JPWO2015159374A1 - Diffraction multifocal ophthalmic lens and method of manufacturing diffractive multifocal ophthalmic lens - Google Patents

Abstract

Provided are a diffractive multifocal ophthalmic lens capable of generating at least three focal points, a diffractive multifocal ophthalmic lens having a novel structure with a high degree of freedom in setting a focal position, and a novel manufacturing method thereof. In the diffractive multifocal ophthalmic lens composed of a plurality of concentric zones, a part or all of the diffractive structure is based on a zone region (1) 16 and a zone region (2) 18 which are set based on predetermined formulas, respectively. And the n-th zone radius of the zone area (1) 16 is the same as the m-th zone radius of the zone area (2) 18, and the zones up to the n-th zone of the zone area (1) 16 are zone areas. (2) Arranged inside 18 and the (m + 1) th and subsequent zones in zone area (2) 18 are arranged outside and adjacent to the nth zone in zone area (1) 16.

Description

  The present invention relates to an ophthalmic lens such as a contact lens or an intraocular lens, and more particularly to a diffractive multifocal ophthalmic lens that generates at least three focal points by diffracted light.

  Conventionally, an ophthalmic lens has been used as an optical element for correcting refractive error in an optical system of the human eye, an alternative optical element after extracting a crystalline lens, or the like. Among them, contact lenses that are used by being attached to the human eye and intraocular lenses that are used by being inserted into the human eye are used directly by the human eye to provide a large field of view and reduce the sense of discomfort. It can be used widely.

  Incidentally, in recent years, an increasing number of people who have reached presbyopia age continue to use contact lenses. The person with such presbyopia has a reduced focus adjustment function, so that a symptom that it is difficult to focus on a nearby object appears. Thus, for such presbyopic patients, a multifocal contact lens that can focus on nearby objects is required. Further, in patients who have undergone cataract surgery, the crystalline lens that controls the adjustment function is removed, so that the symptom that it is difficult to see the vicinity remains even if an intraocular lens is inserted as an alternative. Such intraocular lenses are also required to have a multifocal function having a plurality of focal points. Thus, the need for a multifocal ophthalmic lens is greatly increased reflecting the recent elderly society.

  Examples of a method for realizing such a multifocal ophthalmic lens include a refractive multifocal ophthalmic lens that forms a plurality of focal points based on the refraction principle and a diffractive multifocal ophthalmic lens that forms a plurality of focal points based on the diffraction principle. It has been known. The latter diffractive type ophthalmic lens has a plurality of concentric diffractive structures formed in the optical part of the lens, and a plurality of focal points are formed by the mutual interference action of light waves that have passed through the diffractive structures (zones). Is to give. Therefore, it is possible to set a large lens power while suppressing an increase in the lens thickness as compared with a refractive lens that focuses by the refracting action of a light wave on a refracting surface composed of a boundary surface having a different refractive index. There are advantages.

  In general, a diffractive multifocal lens has a diffractive structure in which the distance between the diffractive zones gradually decreases from the center of the lens toward the periphery in accordance with a certain rule called Fresnel zone. Multi-focality is achieved using origami. Usually, the 0th-order diffracted light is used as a focal point for far vision, and the + 1st-order diffracted light is used as a focal point for near vision. By the distribution of the diffracted light, a bifocal lens having a focal point for near and near can be obtained. A specific Fresnel zone configuration is based on a zone interval having a zone outer radius defined by [Equation 1] below. This [Equation 1] is hereinafter referred to as a Fresnel zone setting formula.

r _n is the outer diameter radius of the n th zone obtained from Equation 1. K is a constant. P is an additional refractive power for setting the focus of the 1st-order diffracted light with reference to the focus of the 0th-order diffracted light. By varying this, the focal position of the 1st-order diffracted light can be changed.

  For example, if the focus of the 0th-order diffracted light is a far focus and the first-order diffracted light is a near focus, increasing P increases the near focus position closer to the lens. That is, when such a lens is used for a human eye, a closer object can be seen. On the other hand, if P is reduced, the near focus position moves away from the lens. In this case, when a lens is used for a human eye, a nearby point that can be viewed is moved away.

  In patients with advanced presbyopia or patients with an intraocular lens inserted, the lens's ability to adjust decreases and disappears. Therefore, it is preferable to apply a lens that is focused closer to the former, such as the former. That is, it is necessary to set a large additional refractive power. On the other hand, in patients whose accommodation power has not decreased so much, it is possible to see the near by combining with their own adjustment power even if the near focus position is not so close. There are cases where it is good. By setting P in consideration of the patient's eye condition, it is possible to obtain a bifocal lens applicable to different requirements for each patient.

  However, it has been found that such a bifocal lens has the following problems to be solved.

  In the bifocal lens, there are two focal points, a far focal point and a near focal point, and there is a blank area between which the focal point does not exist. As the additional refractive power is increased, the blank area is enlarged. A diffractive multifocal lens with a large additional refractive power is applied to patients with reduced accommodation power, but when using such a lens, the distance and the distance are visible, but exist between the two focal points. If you look at something, it causes the problem of not being clear.

  Regulatory power decreases with age. Residual accommodation varies from person to person, but as a general trend, presbyopia begins to be recognized. It is said that it will decline. In the following, diopter is expressed as D as a unit of refractive power.

  Normally, the eye's eye adjustment required for viewing 30 cm in front is about 3.3D. For example, when looking at a point where a person in their 50s takes such an adjustment, an adjustment of about 1.8-2D is required. It becomes insufficient. If such a patient utilizes a bifocal lens, the lens requires an additional refractive power of about 1.8-2D. Further, in the patient who has inserted the intraocular lens, since the crystalline lens is removed, there is almost no residual adjusting force. Such patients require an additional refractive power of 3 to 3.5D. When the additional refractive power is set for such a lens as an intraocular lens as a multifocal ophthalmic lens, it is necessary to further change the additional refractive power given to the lens depending on the setting position of the intraocular lens in the eye. In order to give the above-mentioned 3-3.5D additional refractive power to the eye into which the lens is inserted, the lens itself needs an additional refractive power of 3.5-4D.

  When a bifocal ophthalmic lens designed to have such additional refractive power is used by a patient with advanced presbyopia or a patient who has inserted an intraocular lens, there is a new problem that it is difficult to see the middle region between the distant and the near. It occurs. Here, there is a need for a multifocal lens that can generate a focal point even in a blank area.

  In consideration of such problems, a diffractive multifocal ophthalmic lens having a further increased number of focal points has been proposed in the conventional diffractive multifocal lens. As a specific example, there is an example of a diffractive multifocal lens in which a diffractive structure called a relief for modulating the phase of light is a cosine wave (or sine wave) type or a rectangular type.

  Japanese Patent Laid-Open No. 7-198909 (Patent Document 1) discloses a trifocal diffractive ophthalmic lens based on a relief shape such as a cosine wave type, a triangular pyramid type, or a trapezoidal type. In Patent Document 1, for example, by using a cosine wave-type relief as a basis, the 0th-order diffracted light is distributed to the intermediate focus, the −1st-order diffracted light is distributed to the far focus, and the + 1st order diffracted light is distributed to the near focus. Among them, specifications of a trifocal diffractive ophthalmic lens that generates a focus at three different points in the vicinity are described. In such a relief-shaped trifocal lens, the same additional refractive power is given to the −1st order diffracted light and the + 1st order diffracted light with reference to the intermediate focus that becomes the 0th order diffracted light. In this type of relief structure, for example, if the additional refractive power to the + 1st order diffracted light is P, the same additional refractive power of P is applied to the −1st order diffracted light (although the focal position is reversed). As a result, when the far focus is used as a reference, the intermediate focus has the same effect as the additional refractive power of P (D), and the near focus has 2P (D).

  Japanese Unexamined Patent Application Publication No. 2010-134282 (Patent Document 2) also discloses a trifocal diffractive ophthalmic lens based on a rectangular relief. In Patent Document 2, as in Patent Document 1, the specifications of the trifocal diffractive ophthalmic lens in which the far focus, the intermediate focus, and the near focus are formed by the −1st order diffracted light, the 0th order diffracted light, and the + 1st order diffracted light, respectively, are described. ing.

  In the diffractive lenses having the conventional structures shown in Patent Documents 1 and 2, the additional refractive power between the focal points is basically equal refractive power, and the refractive power of the intermediate focal point is always 1 / refractive power of the near focal point. 2. For example, when the near focus is set to be 4D, the intermediate focus is 2D.

  In recent years, as the use of personal computers increases, opportunities for viewing personal computer monitor screens have increased even for elderly people. Generally, the screen position when viewing the monitor screen is about 50 to 60 cm on the front on average. When 3D is set as the near focus, the intermediate focus comes to a position corresponding to half of 1.5D in the lens of the prior document. This refractive power is about 67cm in terms of distance, and the focus is set at a position far from the monitor screen position. To see the monitor screen clearly, it is necessary to keep the eye position away from the monitor screen. Will be forced to take an attitude. Also, if you move away, the characters on the monitor will become smaller, which will eventually cause problems that are difficult to see.

  As described above, in the diffractive lenses having the conventional structures described in Patent Documents 1 and 2, the near, intermediate, and far focus points are set in conjunction with each other, and there is a problem that the focus cannot be generated in an arbitrary intermediate region. there were.

Japanese Laid-Open Patent Publication No. 7-198909 JP 2010-134282 A

[Problems to be solved by the present invention]
The present invention has been made in the background as described above, and the problem to be solved is a diffractive multifocal ophthalmic lens capable of generating at least three focal points, and the degree of freedom in setting the focal position. It is an object of the present invention to provide a diffractive multifocal ophthalmic lens having a large structure and a novel structure, and a novel manufacturing method thereof.

[Another problem that the present invention can optionally solve]
As a result of the inventor's repeated research to solve the above-mentioned problems, the present inventors have recognized other problems inherent in the above-described diffractive lens having the above-described conventional structure. It became clear that it could be solved if necessary. Therefore, in addition to solving the above-described problems, the present invention can appropriately deal with other problems described below as necessary.

  Another problem that the present invention can arbitrarily solve is that, in a diffractive multifocal ophthalmic lens, for example, a suitable focus group is appropriately developed according to the situation of a lens user (patient), or each focus is This is to meet the demand for varying the intensity ratio of light at a position. When an ophthalmic lens such as a contact lens or an intraocular lens is attached to or inserted into the eye, the range of light emitted from or incident on the ophthalmic lens is determined by the size of the eye pupil. Therefore, the effective aperture diameter on the lens side that substantially determines the entrance and exit of light also changes correspondingly if the pupil changes. The diffractive multifocal lens of the prior document has a basic characteristic that the number of focal points and the focal point position do not change even if the aperture diameter changes.

  Such characteristics can sometimes cause problems with reduced efficiency of light energy due to unnecessary focus generation.

  The size of the pupil changes depending on the brightness of the light. When the pupil is bright, the pupil is small, and when the pupil becomes dark, the pupil becomes large. The pupil has a function of adjusting the amount of light entering the eye, but also has a function of adjusting the depth of focus. In general, the pupil of a person is considerably small in an environment where the illuminance of light is very high, such as a sunny outdoor day. As the pupil becomes smaller, the depth of focus becomes deeper. For example, even in a single focus lens that is focused far away in such an environment, it may be visible to the middle region. Similarly, even when a bifocal ophthalmic lens having a focal point in the far and near directions is used, the depth of the respective focal points becomes deeper in a clear outdoor environment. As a result, the intermediate region is complemented not only from the far depth of focus but also from the near depth of focus. Even in the case of a bifocal ophthalmic lens that has only two focal points, the object in the intermediate region. It will be possible to see. In other words, there is no need to provide an intermediate focus in such an environment. On the other hand, the diffractive lens of the prior document has a characteristic that the intermediate focus is constantly generated regardless of the size of the aperture diameter, so that the intermediate focus is generated even in the situation where the intermediate focus is unnecessary. When the number of focal points increases, the amount of light energy for generating a new focal point is distributed from other focal points, and the brightness and contrast when looking at objects may decrease at the focal point of the distribution source. . Since such a decrease in brightness and contrast may lead to a decrease in the quality of appearance, it is preferable not to set an unnecessary focus in a situation where there is no necessity.

  Considering the work using the personal computer as the target work when viewing the intermediate area, the environment in which such work is performed is mainly indoor standard illuminance (brightness under fluorescent lamps). In such an environment, since the illuminance is lower than that in the clear outdoor environment, the pupil is somewhat expanded accordingly. When the pupil is widened, the depth of focus becomes shallow, so that it is difficult to cover the intermediate area with the depth of focus. Therefore, for the first time, it is necessary to provide a specification for generating an intermediate focus in a lens aperture region corresponding to the pupil diameter of such an environment. If the aperture area where the generation of such an intermediate focus is required is a transition area, in order to keep the quality of visibility at an aperture diameter smaller than the transition area, the far and near two-focus specifications are used. It is preferable that the specification of the diffractive structure is such that an intermediate focal point is generated only in addition to the two focal points in a situation where a transition region is reached.

  The specification that gives a plurality of different focal points with different areas in the lens is not limited to the combination of the intermediate focal point with respect to the far and near focal points, and the focal point is further closer to the far and near focal points. It may also be necessary in a diffractive ophthalmic lens for application. In a patient with early presbyopia with a residual adjustment force of about 2D, it is visible from a far focus to a point about 50 cm in front. Therefore, the prescription of multifocal ophthalmic lenses for such patients is considered to be based on the two focal points for far and near because the necessity and importance of specifications for generating an intermediate focus are not so high. Become. However, even in such patients, a different focus may be required at different positions other than the far and near positions. In an environment where the illuminance is reduced, such as in a dimly lit room, the contrast of the object generally tends to decrease. In this case, even if a near focus is provided, near objects may not be sufficiently visible due to the character size and contrast. In such a situation, a person often takes a physiological action to look closer at an object. In this case, in addition to the two far and near focal points, if another focal point is provided at a point located closer to the near side, it is possible to give a clear view even when an object is further brought closer. Become. In such a situation, the lens aperture diameter corresponding to the pupil diameter at the brightness under twilight becomes the transition region. Therefore, as a multifocal ophthalmic lens that can cope with such usage conditions, the bifocal of far and near is basically used up to the transition area, and another near focus that can be seen closer to the area is also given. It is preferable to make the specifications as possible. In such a multifocal ophthalmic lens, it is necessary to have a design specification in which a lens region newly appearing as the pupil expands (perhaps the outer periphery of the diffractive structure) is focused on a closer position. .

  Thus, there are cases where it is desired to provide a diffractive multifocal ophthalmic lens in which a focal group required for each lens region is effectively arranged according to the use environment and purpose of a patient. In the multifocal ophthalmic lens, it has been extremely difficult to meet such a demand.

[I] Definition of Words Prior to the description of the present invention, the words and phrases used in the present invention are defined as follows.

  The amplitude function (distribution) is a function (distribution) mathematically describing the characteristics as a light wave, and is specifically represented by [Equation 2].

  The phase corresponds to φ (x) in [Equation 2], and is one of the parameters indicating the state as a wave of light. Specifically, it takes the position of the valley and peak of the wave or every elapsed time. The position is determined. It also accelerates or delays the progression of the wave by changing the phase. In the present invention, the phase is expressed by φ, and its unit is radians. For example, one wavelength of light is expressed as 2π radians and a half wavelength is expressed as π radians.

  Phase modulation generally refers to a structure or method provided in a lens that changes the phase of light incident on the lens in some way.

  The phase function is a function that represents a phase change in the exponent part of the [Equation 2] or the cos function. In the present invention, the variable of the phase function is mainly a position r in the radial direction from the center of the lens, and is used to represent the phase φ of the lens at the point r. Specifically, an r-φ coordinate system as shown in FIG. It will be represented by 10. In addition, a representation of the phase distribution in the entire region provided with the phase modulation structure in the same coordinate system is called a phase profile (Profile) or simply a profile. Note that the r axis at φ = 0 is taken as a reference line, and at the point where φ = 0, incident light is emitted without changing its phase. When φ takes a positive value with respect to the reference line, light progresses by the phase, and when φ takes a negative value, the light advances by the phase. In an actual ophthalmic lens, a refracting surface not provided with a diffractive structure corresponds to this reference line (surface).

  The optical axis is a rotationally symmetric axis of the lens, and here refers to an axis extending through the center of the lens to the object space and the image side space.

  The 0th order focal point refers to the focal position of the 0th order diffracted light. Hereinafter, the focus position of the + 1st order diffracted light is referred to as the + 1st order focus.

  A zone is used here as the smallest unit in a diffractive structure. For example, a region where one blaze is formed is called one zone or zone region.

Blaze refers to a form of phase function, for example, a phase that changes in the form of a roof. In the present invention, the basic one of the blaze is that a single flow roof-shaped mountain (ridge line) 12 and valley (valley line) 14 change in a straight line in one zone as shown in FIG. In the present invention, the concept of blaze is also included in the present invention, such as a connection between the mountain 12 and the valley 14 so as to change with a parabolic curve (FIG. 2 (b)) and an uneven shape (square wave shape). In addition, the peak 12 and the valley 14 are connected so as to change as a part of the function of the sine wave (FIG. 2C), and further connected so as to change in a section not including the extreme value in a certain function. Are also included in the concept of blaze. In the i-th zone blaze as shown in unless otherwise indicated in the present invention FIG. 2 (a), the position of the outer diameter radius r _i of the zone and the phase phi _i, the position of the inner diameter radius r _i-1 Basically, the absolute value of the phase φ _i-1 is set to be equal to the reference plane (line), that is, | φ _i | = | φ _i-1 |. The blaze phase function φ (r) is expressed as [Equation 3]. If necessary, the blaze may be arbitrarily shifted in the φ axis direction with respect to the reference plane (line). The blaze shift amount is set by τ in [Equation 3], and the unit is radians.

  The phase constant refers to the constant h defined by [Equation 4] in the blazed phase function.

  Relief is a general term for a micro-concave structure formed on the surface of a lens obtained by specifically converting the lens into a real shape reflecting the optical path length corresponding to the phase defined by the phase profile. A specific method for converting the phase profile into a relief shape is as follows.

  When light is incident on a medium having a certain refractive index, the speed is reduced by the refractive index. The wavelength changes by the amount of delay, resulting in a phase change. Since a positive phase in the phase profile means that the light is delayed, if the light is incident on a region having a high refractive index, it is the same as the case where the positive phase is given. Note that these plus and minus are relative expressions. For example, even if the phase is −2π and −π, even if the phase is the same, the latter is delayed, so a region with a high refractive index is set.

  For example, in the case of having a blazed phase function, the actual blazed level difference is expressed by [Equation 5]. Such a relief shape can be provided on the lens surface by cutting with a precision lathe or molding.

  The intensity distribution is a plot of the intensity of light after passing through the lens over a certain region, and is expressed as a conjugate absolute value of the amplitude function.

[Ii] Aspects of the Present Invention The characteristic aspects of the present invention aimed at solving the above-mentioned [Problems to be solved by the present invention] are as follows using the above defined words and phrases. expressed.

  That is, according to the first aspect of the present invention, in a diffractive multifocal ophthalmic lens composed of a plurality of concentric zones, a part or all of the diffractive structure is a zone region set based on [Equation 6] ( 1) and the zone area (2) set based on [Equation 7], and the nth zone radius of the zone area (1) and the mth zone radius of the zone area (2) are the same. The zone up to the nth zone of the zone area (1) is arranged inside the zone area (2), and the (m + 1) th and subsequent zones of the zone area (2) are the nth zone of the zone area (1). It is characterized by being arranged adjacent to the outside.

  In the diffractive multifocal ophthalmic lens structured according to this aspect, as will be apparent from the analysis and examples described later, at least three focal points are set with a great degree of design freedom and good positional accuracy. Is possible.

  In addition, practically necessary light intensity can be secured at each focal point, and a good appearance can be provided.

  In addition, the position of each zone region can be adjusted and set in the lens radial direction, as will be specifically shown in the embodiments described later. By setting the position of each zone area in consideration of changes in the pupil diameter in vision, it is possible to substantially express the focus according to the environment such as illuminance or to vary the light intensity ratio at the focus position. Become.

  Note that the diffractive multifocal ophthalmic lens having a structure according to the present invention has a specific structure in the zone region connection portion defined by the setting formula, and the zone region connection portion is uniform in the lens radial direction. It is not limited to the location, and it is also possible to set zone region connections at a plurality of locations in the lens radial direction.

  Further, when providing such connecting portions at a plurality of locations in the lens radial direction, three or more types of zone regions may be formed so as to spread over a predetermined width in the lens radial direction, or two or more types of zone regions may be formed. It is also possible to form the zone region with a predetermined width alternately or repeatedly in the lens radial direction.

  Furthermore, the present invention relating to a diffractive multifocal ophthalmic lens can also be configured in the following aspects.

That is, according to a second aspect of the present invention, in the diffractive multifocal ophthalmic lens according to the first aspect, the zone region (2) has different additional refractive powers P ₁ ′, P ₂ ′,. There are a plurality of lens regions in the lens radial direction, and the plurality of zone regions (2 ₁ ), (2 ₂ ),... Adjacent to each other in the lens radial direction are connected at the same zone radius position. Thus, they are arranged on the inner peripheral side and the outer peripheral side adjacent to each other at the zone radius position.

According to this aspect, it is possible to realize a diffractive multifocal ophthalmic lens having a zone region that can provide substantially three or more different focal points in addition to the focal point by the 0th-order diffracted light. The relationship between the zone region (2 ₁ ) and the zone region (2 ₂ ) can be grasped in the same way as the relationship between the zone region (1) and the zone region (2). Therefore, any of the relational expressions between the zone area (2n) and the zone area (2m) described in this specification can be used as a relational expression between the zone area (2 ₁ ) and the zone area (2 ₂ ). It is possible to set a zone according to their relational expression.

  According to a third aspect of the present invention, in the diffractive multifocal ophthalmic lens according to the first or second aspect, the additional refractive power P given by the zone region (1) and the additional refractive power P given by the zone region (2). 'Is made to have a relation of [Equation 8].

  Note that the mathematical expression specifying the present invention is not limited to the above [Equation 8], and represents a technical idea and serves as a design index. For example, an error occurs in a manufacturing process or the like. Therefore, the requirements for a diffractive multifocal ophthalmic lens manufactured and provided with a structure according to the present invention are only required to satisfy the requirements of each formula so as to achieve the intended technical effect. Therefore, it is not necessary to interpret the requirements strictly mathematically, as long as the optical effects of the present invention are exhibited.

According to a fourth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to any one of the first to third aspects, the first zone radius r ₁ of the zone region (1) and the zone region (2) ) In the first zone radius r ₁ ′ is set to have a relation of [Equation 9].

  A fifth aspect of the present invention is the diffractive multifocal ophthalmic lens according to the fourth aspect, wherein α = 0 in the above [Equation 9].

According to a sixth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to any one of the first to fifth aspects, the first zone radius r ₁ of the zone region (1) and the zone region (2) ) Of the first zone radius r ₁ ′ is expressed by [Equation 10] and [Equation 11], respectively.

  A seventh aspect of the present invention is a diffractive multifocal ophthalmic lens according to any one of the first to sixth aspects, wherein in the diffractive structure, at least two radially adjacent zones of the zone are equally spaced. Including equally spaced zones.

  As shown in the examples described later, by using an equally spaced zone as a diffraction zone, the degree of freedom in tuning such as adjustment of the peak position of the light intensity at the focal point is maintained while maintaining the optical characteristics of the basic diffraction structure. Can be bigger.

  According to an eighth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to the seventh aspect, the equally spaced zones are arranged in the zone region (1).

  According to a ninth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to the eighth aspect, the equidistant zone is the number of the (ns) zone radius point of the zone region (1). At least two are included in the range of the (nt) -th zone radius point. However, 0 ≦ t <s <n, and t and s are integers.

  A tenth aspect of the present invention is the diffractive multifocal ophthalmic lens according to any one of the seventh to ninth aspects, wherein the equally spaced zones are arranged in the zone region (2). .

  An eleventh aspect of the present invention is the diffractive multifocal ophthalmic lens according to the tenth aspect, wherein the equally-spaced zone is the (ms−) th zone radius point of the zone region (2). To (mt ′)-th zone radius point. However, 0 ≦ t ′ <s ′ <m, and t ′ and s ′ are integers.

  In the equidistant zone described in the seventh to eleventh aspects of the present invention described above, a diffraction zone is partially formed in either the zone region (1) or the zone region (2). Or may be partially adopted in both of the zone regions.

  According to a twelfth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to any one of the first to eleventh aspects, at least three focal points can be generated by diffracted light. .

  According to a thirteenth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to the eleventh aspect, one of the three focal points is a far vision focal point and the other focal point is near. This is a visual focus, and yet another focus is an intermediate visual focus.

  According to a fourteenth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to the first third aspect, the focal point for far vision is given by zero-order diffracted light of a diffractive structure, and the focal point for near vision and the intermediate point The visual focal point is given by + 1st order diffracted light.

  A fifteenth aspect of the present invention is a diffractive multifocal ophthalmic lens according to any one of the first to fourteenth aspects, wherein the at least three focal points have a lens aperture diameter of 1.2 mm or more in diameter. It was made to generate. In consideration of the fact that the depth of focus increases when the pupil is reduced according to the degree of brightness of the environment as described above, in general, by setting the optical diameter to 1.2 mm or less, it is possible to perform intermediate vision in a clear outdoor environment. By suppressing the occurrence of this, it is possible to efficiently secure the amount of light energy at the required focal point and improve the contrast.

  According to a sixteenth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to any one of the first to fifteenth aspects, the diffraction zone is characterized by a phase function for modulating the phase of light. It is formed with a diffractive structure.

  According to a seventeenth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to the sixteenth aspect, the phase function is a blazed shape function.

  According to an eighteenth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to the seventeenth aspect, the phase function φ (r) of the blazed shape is represented by [Equation 12].

  According to a nineteenth aspect of the present invention, in the diffractive multifocal ophthalmic lens according to any one of the first to eighteenth aspects, the diffractive structure is constituted by a relief structure reflecting an optical path length corresponding to a phase. It is what.

  In the present invention, the diffractive structure that gives diffracted light can be configured with a refractive index distribution capable of modulating the phase, for example. However, it is preferable to use a relief reflecting the optical path length in a geometrical uneven shape such as a chevron according to this embodiment, thereby improving the focus design and accuracy.

  In addition, the present invention provides a method for producing a diffractive multifocal ophthalmic lens including the following steps as a method for advantageously producing the diffractive multifocal ophthalmic lens as described in the first to nineteenth aspects. , Feature. That is, according to the method of the present invention, in manufacturing a diffractive multifocal ophthalmic lens composed of a plurality of concentric zones, a step of determining a diffractive structure (1) that gives a desired additional refractive power P, Determining the diffractive structure (2) that gives another additional refractive power P ′, and the zone radius in the diffractive structure (1) and the zone radius in the diffractive structure (2) are the same radial position r, A step of obtaining an n-th zone in the diffractive structure (1) and an m-th zone in the diffractive structure (2), respectively, and an nth zone region or less in the diffractive structure (1) on the inner peripheral side of the radial position r A diffractive multifocal ophthalmic lens manufacturing method including a step of providing m + 1 or more zone regions in the diffractive structure (2) on the outer peripheral side of the radial position r.

  Further, in the method of the present invention, a mode in which the radial position r is set within a radius range that is greater than or equal to the minimum diameter of the pupil of the wearer and smaller than the maximum diameter can be suitably employed. Thereby, for example, the diffractive multifocal ophthalmic lens according to the fourteenth aspect can be advantageously provided.

  As is apparent from the above description, according to the present invention, the degree of freedom in setting the focal position is ensured as compared with a diffractive multifocal lens having a conventional structure, and thereby, for example, near, middle, far Therefore, it is possible to independently set the focal point at the intermediate position with a large degree of freedom by avoiding the interlocking of the focal points when setting the three focal points.

  In addition, when necessary, for example, by setting the position of each zone area in consideration of changes in the pupil diameter of the wearer, the intensity ratio or intensity ratio changes substantially depending on the usage environment, etc. It is also possible to set the focus. Such a technical effect can be enjoyed as necessary, and is not necessarily achieved in the present invention.

It is a graph of the phase function in a r-phi coordinate system showing the phase (phi) of the light in a diffraction lens by the relationship with the lens radial direction position r. It is a graph which illustrates the blaze as one form of the phase function in a diffraction lens. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 1 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffraction multifocal ophthalmic lens as Example 2 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 3 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffraction multifocal ophthalmic lens as Example 4 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 5 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 6 of this invention, Comprising: (a), (b), (c) is a phase profile of zone area | region (1), (2 ₁ ), (2 ₂ ). (D) shows the combined phase profile, and (e) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 7 of this invention, Comprising: (a), (b), (c) is a phase profile of zone area | region (1), (2 ₁ ), (2 ₂ ). (D) shows the combined phase profile, and (e) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure which shows the combination pattern of the diffraction structure based on the zone radius coincidence condition about zone area | region (1), (2 ₁ ), (2 ₂ ), (2 ₃ ). It is a figure regarding the diffractive multifocal ophthalmic lens as Example 8 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 9 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 10 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 11 of this invention, Comprising: (a), (b), (c) is a phase profile of zone area | region (1), (2 ₁ ), (2 ₂ ). (D) shows the combined phase profile, and (e) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 12 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 13 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 14 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 15 of this invention, Comprising: (a), (b), (c) is a phase profile of zone area | region (1), (2 ₁ ), (2 ₂ ). (D) shows the combined phase profile, and (e) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 16 of this invention, Comprising: (a), (b), (c) is a phase profile of zone area | region (1), (2 ₁ ), (2 ₂ ). (D) shows the combined phase profile, and (e) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 17 of this invention, Comprising: (a), (b), (c) is a phase profile of zone area | region (1), (2 ₁ ), (2 ₂ ). (D) shows the combined phase profile, and (e) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is a graph which shows the intensity distribution of the optical axis direction in the diffraction multifocal ophthalmic lens as Example 18 of this invention. It is a figure regarding the diffractive multifocal ophthalmic lens as Example 19 of this invention, Comprising: (a), (b) shows the phase profile of zone area | region (1), (2), (c) Shows the combined phase profile, and (d) is a graph showing the intensity distribution in the optical axis direction of the diffractive structures formed by the combination. It is the graph which showed the phase profile and intensity distribution in an optical axis direction in the diffractive multifocal ophthalmic lens which varied the phase constant as Example 20 of this invention to (a), (b).

  Hereinafter, the present invention will be clarified more specifically by describing modes for carrying out the present invention.

[A. Example of application of Fresnel spacing]
[A-1. Basic mode using standard Fresnel zone setting formula]
It is assumed that there is a Fresnel zone that gives the additional refractive power P based on [Expression 1] that is the Fresnel zone setting formula described above, and the nth zone radius is expressed by the following [Expression 13]. This zone area is defined as a zone area (1). In the following description, unless otherwise specified, the zone radius indicates the radius of the outer diameter of the zone. Similarly, a different Fresnel zone that gives the additional refractive power P ′ based on the above [Equation 1] is defined as a zone region (2), and the m-th zone radius of the region is represented by the following [Equation 14].

  Now, it is assumed that the additional refractive power P ′ for forming the zone region (2) is expressed by [Equation 15] using the additional refractive power P for forming the zone region (1).

  Substituting [Equation 15] into [Equation 14] yields [Equation 16] below.

Here, when r _n and r _m are equal, Equation 13] from Equation 16], the resulting relational expression [Expression 17].

  From [Equation 17], the following [Equation 18] relational expression is obtained.

  In [Equation 18], since n and m represent zone numbers, they always take integer values. In addition, since a and b in [Equation 18] are defined as integers, there are always combinations of n and m in which both sides are equal. That is, n and m are obtained by dividing a × b × Ω (Ω is an integer of 1 or more), which is a common multiple of a and b, by a or b, respectively. That is, the zone number is expressed by [Equation 19] and [Equation 20].

  As described above, when the additional refractive power P ′ of the zone region (2) is set to be [Equation 15] with respect to the additional refractive power P of the zone region (1), b × Ωth of the zone region (1). And the a × Ωth zone radius of the zone region (2) are the same.

  In addition, when there is a greatest common divisor in a and b, it is displayed by a number divided by the greatest common divisor. For example, when a = 6 and b = 8, the greatest common divisor of both is 2, so the value divided by this is used. a = 6/2 = 3, b = 8/2 = 4, and so on.

  If this relationship is utilized, it is possible to smoothly switch from the b × Ωth zone of the zone region (1) to the (a × Ω + 1) th zone of the zone region (2) and shift. As a result, the zone region (1), the zone region (2), and a part of the interval between the zones can be maintained and connected to form a coexisting diffraction structure. There are a plurality of such diffractive structures having different zone intervals determined by different additional refractive powers in different lens aperture regions. Therefore, a plurality of focal points corresponding to the respective additional refractive powers can be given to different regions of the diffractive lens depending on the size of the aperture.

  In general, the constant K in [Equation 1] is expressed as [Equation 21] using the design wavelength λ. [Equation 13] and [Equation 14] are expressed by [Equation 22] and [Equation 23] when [Equation 21] is used. [Equation 22] and [Equation 23] are hereinafter referred to as “standard setting formulas”.

  Specific examples of zone intervals determined by the standard setting formula are shown in [Table 1]. In [Table 1], the additional refractive power of the zone region (1) is set to P = 4D, and the additional refractive power of the zone region (2) is determined by changing the combination of (a, b) in [Equation 15]. The zone radius calculated by applying [Equation 22] or [Equation 23] for each force is shown. In the calculation, λ = 546 nm.

  In [Table 1], the relationship between the added refractive power and the zone radius of the zone region (1) and the zone region (2) will be examined. Paying attention to the zone of the zone region (2) in which the additional refractive power is 3.2D, P ′ is (4/5) times the additional refractive power P of the reference zone region (1). Therefore, a = 4 and b = 5 are assigned. From [Equation 19] and [Equation 20], the zone numbers having the same zone radius are as follows.

Zone region (1) ... n = 5Ω
Zone area (2) ... m = 4Ω

  From this, the zone radius of zone area (1) n = 5, 10, 15th,... And the zone radius (2) of P ′ = 3.2D, m = 4, 8, 12th,. It can be seen from [Table 1] that the zone radii of each match.

  When the additional refractive power of the zone region (2) is P ′ = 2.6667D, since P ′ = (2/3) × 4 = 2.667667D, a = 2 and b = 3 are assigned. Therefore, the next zone number matches.

Zone region (1) ... n = 3Ω
Zone area (2) ... m = 2Ω

  From Table 1, n = 3, 6, 9,... Zone of the zone area (1) and m = 2, 4, 6,... Of the zone area (2) of P ′ = 2.6667D.・ ・ You can see that the zone radii are the same.

  On the other hand, even when P ′ is larger than the reference additional refractive power P, this relationship is established. For example, when P ′ = 5D, a = 5 and b = 4 are assigned. In this case, n = 4Ω, m = 5Ω, n = 4, 8, 12,... Of the zone area (1) and m = 5 of the zone area (2) of P ′ = 5D, It can be seen that the 10th, 15th,.

  From the above relationship, if the (m + 1) th zone of the zone region (2) is set next to the nth zone of the zone region (1), the zone interval of each region is maintained and one diffraction structure is maintained. It is possible to incorporate different zone regions into the.

  The invention is explained in more detail in the following specific examples. In the detailed description, the calculation simulation method, conditions, and output data used in the present invention are shown below.

  The calculation software used was that which can calculate the amplitude distribution and intensity distribution from each zone based on a diffraction integral formula derived from a theory known in the field called scalar diffraction theory. The intensity distribution on the optical axis was calculated using such calculation software. In the calculation, the light source was set as a point light source existing in the distance, and the parallel light of the same phase was incident on the lens. Further, the calculation was performed on the assumption that the medium in the object-side space and the image-side space was a vacuum, and the lens was an ideal lens with no aberration (all the light emitted from the lens forms an image at the same focal point regardless of the exit position). The calculation was performed with the wavelength = 546 nm and the refractive power of the 0th-order diffracted light of the lens (refractive power as a base) = 7D.

  For the intensity distribution on the optical axis, the distance on the optical axis from the lens is converted into diopter, the focal position of the 0th-order diffracted light is normalized as 0D, and the intensity is plotted against the normalized scale.

  The lens aperture range to be calculated is the region up to the zone number described in each table in the examples unless otherwise specified.

[Example 1]
For the zone region (1) in which the additional refractive power P is P = 4D in [Table 1], the additional refractive power of the zone region (2) is set to a = 4 and b = 5 based on the above [Equation 15]. , P ′ = (4/5) × P = 3.2D is a specific example of a diffractive multifocal ophthalmic lens.

  From [Equation 19] and [Equation 20], between such zone regions, the n = 5th zone radius of the zone region (1) and the m = 4th zone radius of the zone region (2) coincide. Therefore, a new diffractive structure is maintained while maintaining regularity of the Fresnel interval by combining the n = 1 to 5th zone of the zone region (1) and the m = 5 to 7th zone of the zone region (2). Can be set as The specific configuration is that the zone region (1) is arranged at the center of the diffractive structure and the zone region (2) is arranged outside the zone region (1), as if switching the points of the railway track. Thus, the structure is switched from the zone region (2) to the zone region (2). The phase function was set to a blazed function (a function based on the above [Equation 3]) with respect to the zone interval configured as described above, and the phase constant h was set to 0.5. In the following examples, the blaze phase constant was h = 0.5 and the phase shift amount was τ = 0 unless otherwise specified. Table 2 shows the profile of the diffractive multifocal ophthalmic lens based on the zone spacing combined with such a phase structure. In the table, the “zone area (1)” and “zone area (2)” columns indicate the zone interval of each area, and the “combined profile” column indicates that the zone area is switched at a point where the zone radii match. The combined zone spacing is shown. Note that the zone number in the “combined profile” field is i, and is displayed as a new serial number.

  The profile of a diffractive multifocal ophthalmic lens based on the combined zone spacing is shown in FIG. 3A and 3B show the phase profiles 16 and 18 of the zone regions (1) and (2), and the solid lines in the drawing show the zone regions to be combined. FIG. 3C shows a phase profile 20 based on the combined zone spacing. In the following examples, the phase profile of the zone region combined with each zone region is shown as a similar figure. FIG. 3D shows an intensity distribution 22 in the optical axis direction of the diffractive structure configured by switching the zones.

  The intensity peak located at 0D in FIG. 3D is derived from the 0th-order diffracted light in the zone regions (1) and (2). The intensity peak generated at a point of about 3.7D is mainly derived from the focus of the + 1st order diffracted light from the zone region (1), and the intensity peak generated at a point of about 3D is mainly from the zone region (2). This is derived from the focus by the + 1st order diffracted light. The focal point of 0D is set as a focal point for far vision, the focal point of about 3.7D is mainly a focal point corresponding to a near work such as reading, and the focal point of about 3D is a focal point for intermediate vision. It can be seen that the resulting diffractive multifocal ophthalmic lens is a multifocal ophthalmic lens that focuses in the far, middle and near regions.

  In the example of the trifocal diffractive multifocal ophthalmic lens based on the prior art, the focal point of the intermediate region is ½ of the focal point of the near region. For example, if the position of the focal point for near vision is 4D, The focal point is 2D. On the other hand, in the present invention, there is no such limitation, and it can be seen that the focal positions of the near and intermediate regions can be arbitrarily varied by setting the additional refractive powers of the zone regions (1) and (2).

  In this example, since the zone region (1) is arranged at the center of the lens, the image formation characteristic up to an aperture diameter (diameter) of about 2.3 mm mainly contributes from the zone region (1). Accordingly, when the pupil diameter is equal to or smaller than the aperture diameter, that is, when the illuminance is high, the near vision area and the additional refractive power P = 4D are the imaging characteristics of the zone area (1). It functions as a bifocal ophthalmic lens that gives two focal points to the viewing area. Next, when the illuminance decreases and the pupil widens, the zone region (2) is included, and at this stage, a new peak is generated in the intermediate region as shown in FIG. 3 (d). Therefore, as described in the above-mentioned problem (another problem that the present invention can optionally solve), a diffractive multifocal that can appropriately generate the necessary focal point when necessary corresponding to the physiological mechanism of the human pupil. An ophthalmic lens will be obtained. In the following examples, basically, the specification in which the zone region (1) is arranged at the center of the diffractive structure is the object. Therefore, in the situation where the pupil is small, the imaging characteristics of the zone region (1) are first expressed as in this example, and in the situation where the pupil is widened, the imaging characteristics of other different zone areas are additionally expressed. It becomes.

[Example 2]
The additional refractive power of the zone region (1) is the same as in Example 1, and the additional refractive power of the zone region (2) is a = 3, b = 5, and P ′ = (3/5) × P = 2.4D. An example is shown below. In such an example, the n = 5th zone radius of the zone region (1) matches the m = 3rd zone radius of the zone region (2). Therefore, a new diffractive structure was set in which the first to fifth zones of the zone region (1) were arranged inside the diffractive structure and the fourth to sixth zones of the zone region (2) were arranged outside thereof. The zone interval of the zone area (2) was determined from the standard setting equation of [Equation 23]. Details of the diffraction structure are shown in [Table 3]. Further, the phase profiles 24, 26, and 28 of the diffraction structure according to FIGS. 4A, 4B, and 4C and the intensity distribution 30 in the optical axis direction are shown in FIG.

  The intensity peak generated at a point of about 3.9D is mainly derived from the focus of the + 1st order diffracted light from the zone region (1), and the intensity peak generated at a point of about 2 to 3D is mainly generated by the zone region (2 ) From the focal point by the + 1st order diffracted light from Since the additional refractive power of the zone region (2) is set to P ′ = 2.4D, which is smaller than that of the first embodiment, it is shifted to the far peak (0D) side accordingly. I understand.

  In this example, as in the first embodiment, when the lens aperture diameter extends to a range including the zone region (2), a new focus peak is generated in an arbitrarily set intermediate region. It can be seen that the lens can be a diffractive multifocal ophthalmic lens that can solve another problem that can be solved in an automated manner.

[Example 3]
The additional refractive power of the zone region (1) was the same as in Example 1, and the additional refractive power of the zone region (2) was set as P ′ = (2/3) × P = 2.667D. Accordingly, since a = 2 and b = 3, in this example, the zone radius (1) n = 3 and the zone (2) m = second zone radius coincide. By the way, the matching zone radius is not limited to such a zone number, but also matches between zones that are common multiples of a and b as shown in [Equation 19] and [Equation 20]. When Ω in [Equation 19] and [Equation 20] is Ω = 2, n = 3 × 2 = 6th zone in the zone region (1) and m = 2 × 2 = 4th zone in the zone region (2). The radius also matches. Therefore, in this example, based on this relationship, a new structure in which the inside of the diffractive structure is the first to sixth zones of the zone region (1) and the outside is the fifth to eighth zones of the zone region (2). A diffractive structure was set. Details of the diffraction structure are shown in [Table 4]. 5A, 5B, and 5C show phase profiles 32, 34, and 36 of this diffraction structure, and FIG. 5D shows an intensity distribution 38 in the optical axis direction.

  As described above, since the zone radii match even with values that are common multiples of a and b, this example is an example in which the zones are switched by matching the zones with arbitrary common multiples. Switching the zone between the common multiple zones does not affect the set additional refractive power P ', so the + 1st order diffracted light based on the zone region (2) has an intensity peak of about 2.5 to 3D, and the added setting It can be seen that the refractive power can be set within the range of P ′.

[Example 4]
In this example, the same combination of zone areas (1) and (2) as in Example 3 is used to switch to zone area (2) with a zone number different from that in Example 3, and return to zone area (1) again. It consists of The zone radii of the zone region (1) and the zone region (2) coincide with each other because the zone region (1) n = 3, 6,... And the zone region (2) m = 2, 4,.・ ・ Th. Therefore, the inside of the diffractive structure is set to the first to third zones of the zone region (1), the third to fourth zones of the zone region (2) are arranged outside thereof, and the zone region (1) is again arranged outside thereof. 7) to 9th zones are arranged. Details of the diffraction structure are shown in [Table 5]. 6A, 6B, and 6C show the phase profiles 40, 42, and 44 of this diffraction structure, and FIG. 6D shows the intensity distribution 46 in the optical axis direction.

  In addition to the 0D peak based on the 0th order diffracted light and the about 4D peak due to the + 1st order diffracted light in the zone region (1), there are a total of 4 intensity peaks of about 2.4D and 3.3D derived from the zone region (2). Mainly generated. In such an intensity distribution, since there are two peaks in the intermediate region between the near and far regions, it is possible to provide a diffractive multifocal ophthalmic lens in which the visibility of the intermediate region is further ensured. In this way, a diffractive multifocal ophthalmic lens can be obtained even if the region is switched a plurality of times at a point where the zone radii between the zone regions (1) and (2) coincide.

[Example 5]
In this example, the setting positions of the zone areas (1) and (2) in the second embodiment are reversed. That is, the zone regions (1) and (2) in the second embodiment are reversed to the zone regions (2) and (1) in this example, respectively, and the additional refractive power of the zone region (1) is set to P = 2.4D. The additional refractive power of the region (2) is set by P ′ = (5/3) × P = 4D. The zone numbers having the same zone radii are the same as those in the second embodiment. However, the inside of the diffractive structure is the first to third zones of the zone region (1) having the additional refractive power P = 2.4D, and outside the zone number (1). This zone is composed of the sixth to tenth zones in the zone region (2) having an additional refractive power of 4D. Details of the diffraction structure are shown in [Table 6]. FIGS. 7A, 7B, and 7C show the phase profiles 48, 50, and 52 of this diffraction structure, and FIG. 7D shows the intensity distribution 54 in the optical axis direction.

  It can be seen that an intensity peak is generated at a point corresponding to the additional refractive power of each zone region even in a diffractive structure configured by replacing the zone regions. In contrast to Example 2, the shape of the peak in the near and middle regions is slightly different. This is considered to be due to the difference in light interference depending on the permutation of the zone regions.

  In this example, since the zone of the additional refractive power P = 2.4 is arranged on the inner side, when the aperture diameter is small, a focal point is generated at a position based on the additional refractive power, and when the aperture diameter becomes wide, the zone region ( The focal point based on the additional refractive power P ′ = 4 in 2) is generated. The relationship between the aperture diameter and the focus generation is the specification of the multifocal ophthalmic lens in response to a request that the patient in the early stage of the presbyopia described above wants to view closer in an environment where the illuminance is reduced. Is. As described above, the additional refractive power of the zone region (1) may be arbitrarily determined according to the purpose, and the additional refractive power of the zone region (2) may be set larger or smaller than this. is there.

  From the above embodiments, when there are different zone regions that give different additional refractive powers, the new refractive powers are set based on [Equation 15], and the new zone regions are switched and combined at specific zone points. Therefore, it is possible to set a desired diffractive structure and obtain a desired diffractive multifocal ophthalmic lens.

[A-1-1. Switching zones across multiple zone areas]
As is clear from the above [Table 1], there are combinations in which the zone radii coincide between the different zone regions (2). For example, in [Table 1], the third zone when P ′ = 3D and the second zone when P ′ = 2D have the same zone radius. In addition, there are zone radii that are the same in some groups.

This relationship is explained as follows. In the following examples and explanations, different zone areas (2) are represented in different zone areas (2) by zone areas (2 ₁ ), (2 ₂ ), (2 ₃ ),... The additional refractive power of each region is P ₁ ′, P ₂ ′, P ₃ ′,..., The zone number is m ₁ , m ₂ , m ₃ ,. Are represented as (a ₁ , b ₁ ), (a ₂ , b ₂ ), (a ₃ , b ₃ ),.

P ₁ ′, P ₂ ′, P ₃ ′,... Are (a ₁ / b ₁ ), (a ₂ / b ₂ ), (a) for the additional refractive power P of the reference zone region (1), respectively. a ₃ / b ₃ ),... When attention is focused on the additional refractive powers P ₁ ′ and P ₂ ′, the additional refractive powers of both are expressed as [Equation 24] and [Equation 25] using the reference additional refractive power P.

  From [Equation 24] and [Equation 25], [Equation 26] is obtained.

And the m ₁ th zone radius zone region (2 _1), the number [a similar relationship between [number 18] under the condition that the m ₂ th zone radius zone area (2 ₂₎ coincide 27 ] Can be obtained.

In [Equation 27], a ₁ , b ₁ , a ₂ , and b ₂ are defined by integers, so the zones shown by [Equation 28] and [Equation 29] as in [Equation 19] and [Equation 20]. The zone radius matches with the number.

When P ₁ ′ = 3D, (a ₁ , b ₁ ) = (3,4), and P ₂ ′ = 2D, (a ₂ , b ₂ ) = (1, 2), so [Equation 30] [Equation 31] When divided by the greatest common divisor “2” of each coefficient, the result is as follows.

Therefore, the second, fourth, and sixth zone radii of P ₂ ′ = 2D coincide with the third, sixth, and ninth zones of P ₁ ′ = 3D.

  In this way, even between different P's, zones can be switched while maintaining the respective Fresnel zone intervals.

  Using the above relationship, the zone region (1) that gives the reference additional refractive power and another zone that gives different additional refractive power in the zone region (2) can also be incorporated into the diffractive structure. An example in which a diffractive multifocal ophthalmic lens is specifically designed based on this relationship is shown below.

[Example 6]
The additional refractive power of the zone region (1) is P = 4D, and the zone region (2) has a plurality of zones in which two zones of additional refractive powers P ₁ ′ = 2.4D and P ₂ ′ = 3D are structural units. Was used. Incidentally, P ₁ '= 2.4D zone area zone region (2 _1), P _2' = and expressed as 3D zone area zone region (2 _2). The zone radius of each zone area is shown in [Table 7].

Since the additional refractive power of the zone region (2 ₁ ) is P ₁ ′ = (3/5) × P = 2.4D, a ₁ = 3, b ₁ = 5, and n = 5th in the zone region (1) , M ₁ = 3rd zone radius of the zone region (2 ₁ ) matches. Here, there is a zone that can be switched first. Since the additional refractive power of the zone region (2 ₂ ) is P ₂ ′ = (3/4) × P = 3D, a ₂ = 3, b ₂ = 4, and n = 4, 8,. .. and the zone radius (2 ₂ ) of m ₂ = 3, 6,. On the other hand, between the zone region (2 ₁ ) and the zone region (2 ₂ ), from [Equation 28] and [Equation 29], m ₁ = 3 × 4 × Ω = 12Ω and m ₂ = 3 × 5 × Ω. = 15Ω, and the zone radii are the same in a zone of 4Ω and 5Ω divided by the greatest common divisor “3”. From the relationship of these zone radii, the profile of the diffraction structure was set as follows.

First, the center of the diffractive structure was set as the first to fifth zones of the zone region (1), and the fourth zone of the zone region (2 ₁ ) was arranged outside thereof. The sixth zone of the zone region (2 ₂ ) was provided outside the zone region, and the ninth and tenth zones of the zone region (1) were further arranged outside the zone. The phase profiles 56, 58, 60, 62 in which the zone regions are switched are shown in [Table 7] and FIGS. 8 (a) to 8 (d). Further, the intensity distribution 64 in the optical axis direction of the diffractive structure is shown in FIG. The phase profiles 56, 58, 60, and 62 have the same blazed shape as in the above-described embodiment group and a phase constant h = 0.5.

The intensity distribution of this example includes the zone region (2 ₁ ) and the zone region (2 ₂ ), so that the additional refractive power is also influenced by the mutual interference between the zone region group and the zone region (1). The intensity distribution is such that multimodal peaks are continuous over 2 to 4D. Also in this example, when the aperture diameter is small, the bifocal imaging characteristic is formed only by the contribution of the zone region (1), and when the aperture diameter is large, the intensity distribution 64 shown in FIG. 8E is obtained. When the aperture diameter is increased, the intensity distribution 64 shown in FIG. 8E is obtained, which is useful as a multifocal ophthalmic lens that can almost cover the intermediate region from near.

  [Equation 19], [Equation 20], [Equation 28], and [Equation 29], which are the relational expressions in which the zone radii coincide, do not depend on the value of the additional refractive power P of the zone region (1). The results shown in (3) hold true even if the reference additional refractive power P is varied.

The same is true even when only the additional refractive power of the zone region (1) is changed to P = 2.5D without changing the integer ratio for setting the additional refractive power of the zone regions (2 ₁ ) and (2 ₂ ) of the sixth embodiment. Example 7 shows that the zone can be switched.

[Example 7]
In Example 6, the additional refractive power of the zone region (1) is changed from P = 4D to P = 2.5D, and regarding the two zone regions (2 ₁ ) and (2 ₂ ) of the zone region ( ₂ ), In the same manner as in Example 6, the additional refractive power was set at a ₁ = 3, b ₁ = 5, a ₂ = 3, and b ₂ = 4. The additional refractive power of each zone region set under such conditions is as follows.

Zone area (2 ₁ ); P ₁ ′ = (3/5) × P = 1.5D
Zone area (2 ₂ ): P ₂ ′ = (3/4) × P = 1.875D

  Those set in this way can be switched to each zone area with the same zone number as in the sixth embodiment. Details of the diffraction structure are shown in [Table 8]. 9A to 9D show the phase profiles 66, 68, 70, 72 of the diffractive structure, and FIG. 9E shows the intensity distribution 74 in the optical axis direction.

  In this embodiment, since the additional refractive power of the zone region (1) is varied to P = 2.5D, the focal point of the zone region (1) by the + 1st order diffracted light appears as an intensity peak at a point of about 2.5D. The other focus peaks have the same distribution as in Example 6, and show a multi-peak intensity distribution from about 1.3D to 2.2D. From this example, it can be seen that if a relational expression having the same zone radius is used, the intensity distribution of the same pattern is exhibited even if the additional refractive power of the reference zone region (1) is arbitrarily changed. When the additional refractive power of the zone region (1) as shown in this example is 2.5D, an ophthalmic lens, for example, a multifocal contact, for a patient who still has a little adjustment power of his / her own eye. It becomes useful as a lens.

  As can be seen from the above example, by changing the values of a and b in [Equation 15], an additional refractive power different from the standard additional refractive power can be arbitrarily set. For example, in the case of incorporating an additional refractive power zone that is exactly half the reference additional refractive power, a = 1 and b = 2 may be used. In addition, when it is desired to increase the additional refractive power a little, it can be freely set within a range where a and b are integers such as a = 2, b = 3, or a = 3, b = 4. is there. Due to this feature, in the prior art, the setting of the intermediate region focus in the prior art can be arbitrarily set in the present invention.

  Further, in the diffractive lens having the zone structure shown in the present example, for each zone area divided, + 1st order diffracted light having an additional refractive power determined in the area is additionally generated. As a result, a diffractive multifocal ophthalmic lens having such a diffractive structure can form a plurality of different focal points in different regions, and can provide a necessary focal point according to changes in the pupil diameter due to the environment. A multifocal ophthalmic lens can also be obtained.

  This characteristic is ideal in consideration of the relationship between the aperture diameter and the depth of focus that define the substantial incidence or emission range of light in the lens. In other words, since the depth of focus is deep when the pupil diameter is small in the human eye, even if the lens is designed so that the focal point is only in two places in the distance, the depth of focus is substantially applied to the intermediate region. In addition, such an environment with a small pupil diameter is a case where the illuminance is high, such as a sunny day, and there is not much work frequency such as viewing the distance corresponding to the intermediate area in such an environment. Focus generation need not be considered. However, the pupil diameter is slightly enlarged and the depth of focus is shallow in a standard illuminance environment, such as when the work environment is changed to the office, but the lens of the present invention is intermediate in accordance with the transition of such a state. The focus in the region starts to be generated at the right time.

  In general, it is difficult to see the near in an environment where the illuminance is low, such as in twilight, but in response to the request to see the nearer when it gets darker, the diffraction that appears when the illuminance decreases and the pupil expands In the zone region, it is possible to set a different near focus that generates a focus further in front of the near focus set in the inner zone.

[A-2. Zone switching using the extended setting formula]
(Setting formula for setting the zone first radius arbitrarily)
The setting of the zone is not limited to [Equation 1], and other setting formulas may be used. For example, it is also possible in the present invention to use the extended setting formula shown in the following [Equation 32].

  [Formula 1] is of a type in which the zone diameter is set in a form including the first zone diameter. On the other hand, [Formula 32] has a format in which the first zone diameter can be arbitrarily set. Even using such a setting formula, the zones in the present invention can be switched.

Here is r ₁ of the first zone diameter, the add power P, and the design wavelength lambda, and the n-th zone diameter as r _n. The region where the zone radius is determined by [Expression 32] is defined as the zone region (1) as described above.

It is assumed that the zone region (2) is expressed by the same formula. Add power zone area (2) P When ', the first zone radius r _1' and, the m-th zone radius r _m of the zone region (2) is represented by [Expression 33].

The condition that the zone radii of both zone regions coincide with each other is r _n = r _{m, and} therefore, [Expression 34] is obtained from [Expression 32] and [Expression 33].

  [Equation 35] is obtained by rearranging [Equation 34].

  Now, assume that the left side of [Equation 35] is represented by [Equation 36].

  [Equation 37] is obtained from [Equation 35] and [Equation 36].

  It is assumed that the additional refractive power P ′ of the zone region (2) is expressed by the above [Equation 15]. [Equation 38] is obtained from [Equation 15] and [Equation 37].

  Therefore, the zone number (n, m) for any (a, b) is set by [Equation 39] and [Equation 40].

  However, in [Equation 39] and [Equation 40], Ω ′ = Ω + γ (γ is the same as [Equation 36]).

In [Equation 38], the variable α is incorporated in addition to the variables a and b for setting the additional refractive power of the zone region (2). As a condition for matching the zone radii, a condition for changing α is newly added, and the first zone radius of the zone area (1) or the zone area (2) can be arbitrarily set. This further increases the degree of freedom in designing the diffractive multifocal ophthalmic lens. In this way, a series of formulas [Formula 36], [Formula 32], and [Formula 33] that increase the degree of freedom in setting r ₁ and r ₁ ′ by introducing α will be referred to as “extended setting”. It will be called “expression”.

  (A, b) when α is varied by an arbitrary value of α = 0, ± 1, ± 2, ± 3, ± 0.5 based on [Equation 38], [Equation 39], and [Equation 40] The combinations of (n, m) are shown in [Table 9] to [Table 16].

When α = 0, r ₁ = r ₁ ′ according to [Equation 36], and the first zone radii of the zone regions (1) and (2) can be made equal to be arbitrarily variable. In this case, [Equation 39] and [Equation 40] become [Equation 41] and [Equation 42], and the zone radii coincide with numbers obtained by adding 1 to the zone numbers that coincide with each other in the standard setting formula.

  For example, when the additional refractive power of the zone region (1) is set to P = 4D and the additional refractive power of the zone region (2) is set to P ′ = 3D, (a, b) is (a, b) = ( 3, 4). At this time, the zone numbers having the same zone radii are (n, m) = (5, 4), (9, 7), (13, 10),.

  When α is set to a value other than zero, it corresponds to setting the first zone radius of the zone region (2) differently while arbitrarily setting the first zone radius of the zone region (1).

[Table 10] shows the combination of (a, b) and (n, m) when α = 1 is set, and (a, b) = (8, 9) is added to the zone area (2). When the refractive power P ′ is set, (n,
m) = Zone radii of the areas (1) and (2) coincide with the zone numbers of (5, 5), (14, 13),. If P 'is set at (a, b) = (6, 7), the zone is (n, m) = (4, 4), (11, 10), (18, 16), ... The radii match.

  In the case of setting with the standard setting formula, (n, m) = (9, 8) when (a, b) = (8, 9), but in the extended setting formula introducing α shown in this example, (N, m) = (5, 5) matches with the smallest number, and the zone can be switched in a smaller zone area.

  Also, in the same (a, b), when α is varied, the combination of (n, m) also changes. For example, if α = 3, (n, m) = (4, 5), (13, 13),... And α = 1 for (a, b) = (8, 9) The zone radii coincide with numbers different from those in the case ([Table 12]). Thus, the zone radius matching condition can be finely adjusted by setting α, and a diffractive multifocal ophthalmic lens with a higher degree of freedom can be designed.

  Even when α = ± 0.5 ([Table 16]), there are numbers with the same zone radius. Therefore, in [Equation 36], α = β + γ, β is an integer, and γ is 0 or 0.5.

  Further, switching of zones over a plurality of zone areas described in the [A-1] column is also possible.

For example, if (a, b) = (3, 4) in [Table 9], the zone radius of zone areas (1) and (2 ₁ ) is the zone number where (n, m) = (5, 4) Match. Therefore, the inside of the diffractive structure can be set by the first to fifth zones of the zone region ( ₁ ), and the fifth zone of the zone region (2 ₁ ) can be set outside thereof. Assuming that the zone area (2 ₁ ) is set up to the seventh area, the seventh zone again matches the ninth zone radius of the zone area (1), so the outside of the zone area (2 ₁ ) It is possible to set the 10th zone from the zone area (1). The ninth zone radius of the zone region (1) is the eighth zone radius of the zone region (2 ₂ ) when (a, b) = (7, 8), or (a, b ) = (1, 2), which also coincides with the fifth zone radius of the zone region (2 ₃ ). Therefore, in addition to the zone area (1) in the seventh outer zone area (2 _1), the (a, b) = (7, 8) and comprising a zone area (2 ₂₎ ninth and subsequent zones Alternatively, the sixth and subsequent zones of zone (2 ₃ ) where (a, b) = (1, 2) may be arranged. Table 17 shows the relationship between zones in which the series of zone radii coincides, and FIG. 10 shows a combination pattern of diffractive structures based on the coincidence conditions.

  As described above, [Table 9] to [Table 17] indicate the genealogy of the switchable zones, and it is possible to select a desired arrangement and combination from such genealogy. In addition, this invention is not limited to this description example, It can apply also to another combination.

  By using the extended setting formula in this way, it is possible to switch the zone area while arbitrarily setting the first zone radius of the zone area (1), and the conditions for matching the zone radii are more diversified. This further increases the degree of design freedom. A specific example of a diffractive multifocal ophthalmic lens in which the zone is switched using such an extended setting formula is shown below.

[Example 8]
The zone radius of the zone region (1) was set using [Equation 32], where the additional refractive power of the zone region (1) was P = 4D and the first zone radius was r ₁ = 0.3950 mm. Next, when α = 1, the first zone radius of the zone region (2) was obtained from [Equation 36], and r ₁ ′ = 0.1396 mm. From [Equation 33], (a, b) = (2, 3) is set so that the additional refractive power of the zone region (2) becomes P ′ = (2/3) × P = 2.667D using such values. The zone interval of the zone area (2) was set.

  Under these setting conditions, from [Table 10], the zone area (1) and zone area (2) are the zones of (n, m) = (2, 2), (5, 4), (8, 6),. Match by number. Therefore, the inside of the diffractive structure is set by the first and second zones of the zone region (1), the third and fourth zones of the zone region (2) are set outside, and the zone is again outside the zone. The diffractive structure was set by switching the zones so that the sixth to eighth zones of the region (1) were arranged. Details of the phase profiles 78, 80, and 82 of the diffractive structure are shown in [Table 18] and FIGS. 11 (a) to 11 (c), respectively. Further, an intensity distribution 84 in the optical axis direction of the diffractive structure is shown in FIG.

  In the present embodiment, the first zone radius of the zone region (1) is made smaller by using the expansion setting formula, and the first zone diameter of the zone region (2) is also made smaller by setting α = 1. In this example, the zone radii that match in (n, m) = (3, 2) in Example 4 are the same in the second, and the number of zones in the zone region (1) Is one minute less. The optical axis intensity distributions in this example and Example 4 are substantially the same distribution, and it can be seen that the same effect can be obtained even if the number of zones in the region (1) is reduced by one. In this example, the outermost diameter of the diffractive structure is about 1.438 mm in radius, and similar imaging characteristics can be realized with a diameter smaller than the outermost diameter of Example 4 (about 1.567 mm in radius). As an application example of an ophthalmic lens that functions even when the aperture is small, it is useful as an ophthalmic lens for an elderly person whose pupil diameter has decreased with age, for example, an intraocular lens. From this example, it can be seen that the use of the extended setting formula increases the degree of design freedom.

[Example 9]
The zone radius of the zone region (1) was set using [Equation 32] with the additional refractive power of the zone region (1) being P = 4D and the first zone radius being r ₁ = 0.6033 mm. This set value is set to a value slightly larger than that given by the standard setting formula. In this example, α = 0 and the first zone radius of the zone region (2) is the same as that of the region (1). Using this value, the zone region (2) is set such that (a, b) = (2, 3) so that the additional refractive power of the zone region (2) becomes P ′ = (2/3) × P = 2.667D. Set the zone interval.

  Under these setting conditions, zone areas (1) and (2) are zone numbers (n, m) = (4, 3), (7, 5), (10, 7),. Match. Therefore, the inside of the diffractive structure is set as the first to seventh zones of the zone region (1), and the sixth to eighth zones of the zone region (2) are arranged outside the diffractive structure. Details of the phase profiles 86, 88, and 90 of the diffractive structure are shown in [Table 19] and FIGS. 12 (a) to 12 (c).

  The intensity distribution 92 in the optical axis direction of such a diffractive structure is as shown in FIG. 12D, and peaks forming focal points in the near and intermediate regions are generated based on the zone regions (1) and (2). Compared with Example 3 in which the added refractive powers of the zone regions (1) and (2) are the same as in this example, in Example 3, the zone region (1) is first to sixth and the region (2) is fifth to eighth. In this example, the area (1) is first to seventh, the area (2) is sixth to eighth, and the total number of constituent zones remains unchanged. The difference is that the number of constituent zones in each region is one more in region (1) and one less in region (2). In this example, as shown in FIG. 12 (d), an intensity distribution 92 substantially similar to that in Example 3 (FIG. 5 (d)) is provided, but an intensity peak is also generated in the vicinity of about 2.1D (FIG. 12 (d). ) Arrow). From this behavior, it can be seen that the range of focus generation in the intermediate region is wider than in the third embodiment.

  Thus, it can be seen that more detailed adjustment of the focus generation is possible by using the extended setting formula.

  In the extended setting formula, the first zone radius of the zone region (1) can be arbitrarily set, but a value determined from the standard setting formula may be used. In this case, the first zone radius of the zone region (2) can be set with a radius different from that according to the standard setting formula by varying α. Therefore, it is possible to design with a high degree of freedom similar to the above-described embodiment group.

  In this case, from [Equation 22] and [Equation 36], the first zone radius of the zone region (2) is determined by [Equation 43].

  An example in which α is varied while the first zone radius of the zone region (1) is determined by a standard setting equation is shown below.

[Example 10]
The additional refractive power of the zone region (1) is P = 4D, and the first zone radius is determined by the standard setting formula as before, and r ₁ = 0.5225 mm. Α in the extended setting equation was set to α = −1, and the first zone radius of the zone region (2) was calculated based on [Equation 43], and r ₁ ′ = 0.6399 mm. The interval between the zone regions (2) was determined by [Equation 33] so that the additional refractive power of the zone region (2) was P ′ = (4/5) × P = 3.2D. In such a combination, the fourth zone radius of the zone region (1) and the third zone radius of the zone region (2) match from [Table 13]. Therefore, the inner side of the diffractive structure is constituted by the first to fourth zones of the zone region (1), and the outer side thereof is constituted by the fourth to sixth zones of the zone region (2). Details of the phase profiles 94, 96, and 98 of the diffractive structure are shown in [Table 20] and FIGS. 13 (a) to 13 (c), respectively. Further, the intensity distribution 100 in the optical axis direction is shown in FIG.

  In this example and Example 1, the addition power setting (a, b) is the same combination, but in this example, the number of zones in the zone region (1) is one less than that in Example 1. It has become. Accordingly, in this example, the outermost radius of the diffractive structure is about 1.455 mm, and it can be seen that substantially the same intensity distribution is expressed with the outermost radius smaller than about 1.546 mm in Example 1. This example is also useful as an example of an ophthalmic lens that can be applied to a patient having a small pupil diameter.

[Example 11]
The additional refractive power, the first zone radius, and α of the zone region (1) are the same as those in the tenth embodiment, and the zone region (2) and zone regions (2 ₁ ) and (2 ₂ ) that give two different types of additional refractive power are used. Consists of. The additional refractive power of the zone region (2 ₁ ) is P ₁ ′ = (2/3) × P = 2.667 D, and the additional refractive power of the zone region (2 ₂ ) is P ₂ ′ = (4/5) × P = 3.2D. The first zone radius of the regions (2 ₁ ) and (2 ₂ ) is 0.6399 mm from [Equation 43], and the zone interval corresponding to each additional refractive power is determined from [Equation 33]. In such a combination, from [Table 13], the sixth zone radius of the zone region ( ₁ ) and the fourth zone radius of the zone region (2 ₁ ) match. In addition, since the ninth zone radius of the region ( ₁ ) matches the sixth zone radius of the region (2 ₁ ) and the seventh zone radius of the region (2 ₂ ), respectively, the zone region (2 ₁ ) The sixth zone radius and the seventh zone radius of the region (2 ₂ ) also coincide with each other. From this relationship, the diffraction structure was set as follows. The inside of the diffractive structure is composed of the first to sixth zones of the zone region ( ₁ ), the fifth and sixth zones of the zone region (2 ₁ ) are arranged on the outer side, and the zone is on the outer side. The eighth and ninth zones of the region (2 ₂ ) were arranged. Details of the phase profiles 102, 104, 106 and 108 of the diffraction structure of this example are shown in [Table 21] and FIGS. 14 (a) to (d). Further, FIG. 14E shows an intensity distribution 110 in the optical axis direction of the diffractive structure.

  In this example, peaks having substantially the same intensity are generated in the near vision region of about 4D and the intermediate vision region of 3D. Such a focal region corresponds to a distance that is just right for a patient who has an intraocular lens inserted therein to read and monitor a personal computer monitor, and thus is a multifocal intraocular lens suitable for patients who place importance on such work.

The combination of the zone areas in this example is possible even when both the zone areas (1) and (2) use the standard setting formula. However, when the standard setting formula is used, the zone area (2 ₁ ) and the area are used. The zone number at which (2 ₂ ) is switched is not a small number as in this example, but is as large as m ₁ = 10 and m ₂ = 12. Therefore, since the region (2 ₂ ) is arranged on the very outside of the diffractive structure (about 2 mm in zone radius), there is a possibility that the region (2 ₂ ) may not fall within the range of the pupil diameter at general illuminance. Characteristics may not be manifested. However, if the extended setting formula is used as in this example, zone switching can be realized within a region sufficiently within the pupil, and such a concern can be avoided. In this way, a more detailed design is possible by using the extended setting formula.

  In the expansion formula using α, the zone region (1) is set as a standard setting, and when α = 2, the first zone radius of the zone region (2) becomes zero from [Equation 43], The two-zone radius becomes the substantial first zone radius ([Table 22]). This is an example in which the first zone is replaced with the second zone when the zone region (2) is also defined by the standard setting formula ([Table 1]). In this case, the zone number in which the zone radii in [Equation 38] match is a × n = b × (m−1). Therefore, if m−1 = m ′ is replaced, a × n = b × m ′. Thus, this is exactly the same as [Expression 18] of the standard setting formula. That is, it can be seen that the formula group ([Equation 36] to [Equation 43]) into which α is introduced is an extended formula for matching the zone diameters including the standard setting formula.

[A-3. A mode in which the zone radii can be matched even if the additional refractive power is not determined by an integer ratio (a mode based on a general setting formula)]
Up to this point, the zone radius coincidence condition has been determined by expressing the additional refractive power P ′ of the zone region (2) as an integer ratio based on the above [Equation 15] as the zone radius coincidence condition. Next, a description will be given of a method for making the zone radii coincide with an arbitrary additional refractive power without determining the integer ratio.

  If the nth and mth zone radii of the zone regions (1) and (2) represented by [Expression 32] and [Expression 33] are the same, the relational expression of [Expression 44] is obtained.

  [Equation 44] shows a relational expression for determining the first zone radius of the zone area (2). This expression is the first zone radius of the zone area (1) as the input value, the zone area (2 ) Additional refractive power P ′ and a zone number that can be matched may be arbitrary. That is, the zone radius (2) configured based on the first zone radius matches the zone value (1) with the zone radius (1). Therefore, when this equation is used, the additional refractive power of the zone region (2) need not be determined by an integer ratio, and the zone numbers that can be matched can be arbitrarily set. An example of a diffractive multifocal ophthalmic lens based on switching of zones between zone regions set based on such an expression is shown below.

[Example 12]
The additional refractive power of the zone region (1) was set to P = 4D, and the first zone radius was set to r ₁ = 0.5225 mm from the standard setting formula. The additional refractive power of the zone region (2) is P ′ = (1 / √4.5) × P = 1.8856D, and the zone region (1) and the zone region (2) have a zone number (n, m) = ( When the first zone radius r ₁ ′ of the zone region (2) was determined from [Equation 44] so as to agree with 5, 3), r ₁ ′ = 0.4547 mm was obtained. When the zone interval of the zone region (2) was obtained from [Equation 33] based on the first zone radius, the zone intervals shown in [Table 23] were obtained.

  From [Table 23], it can be seen that the fifth zone radius of the zone region (1) and the third zone radius of the zone region (2) match. Based on this relationship, the first to fifth zones of the zone region (1) are arranged inside the diffractive structure, and the fourth to sixth zones of the zone region (2) are arranged outside thereof. A diffraction structure was adopted. Details of the phase profiles 112, 114, and 116 of the diffractive structure are shown in [Table 23] and FIGS. 15 (a) to 15 (c). Further, an intensity distribution 118 in the optical axis direction of the diffractive structure is shown in FIG. From FIG. 15 (d), peaks derived from the zone regions (1) and (2) are generated in the near region (about 3.9D point) and the intermediate vision region (about 1.6 to 1.9D point), respectively. I understand that.

  In this example, the additional refractive power of the zone region (2) is set to (1 / √4.5) × P = 1.8856D. Such an additional refractive power is not determined by an integer ratio of a and b with respect to the additional refractive power P of the zone region (1). However, when [Equation 44] is used, the additional refractive power cannot be expressed by an integer ratio. However, it can be seen that the zone interval can be set so that the zones can be switched. In this example, the additional refractive power of the zone region (2) is set to 1.8856D, which is smaller than that of the above-described example group. Therefore, when it is used as an intraocular lens, in addition to the far vision and near vision focus, a multi-diffractive diffraction lens with a focus for intermediate vision set at a position suitable for viewing at a slightly distant point such as a television. It becomes a focal intraocular lens.

[Example 13]
An example in which the first zone radius of the zone region (1) is the same as in Example 12 except that r ₁ = 0.4 mm will be described. In this case, the first zone radius of the zone area (2) for the same zone number and zone radius as in Example 12 was r ₁ ′ = 0.3062 mm. Based on the respective first zone radii, the zone intervals of both areas set from [Expression 32] and [Expression 33] are as shown in [Table 24]. From this relationship, a combination of zone regions (1) and (2) was used as a diffraction structure in the same manner as in Example 12. Details of the phase profiles 120, 122, and 124 of this example are shown in Table 24 and FIGS. Further, the intensity distribution 126 in the optical axis direction is shown in FIG. It can be seen that the same intensity distribution as in Example 12 is exhibited. In this way, it can be seen from this example that the zone can be switched even if the first zone radius of the zone region (1) is arbitrarily varied while the additional refractive power of the zone region (2) is expressed by a non-integer ratio. .

  It has been described from the above example that by using [Equation 44], it is possible to set an area in which the zone can be switched without setting the additional refractive power P ′ of the zone area (2) with an integer ratio. Thus, [Equation 44] is a more generalized setting expression (hereinafter referred to as “general setting expression”) that can be applied to any additional refractive power. [Equation 44] is naturally applicable to the additional refractive power that can be expressed by the integer ratio used in the standard or the extended setting formula. Next, an application example of [Equation 44] when expressed as an integer ratio will be described.

[Example 14]
The additional refractive power and the first zone radius of the zone region (1) were set to P = 4D and r ₁ = 0.5225 mm, respectively, and the additional refractive power of the zone region (2) was set to P ′ = 2.75D. Based on [Equation 44], the first zone radius of the zone region (2) is determined so that the zone numbers having the same zone radius are (n, m) = (6, 4). R ₁ ′ = 0.6684 mm It became. The zone intervals of the respective areas obtained from [Equation 32] and [Equation 33] are as shown in [Table 25]. Due to the coincidence of the zone radii, the first to sixth zones of the zone region (1) are arranged inside the diffraction structure, and the fifth to seventh zones of the zone region (2) are arranged outside thereof. . Details of the phase profiles 128, 130, and 132 of this diffractive structure are shown in Table 25 and FIGS. 17A to 17C. Also, the intensity distribution 134 in the optical axis direction is shown in FIG. It can be seen that peaks are generated that focus on the near and intermediate regions based on the + 1st order diffracted light in the zone regions (1) and (2).

The additional refractive power P ′ in this example is set by P ′ = (11/16) × 4 = 2.75D, and is expressed by an integer ratio such as a = 11, b = 16 in the standard setting formula. It is possible to do. In this case, the zone radius coincides with the 16th zone of the zone region (1), that is, r ₁₆ = 2.09 mm, so that the region (1) and the region (2) are switched considerably outside the lens. Become. If the zone radius coincidence point is far outside the lens, there is a high possibility that the zone switching point will not enter the pupil, and the zone region (2) may not be set within the lens aperture corresponding to the pupil. There is. Therefore, even when the additional refractive power P ′ is represented by an integer ratio, it is desirable to use the general formula [Equation 44] as shown in this example when the number of matching zone radii is large.

Incidentally, the zone radii r _m zone region defined by the general formula for setting (2) is a zone radius equivalent in the case of the outermost radius of the zone region (1) to r ₁ 'in Equation 33]. In other words, 'the r _1' r ₁ in [Expression 33] as = r _n, the zone radius defined by m = 2 or later, it is also good as a zone radius zone region after switching (2). The specific expression is as shown in [Equation 45]. By using [Equation 45], the zone that can be switched from the zone area (1) to the area (2) without going through [Equation 44]. The radius is determined immediately.

Calculated outermost radius to become the zone number n = 5 in the zone radius r ₅ = 1.1683mm substituted into r _n [Expression 45], m = 2 and subsequent numbers zone region (1) In the examples 12 The zone radius of the zone area (2) to be performed is shown in [Table 26]. For reference, the zone radius (defined by [Equation 33] and [Equation 44]) of the zone region (2) shown in Example 12 is also shown. It can be seen that the zone radii after 1.1683 mm coincide. Similarly, the zone radius (2) of the thirteenth and 14th embodiments is calculated using [Equation 45], and the zone radius of the zone zone (2) after switching is the same as the zone radius determined by [Equation 45]. It turns out that

As described above, when [Equation 45] is used, it is possible to easily set a region of an arbitrary additional refractive power at an arbitrary point. An example in which the additional refractive power is arbitrarily determined and the zone is switched at an arbitrary zone position is shown in [Table 27]. The first to fourth zones are zone regions (1) having an additional refractive power P = 4D using a standard setting formula. The fifth to seventh zones correspond to the zone region (2 ₁ ). Using [Equation 45], the additional refractive power is P ₁ ′ = 2.6D, and the outermost radius (first) of the zone region (1) The fourth zone radius) is calculated by r _n and m is m = 2 to 4. The eighth to eleventh zones correspond to the zone region (2 ₂ ). Similarly, using [Equation 45], the additional refractive power is P ₂ ′ = 3.3D, and the outermost radius of the zone region (2 ₁ ) in which the (seventh zone radius in the table) was calculated as r _n, and the m to m = 2 to 5. The zones of the respective areas obtained by such calculation have the same zone radius at the switching point, and form one diffraction structure.

  As explained above, it is first found that the zone radii are matched by conceiving that the additional refractive power is expressed as an integer ratio in the standard setting formula, and that the diffractive structure in which the zone region is switched can be set at the matching point. showed that.

  It was shown that the degree of freedom of zone switching can be further increased by extending and generalizing the standard setting formula. In this way, the diffractive structure with the switched zone regions can optimize the focus formation for each aperture diameter corresponding to different environments, so that it is useful as a multifocal ophthalmic lens that can solve the aforementioned problems. It becomes.

[B. Aspect including non-Fresnel spacing]
The switching of the zone areas described in the [A] column is basically made up of Fresnel zone intervals determined by [Equation 1]. However, in some cases, the non-Fresnel zone spacing may be part of the configuration.

  Here, the non-Fresnel interval means a zone interval in which a zone radius is not determined by [Equation 1] within a certain region. In general, various diffractive structures can be adopted in which the zone interval can be set by an arithmetic expression or the like, and the focal point can be controlled and expressed by the diffractive action of the zone region. For example, in the case where zones having the same zone interval are included in the region, such a zone having an equal interval is an example of a non-Fresnel interval.

  A zone switching method when an equally spaced zone is part of the configuration as a non-Fresnel interval will be described based on the following embodiment.

[Example 15]
In the Fresnel interval where the additional refractive power is P = 4D and the first zone radius is r ₁ = 0.5225 mm, the section corresponding to the second zone radius to the fifth zone radius is divided into three equal parts, These zones were designated as third, fourth and fifth zones, respectively. In this example, the zone region (1) is formed of such a zone configuration. The additional refractive power of the zone region (2 ₁ ) is P ₁ ′ = 2.4D, and the additional refractive power of the zone region (2 ₂ ) is P ₂ ′ = 3D. Determined. The zone intervals of each region are shown in [Table 28].

Since the additional refractive power of the zone region (2 ₁ ) is set as P ₁ ′ = (3/5) × 4 = 2.4D, the fifth of the zone region (1) and the fifth of the zone region (2 ₁ ) The third zone radius matches. Further, the fifth zone radius of the fourth and the zone area of zone region (2 ₁₎ (2 ₂₎ coincide. Further, the sixth zone radius of the zone region (2 ₂ ) and the eighth zone radius of the zone region (1) also coincide. Based on the above relationship, the diffraction structure was determined as follows. The inner side of the diffractive structure is arranged in the first to fifth zones of the zone region ( ₁ ), the fourth zone of the zone region (2 ₁ ) on the outside, and the fourth zone of the zone region (2 ₂ ) on the outside. The ninth zone and the ninth and tenth zones of the zone that is to return to the zone region (1) again are arranged outside the sixth zone. Details of the phase profiles 136, 138, 140, 142 of the diffractive structure are shown in [Table 28] and FIGS. 18 (a) to 18 (d). Further, an intensity distribution 144 in the optical axis direction is shown in FIG.

  In this example, the zone from the second zone radius to the fifth zone radius of the zone region (1) in the sixth embodiment is equally divided into three, and the third, fourth, and fifth zone intervals are Δr = 0. .1431 mm, which is composed of equally spaced zones, and the other specifications are the same as those of the sixth embodiment. Also in this example, since the outermost radius of the region (1) arranged in the center of the diffractive structure is not changed, switching can be performed with the same zone number as other regions as in the sixth embodiment. Comparing the intensity distribution 144 in the optical axis direction of this example with the intensity distribution 64 in the optical axis direction of Example 6 (FIG. 8E), the peak in the far vision region (0D) and the peak in the near vision region are compared. Although there is no difference in the appearance position and intensity of (about 4D), the peak at the position of about 3.4D in Example 6 is reduced in intensity in this example, and instead the peak intensity at the position of about 2.9D is It is increasing (arrow in the figure). As a result, the peak of about 3.4D as the focal point for intermediate vision in Example 6 could be shifted to a 2.9D point a little apart in this example, and fine adjustment was made by introducing such an equally spaced zone. I understand. The intensity distribution 144 shown in this example is a distribution in which an intermediate focus is generated at a distance suitable for visually recognizing a personal computer monitor in a patient with an intraocular lens inserted. On the other hand, it can be a suitable multifocal intraocular lens.

[Example 16]
In the Fresnel interval where the additional refractive power is P = 4D and the first zone radius is r ₁ = 0.5225 mm, the section corresponding to the second zone radius to the sixth zone radius is divided into four equal parts, These zones were designated as third, fourth, fifth and sixth zones, respectively. In this example, the zone region (1) is formed of such a zone configuration. The additional refractive power of the zone region (2 ₁ ) is P ₁ ′ = 2.6667D, and the additional refractive power of the zone region (2 ₂ ) is P ₂ ′ = 3.2D. A zone interval was defined. Such zone intervals are shown in [Table 29].

Since the additional refractive power of the zone region (2 ₁ ) is set as P ₁ ′ = (2/3) × 4 = 2.66767D, the sixth zone region (1) and the second zone region (2 ₁ ) The fourth zone radius matches. Further, the sixth zone radius of the fifth and the zone area of zone region (2 ₁₎ (2 ₂₎ coincide.

Based on the above relationship, the diffraction structure was determined as follows. The inner side of the diffractive structure is arranged in the first to sixth zones of the zone region ( ₁ ), the fifth zone of the zone region (2 ₁ ) on the outer side, and the fifth zone of the zone region (2 ₂ ) on the outer side. 7th and 8th zones were arranged respectively. Details of the phase profiles 146, 148, 150, and 152 of the diffractive structure are shown in [Table 29] and FIGS. 19 (a) to 19 (d). Further, an intensity distribution 154 in the optical axis direction is shown in FIG.

  The zone region (1) of this example divides the section corresponding to the sixth zone radius from the second zone radius into four equal parts among the Fresnel intervals determined by [Equation 22], and one interval is Δr. = 0.1352 mm is the third to sixth constituent zones. Compared to the fifteenth embodiment, the interval between the equally spaced zones is narrowed, and the number of equally spaced zones is increased by one. The outermost radius of the diffraction structure of this example is the same as that of the fifteenth embodiment. When the intensity distribution is compared in the range of such a diffractive structure, the intensity of the near vision peak and the intermediate vision peak in Example 15 are just reversed. Therefore, when the ophthalmic lens according to the present example is used as an intraocular lens, the appearance of the intermediate region is enhanced as compared with the fifteenth embodiment, and the personal computer monitor screen and the like can be seen more clearly. As shown in this example, the intensity balance can be finely adjusted by slightly changing the configuration of the equally spaced zones.

[Example 17]
In the Fresnel interval where the additional refractive power is P = 3D and the first zone radius is r ₁ = 0.6033 mm, the section corresponding to the second zone radius to the fifth zone radius is equally divided into three equal intervals. These zones were designated as third, fourth and fifth zones, respectively. In this example, the zone region (1) is formed of such a zone configuration. The additional refractive power of the zone region (2 ₁ ) is P ₁ ′ = 1.8D, and the additional refractive power of the zone region (2 ₂ ) is P ₂ ′ = 2.25D. A zone interval was defined. Such zone intervals are shown in [Table 30].

This example does not change the setting conditions of the equally spaced zones in Example 15 and the additional refractive power setting conditions (integer ratio) of the zone areas (2 ₁ ) and (2 ₂ ), but the additional refractive power of the zone area (1). Only P = 3D. Note that the interval between the equal interval zones is changed to Δr = 0.653 mm in accordance with the setting of the additional refractive power. Details of the phase profiles 156, 158, 160, 162 of the diffraction structure of this example are shown in [Table 30] and FIGS. 20 (a) to 20 (d). Moreover, the intensity distribution 164 in the optical axis direction is shown in FIG.

  In this example, the zone configuration is performed under the same conditions as in Example 15 except that the additional refractive power of the zone region (1) is set to P = 3D. Therefore, the position where the peak due to the + 1st order diffracted light appears shifts to the far peak side as the additional refractive power changes. However, the intensity distribution 164 itself is similar to that of the fifteenth embodiment. Thus, even if the additional refractive power of the zone region (1) is changed, if the setting conditions such as the zone switching number are the same, the form of the intensity distribution is maintained although the focal position varies. That is, it is understood that the setting conditions as shown in this example may be used when only a peak position is changed while maintaining a certain intensity distribution.

  The ophthalmic lens having a weakened additional refractive power as in this example is a multifocal intraocular that is useful for patients who place importance on visibility in the range of about 40 to 1 m, even for intraocular lens subjects. Become a lens. On the other hand, a contact lens user is a multifocal contact lens that is useful for a patient who wants to compensate for a decrease in accommodation power and view closer.

  In Examples 15 to 17, the zone is configured based on the standard setting formula. However, even when a non-Fresnel interval is included, the zone may be configured using the extended setting formula or the general setting formula. .

For example Example 16 is an example in which switching was the next to add power P ₂ '= 3.2D become zone region (2 ₂₎ of the zone region (2 _1), region (2 ₂₎ to If it is desired to switch to a zone region that gives another different additional refractive power as a switching destination of, it is possible to easily switch to a zone of any additional refractive power by using the general formula [Equation 44] or [Equation 45]. It becomes.

[Example 18]
Switching to zone region (2 ₂₎ to give another different add power from the zone region (2 ₁₎ of Example 16 were conducted on the basis of a general set formula [number 45]. Since the outermost radius of the zone region (2 ₁₎ was 1.4309Mm, this value as r _n [Expression 45], the add power zone area to change (2 ₂₎ and 3.8D, such The additional refractive power was substituted into P ′ in [Equation 45], and the zone interval of the zone region (2 ₂ ) was determined. Details of the diffraction structure of this example are shown in [Table 31]. FIG. 21 shows the intensity distribution 166 in the optical axis direction. In the table, the outermost radius of the zone region (2 ₁ ) is shown as the first zone radius of the region (2 ₂ ). By changing the additional refractive power of the zone region (2 ₂ ) to 3.8D, the intensity distribution of the near vision peak and the intermediate vision peak is approximately equal to that of the embodiment 16, resulting in an intensity distribution.

  As can be seen from the eighteenth embodiment, the general setting formula can be used for the one including the non-Fresnel interval, and the design with more flexibility can be performed.

In Examples 15-18, the example in which the equally-spaced zone as the non-Fresnel interval is a part of the configuration of the zone region (1) has been described. However, the equally-spaced zone may be provided in another region. 1), (2 ₁ ), (2 ₂ ),... May be set in any one zone or a plurality of regions.

[Example 19]
A setting example in which a part of the configuration of the zone region (2) is set as an equal interval zone based on the third embodiment is shown below. In this example, the sixth zone of the zone region (2) in the third embodiment is divided into two equal parts by dividing the sixth zone of the zone region (2) into equal zones. At this time, the interval between the equally spaced zones is Δr = 0.0683 mm. As a result of dividing the zone into two equal parts, in this example, the number of constituent zones in the zone region (2) is increased by one. There is no change from the third embodiment except that such equally spaced zones are set. Details of the phase profiles 168, 170, and 172 of the diffraction structure of this example are shown in [Table 32] and FIGS. 22 (a) to 22 (c). Further, the intensity distribution 174 in the optical axis direction is shown in FIG. In this example, since the sixth zone of the third embodiment is divided into two equal parts, a profile in which two zones having a narrow interval are arranged. In this example, the intensity of the peak in the intermediate region is reduced as compared with the third embodiment due to the effect of the equidistant zone, and instead, the intensity distribution in which the peak intensity in the near region increases is shown. That is, in Example 3, the peak intensity of the intermediate region was enhanced, but in this example, while maintaining the peak position of Example 3, the intensity of the peak in the intermediate region is suppressed, and the intensity of the near region is increased. Increased specifications. Therefore, it becomes useful as a multifocal ophthalmic lens with an emphasis on near vision as compared with Example 3.

  As shown in this example, when an equally-spaced zone is set as an example of a non-Fresnel interval, an area other than the zone area (1) may be targeted as a setting location of such a zone.

  In Examples 15 to 19, the example in which the equally spaced zones having the same zone interval are used as the non-Fresnel interval has been described. However, the non-Fresnel interval is not limited to the equally spaced zone. A configuration including zones with different intervals can also be used favorably in the present invention.

  In the present invention, the phase constant h of the blaze is mainly described with h = 0.5, but the present invention is not limited to such a value. In general, in a diffractive multifocal lens having a blazed phase profile, the distribution ratio of 0th-order diffracted light and other orders of diffracted light can be varied by varying the phase constant h. Also in the present invention, the peak intensity at each focal point can be controlled by varying the phase constant. Example 20 is an example when the phase constant h is varied.

[Example 20]
An example in which the phase constant h is varied and the profile of the fourth embodiment is targeted is as follows. In Example 4, the characteristic that the peak intensity in the intermediate region is slightly larger than that in the near region is shown. In this example, the phase constant h was varied for the purpose of varying the peak intensity ratio between the near and intermediate regions while maintaining the peak appearance position of Example 4. The zone radius of the diffraction structure of this example was the same as that of Example 4, and the phase constant was varied as shown in [Table 33]. Details of the phase profile 176 of the diffractive structure associated with the variation of the phase constant are shown in Table 33 and FIG. In this example, the phase number of the zone number i = 3 and the sixth zone is set to h = 0.7, and the phase number of the zone number i = 4 and the fifth zone is changed to h = 0.3. The intensity distribution 178 of the diffraction structure of this example is shown in FIG. It can be seen that in this example, the peak intensity in the intermediate region decreases and the peak intensity in the near region increases with the variation of the phase constant. It can be seen that the appearance position of each peak is the same as in Example 4, and that the peak intensity can be finely adjusted by varying the phase constant.

  The method of modulating the phase constant is not limited to such an embodiment, but may be a structure in which the phase constant is modulated according to a certain rule for each zone, for example, a phase modulation structure called apodization. Good.

[Appendix]
The technical idea of the present invention has been described in detail with reference to some typical embodiments. However, the present invention is not construed as being limited by these specific descriptions, and those skilled in the art will understand. Various changes, corrections, improvements, and the like can be added based on knowledge, and all such embodiments are included in the scope of the present invention as long as they do not depart from the spirit of the present invention.

  For example, with respect to the location of the diffractive structure, the diffractive structure shown in each of the above embodiments may be set on either the front surface or the rear surface of the target ophthalmic lens. Or you may install in the inside of a lens. Further, as described in, for example, Japanese Patent Application Laid-Open No. 2001-42112, the diffractive structure according to the present invention can be formed on a laminated surface made of two materials having different refractive indexes.

  Further, examples of the ophthalmic lens to which the present invention can be applied include contact lenses, eyeglasses, intraocular lenses, and the like. Furthermore, the present invention can be applied to a corneal insertion lens that is implanted in the corneal stroma to correct vision, or an artificial cornea. In contact lenses, it is preferably used for hard oxygen-permeable hard contact lenses, water-containing or non-water-containing soft contact lenses, and oxygen-permeable water-containing or non-water-containing soft contact lenses containing a silicone component. be able to. In addition, as an intraocular lens, a hard intraocular lens, a soft intraocular lens that can be folded and inserted into the eye, a phakic intraocular lens (phakic IOL), an intraocular lens for additional insertion (add-on) IOL) and the like can be suitably used for any intraocular lens.

16, 24, 32, 40, 48, 56, 66, 78, 86, 94, 102, 112, 120, 128, 136, 146, 156, 168: phase profile (zone region (1)),
18, 26, 34, 42, 50, 80, 88, 96, 114, 122, 130, 170: phase profile (zone region (2)),
20, 28, 36, 44, 52, 62, 72, 82, 90, 98, 108, 116, 124, 132, 142, 152, 162, 172, 176: phase profiles (combinations),
58, 68, 104, 138, 148, 158: phase profile (zone region (2 ₁ )),
60, 70, 106, 140, 150, 160: phase profile (zone region (2 ₂ ))

Claims (21)

In a diffractive multifocal ophthalmic lens composed of a plurality of concentric zones, part or all of the diffractive structure is set based on the zone region (1) set based on [Equation 1] and [Equation 2]. Zone area (2), and the n-th zone radius of zone area (1) is the same as the m-th zone radius of zone area (2), up to the n-th zone area (1). Zone is arranged inside the zone area (2), and the (m + 1) th and subsequent zones of the zone area (2) are arranged outside and adjacent to the nth zone of the zone area (1). A diffractive multifocal ophthalmic lens.

There are a plurality of zone regions (2) in the lens radial direction having different addition refractive powers P ₁ ′, P ₂ ′,..., And the plurality of zone regions (2 ₁ ), (2 ₂ ),. The adjacent ones in the lens radial direction are connected at the same zone radius position so that they are adjacent to each other at the zone radius position and are arranged on the inner peripheral side and the outer peripheral side. The diffractive multifocal ophthalmic lens described. 3. The diffractive multifocal ophthalmic lens according to claim 1, wherein the additional refractive power P provided by the zone region (1) and the additional refractive power P ′ provided by the zone region (2) have a relationship of [Equation 3].

The first zone radius r ₁ of the zone region (1) and the first zone radius r ₁ 'of the zone region (2) are in a relationship of [Equation 4]. The diffraction multifocal ophthalmic lens according to any one of 1 to 3.

  The diffractive multifocal ophthalmic lens according to claim 4, wherein α = 0 in the [Equation 4]. The first zone radius r ₁ of the zone region (1) and the first zone radius r ₁ ′ of the zone region (2) are represented by [Equation 5] and [Equation 6], respectively. Item 6. The diffractive multifocal ophthalmic lens according to any one of Items 1 to 5.

  The diffractive multifocal ophthalmic lens according to any one of claims 1 to 6, wherein the diffractive structure includes an equally spaced zone in which at least two radially adjacent zones of the zone are equally spaced. .   The diffractive multifocal ophthalmic lens according to claim 7, wherein the equally spaced zones are arranged in the zone region (1). The diffraction according to claim 8, wherein the equally-spaced zones include at least two in the range from the (ns) zone radius point to the (nt) zone radius point of the zone region (1). Multifocal ophthalmic lens.
However, 0 ≦ t <s <n, and t and s are integers.   The diffractive multifocal ophthalmic lens according to any one of claims 7 to 9, wherein the equally spaced zones are arranged in the zone region (2). 11. The equidistant zone includes at least two in the range from the (m−s ′) th zone radius point to the (m−t ′) th zone radius point of the zone region (2). Diffractive multifocal ophthalmic lens.
However, 0 ≦ t ′ <s ′ <m, and t ′ and s ′ are integers.   The diffractive multifocal ophthalmic lens according to any one of claims 1 to 11, wherein at least three focal points can be generated.   13. The diffraction according to claim 12, wherein one of the three focal points is a far vision focal point, the other focal point is a near vision focal point, and the other focal point is an intermediate vision focal point. Multifocal ophthalmic lens.   The diffractive multifocal ophthalmic lens according to claim 13, wherein the far vision focus is provided by 0th-order diffracted light having a diffractive structure, and the near vision focus and intermediate vision focus are provided by + 1st order diffracted light.   The diffractive multifocal lens according to claim 1, wherein the at least three focal points are generated at a lens aperture diameter of 1.2 mm or more in diameter.   The diffractive multifocal ophthalmic lens according to claim 1, wherein the diffractive zone is formed with a diffractive structure characterized by a phase function for modulating the phase of light.   The diffractive multifocal ophthalmic lens according to claim 16, wherein the phase function is a blazed function. The diffractive multifocal ophthalmic lens according to claim 17, wherein the phase function φ (r) of the blaze shape is expressed by [Equation 7].

  The diffractive multifocal ophthalmic lens according to any one of claims 1 to 18, wherein the diffractive structure is configured by a relief structure reflecting an optical path length corresponding to a phase. When manufacturing a diffractive multifocal ophthalmic lens composed of a plurality of concentric zones,
Determining a diffractive structure (1) that provides the desired additional refractive power P;
Determining a diffractive structure (2) that provides another desired additional refractive power P ′;
The nth zone in the diffractive structure (1) and the mth zone in the diffractive structure (2) are such that the zone radius in the diffractive structure (1) and the zone radius in the diffractive structure (2) are the same radial position r. Obtaining each zone, and
The step of providing the nth or less zone region in the diffractive structure (1) on the inner peripheral side of the radial position r, and the m + 1st or higher zone region in the diffractive structure (2) on the outer peripheral side of the radial position r. And a method for producing a diffractive multifocal ophthalmic lens.   21. The method of manufacturing a diffractive multifocal ophthalmic lens according to claim 20, wherein the radial position r is set within a radius range that is equal to or larger than the minimum diameter of the pupil of the wearer and smaller than the maximum diameter.

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