and such that the transition point is positioned closer to the peaks of the diffraction grating than to the troughs, and - applying said monofocal central area and said diffraction grating according to said determined transition point.

12. The method according to claim 11, wherein The transition point is positioned so that when r 2 When observed in space, the distance between the peak amplitude value and the transition point measured in the radial direction r of the lens body is less than the distance between the peak amplitude value and the transition point measured in the radial direction r 2 0.2 times the period of the diffraction grating in space.

13. The method according to claim 11 or 12, wherein: At least one of the amplitude profile h(r) of the monofocal central region and the amplitude profile H(r) of the diffraction grating is adapted to provide coincident amplitude values of the monofocal central region and the diffraction grating at the transition point.

14. The method according to claim 11 or 12, further comprising determining the radial shift of the transition point and the diffraction grating based on the distribution of light incident on the lens in the target focus, such that for pupil size: - the intensity of the light distributed in each of said target foci is within a predetermined intensity range for each individual target focus, and - the total intensity of the light distributed in the target focus is within a predetermined sum range, and - A ratio of the intensities of light distributed in the target focus for farsightedness and nearsightedness is within a predetermined ratio range.

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