RU2779523C2 - Ocular multifocal diffraction lens - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to ocular lenses, more specifically to ocular contact and intraocular multifocal diffraction lenses providing diffraction orders with adjustable light distribution for different pupil sizes. An ocular multifocal lens is proposed, containing at least focal points for close-distance vision, medium-distance vision, and long-distance vision, having a light-transmitting lens body containing an optical axis and providing a refractive focal point, as well as a diffraction grate passing concentrically in a radial direction through at least part of at least one surface of the mentioned lens body, providing a set of diffraction focal points. The mentioned diffraction grate is periodic in r² space, intended for work as a beam splitter for the distribution of light incident on the mentioned lens body at the mentioned refractive and diffractive focal points, wherein the mentioned refractive focal point provides the mentioned focal point for medium-distance vision, and the mentioned diffractive focal points provide the mentioned focal points for close-distance vision and long-distance vision. The mentioned diffraction grate of the mentioned ocular multifocal lens contains a continuous periodic function of a phase profile, passing in a radial direction of the mentioned lens body, and the mentioned continuous periodic function of the phase profile contains an argument modulated depending on a radial distance to the mentioned optical axis of the mentioned lens body, wherein the mentioned argument is modulated so that to provide periodic smooth transitions on the mentioned continuous periodic function of the phase profile. In this case, positions of the mentioned transitions are periodic in r² space, and each transition passes through a part of the period of the mentioned continuous periodic function of the phase profile in such a way that at least one period of the continuous periodic function of the phase profile is modulated differently than at least one other period, thereby adjusting the mentioned light distribution at the mentioned diffraction focal points, wherein each transition contains at least one of: a transition providing displacement, preferably spatial and/or radial, in the mentioned continuous function of the phase profile in the radial direction of the mentioned lens body, and the transition providing displacement, preferably spatial and/or radial, in the mentioned continuous periodic function of the phase profile in a direction transverse to the mentioned at least one surface of the mentioned lens body, thereby adjusting the mentioned distribution of light incident on the mentioned lens body.

EFFECT: improvement of a design solution of an ocular lens, which would provide freedom in the determination of diffraction orders or focal points, as well as adjustment or control of the relative intensity of light at all target focal points, in particular for different pupil sizes, avoiding as much as possible the light diffraction in diffraction orders that do not contribute to target focal points, thereby providing an improved overall user experience.

13 cl, 26 dwg

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The present invention relates generally to ophthalmic lenses, and more specifically to ophthalmic contact and intraocular multifocal diffractive lenses providing diffraction orders with tunable light distribution for different pupil sizes.

BACKGROUND OF THE INVENTION

Ophthalmology is the branch of medicine that studies the anatomy, physiology and diseases of the human eye.

The anatomy of the human eye is quite complex. The main structures of the eye include the cornea, a spherical transparent tissue on the outer front of the eye; the iris, which is the colored part of the eye; pupil, an adaptable opening in the iris that regulates the amount of light received by the eye; lens, a small transparent disk inside the eye that focuses light rays onto the retina; the retina, which is the layer that forms the back or back of the eye and converts perceived light into electrical impulses that travel through the optic nerve to the brain. The posterior chamber, that is, the space between the retina and the lens, is filled with aqueous humor, and the anterior chamber of the eye, that is, the space between the lens and the cornea, is filled with the vitreous, a transparent gelatinous substance.

The natural lens has a flexible, transparent, biconvex structure, and together with the cornea refracts light, focusing it on the retina. The lens is flatter on its anterior side than on its posterior side, and its curvature is controlled by the ciliary muscles, to which the lens is connected by supporting ligaments called zonules. By changing the curvature of the lens, the focal length of the eye changes to focus on objects at different distances. In order to view an object at a short distance from the eye, the ciliary muscles contract and the lens thickens, becoming more round, and thus high refractive power. Changing the focus to view an object at a greater distance requires relaxation of the lens, and thus increasing the focal length. This process of changing the curvature and focal length of the eye to form a sharp image of an object on the retina is called accommodation.

In humans, the refractive power of the lens in its natural environment is approximately 18-20 diopters, approximately one-third of the full refractive power of the eye. The cornea supplies the remaining 40 diopters of the full optical power of the eye.

As the eye ages, the opacity of the lens increases and cataracts occur. Certain medical conditions such as diabetes, trauma, and certain medications and overdose of ultraviolet light can also cause cataracts. Cataracts are painless and result in cloudy, blurry vision. Methods for treating cataracts include surgery where the cloudy lens is removed and replaced with an artificial lens, commonly called an intraocular lens, IOL.

Another age-related effect is called presbyopia, which manifests itself in difficulty reading small print or clearly viewing close-up images. It is believed that presbyopia is usually caused by a thickening and loss of flexibility of the natural lens in the eye. Age-related changes also occur in the ciliary muscles surrounding the lens. As elasticity decreases, it becomes more difficult to focus on objects that are close to the eye.

Various intraocular lenses are also used to correct other visual impairments such as nearsightedness or myopia, where the eye is unable to see distant objects caused, for example, by a cornea that has too much curvature. The effect of myopia is that light rays from distant objects are focused at a point in front of the retina rather than directly on its surface. Also known are hyperopia, or farsightedness, caused by an abnormally flat cornea so that light rays entering the eye are focused behind the retina, preventing close objects from being focused, and astigmatism, which is another common cause of visual impairment, in which images become blurry due to irregular the shape of the cornea.

In most cases, intraocular lenses are implanted in the patient's eye during cataract surgery to compensate for the loss of optical power of the removed lens. Modern IOL optics are designed to have multifocal optics for near, intermediate and far vision, and are also called multifocal IOL, MIOL, or more specifically trifocal lenses. Presbyopia is corrected with glasses or contact lenses, and multifocal optics can also be used. Multifocal eye lenses use two optical principles, refraction (refraction) and diffraction.

In order to illustrate the physical difference between these principles, this description uses the wave model of light. In this model, an electromagnetic wave propagates in a specific direction at a specific speed, and has a specific wavelength, amplitude, and phase.

Refraction is the deflection that a light wave experiences when passing from one medium, such as air or liquid, to another medium, such as glass or plastic, which has a different propagation speed of the light wave.

Diffraction in its basic form is based on the physical effect that light waves, falling on the irregularities of the object, become a source of secondary light waves. These secondary waves can interfere with each other in an amplifying and attenuating manner. Amplifying interference occurs when the difference in the optical paths of waves arriving at a particular point is a multiple of their wavelength so that their amplitudes are amplified. In such a case, the waves are also said to be in-phase. Weakening interference occurs when the difference in optical path length traveled by interfering light waves is an odd multiple of half a wavelength, such that the crest of one wave meets the trough of another wave, and the waves partially or completely cancel each other out. In such a case, the waves are also said to be out of phase.

A multifocal eye lens typically has a biconvex or plano-convex shape, or a biconcave or plano-concave shape, the curvature and thickness of which is configured to provide a first focal point on its optical axis by refraction. On one or both of the front and rear surfaces of the lens, a transmissive surface relief or diffraction grating may be provided, consisting of regularly or periodically arranged ribs and/or grooves designed to scatter transmitted light and located in concentric rings or zones on the corresponding lens surface. The periodic spacing or pitch of the ribs and/or grooves essentially determines the points of attenuating and amplifying interference on the optical axis of the lens. The shape and height of the ribs and/or grooves control the amount of incident light that is provided at the amplifying interference point by means of diffraction. Points of amplifying interference are commonly referred to as diffraction orders or focal points. The diffractive relief may be designed, for example, to provide the second and third focal points of the trifocal lens other than the refractive focal point.

Modern multifocal eye lenses are typically designed using two well-known types of basic diffraction gratings or patterns - sawtooth type and binary type. As used herein, the term "sawtooth type" or "serrated type" means a class of transmissive diffraction gratings or patterns consisting of a plurality of periodically repeating, adjacent, prism-shaped transparent diffractive optical elements (DOEs) having a monotonically inclined light-receiving surface, such as a linear or curved, monotonically inclined light-receiving surface. The term "binary type" in this description means a class of transmissive diffractive reliefs, consisting of many periodically repeating, spaced transparent DOE rectangular or prismatic shape.

To work as a lens, the repetition period or pitch of the scalloped grating must decrease monotonically in the radial direction r from the center or optical axis of the lens. More specifically, if the first period starts at the center of the lens and the second period starts at (1*k) ^0.5 , where k is a constant, then the third period starts at (2*k) ^0.5 , the fourth at (3* k) ^0.5 etc. Accordingly, in diffractive optics it is advantageous to represent the grating in the so-called r ² space. Namely, the parameter along the horizontal axis varies with r ² , so that the period appears at equidistant repetition.

Calculation of focal points, ie diffractive orders, of such primary reliefs is known and simple to those skilled in the art of diffractive optical lenses. In most cases, for use as an eye lens, the period or pitch of the main reliefs or gratings is chosen to have first and/or second orders of diffraction to provide target focal points. The reason for this is that with these major reliefs, most of the light is diffracted into lower diffraction orders. During the design process, the relief is built with an amplitude profile to obtain the desired light intensity profile at the refractive focal point and diffracting into the first and/or second diffraction orders of these basic gratings or reliefs. However, this approach does not automatically result in an optimal distribution of light falling on the lens, because some light is also distributed over higher diffraction orders that are not used, making it difficult to adjust or control the relative distribution of light between lens focal points for different pupil sizes. which can significantly reduce the overall effectiveness of a multifocal lens.

European Patent Nos. 2377493 and 2503962, for example, attempt to eliminate this performance degradation for trifocal intraocular lenses by superimposing diffractive reliefs or gratings, each designed to individually provide one of the target diffractive focal points of the lens. Steps of reliefs or gratings should be chosen in such a way that the second order of diffraction of one profile coincides with the first order of diffraction of another profile. In addition to the fact that the freedom of design of such an intraocular lens is thus limited to specific focal lengths at which the first and second diffraction orders of various reliefs coincide, it should be understood that light diffracted into higher diffraction orders and not added to any of the target focal points is still lost. Accordingly, these designs do not provide an effective remedy for diffraction loss in intraocular lenses.

International patent application WO2017/055503 discloses a superposition of different types of basic diffraction reliefs or gratings, such as sawtooth type and binary type, each having the same first order focal point. This combined focal point provides one of the target diffractive focal points of the lens. However, for the purposes of designing a multifocal lens such as a trifocal lens, this design becomes complicated because the other target focal point of the lens arises from the sum of superimposed profiles and therefore cannot be individually calculated and targeted in advance.

European patent application EP 2375276 notes that controlling or adjusting the distribution of light at the focal points of diffraction reliefs or gratings, such as sawtooth type and binary type, commonly referred to as stepped DOE, by changing the shape and height or amplitude of the optical transfer function of the diffraction grating can lead to diffraction gratings having sharp edges in their height profile that would be difficult to produce.

To this end, EP 2375276 discloses smoothing the sharp edges of a stepped diffraction pattern or grating by any of the curve approximations using sine and cosine functions, polynomial expressions, filtering or convolution using a super Gaussian function. Smoothing causes the sharp edges or steps of the sawtooth or binary DOE to stretch or expand in the radial direction of the lens. EP 2375276, however, is silent on providing different light distributions for different pupil sizes for a given set of target focal points.

Published patent application US 2006/0116764 discloses diffractive zones that can be located within a portion of the lens surface, called the apodization zone, surrounded by a peripheral part of the surface, which is essentially devoid of diffractive structures. These diffractive zones can be separated from each other by a plurality of steps located at zone boundaries that have substantially uniform heights. Alternatively, the step heights may be non-uniform. For example, step heights can progressively decrease as a function of increasing distance from the optical axis of the lens. This apodization adjusts the distribution of light at the refractive focal point relative to the diffractive focal points.

None of the aforementioned prior art publications makes it possible to adjust the distribution of light at the target focal points individually, and for example differently for different pupil sizes. Accordingly, there is a need for an improved ocular lens design that provides freedom in defining diffraction orders or focal points, as well as setting or controlling the relative light intensity at all target focal points, in particular for different pupil sizes, avoiding diffraction as much as possible. light in diffractive orders that do not contribute to the target focal points, thereby providing an improved overall user experience.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides an ophthalmic multifocal lens comprising at least focal points for near vision, intermediate vision, and long distance vision, having a light-transmitting lens body comprising an optical axis, and providing a refractive focal point as well as periodic a light-transmitting diffraction grating extending concentrically in the radial direction through at least a portion of at least one surface of the lens body providing a set of diffractive focal points, wherein the diffraction grating is designed to operate as a beam splitter for distributing light incident on the lens body into the refractive and diffractive focal points, wherein the refractive focal point provides the focal point for medium distance vision, and the diffractive focal points provide focal points for near and far vision, wherein the diffractive focal point the grating has an optical transfer function containing a continuous periodic phase profile function extending in the radial direction of the lens body. This continuous periodic phase profile function contains an argument modulated as a function of the radial distance to the optical axis of the lens body, thereby adjusting the distribution of light incident on the lens body.

The present invention is based on the understanding that an eye lens having a continuous periodic phase profile function extending in the radial direction of the lens body causes less discomfort and visual impairment compared to a lens having a discontinuous or jagged type phase profile function. A function is said to be continuous when, at every point or value of its argument, i.e., variable, member, or expression operated on by the function, (i) the function is defined at that point, (ii) the limits of the function, when the argument is approximated from the right and from the left, exist and are equal, and (iii) the limit of the function as the argument approaches that point is equal to the value of the function at that point.

In accordance with the present invention, designing the phase profile function of the optical transfer function or the light transmission function of a diffraction grating as a continuous periodic function of the phase profile allows freedom in the choice of target focal points, as well as control over the distribution of light at the target focal points, wherein the relative distribution of light at the diffraction and/or The refractive focal points are tuned by modulating the argument of the phase profile function as a function of the radius or radial distance to the optical axis of the lens body.

Lenses having a continuous periodic phase profile function, among other things, are less susceptible to error in the calculation of diopters, i.e. to an error in calculating the required refractive power correction for a particular user, for example due to less accurate measuring equipment used by the doctor in the case of an intraocular lens or the equipment used by the ophthalmologist if a contact lens is fitted. In addition, it is reported that the sensitivity to lens displacement (decentering) in the case of intraocular lenses, which can occur after lens installation due to its tilt and displacement, is negligible for lenses having a continuous periodic phase profile function. It has also been noted that such lenses are less likely to create glare, that is, obstruction of vision in the presence of bright light, such as direct or reflected sunlight, or artificial light, such as car headlights at night, scattering due to irregularities in the path along which the incident light passes through the lens and also creates fewer ghosting, i.e. white or colored light rings or spots visible in low light, i.e. under mesopic conditions.

Lenses having a continuous periodic phase profile function, especially in the case of smooth curves, have the advantage that they are easier to manufacture according to the design profile. Profiles containing sudden offsets and sharp points will always lead to increased production errors.

The above advantages are due in large part to the absence of sharp-edged concentric rings or zones in a diffraction grating having a continuous periodic phase profile function. With the present invention, in particular, it is now possible, by modulating the argument of the continuous periodic phase profile function, to effectively adapt or adjust the relative light distribution or energy distribution at each of the target focal points of the periodic phase profile function. Therefore, the present invention provides multifocal ophthalmic lenses having the advantages mentioned above and being customizable in terms of individual light distribution at all of its respective or usable focal points.

In accordance with one embodiment of the present invention, the argument is modulated by periodic smooth transitions on a continuous periodic phase profile function, i.e., the corresponding height profile or grating optical transfer function implemented by a continuous periodic phase profile function.

By introducing periodic smoothed transitions into a continuous periodic phase profile function, ie the corresponding height profile, the implementation of an optical transfer function containing such a phase profile function is not a problem for machining. By smoothing transitions, no or only minor artifacts are introduced into the diffraction grating so that the properties of a tuned lens including a continuous periodic phase profile function are maintained with respect to less undesirable optical effects such as stray light, chromatic aberration, halo, flare, scattering, etc. .P.

In one further embodiment of an ophthalmic multifocal lens in accordance with the present invention, the distribution of light at each transition is extended over a portion of the period of a continuous periodic phase profile function, thereby adjusting the distribution of light at the diffractive focal points, with each transition comprising at least one of:

- a transition that provides a shift in a continuous periodic function of the phase profile in the radial direction of the lens body, and

- a transition that provides a shift in a continuous periodic function of the phase profile in a direction transverse to at least one surface of the lens body.

It has been found that a transition providing a local shift in the period of a continuous periodic function of the phase profile in the radial direction of the lens body and/or in the direction transverse to at least one surface of the lens body causes a change in the relative distribution of light between the diffractive focal points, i.e. focal points for near and far vision, compared to a continuous periodic phase profile function without such modulation of the argument. Whether the relative light distribution moves to the focal point for near vision or the focal point for far vision depends on the direction of the local displacement in the period of the continuous periodic phase profile function.

In another embodiment of the ophthalmic multifocal lens in accordance with the present invention, transitions providing a shift in the continuous periodic phase profile function in the radial direction of the lens body are located at the position of at least one of the leading and trailing edges or slope of the continuous periodic phase profile function, and transitions , providing a shift in the continuous periodic function of the phase profile in the direction transverse to at least one surface of the lens body, are located in the position of at least one of the crest and trough of the continuous periodic function of the phase profile.

It has been found that already small offsets in the radial direction of the lens body, located on one or both of the leading and trailing fronts, and relatively small offsets transverse to the radial direction on one or both of the crest and trough, very effectively affect the ratio of light distributed between diffraction foci.

The argument can be modulated such that transitions are provided in multiple periods of the continuous periodic phase profile function, ie multiple adjacent periods or multiple non-adjacent periods depending on the desired light distribution setting. In addition, combinations of different types of modulation are possible, i.e. combinations of transitions at the leading and trailing edges or slopes of the continuous periodic phase profile function and transitions at or close to the crest or trough of the continuous periodic phase profile function.

In accordance with one additional embodiment of the present invention, these transitions in a continuous periodic phase profile function may comprise:

- transitions that provide an identical shift in the continuous periodic function of the phase profile in the set of periods of the continuous periodic function of the phase profile,

- transitions providing a shift in the continuous periodic phase profile function, which increases over a plurality of periods of the continuous periodic phase profile function, and

- transitions that provide a shift in the continuous periodic function of the phase profile, which decreases on the set of periods of the continuous periodic function of the phase profile.

The term "identical" refers to transitions that periodically provide a substantially identical shift in a continuous periodic function of the phase profile. The terms "increases" or "decreases" refer to transitions by which the displacement in the continuous periodic phase profile function increases or decreases, respectively, over a plurality of periods in the lens body radial direction.

In the case of an identical shift in the set of periods of the continuous periodic phase profile function, the distribution of light at the focal points remains essentially constant over the area of the lens body, that is, in the number of periods of the continuous periodic phase profile function in which these transitions occur. By providing several, for example adjacent, areas on the lens body with mutually different offsets, different light distributions can be provided for different pupil sizes.

By changing the modulation of the argument of the continuous periodic function of the phase profile along the surface of the lens body, that is, in the radial direction from the optical axis, the distribution of light at the focal points will change depending on the surface area of the lens body that is exposed to the incident light. Thus, the relative distribution of light at the focal points is made dependent on the size of the user's pupil. In most cases, the pupil has a small size when reading a book, etc., since this usually occurs in good lighting conditions. However, darker conditions in which the pupil dilates are often encountered during critical situations, such as driving or cycling. In these latter cases, it is desirable to have more light at the focal point for long distance vision than would be expected with relatively small pupil sizes.

When using transitions that provide one of increasing or decreasing displacement in a plurality of periods across the lens body area, i.e., a number of periods of a continuous periodic phase profile function in which there are transitions, the relative distribution of light at the diffractive focal points will gradually change with pupil size.

For example, it has been observed that by modulating an argument, such as three to five adjacent periods of a continuous periodic phase profile function, a significant contribution is made to tuning the relative distribution of light at the diffraction focal points for incident light in the region of the lens on which these periods are located.

Thus, for example, the argument of the first set of three to five contiguous periods of a continuous periodic phase profile function starting from the optical axis of the lens body corresponding to a relatively small pupil size can be periodically modulated such that light distributed to a close focal point improves in compared to focal points for intermediate and long distance vision. In this case, by modulating the argument of an additional set of three to five adjacent periods of the continuous periodic phase profile function, adjacent or radially spaced from the first set, the light distributed to the focal point for long distance vision is improved compared to the focal points for near vision. and medium distance vision.

Accordingly, the spatially distributed modulation of the argument of the continuous periodic function of the phase profile, that is, in the presence of various modulations over the area or surface of the lens body, that is, changing continuously, in parts or discretely depending on the radial distance to the optical axis of the lens body, provides an effective adjustment of the light distribution at focal points for different pupil sizes.

In one further embodiment of the ophthalmic multifocal lens according to the present invention, the phase profile continuous periodic function argument is differently modulated over the lens body, thereby adjusting the distribution of light incident on the lens body differently for different pupil sizes. In particular, in this case, the argument is modulated in a number of adjacent periods of a continuous periodic phase profile function covering at least one region of the lens body, and the number of adjacent periods and the strength and/or type of modulation of the argument differ in different regions on the lens body.

In one embodiment of the present invention, a multifocal ophthalmic lens is provided in which the phase profile continuous periodic function argument is modulated to provide first trifocal properties in a first region of the lens surface extending in the radial direction and including the optical axis, these first trifocal properties giving priority to the distribution of light in focal point for near vision, and providing a second trifocal property in a second region of the lens surface extending beyond the first region in the radial direction of the lens towards the circumferential edge of the lens body, these second trifocal properties facilitating the distribution of light to the focal point for viewing at great distance.

In another embodiment of the ophthalmic multifocal lens in accordance with the present invention, the argument is modulated so as to provide, for the same period length of the continuous periodic phase profile function, the first and second transitions spaced apart in the radial direction of the lens body, the second transition at least partially counteracting the operation first transition.

By substantially counteracting the first and second transitions in the period length of the continuous periodic phase profile function, deviations in the period of the continuous periodic phase profile function, and thus in the position of the target focal points, are effectively prevented. In addition, it is thus possible to modify each period of the continuous periodic phase profile function independently and in a controlled manner in order to obtain the desired local contribution to the intensity distribution. The amount of light distributed at the refractive focal point is essentially independent of such transitions and remains essentially the same as compared to a continuous periodic phase profile function without transitions.

In yet another further embodiment of the ophthalmic multifocal lens according to the present invention, the argument is modulated according to an argument modulation function, which in particular is a periodic function having a period equal to the period of a continuous periodic phase profile function, in particular a periodic function symmetrical around the optical axis , containing one of a continuous function, a continuous trigonometric function, a triangular function, and a trapezoid function. Such a periodic modulation of the argument can provide, for example, smooth transitions to a continuous periodic phase profile function, as discussed above.

Since the diffraction grating has a periodic structure, the phase profile function of the optical transfer function is a periodic function, and therefore can be expanded in a Fourier series. Optimizing the overall light distribution efficiency at the target refractive and diffractive focal points requires that the sum of the light energies of the diffraction orders associated with the target focal points be maximized. The light energy of each order corresponds to the square of the absolute value of the Fourier coefficient Tk of the corresponding diffraction order k.

For example, in the case of a wave splitting trifocal eye lens, in which the refractive focal point represents the focal point of view at an intermediate distance, and the diffractive focal points represent the focal points for near and far vision, respectively, the expression | τ _-m | ² + |τ ₀ | ² + |τ _P | ² , in which the indices -m, 0, and p represent the diffractive order providing the focal point for near vision, the refractive focal point providing medium distance vision, and the diffractive order providing the focal point for long distance vision, respectively.

The value of the diffraction orders -m and p need not be equal. In the present invention, when the value of m is equal to the value of p, for example, m=p=1, the wave splitter is called a symmetrical wave splitter, and if the values of m and p are different, the wave splitter is called asymmetric.

The above limitation of optimizing the overall light distribution efficiency at the target refractive and diffractive focal points so that the sum of the light energies of the diffraction orders associated with the target focal points is maximum does not imply that the light energies at each target refractive and diffractive focal point must be equal. Accordingly, an optimal phase function can be obtained depending on both the target focal points and the target light intensities or light energies at the target focal points.

The term "concentric" in relation to the repeating DOEs of a diffraction grating according to the present invention should not be limited to concentric circular or annular zones, but includes, for example, concentric elliptical or oval zones, or in general any type of zones of concentric rotational shape.

According to "Analytical derivation of the optimum triplicator", by F. Gori et al., in Optics Communication 157 (1998), p. 13-16, which is incorporated herein by reference, for a planar symmetrical wave splitter comprising two diffractive focal points at diffraction orders of +1 and -1 and a refractive focal point at order 0, a phase profile function providing optimum overall efficiency, i.e. The splitting of an incident light beam with the highest conceivable efficiency at focal points at diffraction orders of +1 and -1 and at order 0 can be expressed by a single continuous expression or closed-form function.

In one embodiment of a multifocal eye lens in accordance with the present invention, the diffraction grating is configured to operate as a wave splitter and contains two diffractive focal points in diffraction orders of +1 and -1, with a continuous periodic phase profile function being expressed by a single continuous expression or a closed function forms according to the formula:

where:

ϕ(r) - continuous periodic phase function of the diffraction grating,

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

Α(r) - amplitude modulation function of the continuous periodic function of the phase profile in the radial direction of the lens body,

F[α*G] - function of the lens body in the radial direction, providing the wave splitting operation,

G(r) is a continuous periodic function in the space r ² ,

α(r) - modulation function of the value of the argument G,

S(r) - function of angular modulation of argument G in space r ² , [mm ² ],

T is the period or step of the diffraction grating in space r ² , [mm ² ], and

B(r) - amplitude modulation function of the continuous periodic function of the phase profile,

moreover, at least one of the modulation function of the argument value α(r) and the angular modulation function of the argument S(r) contains an argument modulated as a function of the radial distance to the optical axis of the lens body.

The functions α(r) and S(r) can be independently selected to modulate the argument of the continuous periodic phase profile function to adjust the light distribution at the target focal points for different pupil sizes.

In accordance with the present invention, the distribution of light at the diffractive and refractive focal points can be further tuned by adapting at least one of the amplitude modulation function Α(r) and the amplitude modulation function B(r) of the continuous periodic phase profile function.

The amplitude modulation functions Α(r) and B(r) provide additional control over the amount of light distributed between diffraction orders ±1 and order 0 depending on pupil size. In most cases, provided that the largest phase loss in the phase profile is below the calculated wavelength, increasing either or both of the amplitude modulation functions will result in more light being diffracted in ±1 diffraction orders, i.e., at diffractive focal points, compared to order 0 or refractive focal point, while reducing either or both of the amplitude modulation functions will increase the amount of light provided at the refractive focal point compared to diffractive focal points.

The amplitude modulation functions may vary depending on the radial distance from the center or optical axis of the lens for apodization purposes. Amplitude variation is a way of controlling the relative intensity of light at an intermediate, ie refractive, focal point. In practical embodiments in accordance with the present invention, the amplitude modulation functions Α(r) and B(r) may be constant across the lens body portion.

It can be proven that the phase profile function ϕ(r) in equation (1), where F[α*G] is the inverse tangential function and G(r) is a sinusoidal function, with S(r)=0, Α(r )=1 and B(r)=0 is a continuous periodic function of the phase profile of a planar grating dividing an incident light beam with the highest conceivable efficiency at focal points at diffraction order ±1 and at order 0, as disclosed by Gori et al. .

The argument value modulation function or light distribution parameter α(r) according to Gori et al. determines the amount of light distributed among the ±1 and 0 diffraction orders. The overall efficiency of such a phase profile function ϕ(r) for planar gratings is over 0.925. In the case of a constant value of α(r)=2.65718, the light energy in a flat diffraction grating is evenly distributed among the target focal points.

Therefore, the continuous periodic phase profile function, in addition to the above benefits, optimizes the overall efficiency of light distribution at the target refractive and diffractive focal points, avoiding as much as possible the diffraction of light in diffraction orders not conducive to the target focal points, thereby providing an improved overall user experience.

Since the optimal tripler according to Gori et al. is computed for a linear or planar phase grating by converting it to a lens such that the distances between periods of the phase profile function are, for example, dependent on the square root, an equal distribution of light at the focal points is achieved by the present invention by modulating argument of the continuous periodic function of the phase profile. For example, an almost uniform distribution of light at focal points over the lens body area is provided when the value of the angular modulation of the argument S(r)=0.33, the value of the modulation function of the argument value or the light distribution parameter α(r) on a part of the lens body is equal to 2, 65718, and the amplitude modulation functions have constant values Α(r)=0.96 and B(r)=0. Those skilled in the art will appreciate that other values of the modulation functions or modulation parameters mentioned above can also result in a nearly uniform distribution of light at the focal points of the lens.

In most cases, to adjust the distribution of light, the angular modulation function of the argument S(r) can be set to a constant value over part or all of the lens body. In practice, S(r) values can range between -0.5*T and 0.5*T in the space r². In particular, S(r) may have a constant value ranging between 0.35*T and 0.5*T and/or between -0.05*T and -0.15*T, in particular S(r)=0 ,42*T in space r². The region between 0.35T and 0.50T offers a good intensity distribution for these three foci, with the ability to adjust according to how far vision dominance is desired. The value S(r)=0.42*T provides a good balance of foci for the eye lens. The area between -0.05T and -0.15T gives a relatively even distribution of light. This area is also very suitable for argument modulations that (locally or across the lens) contribute to the far focal point, since the perturbations created by such modulation are negligible. In some areas, there may be slight increases in higher orders when argument modulation is applied.

The constant value of the angular modulation function of the argument S(r) represents the phase shift of the continuous periodic phase profile function and determines the onset of the slope of the phase profile function, and therefore whether more light will diffract into +1 diffraction order or -1 diffraction order depends on the sign and the magnitude of the phase shift, respectively. It is advantageous to express these phase shifts as a fraction of the lattice period T, for example S=±0.25*T. Those skilled in the art will appreciate that a particular phase shift including integer values of the grating period T will have the same effect as the corresponding phase shift within one period T.

By properly selecting the modulation function of the argument value or the light distribution parameter α(r), it is possible to adjust the amount of light that is distributed in the 0th order, that is, the focal point of view at the middle distance in the present invention. In accordance with the present invention, α(r) may have a constant value over part or all of the lens body. In practice, the values of α(r) may vary, for example, from 2 to 3.

In practical embodiments in accordance with the present invention, the amplitude modulation functions Α(r) and B(r) may also have a constant value over part or all of the lens body, i.e. providing aggregated amplitude modulation parameters that may be, for example, in the range from 1.4 to 0.6.

By setting any or all of the modulation variables α(r), S(r), Α(r), and B(r) to appropriate values in the lens body portion in its radial direction, the light intensity profile of a trifocal intraocular lens, for example, can be effectively tuned for different pupil sizes.

The surface of the lens body can also be modified by applying Fourier filtering or kernel convolution or other known signal processing techniques can be used to smooth or slightly change the lens profile to change the distribution of energy between diffraction orders or to remove unwanted stray light. Such modifications are often easier to apply in r ² space.

In one embodiment of an ophthalmic multifocal lens according to the present invention, based on the phase profile function ϕ(r) disclosed in Equation (1) above, the height profile H(r) of the lens grating can be expressed by a single continuous closed shape function defined by how:

where:

H(r) - height profile of the diffraction grating of the lens, [nm],

λ - constructive wavelength of the lens, [nm],

n is the refractive index of the lens body,

n _m is the refractive index of the medium surrounding the lens body, and

For the phase profile function ϕ(r) in equation (1), in which F[α*G] is an inverse tangential function and G(r) is a sinusoidal function, Α(r)=1 and B(r)=0, for example, the height profile H(r) of the diffraction grating of the lens disclosed in the above equation (2) is a continuous closed-form geometric function based on the sine and cosine functions, and accordingly does not have any sharp transitions that are difficult to produce in the lens body. Accordingly, this height profile or height function H(r) provides not only optimal performance, but also allows precise manufacturing and therefore accurate fitting of lenses that provide target focal points and targeted light distribution among the target focal points.

The trifocal properties of an eye lens according to the present invention may be limited to a first region in the radial direction of the surface of the lens body, including the optical axis. In addition, outward in the radial direction of the lens behind the first region and towards its peripheral edge, the lens may include, for example, a second region having bifocal properties, such as providing in this second region only focal points for medium and long distance vision.

In practice, numerical methods may be required to calculate the phase function or phase profile function that optimizes the overall efficiency of light distribution at the focal points of refraction and diffraction of a symmetric or asymmetric beam splitter having focal points for near and far vision that differ from the first diffraction order by ± 1 as explained above.

Furthermore, it should be noted that the teachings of the present invention are equally applicable to designing and adjusting the light distribution of a multifocal eye lens having four target focal points, i.e. a so-called four-focal lens, or even a multifocal eye lens having five target focal points, then there is a so-called five-focal lens.

In a second aspect, the present invention provides a method for manufacturing an ophthalmic multifocal lens having at least focal points for near vision, intermediate vision, and long distance vision, having a light-transmitting lens body, comprising an optical axis providing a refractive focal point, and a periodic light-transmitting diffraction grating extending concentrically in the radial direction through at least a portion of the surface of the lens body providing a set of diffractive focal points, the diffraction grating being designed to act as a beam splitter for distributing light incident on the lens body at the refractive and diffractive focal points, wherein the refractive focal point provides the focal point for medium distance vision and the diffractive focal points provide focal points for near vision and long distance vision, the method comprising: following stages:

- determination of target focal points for near vision, intermediate distance vision and long distance vision;

- determination of the target distribution of the incident light at the target focal points;

providing a light-transmitting lens body having a refractive focal point providing a target focal point for mid-distance vision;

- providing a diffraction grating having an optical transfer function containing a continuous periodic phase profile function extending in the radial direction of the lens body, providing target focal points for near vision and far vision, as well as light distribution at the target focal points,

and has the following stages:

- providing a continuous periodic phase profile function having a modular argument as a function of the radial distance to the optical axis of the lens body,

- adjusting the distribution of light at the target focal points to ensure the target distribution of light by modulating the argument over the lens body, providing a modulated argument,

- providing a grating height profile in accordance with a periodic phase profile function containing a modulated argument, and

- production of an ophthalmic multifocal lens by applying a diffraction grating to the lens body in accordance with the height profile.

A lens grating height profile defining the height and position of the DOE that extends as rings, ovals, or other rotationally shaped areas on the lens surface concentric to the optical axis or center of the lens, can be applied to the lens body, for example, by any of the laser micromachining techniques. , diamond turning, 3D printing or any other mechanical or lithographic surface treatment. A lens with the same optical effect can also be created by holographic means, using a holographic optical element to distribute light to desired foci.

The lens body may comprise any material of hydrophobic acrylic, hydrophilic acrylic, silicone, or any other suitable light transmitting material.

In the method according to the present invention, the phase profile continuous periodic function argument can be modulated to produce an ophthalmic multifocal lens in accordance with the first aspect of the present invention, in particular a lens having different target light distributions at target focal points for different pupil sizes.

Although a continuous periodic phase profile function can be mathematically calculated analytically, in accordance with the present invention, the phase profile function of a diffraction grating of a lens can be obtained using computer calculations, in which the phase profile function is represented by a Fourier series, and each order of diffraction is represented by the corresponding Fourier coefficient. The phase profile function can be computed such that the sum of the squares of the absolute values or the weighted squares of the absolute values of the Fourier coefficients of the diffraction orders associated with the target focal points is maximized.

The continuous phase profile function and the lens height profile in the method of the present invention can be obtained remotely from the lens manufacturing equipment. Features of the height profile of the diffraction grating of the lens can be directed to the production site or equipment using data transmission over a practically accessible telecommunications network, such as the Internet.

Tuning and smoothing of the optical properties and distribution of light at the target refractive and diffractive focal points can be applied such that the amount of light diffracted into one particular focal point or order is distributed or smeared along a portion of the optical axis to provide an eye lens having improved depth of field ( ED).

In a third aspect, the present invention provides the above-described ocular multifocal lens used as one of a contact lens, an intraocular lens, an aphakic contact lens, an aphakic intraocular lens, and a spectacle glass. It should be noted that in the case of an intraocular lens, its body usually takes the form of a biconvex or plano-convex optically transparent disk. In the case of a contact lens or spectacle lens, its body may take on any of biconvex or plano-convex and biconcave or plano-concave shapes, or combinations thereof, whether or not enhanced by additional optical corrections on or in an optically transparent body.

These and other aspects of the present invention will become apparent and will be explained with reference to the examples described later in this document.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 schematically illustrates the focusing of light rays from several distances in the human eye.

Fig. 2a schematically illustrates a top view of a typical prior art multifocal aphakic intraocular lens.

Fig. 2b schematically illustrates a side view of the multifocal aphakic intraocular lens shown in FIG. 2a.

Fig. 3 schematically illustrates in cross section the optical operation of a prior art diffractive lens comprising a biconvex light-transmitting body and a light-transmitting diffraction grating.

Fig. 4 schematically illustrates the relative distribution of energy between target diffraction orders for a symmetrical planar beam splitter with optimal efficiency as a function of a constant amplitude modulation function of the argument α(r).

Fig. 5a-25b schematically illustrate examples of height profiles, argument modulation parameters, and argument modulation functions of diffraction gratings on a biconvex lens body in accordance with the present invention, as well as corresponding computer-simulated light intensity distributions.

Fig. 26 illustrates, using a simplified flowchart, the steps of a method in accordance with the present invention for manufacturing a multifocal ophthalmic lens.

DETAILED DESCRIPTION

Fig. 1 shows in a simplified way the anatomy of the human eye 10 to illustrate the present invention. The front of the eye 10 is formed by the cornea 11, a spherical transparent tissue that covers the pupil 12. The pupil 12 is the adaptable light-receiving part of the eye 10 that controls the amount of light received by the eye 10. Light rays passing through the pupil 12 are received by the lens 13, a small transparent and a floppy disc in the eye 10 which focuses the light beams onto the retina 14 at the back of the eye 10. The retina 14 serves to form the image of the eye 10. The posterior chamber 15, i.e. the space between the retina 14 and the lens 13, is filled with aqueous 16 of the eye, that is, the space between the lens 13 and the cornea 11, is filled with the vitreous body, a transparent gelatinous substance. Reference numeral 20 indicates the optical axis of the eye 10.

For sharp and clear vision at a distance, the lens 13 must be relatively flat, while for sharp and clear vision at a near distance, the lens 13 must be relatively curved. The curvature of the lens 13 is controlled by the ciliary muscles (not shown), which in turn are controlled by the human brain. A healthy eye 10 is able to adapt, i.e. control the lens 13 so as to provide a sharp and clear image at any distance in front of the cornea 11 between the far region and the near region.

Eye lenses or artificial lenses are used to correct the vision of the eye 10 in combination with the lens 13 when the eye lens is placed in front of the cornea 11 or to replace the lens 13. In the latter case, the lenses are also referred to as aphakic eye lenses.

Multifocal eye lenses are used to improve or correct the vision of the eye 10 for various distances. In the case of trifocal eye lenses, for example, the eye lens is intended for sharp and clear vision at three more or less discrete distances or focal points, commonly referred to as far, intermediate, and near focal points, which in FIG. 1 are denoted by reference numerals 17, 18 and 19, respectively. Light rays from objects located at or near these distances or focal points 17, 18 and 19 are correctly focused on the retina 14, i.e. in such a way that they project sharp and clear images of these objects. Focal points 17, 18 and 19 in practice can correspond to focal lengths ranging from a few meters to tens of centimeters and up to centimeters, respectively.

The amount of correction that an eye lens provides is called the optical power (OP) and is expressed in diopters, D. The optical power OP is calculated as the reciprocal of the focal length f in meters. Thus, OP=1/f, where f is the respective focal length from the lens to the respective focal point for far 17, intermediate 18, or near 19 vision. The optical power of a set of lenses is found, for example, by adding the optical powers of the constituent lenses. The optical power of a healthy human lens 13 is approximately 20 D.

Fig. 2a shows a top view of a typical ophthalmic multifocal aphakic intraocular lens 30, and FIG. 2b shows a side view of lens 30. Lens 30 includes a light transmitting circular disk-shaped lens body 31 and a pair of haptic elements 32 that extend outward from lens body 31 to support lens 30 in the human eye. The lens body 31 is biconvex in shape, comprising a central portion 33, a front surface 34, and a rear surface 35. The lens body 31 further comprises an optical axis 29 extending through the front and rear surfaces 34, 35 and through the center of the central portion 33. Those skilled in the art should it should be understood that the optical axis 29 is a virtual axis for the purpose of referring to the optical properties of the lens 30. The convex lens body 31 in one practical embodiment provides a refractive power of approximately 20D.

In the shown embodiment, on the front surface 34 of the body 31 of the lens is a periodic light-transmitting diffraction grating or relief 36, consisting of rings or zones passing concentrically with respect to the optical axis 29 through the Central part 33 at least part of the front surface 34 of the body 31 of the lens. The diffraction grating or relief 36 provides a set of diffractive focal points. Although not shown, the diffraction grating or relief 36 may also be located on the rear 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 zones, and includes, for example , concentric elliptical or oval zones, or more generally any type of zone of concentric rotational shape.

In practice, the optical diameter 37 of the lens body 31 is approximately 5-7 mm, while the overall outer diameter 38 of the lens 30, including the haptics 31, is approximately 12-14 mm. The lens 30 may have a central thickness 39 of approximately 1 mm. In the case of ophthalmic multifocal contact lenses and spectacle or ophthalmic glass lenses, the haptic elements 32 are not provided in the lens body 31, while the lens body 31 may have a plano-convex, biconcave, or plano-concave shape, or combinations of convex and concave shapes. The lens body may comprise any material of hydrophobic acrylic, hydrophilic acrylic, silicone, or any other suitable light-transmitting material for use in the human eye in the case of an aphakic ophthalmic lens.

Fig. 3 schematically illustrates the optical operation of a known periodic light-transmitting diffraction grating or pattern 42 of a lens 40 comprising a biconvex light-transmitting circular disk-shaped lens body 41. The lens 40 is shown in cross section in the radial direction of the lens body. The diffraction grating or pattern 42 comprises a plurality of repeating, adjacent prismatic transparent diffractive optical elements (DOEs) 43. The DOEs 43 are arranged in concentric zones around the central portion 45 of the lens body 41, similar to the rings or zones of the grating or pattern 36 shown in FIG. 2a. For illustrative purposes, the DOEs 43 of a diffraction grating 42 are shown as known toothed or sawtooth type elements comprising a continuous inclined light receiving surface 44, such as a linear or curved inclined light receiving surface 44. Gratings or reliefs in which the DOEs 43 are spaced apart in the radial direction of the body 41 lenses are called binary type reliefs (not shown). The repetition period or step DOE 43 decreases monotonically in the radial direction from the center or optical axis of the lens and depends on the square of the radial distance.

The incident or primary light beam 46 that passes through the grating 42 and the lens body 41 is respectively diffracted and refracted to give the output or secondary light beam 47 . The refracted and diffracted light waves 47 form a plurality of focal points on the optical axis 48 of the lens 40 due to the amplifying interference of the light waves 47. Amplifying interference occurs when the difference in optical path lengths between the light waves 47 coming from the lens body 41 to one particular focal point is a multiple of their wavelength, that is, light waves are in phase, so their amplitudes are summed and amplified. When the difference in the optical path length of the light waves 47 coming from the lens body 41 is an odd multiple of half a wavelength, so that the crest of one wave corresponds to the trough of another wave, the light waves 47 partially or completely cancel each other, that is, the light waves are mismatched in phase and do not give focal points on the optical axis 48 of the body 41 of the lens.

Points of amplifying interference at various distances from the lens body 41 are commonly referred to as diffractive orders. The focal point which corresponds to the focal point which arises due to the refractive action of the curvature of the lens 40 is designated as the zeroth order, 0. zero order on the drawing plane, i.e. at some distance in the direction of the lens body 41, and are defined by the orders -1, -2, -3, etc., if the corresponding focal point is formed to the right of the zero order on the drawing plane, i.e. some distance in the direction from the lens body 41, as illustrated in FIG. 3.

The diffractive relief 42 may be designed to provide focal points at various distances from the lens body 41. The periodic interval or pitch of the DOE 43 essentially determines where on the optical axis 48 of the lens the points of attenuating and amplifying interference occur, that is, the position of the diffraction orders on the optical axis 48. The amount of incident light that is provided at the point of amplifying interference, that is, near or in one specific diffraction order can be controlled by the shape and height of DOE 43.

In the case of a diffraction grating or pattern 42 providing diffraction orders that are regularly spaced on either side of the zeroth order, the grating or pattern is referred to as a symmetrical wave splitter because the incident light beam 45 is symmetrically diffracted or split about the zeroth order. A grating or relief that creates an irregular arrangement of diffraction orders, such as +1, +2, -3, -5, is called an asymmetric beamsplitter.

Light energy in light waves 47 that are focused or diffracted into focal points or orders that do not contribute to image formation on the retina 14 of the human eye 10 is wasted and reduces the overall performance of the lens 40 and hence the quality of the images perceived by the person using such a lens. In practice, for optimal lens design, it is preferred that foci for providing or correcting far, intermediate, and near vision of the human eye, such as those shown in FIG. 1 could be set in advance, and a diffraction grating 42 that maximizes the overall light energy efficiency obtained from the incident light beam 46 at these given focal points is optimal.

In the scientific literature, a diffraction grating optimizing the overall light distribution efficiency at a given or target refractive and diffractive focal points or orders is found from defining a phase-only function or phase profile that generates the target diffraction orders with the maximum overall efficiency r| or a criterion defined as the sum of the normalized light energies of all these target orders.

Those skilled in the art will appreciate that the lens body 41 may comprise a plano-convex, biconcave, or plano-concave shape, as well as combinations of convex and concave shapes (not shown).

Assume that a circular disc-shaped lens has a diffraction grating, such as shown in FIG. 2a, 2b and 3. If the grating phase profile function is denoted as φ(r), the optical transfer function of the grating to be determined is given by: T(r)=exp[iφ(r)], where exp represents the exponential function, i represents the imaginary unit , and r represents the radial distance or radius from the center or optical axis of the lens body with repeated DOEs.

Since the diffraction grating is a periodically repeating structure, T(r) can be expanded in a Fourier series:

where τ _n represents the Fourier coefficient of the nth order of diffraction, P is the period or grating spacing, and n is a positive integer including zero.

Maximizing the overall efficiency requires that the sum of the normalized energies of the target focal points or orders be equal to 1, i.e.:

For example, in the case of a wave splitting trifocal eye lens, in which the refractive focal point represents the focal point of view at an intermediate distance, and the diffractive focal points represent the focal points for near and far vision, respectively, the expression | τ _-m | ² + |τ ₀ | ² + |τ ^P | ² , in which the indices -m, 0, and p represent the diffractive order providing the focal point for near vision, the refractive focal point providing medium distance vision, and the diffractive order providing the focal point for long distance vision, respectively. An optimal phase function can also be obtained depending on the weighted intensities or energies of the light at the target focal points.

The value of the diffraction orders -m and p need not be equal. In the present invention, when the value of m is equal to the value of p, for example, m=p=1, the wave splitter is called a symmetrical wave splitter, and if the values of m and p differ, the wave splitter is called asymmetric.

In accordance with the present invention, the general expression for a continuous periodic phase profile function is as follows:

where:

ϕ(r) - continuous periodic phase function of the diffraction grating,

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

Α(r) - amplitude modulation function of the continuous periodic function of the phase profile in the radial direction of the lens body,

F[α*G] - function of the lens body in the radial direction, providing the wave splitting operation,

G(r) is a periodic function in the space r ² ,

α(r) - modulation function of the value of the argument G,

S(r) - function of angular modulation of argument G in space r ² , [mm ² ],

T is the period or step of the diffraction grating in space r ² , [mm ² ], and

B(r) is the amplitude modulation function of the continuous periodic phase profile function.

In accordance with the present invention, to control or adjust the amount of light distributed at the focal points, the modulation of the argument of the continuous periodic function F[α*G] as a function of the radius or radial distance in the lens body is provided by the modulation function of the argument value α(r) of the function G(r ) and the angular modulation function of the argument S(r) of the function G(r). The amplitude modulation functions Α(r) and B(r) provide additional control or adjustment of the amount of light distributed between the diffraction focal points and the refractive focal point.

Fig. 4 graphically illustrates the relative energy distribution between the first diffraction orders ±1, represented by the dotted line |τ ₁ |, and the zeroth order, represented by the solid line |τ ₀ | in the case of a constant value of the modulation function of the value of the argument α(r) for a linear or planar optimal tripler diffraction grating having a continuous periodic phase profile function:

Equation (5) is presented by F. Gori et al. in "Analytical derivation of the optimum triplicator", Optics Communication 157 (1998), p.13-16.

The light distribution parameter α(r) determines the amount of light that is distributed among the diffraction orders ±1 and 0. According to Equation (5), for the value α=2.65718, denoted by reference numeral 49 in FIG. 4, the light energy is evenly distributed among all the target focal points, i.e. among the diffraction orders ±1 and 0. The overall efficiency η that can be achieved with such a phase profile function ϕ(r) is more than 0.925.

In one embodiment of the ophthalmic multifocal lens according to the present invention, based on the phase profile function ϕ(r) disclosed in equations (1) and (2) above, the height profile or height function H(r) of the diffraction grating of the actual lens is expressed by the single closed-form continuous function defined as:

where:

H(r) - lens height profile, [nm],

λ - constructive wavelength of the lens, [nm],

n is the refractive index of the lens body,

n _m is the refractive index of the medium surrounding the lens body.

Fig. 5a-22f schematically illustrate examples of the height profile or height function H(r) of equation (6) and computer-simulated light intensity distributions for the body 31 of the biconvex eye lens 30 shown in FIG. 2a, 2b of a type containing such height profiles. Lens 30 is designed to target a zero order focal point of 20 diopters (D) and first order focal points of 21.5D and 18.5D, which are symmetrical about the zero order. Thus, it provides a 20D mid-range focal point for zero order, a 18.5D long-range focal point for -1 diffractive order, and a 21.5D close-range focal point for diffractive order. +1. Those skilled in the art will appreciate that these powers or focal points may differ for actual lenses depending on the target focal points. The examples were computed using MATLAB™ based simulation software.

The height profile H(r) is shown in µm along the vertical axis. It is assumed that the optical axis passing through the center of the lens body is at the radial position r=0, while the radial distance r, measured outward from the optical axis, is expressed in mm along the vertical axis. In the intensity profiles, the intensity I of the diffracted light is plotted in arbitrary units along the vertical axis as a function of the power in diopters (D) plotted along the horizontal axis.

In these designs, the design wavelength λ of the lens is assumed to be 550 nm, the refractive index n of the lens body is assumed to be 1.4618, and the refractive index n _m of the medium surrounding the lens body is assumed to be 1.336. Unless otherwise stated, amplitude modulation function Α(r)=1, amplitude modulation function B(r)=0, and argument value modulation function α(r)=2.65718. Period T=0.733 mm ² in space r ² .

Reference numeral 50 in FIG. 5a shows the height profile or height function H(r) according to equation (6) in space r ² expressed in mm ² and FIG. 5b shows the same height function along a linear scale as a function of the radial distance r. In this example, the angle modulation function of the argument is S(r)=0, i.e. there is no phase shift or angle modulation of the argument.

Reference numeral 51 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 50 H(r). See FIG. 2a and 2b.

As can be seen in FIG. 5a, in space r ² each period T of the height profile 50 H(r) is shown with equal length. The height profile or height function H(r) is a single closed-form continuous geometric function that defines concentric DOEs that do not have sharp transitions that are difficult to create in the lens body. Accordingly, the diffraction grating height profile 50 H(r) not only provides optimum performance, but also allows for precise manufacturing and hence precise fitting of lenses to provide target focal points and targeted light distribution among the target focal points.

The amount of light diffracted by a lens having a height profile 50 H(r) is shown by the intensity simulation results in FIG. 5c. Reference numeral 54 refers to a diffraction order of 0 providing a focal point for medium distance vision, reference numeral 52 refers to a diffraction order of -1 providing a focal point for long distance vision, and reference numeral 53 refers to a diffraction order of +1 providing a focal point point of view at close range. As seen in FIG. 5c, in contrast to the lens phase profile computed for the flat optimal tripler by Gori et al., for α(r)=2.65718, the amount of light incident on the curved lens body is unevenly distributed at the target focal points. This is because the periodic phase profile function of the optimal tripler by Gori et al. is calculated for a lens with a linear or planar phase grating for which the distances between periods show a linear relationship, while when it is converted to a lens, the distances between periods of the phase profile function become square root dependent.

Fig. 6a shows the height profile H(r) according to the above equation (6) as a function of the radial distance r, however modulated by a constant angular modulation of the argument S=0.25*T, denoted by reference numeral 60. Reference numeral 61 refers to the outer circumference of the front surface 34 of the body 30 lenses.

The amount of light diffracted by the lens is shown by the simulation results in FIG. 6b. Reference numeral 64 refers to diffraction order 0, reference numeral 62 refers to diffraction order -1, and reference numeral 63 refers to diffraction order +1. As seen from FIG. 6a, with this S angle modulation, relatively more light is diffracted in the +1 order compared to the height profile 50 having no S angle modulation.

Angular modulation of the argument in the other direction, ie S=-0.25*T, illustrated by height profile 70 in FIG. 7a shows that the relatively largest amount of light diffracts into the +1 order corresponding to the close vision focal point 73, as shown in the intensity profile in FIG. 7b. On FIG. 7b, it can be seen that relatively less light is diffracted in the -1 (72) order, hence this modulation provides a relatively large increase in light intensity for near vision. Reference numeral 71 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 70 H(r).

By shifting the phase function, i.e. the height profile, the relative amount of light between diffraction orders can be controlled or adjusted to provide a targeted light distribution by the lens and/or to correct for tolerances and other manufacturing variances, such as when manufacturing a lens.

As mentioned above, it is advantageous to express the angular modulation of the argument S as a fraction of the lattice period T in the space r ² . In practical embodiments, the angular modulation of the argument may range from approximately S=-0.5*T to approximately S=0.5*T in r ² space, including multiples of the period T, depending on the required light correction between focal points. points of view at close, intermediate and far distances.

Fig. 8a shows the height profile or height function H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one embodiment of a trifocal intraocular eye lens according to the present invention, denoted by reference numeral 80. FIG. 8b shows a height profile 80 in space r ² . The argument angle of the grating height profile 80 is modulated by a modulation function S(r) having a constant value S=0.315*T and an amplitude modulation function Α(r)=1.013. Reference numeral 81 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 80 H(r).

The light distribution achieved by a diffraction grating having a height profile 80 is shown in FIG. 8c. As seen from FIG. 8c, an equal amount of light is diffracted into the long-distance focal points 82 and close-view focal points 83, while relatively less light is distributed into the mid-distance focal point 84.

Fig. 9a shows the height profile or height function H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one embodiment of a trifocal intraocular eye lens in accordance with the present invention, denoted by reference numeral 90. Height profile argument angle 90 modulated by the modulation function S(r) having a constant value S=0.33*T, and by the amplitude modulation function Α(r)=0.96. Reference numeral 91 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 90 H(r).

The light distribution achieved by a diffraction grating having a height profile 90 is shown in FIG. 9b. As seen from FIG. 9b, with the above modulation parameters of the argument, the focal points for long distance vision 92, close distance 93 and medium distance 94 are distributed equal amounts of light.

Instead of a constant value of the angular modulation function of the argument S(r) and/or a modulation function of the magnitude of the argument or the light distribution parameter α(r), as well as any or both of the amplitude modulation functions Α(r) and B(r), as illustrated above , in accordance with the present invention, the modulation functions of the angle and the magnitude of the argument S(r) and/or α(r), respectively, as well as the amplitude modulation functions Α(r) and B(r) may contain modulation functions that vary depending on the radial distance to the optical axis of the lens body, in order to achieve an appropriate target light distribution or focus improvement by adjusting the light distribution at the target focal points or target foci, in particular to provide a pupil size dependent light distribution at the focal points.

Fig. 10a-13c illustrate the effect on light distribution of an ophthalmic multifocal lens according to the present invention, in which the continuous periodic profile function argument is modulated by the periodic angular modulation function of the argument or the periodic function of the argument magnitude modulation, providing periodic transitions in the continuous periodic function of the phase profile, that is, in lens height profile.

Fig. 10a shows the height profile or height function 100 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention, modulated by a periodic angular modulation function 105 of the argument S(r) shown in FIG. 10b. Function 105 angular modulation of the argument is a periodic rectangular wave function having a period equal to the period of the continuous periodic function 100 height. The value of S(r) 105 varies in the range S=±0.07*T, and is displayed along the vertical axis in FIG. 10b. Reference numeral 101 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 100 H(r).

In the example shown, the rising or leading edge 106 of the angular modulation function 105 creates a transition 108 that shifts the height profile function 100, i.e., a continuous periodic function of the grating phase profile, in the radial direction outward r of the lens body, located on the rising or leading edge of the function 100 height profile. The falling or trailing edge 107 of the angle modulation function 105 creates a transition 109 that shifts the height profile function 100 radially into the lens body, counteracts the offset from the transition 108 and is located on the trailing or falling edge of the height profile function 100.

The light distribution achieved by a diffraction grating having a height profile 100 is shown in FIG. 10c. As seen from FIG. 10c, when using the above argument angle modulation function 105, relatively more light is distributed or converged to the focal point for long distance vision 102 compared to the focal point for near vision 103. The amount of light distributed to the focal point for intermediate distance vision 104 , is substantially equal to the amount of light distributed to the focal point for view at the average distance 54 of the height profile 50 shown in FIG. 5, which does not have angular modulation of the argument.

Accordingly, when using the angle modulation function 105 of the argument, a strong increase in the relative amount of light at the focal point 102 for long distance vision is achieved.

Fig. 11a shows the height profile or height function 110 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention, modulated by a periodic angular modulation function 115 of the argument S(r) shown in FIG. 11b. Function 115 angular modulation of the argument is a periodic rectangular wave function having a period equal to the period of the continuous periodic function 110 height. The value of S(r) 115 varies in the range S=±0.07*T, and is displayed along the vertical axis in FIG. 11b. Reference numeral 111 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 110 H(r).

In the example shown, the rising or rising edge 116 of the angular modulation function 115 creates a transition 118 that shifts the height profile function 110, i.e., a continuous periodic function of the grating phase profile, in the radial direction outward r of the lens body, located on the trailing or falling edge of the function 110 height profile. The falling or trailing edge 117 of the angle modulation function 115 creates a transition 119 that shifts the height profile function 110 radially into the lens body, counteracts the offset from the transition 118, and is located on the leading or rising edge of the height profile function 110.

The light distribution achieved by a diffraction grating having a height profile 110 is shown in FIG. 11c. As seen from FIG. 11c, when using the above argument angle modulation function 115, relatively more light is distributed or converged to the focal point for close vision 113 compared to the focal point for long distance vision 112. The amount of light distributed to the focal point for intermediate distance vision 114 , is substantially equal to the amount of light distributed to the focal point for view at the average distance 54 of the height profile 50 shown in FIG. 5, which does not have angular modulation of the argument.

Accordingly, when using the angle modulation function 115 of the argument, a strong increase in the relative amount of light at the focal point 113 for near vision is achieved.

Fig. 12a shows the height profile or height function 120 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention modulated by a periodic modulation function 125 of the argument value α(r) shown in FIG. 12b. Function 125 modulation of the magnitude of the argument is a periodic rectangular wave function having a period equal to the period of the continuous periodic function 120 height. The value of α(r) 125 is normalized to the value of α=2.65718, displayed along the vertical axis in FIG. 12b and is in the range 1.4≥α(r)/2.65718≥0.7. The angle modulation function of the argument S(r)=0 for the height profile function 120. Reference numeral 121 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 120 H(r).

In the example shown, the rising or rising edge 126 of the argument value modulation function 125 creates a transition 128 that shifts the height profile function 120, i.e., a continuous periodic function of the grating phase profile, in a direction transverse to at least one surface 34 of the lens body 30 and upwards. in the direction of the outer circle 121. The transition 128 is located on the top or crest of the height profile function 120. The descending or trailing edge 127 of the modulation function 125 of the argument magnitude creates a transition 129 that shifts the height profile function 120, i.e., a continuous periodic function of the phase profile of the diffraction grating, in a direction transverse to at least one surface 34 of the lens body 30 downward, i.e., away from the outer circumference 121. The transition 129 is positioned at the bottom or in the valley of the height profile function 120 and resists displacement by the transition 128.

The light distribution achieved by a diffraction grating having a height profile 120 is shown in FIG. 12c. As seen from FIG. 12c, when using the above argument value modulation function 125, relatively more light is distributed or converged to the focal point for long distance vision 122 compared to the focal point for near vision 123. The amount of light distributed to the focal point for intermediate distance vision 124 , is substantially equal to the amount of light distributed to the focal point for view at the average distance 54 of the height profile 50 shown in FIG. 5 having no angular modulation of the argument and modulation of the magnitude of the argument.

Accordingly, by using the argument angle modulation function 125, a strong increase in the relative amount of light at the focal point 122 for long distance vision is achieved.

Fig. 13a shows the height profile or height function 130 H(r) in accordance with the above equation (6) as a function of the radial distance r of the diffraction grating in one example of a trifocal intraocular lens in accordance with the present invention, modulated by a periodic function 135 of modulation of the argument value α(r) shown in FIG. 13b. Function 135 modulation of the magnitude of the argument is a periodic rectangular wave function having a period equal to the period of the continuous periodic function 130 height. The value of α(r) 135 is normalized to the value of α=2.65718, displayed along the vertical axis in FIG. 13b and is in the range 1.4≥α(r)/2.65718≥0.7. The angle modulation function of the argument S(r)=0 for the height profile function 130. Reference numeral 131 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 130 H(r).

In the example shown, the falling or trailing edge 136 of the argument value modulation function 135 creates a transition 138 that shifts the height profile function 130, i.e., a continuous periodic function of the grating phase profile, in a direction transverse to at least one surface 34 of the lens body 30 and downwards. , that is, from the outer circle 131. The transition 138 is located on the top or crest of the height profile function 130. The rising or rising edge 137 of the argument value modulation function 135 creates a transition 139 that shifts the height profile function 130, i.e., a continuous periodic function of the grating phase profile, in a direction transverse to at least one surface 34 of the lens body 30 upward, i.e. . to the outer circle 131. The transition 139 is located at the bottom or in the valley of the function 130 of the height profile and counteracts the displacement of the transition 138.

The light distribution achieved by a diffraction grating having a height profile 130 is shown in FIG. 13c. As seen from FIG. 13c, when using the above argument value modulation function 135, relatively more light is distributed or converged to the focal point for close vision 133 compared to the focal point for long distance vision 132. The amount of light distributed to the focal point for intermediate distance vision 134 , is substantially equal to the amount of light distributed to the focal point for view at the average distance 54 of the height profile 50 shown in FIG. 5 having no angular modulation of the argument and modulation of the magnitude of the argument.

Accordingly, by using the angle modulation function 135 of the argument, a strong increase in the relative amount of light at the focal point 133 for near vision is achieved. One skilled in the art will appreciate that it is possible to combine periodic offsets of the height profile function in a direction transverse to at least one surface 34, as shown, for example, in FIG. 10 and 11 with offsets to the height profile function parallel to the radial direction of the lens body as shown in FIG. 12 and 13 to enhance the tuning effect. In this way, the relative intensities of the diffraction focal points can be very strongly changed.

On FIG. 10a, 11a, 12a and 13a, it can be seen that the transitions provided by the respective modulation functions shown in FIG. 10b, 11b, 12b and 13c cause abrupt shifts in the height or phase profile functions, which in practice can cause machining problems in the manufacture of a lens having such a height profile.

In accordance with the present invention, it is expedient to modulate the argument of the continuous periodic phase profile function by producing periodic smooth transitions or offsets on the continuous periodic phase profile function, i.e. the corresponding height profile or optical transfer function of the diffraction grating represented by the continuous periodic phase profile function.

Fig. 14a shows the height profile or height function 140 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention, modulated by a periodic angular modulation function 145 of the argument S(r) shown in FIG. 14b. Different from the rectangular angle modulation function 105 of the argument shown in FIG. 10b, the angular modulation periodic function 145 of the argument S(r) is a trapezoidal function having a period equal to that of the continuous periodic height function 140 . The maximum value of S(r) 145 varies in the range S=±0.08*T, and is displayed along the vertical axis in FIG. 14b. Reference numeral 141 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 140 H(r).

In the example shown, the rising or leading edge 146 of the angle modulation function 145 creates a smooth transition 148 that provides a linear gradual shift of the height profile function 140, i.e., a continuous periodic function of the grating phase profile, in a radial direction outward r of the lens body located at the ascending or forward front feature 140 height profile. The falling or trailing edge 147 of the angular modulation function 145 creates a transition 149 that provides a linear gradual shift of the height profile function 140 in the radial direction into the lens body, counteracting the offset from the transition 148 and located on the trailing or decreasing edge of the height profile function 140. The transitions created by the S(r) 145 function redistribute the light to the focal point for long distance vision.

Fig. 15a shows the height profile or height function 150 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention, modulated by a periodic angular modulation function 155 of the argument S(r) shown in FIG. 15b. Different from the rectangular angle modulation function 115 of the argument shown in FIG. 11b, the angular modulation periodic function 155 of the argument S(r) is a trapezoidal function having a period equal to that of the continuous periodic height function 150. The maximum value of S(r) 155 varies in the range S=±0.08*T, and is displayed along the vertical axis in FIG. 15b. Reference numeral 151 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 150 H(r).

In the example shown, the rising or leading edge 156 of the angle modulation function 155 creates a smooth transition 158 that provides a linear gradual shift of the height profile function 150, i.e., a continuous periodic function of the grating phase profile, in the radial direction outward r of the lens body, located at the rear or decreasing front features 150 height profile. The falling or trailing edge 157 of the angular modulation function 155 creates a smooth transition 159 that provides a linear gradual shift of the height profile function 150 in the radial direction into the lens body, counteracting the offset from the transition 118 and located on the leading or rising edge of the height profile function 110. The transitions created by the S(r) 155 function redistribute light to the focal point for near vision.

By introducing periodic smooth transitions 148, 149 and 158, 159 into the continuous periodic phase profile functions, i.e., the corresponding height profiles 140, 150, respectively, the implementation of an optical transfer function containing such a phase profile function does not pose a problem for machining. By smoothing transitions, no or only minor artifacts are introduced into the diffraction grating so that the properties of a tuned lens including a continuous periodic phase profile function are maintained with respect to less undesirable optical effects such as stray light, chromatic aberration, halo, flare, scattering, etc. .P.

One skilled in the art will appreciate that the argument value modulation functions 125 and 135 shown in FIG. 12b and 13b, respectively, can also be replaced by trapezoidal argument magnitude modulation functions, thereby providing smooth transitions, i.e. gradual shifts in a direction transverse to the surface of the lens body containing the corresponding diffraction grating (not shown). In accordance with the present invention, other periodic functions of angle and/or magnitude of the argument can be used, containing, for example, one of a continuous function, a continuous trigonometric function, a triangular function, etc., providing non-linear gradual displacements.

Fig. 16a shows an exemplary height profile or height function 160 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention modulated by a periodic angular modulation function 165 of the argument S (r) shown in Fig. 16b. Unlike the linear smoothing shown in FIG. 15, in this example smoothing is provided by cubic spline interpolation. Modulation of the argument value is provided at the so-called basic phase value, selected at S=0.33*T, while the maximum value of S(r) is in the range 0.41*T≥S(r)≥0.25*T and displayed along the vertical axis in FIG. 16b. Reference numeral 161 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 160 H(r). It should be borne in mind that other basic phase values may be chosen.

In the example shown, the descending or trailing edge 166 of the angular modulation function 165 of the argument creates a smooth transition 168 providing a linear gradual shift of the height profile function 160, that is, a continuous periodic function of the phase profile of the diffraction grating, in the radial direction outward r of the lens body, located on the ascending or front front features 160 height profile. The rising or leading edge 167 of the angular modulation function 165 creates a smooth transition 169 that provides a linear gradual shift of the height profile function 160 in the radial direction into the lens body, counteracting the offset from the transition 168 and located on the trailing or decreasing edge of the height profile function 160. The transitions provided by the S(r) function 165 provide a redistribution of light to the near focal point 163 as compared to the far focal point 162 as shown in the light intensity or energy distribution diagram of FIG. 16c. Reference numeral 164 refers to the amount of light distributed to the focal point for intermediate distance vision.

One skilled in the art will appreciate that the angle modulation functions and the magnitude modulation functions shown in the previous drawings may be interchanged and combined to provide, i.e., tune, the originally designed or selected continuous periodic phase or height profile function to to achieve the target or desired distribution of light at the target focal points.

The present invention is particularly suitable for providing distribution of light at target focal points depending on pupil size. This can be achieved in several ways by suitably modulating the argument of the continuous periodic phase profile function.

Fig. 17a shows an exemplary height profile or height function 170 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention modulated by a periodic angular modulation function 175 of the argument S (r) shown in Fig. 17b. In this example, the periodic function 175 of the angular modulation of the argument S(r) has a first part, denoted by reference numeral 176, extending at a radial distance of 1.7 mm from the optical axis, and a second part 177, extending from a radial distance of 1.7 mm outward to the circumference. lens body.

The first part 176 of the angular modulation function of the argument consists of a trapezoidal function having a period equal to the period of the continuous periodic height function 170, providing smooth transitions on the leading/back edges of the height profile function 170. In this first part, the value of S(r) varies in the range of S=±0.02*T, and is displayed along the vertical axis in FIG. 17b.

The second part 177 of the angular modulation function of the argument consists of a trapezoidal function having a period equal to the period of the continuous periodic height function 170, similarly providing smooth transitions on the leading/back edges of the height profile function 170. In this second part, the value of S(r) varies in the range of S=±0.1*T, and is displayed along the vertical axis in FIG. 17b.

Fig. 17c-17f show intensity profiles for light partially incident on the lens body for several distances from the optical axis, thus simulating several pupil sizes. Fig. 17c refers to a pupil diameter of 3 mm, FIG. 17d refers to a pupil diameter of 3.75 mm, FIG. 17e refers to a pupil diameter of 4.5 mm, and FIG. 17f refers to a pupil diameter of 6 mm. A pupil diameter of approximately 3 mm corresponds to a situation in which the amount of light in focus for near vision should be relatively improved, while a pupil diameter of approximately 6 mm corresponds to a situation in which relatively more light in focus for distance vision is preferred.

On FIG. 17c-17f, the intensity values are shown normalized to the intensity for mid-distance vision, ie at 20D, denoted as In. The focal point for close vision is set to 21.5D and the focal point for long distance vision is set to 18.5D. For each intensity diagram, the ratio of the distribution R of the amount of light at the focal points for vision at a long distance (In-far) and for vision at a close distance (In-near), that is, R=In-far/In-near, is shown. If R is 1, an equal amount of light is combined at the diffractive focal points. With R<1, relatively more light is distributed to the focal point for near vision compared to the focal point for far vision. With R>1, relatively more light is distributed to the focal point for far vision compared to the focal point for near vision.

From the simulated normalized light intensities and calculated light distribution ratios, it can be seen that the first part 176 of the angular modulation function 175 of the argument compared to its second part 177 promotes near vision for small pupil diameters, i.e. 3 mm and 3.75 mm, providing values R 1.08 and 1.04, respectively, while long distance vision is facilitated by the second part 177 for large pupil diameters, i.e. 4.5 mm and 6 mm, providing R values of 1.18 and 1.46, respectively.

Fig. 18a shows an exemplary height profile or height function 180 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention modulated by a periodic angular modulation function 185 of the argument S (r) shown in Fig. 18b. In this example, the periodic function 185 of the angular modulation of the argument S(r) consists of a trapezoidal function having a period equal to the period of the continuous periodic function 180 of the height, providing smooth transitions on the leading/back edges of the function 180 of the height profile. The value of S(r) 185 increases exponentially in a radial direction outward towards the circumference of the lens body, from S=0 to S=±0.1*T, and is displayed along the vertical axis in FIG. 18b.

Fig. 18c-18f show normalized intensity profiles for light partially incident on the lens body for several distances from the optical axis, in accordance with FIG. 17c-17f, respectively. From the simulated normalized light intensities and the calculated light distribution ratios R, it can be seen that the angular modulation of the 185 argument modestly enhances or promotes near vision for a small pupil diameter of 3 mm, resulting in an R value of 1.74, compared to an R value of 1.90 for the diameter Pupil 6 mm, contributing to vision at a great distance.

Fig. 19a shows an exemplary height profile or height function 190 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention modulated by a periodic angular modulation function 195 of the argument S (r) shown in Fig. 19b. In this example, the periodic function 195 of the angular modulation of the argument S(r) consists of a trapezoidal function having a period equal to the period of the continuous periodic function 190 of the height, providing smooth transitions on the leading/back edges of the function 190 of the height profile. The value of S(r) 195 decreases exponentially in the radial direction outward to the circumference of the lens body relative to the base phase shift S=0.33*T within 0.38*T≥S(r)≥0.2*T, and is displayed along vertical axis in Fig. 19b.

Fig. 19c-19f show normalized intensity profiles for light partially incident on the lens body for several distances from the optical axis, in accordance with FIG. 17c-17f, respectively. From the modeled normalized light intensities and the calculated light distribution ratios R, it can be seen that the angular modulation of argument 195, in contrast to the previous examples, enhances or promotes distance vision for smaller pupil diameters of 3 mm and 3.75 mm, providing R values of 1.6 and 1.67, respectively. Close vision is improved for large pupil diameters compared to smaller pupil sizes, providing corresponding R values of 1.44 for a pupil diameter of 4.5 mm and 1.27 for a pupil diameter of 6 mm. Please note that this type of lens is a special case and can be used to provide unusually strong corrections.

The embodiments of the present invention described and shown in FIGS. 18a-f and 19a-f have the advantage of providing gradually varying intensity distributions for different pupil sizes without abrupt change between different zones, as shown for example in FIG. 17b, thereby providing less annoyance and a correspondingly improved experience for the user.

Fig. 20a shows an exemplary height profile or height function 200 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention modulated by a periodic angular modulation function 205 of the argument S (r) shown in Fig. 20b. In this example, the periodic angle modulation function 200 of the argument S(r) has a first part, denoted by reference numeral 206, extending at a radial distance of 1.5 mm from the optical axis, and a second part 207, extending from a radial distance of 1.5 mm outward to the circumference. lens body.

The first part 206 of the function 205 of the angular modulation of the argument consists of a trapezoidal function having a period equal to the period of the continuous periodic function 200 of the height, providing smooth transitions on the leading/back edges of the function 200 of the height profile. In this first part, the value of S(r) decreases exponentially in a radial outward direction to the circumference of the lens body with respect to the base phase shift S=0.33*T. The second part 207 of the angular modulation function 205 of the argument consists of a trapezoidal function having a period equal to the period of the continuous periodic height function 200, similarly providing smooth transitions on the leading/back edges of the height profile function 170. In this second part, the value of S(r) increases exponentially in a radial outward direction to the circumference of the lens body with respect to the base phase shift S=0.33*T. In the first part, the maximum value of S(r) 205 is in the range of 0.44*T≥S(r)≥0.28*T, and in the second part 207 in the range of S=±0.20*T, and is displayed along the vertical axes in Fig. 20b.

Fig. 20c-20f show normalized intensity profiles for light partially incident on the lens body for several distances from the optical axis, in accordance with FIG. 17c-17f, respectively. From the modeled normalized light intensities and the calculated light distribution ratios R, it can be seen that the angular modulation of the argument 205 strongly contributes to the distribution of light to the focal point for near vision for the smaller pupil diameters of 3 mm and 3.75 mm, as well as for pupil diameter 4, 5 mm, providing R values of 0.68, 0.89 and 0.93, respectively. Long-distance vision improves slightly for the larger pupil diameter of 6 mm compared to the smaller pupil sizes, resulting in a corresponding R value of 1.08.

Fig. 21a shows the height profile or height function 210 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention, modulated by a periodic modulation function 216 of the argument value α(r) shown in FIG. 21b and an angle modulation function 215 of the argument S(r).

The argument value modulation function 216 is a stepwise or piecewise increasing function in the radial direction from the center of the lens body. The width of these sections or steps is equal to the period of the continuous periodic function 210 height. The value of α(r) 216 is normalized to the value of α=2.65718, displayed along the vertical axis in FIG. 21b and is in the range 2≥α(r)/2.65718≥0.9. In the example shown, the argument value modulation function 216 causes the height profile or height function 210 to periodically increase with increasing distance from the optical axis, creating the effect of apodization of the height profile 210.

Function 215 angular modulation of the argument S(r) consists of a trapezoidal function having a period equal to the period of a continuous periodic function 180 height, providing smooth transitions on the front/back edges of the function 210 height profile. The value of S(r) 215 increases exponentially in a radial direction outward towards the circumference of the lens body, from S=0 to S=±0.1*T, and is displayed along the vertical axis in FIG. 21c.

Fig. 21h shows the light distribution or intensity profile for a lens containing a diffraction grating having a height profile function 210. As seen from FIG. 21h, due to the angular modulation function 215 of the argument S(r), the amount of incident light distributed to the focal point 212 for long distance vision is much greater than the amount of incident light distributed to the focal point 213 for near vision. In addition, compared to the intensity profile shown in FIG. 5b, for example, the amount of light at the focal point 214 for mid-distance vision is reduced by the modulation function 216 of the angle value α(r).

Fig. 21d-21g show normalized intensity profiles for light partially incident on the lens body for several distances from the optical axis, in accordance with FIG. 17c-17f, respectively. From the modeled normalized light intensities and the calculated light distribution ratios R, it can be seen that the argument magnitude modulation function 216 enhances or promotes far vision for all pupil diameters of 3 mm, 3.75 mm, 4.5 and 6 mm, providing relatively high numbers R values of 2.03, 2.07, 2.05 and 2.13, respectively, compared to the R values of the previous examples. From the normalized intensity profiles shown in FIG. 21f and 21g, it can be seen that the amount of light distributed to the focal point for intermediate distance vision decreases with increasing α(r) 216.

Fig. 22a shows the height profile or height function 220 H(r) according to Equation (6) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention modulated by a periodic angle modulation function 225 of the argument α(r) shown in FIG. 22b, which is equal to the periodic angular modulation function 215 of the argument S(r) shown in FIG. 21b. In addition, height apodization is applied to the height profile function 220 with an amplitude modulation function Α(r) that increases exponentially with increasing radial distance from the optical axis of the lens (not shown). It should be noted that the height profile function 220 is shown on an enlarged scale compared to the height profile functions of the previous examples.

From the normalized intensity profiles shown in FIG. 22c-22f, it can be deduced, inter alia, that the amount of incident light distributed to the focal point for medium distance vision decreases with increasing amplitude modulation Α(r). The calculated light distribution ratios R show that near vision improves relatively for smaller pupil diameters of 3 mm and 3.75 mm, respectively R=1.97 and R=2.01, while far vision improves for larger pupil diameters. 4.5 and 6 mm, providing relatively high R values of 2.05 and 2.27, respectively.

Therefore, with the exemplary profiles shown in FIG. 21a and 22a, it is demonstrated that by apodization by one or both of argument magnitude modulation and amplitude modulation, the amount of light distributed to the mid-distance focal point, i.e., the refractive focal point, can be effectively tuned. The tuning of light distribution at diffractive focal points, including pupil-dependent tuning, has been demonstrated by various examples of angular modulation of the argument.

In addition, it has been observed that apodization using modulation of the magnitude of the argument to achieve a similar effect in terms of adjustment requires a smaller increase in the height function H(r) in the radial direction of the lens body and a smaller absolute height function difference over the lens body from the optical axis to the body circumference. lenses compared to apodization due to amplitude modulation. A smaller absolute height difference is preferable from a manufacturing point of view. In addition, such a profile is less sensitive to the accumulation of dust, dirt, moisture, and the like. Accordingly, apodization by modulating the magnitude of the argument is more preferable than amplitude modulating the height function or height profile.

Although the previous examples have shown the adjustment of light distribution at the focal points of a lens containing a diffraction grating having a height profile in accordance with a continuous periodic phase profile function based on the above equation (6), the ideas of the present invention are not limited to this particular type of continuous periodic phase profile function. profile.

Fig. 23a and 23b illustrate by way of example the height profile or height function H(r) of a true sinusoidal continuous periodic phase profile function according to equation (7) below:

where:

H(r) - lens height profile, [nm],

Α(r) - amplitude modulation function of the continuous periodic function of the phase profile in the radial direction of the lens body,

λ - constructive wavelength of the lens, [nm],

n is the refractive index of the lens body,

n _m is the refractive index of the medium surrounding the lens body,

S(r) is the angular modulation function of the argument G in the space r ² , [mm ² ], and

T is the period or step of the diffraction grating in space r ² , [mm ² ].

Fig. 23a shows the height profile or height function H(r) 230 in r2 space expressed in mm2, and FIG. 23b shows the same function of height 230 along a linear scale as a function of radial distance r. In this example, the angle modulation function of the argument is S(r)=0, i.e. there is no phase shift or angle modulation of the argument.

The height profile H(r) is shown in µm along the vertical axis. It is assumed that the optical axis passing through the center of the lens body is at the radial position r=0, while the radial distance r, measured outward from the optical axis, is expressed in mm along the vertical axis. Reference numeral 231 refers to the outer circumference of the front surface 34 of the lens body 30 having a diffraction grating or relief 36 containing the diffraction profile function 230 H(r). See FIG. 2a and 2b.

In this design, the design wavelength λ of the lens is taken to be 550 nm, the refractive index n of the lens body is taken to be 1.4618, and the refractive index n _m of the medium surrounding the lens body is taken to be 1.336. The amplitude modulation function Α(r)=0.225. In the case of Α(r)=0.5, a maximum phase loss of 1 wavelength A is obtained. Period T=0.55 mm ² in space r ² .

Fig. 23c shows the computer-simulated light intensity distribution of the body 31 of the biconvex eye lens 30 shown in FIG. 2a, 2b of the type containing a diffraction grating having a height profile of 230. In this intensity profile, the diffracted light intensity I is plotted in arbitrary units along the vertical axis as a function of diopter power (D) plotted along the horizontal axis.

For purposes of illustration, this lens is designed to target a 20 diopter (D) zero order focal point and 22D and 18D first order focal points symmetrically about the zero order. Thus, it provides a focal point for view at an average distance of 234 in 20D for a zero-order focal point, a focal point for view at a long distance of 232 in 18D for a diffractive order of -1, and a focal point for a close view of 233 in 22D for a diffractive order +1.

Fig. 24a shows an exemplary height profile or height function 240 H(r) according to Equation (7) above as a function of the radial distance r of a diffraction grating in one example of a trifocal intraocular lens according to the present invention modulated by a periodic angular modulation function 245 of the argument S (r) in accordance with the present invention shown in FIG. 24b. In this example, the periodic function 245 of the angular modulation of the argument S(r) has a first part, denoted by reference numeral 246, extending at a radial distance of 1.75 mm from the optical axis, and a second part 247, extending from a radial distance of 1.75 mm outward to the circumference. lens body.

The first part 246 of the angular modulation function of the argument consists of a trapezoidal function having a period equal to the period of the continuous periodic function 240 of the height, providing smooth transitions on the leading/back edges of the function 240 of the height profile. In this first part, the value of S(r) varies in the range of S=±0.045*T, and is displayed along the vertical axis in FIG. 24b.

The second part 247 of the angular modulation function of the argument consists of a trapezoidal function having a period equal to the period of the continuous periodic height function 240, similarly providing smooth transitions on the leading/back edges of the height profile function 240. In this second part, the value of S(r) varies in the range of S=±0.1*T, and is displayed along the vertical axis in FIG. 24b.

Fig. 24c-24f show normalized intensity profiles for light partially incident on a lens body having a height function 240 for several distances from the optical axis, in accordance with FIG. 17c - 17f. From the simulated normalized light intensities and calculated light distribution ratios, it can be seen that the first part 246 of the angular modulation function 245 of the argument promotes near vision for small pupil diameters, i.e. 3 mm and 3.75 mm, providing R values of 0.92 and 0, 90, respectively, while long distance vision is facilitated by the second portion 247 for large pupil diameters, i.e., 4.5 mm and 6 mm, providing R values of 1.05 and 1.24, respectively.

The optical transfer function or light transmission function in the present invention may have variable light transmission properties in the radial direction r of the lens. In particular, while at a distance of approximately 2-3 mm outward from the center of the lens, the optical transfer function or light transmission function has a phase profile that provides trifocal properties, and at the same time contains bifocal properties from a radial distance of approximately 2-3 mm to circular edge of the lens with a radius of r=5-7 mm. See FIG. 2a.

In addition, it should be noted that the ideas illustrated above are equally applicable to the design of a multifocal eye lens having, for example, an asymmetric diffraction grating and/or four target focal points, i.e. a so-called four-focal lens, or even five target focal points. , that is, the so-called five-focal lens.

Fig. 25 illustrates, as an example, a continuous periodic function of the profile H(r) of the height of a five-focal lens along a linear scale as a function of the radial distance r, and this lens contains a diffraction grating based on a continuous periodic function of the phase profile in accordance with the following equation (8):

where:

ϕ(r) - continuous periodic phase function of the diffraction grating,

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

atan2 refers to arc tangent with 2 arguments,

Α(r) - amplitude modulation function of the continuous periodic function of the phase profile in the radial direction of the lens body,

γ(r) and δ(r) are the modulation functions of the argument,

S(r) is the angular modulation function of the argument in space r ² , [mm ² ], and

T is the period or step of the diffraction grating in space r ² , [mm ² ].

The continuous periodic function (8) of the phase profile is based on the present invention, as well as the publication of 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.

The amount of light diffracted by a lens having a diffraction profile comprising a height profile 250 H(r) is shown by the intensity simulation results in FIG. 25b. Reference numeral 254 refers to diffraction order 0 providing a focal point for mid-distance view, reference numerals 252 and 255 refer to diffraction orders -1 and -2, respectively, providing focal points for long distance vision, and reference numerals 253 and 256 refer to the +1 and +2 diffraction orders, providing focal points for near vision. In this solution, the focal point for the medium distance view is set to 20D, the focal points for the long distance view are set to 18.5D and 17D, and the focal points for the close view are set to 21.5D and 23D.

In accordance with the present invention, the distribution of incident light at the focal points can be tuned using amplitude and argument modulation implemented by one or more of the functions Α(r), S(r), γ(r), and δ(r). For the exemplary height function 250, the following settings apply: Α(r)=1, S(r)=0, γ(r)=0.459 and δ(r)=0.899, T=0.733 mm ² in r ² space, design wavelength lens is 550 nm, the refractive index n of the lens body is 1.4618, and the refractive index n _m of the medium surrounding the lens body is 1.336 nm.

The simplified block diagram 260 in FIG. 26 illustrates the steps of a method for manufacturing a multifocal ophthalmic lens in accordance with the present invention. The direction of the sequence of stages in the drawing is from top to bottom.

In the first step, at least the target focal points of the lens for near, intermediate, and far vision are set, that is, the Set Target Focal Points block 261 is executed. In the second stage, the target relative light distribution between different focal points for different user pupil sizes is determined, that is, the Set Relative Light Distributions block 262 is executed. Selected pupil sizes may, for example, vary in the ranges 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. related to intermediate and long distance vision.

Then, a light-transmitting lens body having a refractive focal point providing a target focal point for intermediate distance vision is selected, that is, the Select Lens Body block 263 is executed. To provide diffraction focal points, a continuous periodic function of the grating phase profile is computed, either analytically or numerically using a suitably programmed processor or computer. A continuous periodic phase profile function may, for example, be computed to optimize the overall efficiency of light distribution at target refractive and diffractive focal points throughout the lens body or for a certain pupil diameter size, such as 6 mm, i.e. the Calculate Phase Profile step 264 is performed.

In the next step, the computed phase profile function is adapted to fine-tune and/or smooth the desired or target optical properties of the lens, such as the desired relative distribution of light between the target focal points, i.e., the Adjust Intensity step 265 is performed. This intensity setting may likewise be processed by a suitably programmed processor or computer, and may include the modulation described above and shown, for example, in the examples of FIG. 6a-25b. This is also necessary to account for optical deviations at the target focal points and profile due to tolerances and the like, such as during machining or lens manufacturing.

Finally, the geometric height profile of the diffraction grating for manufacturing the lens is calculated, ie, Height Profile Processing step 266 is performed, again using a suitably programmed processor. Finally, a height profile or grating height function that defines the height and position of the DOE, which are located on the lens surface concentrically around its optical axis or center, is applied to the lens body, for example by laser micromachining, diamond turning, 3D printing, or any other mechanical or lithographic surface treatment technology. Thus, step 267 Machining is performed.

The calculations in step 264 may be based on power spectrum calculations from the Fourier series representation of the grating such that the sum of the squares of the absolute values of the Fourier coefficients of the diffraction orders associated with the target focal points is maximized. As noted above, this calculation can be done while limiting equal or weighted target light intensities at the target focal points.

Calculations of the continuous periodic function of the phase profile of the optical transfer function or the lens transmission function and the grating height profile in the method of the present invention can be performed remotely from the lens machining equipment. Features of the calculated grating can be sent to machining equipment by data transmission over a practically accessible telecommunications network such as the Internet (not shown).

Other variations of the disclosed examples and embodiments can be understood and implemented in the implementation of the claimed invention by experts in the art on the basis of a study of the drawings, description and appended claims. In the claims, the words "comprising" do not exclude other elements or steps, and the mention of an element in the singular does not exclude its plurality. The fact that certain measures are listed in mutually different dependent claims does not mean that a combination of these measures cannot be used to advantage. Any reference designations in the claims should not be construed as limiting the scope of its scope. Like reference numerals refer to the same or equivalent elements or operations.

Claims (46)

1. An eye multifocal lens containing at least focal points for near vision, intermediate vision and long distance vision, having a light-transmitting lens body containing an optical axis and providing a refractive focal point, as well as a diffraction grating extending concentrically in in a radial direction through at least a portion of at least one surface of said lens body providing a set of diffraction focal points, wherein said diffraction grating is periodic in r ² space, designed to operate as a beam splitter to distribute light incident on said lens body in said refractive and diffractive focal points, wherein said refractive focal point provides said focal point for medium distance vision, and said diffractive focal points provides said focal points for near vision, and vision at a great distance, characterized in that said diffraction grating of said ophthalmic multifocal lens comprises a continuous periodic phase profile function extending in the radial direction of said lens body, said continuous periodic phase profile function contains an argument modulated depending on the radial distance to said optical axis of said lens body, wherein said argument is modulated so as to provide periodic smooth transitions on said continuous periodic phase profile function, wherein the positions of said transitions are periodic in space r ² and each transition traverses a portion of the period of said continuous periodic phase profile function such that at least one period of the continuous periodic phase profile function is modulated differently than at least one other period, thereby tuning said light distribution at said diffraction focal points, with each transition comprising at least one of: - a transition providing a displacement, preferably spatial and/or radial, in said continuous phase profile function in the radial direction of said lens body, and - a transition providing a displacement, preferably spatial and/or radial, in said continuous periodic phase profile function in a direction transverse to said at least one surface of said lens body, thereby adjusting said distribution of light incident on said lens body. 2. The eye multifocal lens according to claim 1, in which the transitions that provide a shift on the mentioned continuous periodic phase profile function in the radial direction of the said lens body are located in the position of at least one of the leading and trailing edges or slope of the mentioned continuous periodic phase profile function , and transitions providing a shift on said continuous periodic phase profile function in a direction transverse to said at least one surface of said lens body are located at the position of at least one of the crest and trough of said continuous periodic phase profile function. 3. An eye multifocal lens according to claim 1 or 2, wherein said junctions comprise at least one of the following: - transitions providing an identical shift in said continuous periodic phase profile function in a plurality of periods of said continuous periodic phase profile function, transitions providing a shift in said continuous periodic phase profile function that increases over a plurality of periods of said continuous periodic phase profile function, and transitions providing a shift in said continuous periodic phase profile function that decreases over a plurality of periods of said continuous periodic phase profile function. 4. Eye multifocal lens according to paragraphs. 1, 2, or 3, in which said argument is modulated so as to provide, for the same period length of said continuous periodic phase profile function, first and second transitions spaced apart in the radial direction of said lens body, said second transition at least partially counteracting the operation mentioned first transition. 5. An ocular multifocal lens according to any one of the preceding claims, wherein said argument is modulated according to an argument modulation function, which in particular is a periodic function having a period equal to the period of said continuous periodic phase profile function, comprising one of a continuous function, a continuous trigonometric function, triangular function and trapezoidal function. 6. An ocular multifocal lens according to any one of the preceding claims, wherein said argument of said continuous periodic phase profile function is differently modulated throughout said lens body, thereby adjusting said distribution of light incident on said lens body differently for different pupil sizes , in particular in which said argument is modulated in a number of adjacent periods of said continuous periodic phase profile function covering at least one area of said lens body, wherein said number of adjacent periods and the modulation of said argument differ in different areas on said lens body. 7. An ocular multifocal lens according to any one of the preceding claims, wherein said diffraction grating is configured to operate as a wave splitter and contains diffractive focal points in the +1 and -1 diffraction orders and said continuous periodic phase profile function is expressed as:

where: ϕ(r) - continuous periodic phase function of said diffraction grating, r - radial distance or radius directed outward from said optical axis of said lens body, mm, A(r) is the amplitude modulation function of said continuous periodic phase profile function in the radial direction of said lens body, F[α*G] - function of the lens body in the radial direction, providing the mentioned wave splitting operation, G(r) is a continuous periodic function in the space r ² , α(r) - modulation function of the value of the argument G, S(r) - function of angular modulation of argument G in space r ² , mm ² , T is the period or step of the said diffraction grating in space r ² , mm ² , and B(r) is the amplitude modulation function of said continuous periodic phase profile function, wherein at least one of said argument value modulation function α(r) and said argument angle modulation function S(r) comprises said argument modulated as a function of the radial distance to said optical axis of said lens body. 8. An ocular multifocal lens according to claim 7, wherein said distribution of light at said refractive and diffractive focal points is further tuned by adapting at least one of said amplitude modulation function A(r) and said amplitude modulation function B(r) of said continuous periodic function of the phase profile. 9. Eye multifocal lens according to claim 7 or 8, in which F is an inverse tangential function, G is a sinusoidal function, said function of modulating the value of the argument α(r) has a constant value in the range of 2.5-3, and said function angular modulation of the argument S(r) has a constant value ranging from -0.5*T to 0.5*T in the space r ² , in particular in which S(r) has a constant value ranging from 0, 30*T to 0.50*T in r ² space, more specifically wherein S(r) has a constant value ranging from -0.05*T to -0.15*T in r ² space, and more more specifically, in which S(r)=0.42*T in space r ² . 10. An ocular multifocal lens according to any one of the preceding claims, wherein said argument of said continuous periodic phase profile function is modulated to provide first trifocal properties in a first region of said surface of said lens extending in the radial direction and including said optical axis, wherein said first trifocal properties give priority to distributing light to said focal point for near vision, and providing second trifocal properties in a second region of said surface of said lens extending beyond said first region in the radial direction of said lens towards the circumferential edge of said lens body, wherein said second trifocal properties favor the distribution of light to said focal point for long distance vision. 11. A method for producing an ophthalmic multifocal lens having at least focal points for near vision, intermediate vision and long distance vision, having a light-transmitting lens body comprising an optical axis providing a refractive focal point, as well as a periodic light-transmitting diffraction grating , passing concentrically in the radial direction through at least part of the surface of said lens body, providing a set of diffraction focal points, and said diffraction grating is designed to operate as a beam splitter for distributing light incident on said lens body at said refractive and diffractive focal points, wherein said refractive focal point provides said focal point for medium distance vision, and said diffractive focal points provide said focal points for near and far vision. distance, said method comprising the following steps: - determination of target focal points for near vision, intermediate distance vision and long distance vision; - determining the target distribution of the incident light at said target focal points; providing said light-transmitting lens body having a refractive focal point providing said target focal point for medium distance vision; - providing said diffraction grating having an optical transfer function containing a continuous periodic phase profile function extending in the radial direction of said lens body, providing said target focal points for near vision and long distance vision, as well as light distribution in said target focal points points, and has the following stages: - providing said continuous periodic phase profile function having a modulus argument as a function of the radial distance to said optical axis of said lens body, - adjusting said light distribution at said target focal points to provide said target light distribution by modulating said argument over said lens body, providing a modulated argument, - providing a height profile of said grating in accordance with said periodic phase profile function containing said modulated argument, and - manufacturing said ophthalmic multifocal lens by depositing said diffraction grating on said lens body in accordance with said height profile, moreover, said modulated argument provides periodic smooth transitions on said continuous periodic phase profile function, while the positions of said transitions are periodic in space r ² and each transition passes through part of the period of said continuous periodic phase profile function in such a way that at least one period of the periodic the phase profile function is modulated differently than at least one other period, thereby tuning said light distribution at said diffraction focal points, with each transition comprising at least one of: - a transition providing a displacement, spatial and/or radial, in said continuous phase profile function in the radial direction of said lens body, and - a transition providing a displacement, spatial and/or radial, in said continuous periodic phase profile function in a direction transverse to said at least one surface of said lens body, thereby adjusting said distribution of light incident on said lens body. 12. The method of claim 11, wherein said argument of said continuous periodic phase profile function is modulated to produce said multifocal ophthalmic lens according to any one of claims. 1-10. 13. An ocular multifocal lens provided according to any one of the preceding claims, configured as one of a contact lens, an intraocular lens, an aphakic contact lens, an aphakic intraocular lens, and a spectacle glass.

Images