DE2707601A1 - OPHTHALMIC LENSES AND METHOD OF TRAINING AN OFF-AXIS CORRECTION OF THE SAME - Google Patents

Description

PATENT ADVERTISER η ι rcdi im « D-I BERLIN 33 ι c ο 7 7

MANFREDMIEHE falkenr.ED4 ^1: > · ^ · "

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* ^ * üS / 02/2311

AO-3038

AMERICAN OPTICAL CORPORAT IO N Southbridqe, Mass. 01550 , USA

Ophthalmic lenses and methods of providing an off-axis correction thereof

Corrected ophthalmic lenses are provided in which off-axis correction is achieved using a gradation of the refractive index between the optical Center and the edges of the lenses along with appropriate selection of the surface curvature and the center point thickness.

The invention relates to improvements in ophthalmic lenses and in particular the correction of off-axis errors by means of a radial gradation of the refractive index between the optical center and the edges of the lenses together with a corresponding selection of the surface curvatures and the Center thickness.

In connection with the calculation of corrected spectacle lenses, very detailed calculations are usually made for the off-axis portions of the lenses are performed and the base curve selected which gives the best performance, i. the "tool" employed by those skilled in the art is the total amount employed on a given lens Bend.

Off-axis errors of major importance are the astigmatism and the curvature of field (power errors), with a third Abberation, the distortion, is lighter in weight but still an important consideration.

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Recent attempts to improve the off-axis correction of ophthalmic lenses have passed in the application of aspherical elements, taking non-spherical surface curvatures along with an appropriate selection of the base curve can be applied in order to continue to reduce the off-axis astigmatism and field curvature while simultaneously Improving the distortion.

Aspherical surface curvatures for off-axis correction can be applied very easily and economically to lenses, that can be cast, i.e. plastic lenses, but this working method can also be used in conjunction with the skew correction be carried out with glass lenses.

The current state of the art is aimed at one or a combination several of the stated procedures for reducing off-axis aberrations in ophthalmic lenses are limited. There is thus the need to find ways of working that make it easier and more economical, this is true especially for glass, to carry out appropriate corrections and greater versatility in terms of the choice of too corrective aberration and this applies in particular to the so-called oblique correction.

An object on which the invention is based therefore consists in providing an off-axis correction in the case of ophthalmic lenses, if necessary without creating aspherical surface treatment, which however is comparable to and / or an improvement over the Represents applying aspherical elements.

Another object of the invention is to to achieve aspherical correction in lenses, a greater degree of skew correction can and also be achieved improved values for the primary aberrations of the astigmatism and the curvature of field can be obtained.

Another object of the invention is to to give the person skilled in the art the opportunity to deal with the problems of aberration with greater versatility to tackle this as previously by means of the only limited use

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able "tool" of the controlled surface bending was possible, according to the invention, however, work is carried out without surface bending. There is a more general object on which the invention is based to provide simple and with greater versatility corrected ophthalmic lenses as compared to the prior art create, with improved economic efficiency in particular corrections of aberrations and greater freedom with regard to the Applying the variables of the selection of the base curve and the asphericity in the correction of oblique aberrations is given.

According to the invention, an off-axis correction in ophthalmic lenses is at least partially achieved by changing the refractive index of the lens via the controlled amounts starting from the optical center point takes place radially in the direction of the edge of the lens. Using conventional spherical and / or toric lens surfaces with preselected diopter values are off-axis corrections of the lens aberrations comparable to and improved over those that can be achieved with aspherical surfaces. Thus, the relatively intricate and costly procedures of applying aspheric corrections to the glass lenses can be avoided without that there is a loss in the quality of the skew correction. In this context, a lens base curve can be chosen so that the astigmatism is kept as small as possible, and a refractive index gradient is used to control the curvature of the field.

Even better corrections can be made by applying a refractive index gradient together with an aspherical surface and of course with careful selection of the base curve. The base curve can be selected with the aim of reducing it the distortion and the asphericity can be selected to keep the astigmatism as small as possible and the gradient of the refractive index is used to to reduce.

An embodiment of the invention is shown in the drawings and is described in more detail below. Show it:

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Fig. 1 is a schematic representation of the conventional geometry iind of the basic requirements for the calculation of Spectacle lenses;

Figure 2 is a graph showing the optical performance of a conventional +3.00 Dipptrian spherical lens expressed in tangential and sagittal power errors;

FIG. 3 is a graph similar to FIG. 2 showing the shows optical performance of a +3.00 diopter lens having off-axis corrections according to the invention;

Figure 4 is a cross-sectional view of an ophthalmic lens, wherein the hatching represents the gradient of the refractive index;

Fig. 5 and 6 modes of operation, as they are suitable for the production of lens blanks, the radially directed gradations of the Have refractive index;

7 and 8 show further working methods for training of gradations of the refractive index in the lens blanks.

FIG. 1 explains the conventional geometrical assumptions on the basis of which spectacle lenses are designed. In the figure the point P is a point on the reference sphere C at which it would be useful to make the same optical corrections as they do at the vertex V of the lens L. The problems that arise here are classic and can be found in the literature, e.g. BechtoJd Edwin W. "The Abberations of Ophthalmic Lenses", Am.Jl. of Op. and Arch. Am. Acad.Optom. 35 (1) 10-24, 1958; Davis, John K., Henry G. Fernald, and Arline W. Raynor, "An Analysis of Ophthalmic Lens Design ", Am. Jl. Of Op. And Arch. Am. Acad. Optom. 41 (7) 400-t421, 1964; Davis, John K., Nery G. Fernald and Arline W. Raynor, "The Design of a General Purpose Single Vision Lens Series" Am. Al. of Op. and Arch. Am Acad. Optorn. April 1965; and Davis, John K. "Stock Lenses and Custom Design" Am. Jl.of Op., December 1967.

Fig. 2 shows the result of conventional calculations and shows expressed in the tangential (t) and sagittal (s)

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meridional strength defects the performance as it is for a + 3.00 spherical correction lens is possible. The numerical values are given for the commonly occurring 28.5 rotation center distance (CR) and a refractive index of 1.56. the Curvatures of the anterior surface, posterior surface, and mean thickness are 6.72 diopters, -4 diopters and 3.76 mm.

One sees immediately that for a concave base curve of approximates - 4.00 diopters the average field of curvature (power error) amounts to approximately "0", i.e. the sagittal error amounts to is about -0.9 diopters and the tangential error is about +0.9 diopters. To set this astigmatism to "0" however, a concave base curve slightly steeper than -6.00 diopters would be required, and that Field of curvature (power error) would be increased to about - 0.17 diopters. It can thus be seen that the power error and the astigmatism are both not reduced to zero by conventional means Lens design works can be reduced. Thus, the differences are based on the different manufacturers manufactured lenses on the various types of tradeoffs made by their respective manufacturers.

In the following table I the sagittal and tangential strengths, the sagittal and tangential errors and the astigmatism are shown, which are included in the example lens + 3.0O diopters occur at different angles A (Fig. 1).

Table I.

Refractive index is 1.56 Refractive index increment is 0.0000 The center of rotation distance is 28.5 mm axial strength is 3.00 diopters.

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angle Sagittal Tangentials S. t Astigmatis h ° strength strength failure failure mus 5 3.00 3.00 - 0.00 0, OO 0.01 10 2.99 3.01 -0.01 0.02 0.02 15th 2.98 3.03 - 0.02 0.04 0.05 20th 2.97 3.06 - 0.03 0.06 0.09 25th 2.95 3.08 - 0.05 0.09 0.14 3O 2.92 3.11 - 0.09 0.09 0.19 35 2.88 3.12 - 0.12 0.12 0.24

The optimum of an off-axis ophthalmic lens correction would of course consist in achieving a simultaneous correction of the oblique astxgmatism and the curvature of field (strength errors). According to the invention, this can be achieved by using a gradient of the refractive index in the lens blank, which is used to manufacture the lens, see Table II below.

Table II

Refractive Index = 1.56 Refractive Index Increment = 0.0050 Center of rotation distance = 28.5 axial power = 3.00 diopters.

angle

Sagittal tangents

strength

strength

Error error tism

Astigma index

5 3, O2 3.02 0.02 0.03 0, OO 1.5650 1O 3.04 3.04 0.04 0.05 0.01 1.5700 15th 3.05 3.06 0.05 0.06 0.01 1.5750 20th 3.04 3, O6 0.04 0.06 0.02 1.5800 25th 3.03 3.05 0.03 0.05 0.02 1.5850 30th 3.00 3.02 -0.00 0.02 0.02 1.5900 35 2.96 2.97 -0.04 -0.03 0.01 1.5950

Table II shows a lens whose anterior surface has a curvature of + 8.64 diopters, its posterior surface has a curvature of -6, OO diopters, which is 3.84 mm thick and has a refractive index of 1.56 on its axis.

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sits and leads to an axial thickness of 3.00 diopters. the Lens is provided with a gradient of the refractive index which increases from the center to the edge by Ink pure te of 0.0050 per every 5 ° increase to the angle Ά (Fig. 1). The Center of Rotation Distance (CR) is 28.5mm and this is a common range in ophthalmic corrective lenses. On one Point of 30 °, the oblique astigmatism is reduced to near "O" (i.e. 0.02) while the curvature of field (strength error) has been reduced to substantially "0" (i.e. sagittal error is -0.00 and tangential error is 0.02). At this 6th place, the refractive index has been increased to 1.5900.

With particular reference to FIG. 3, there are plotted the sagittal (s) and tangential (t) errors for the lens used in the example according to Table II. Man sees that by selecting a concave base curve of -6.25 diopters or slightly less, one is essentially complete correction of the oblique astigmatism and the field curvature (power error) can be achieved for a viewing angle A of 30 °. For skew angles of less than 30 ° it can be seen from Table II that only a slightly smaller, but essentially complete correction of the oblique astigmatism and the field curvature has occurred.

In all of the embodiments of the present invention, a gradual index of refraction gradient is used, i.e., 0.0050 per 5 ° change in angle A. By applying a continuous and / or non-linear gradient in the refractive index between the center and the edges of a lens can improve the oblique astigmatism and the Field curvature correction can be achieved.

Using the above example of a lens with an axial For a thickness of 3.00 diopters and a center of rotation distance (CR) of 28.5 mm, Table III below explains a change in the refractive index between the lens center and the peripheral parts, which are used to achieve an off-axis correction over the entire lateral field of view, e.g. from 0 ° to a correction lens.

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Table III Refractive index ■ 1.56 Center of rotation distance ■ 28.5 mm

axial strength * 3.00 diopters

angle
A ° Sagittal
strength Tangentials
strength S.
failure t
failure Astigmatis
mus index 5 3.00 3.00 -0.00 -0.00 0.00 1.56OO 10 3.00 3.01 0.00 0.01 0.01 1.5630 15th 3.00 3.01 -0.00 0.01 0.01 1.5660 20th 2.99 3.0O -0.01 0.00 0.0J 1.5700 25th 2.99 3.01 -0.01 0.01 0.02 1.5785 30th 2.99 3.01 -0.01 0.01 0.02 1.5885 35 3.00 3.01 -0.00 0.01 0.01 1.6025

Referring to Tables II and III, it can be seen that the Gradation of the refractive index has very little effect on off-axis astigmatism. The astigmatism remains zero or closely adjacent to this over all lateral viewing angles A, i.e. from 0 ° to 35 °. However, the gradation of the refractive index has the effect of a decisive reduction in the curvature of the field (strength error). You can see, for example, that at an oblique view of 35 ° (Table II) the error in the sagittal meridian reduced to -0.04 diopters and in the tangential meridian to -0.03 diopters has been. The base curve can thus be strategically selected while correcting the off-axis astigmatism the conventional working method and is then able to apply a gradient of the refractive index in the inventive method Way, whereby the field curvature (strength error) turned off or is reduced to an insignificant value.

In the above examples of using a Gradation of the refractive index, the refractive index has been smallest at the center or axis of the lens and is increasing Outward directions towards the edges of the lens. However, this is not necessarily the direction of the gradient of the Refractive index that should be used for all lenses. The direction of the gradient of the refractive index, i.e. whether the same

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decreases or increases in the directions away from the center of the lens will depend on the power range in which one is working and what one wishes to achieve with regard to the off-axis corrector. When working with lenses with high plus power, such as Star lenses can, for example, have a refractive index with the highest value at the lens center point and sloping down from the center point of the edge require the best results.

Tables IV, V and VI below show that a suitable The direction of gradation of the index of refraction for a high plus power lens, e.g., a star lens, is one that decreases from the center of the lens towards its periphery.

Table IV

Refractive index = 1.56
Refractive Index Increment = 0.0000
Distance from the center of rotation = 25.0 mm axial thickness - 14.00 diopters.

angle
A ° Sagittal
strength Tangentials s
Strength failure -0.00 t
failure Astigmatism 5 14.00 14.05 -0.00 0.04 0.04 10 14.00 14.18 -0.00 0.17 0.18 15th 14.00 14.40 -O, O1 0.40 0.40 20th 14.00 14.74 -0.00 0.74 0.74 25th 14.00 15.22 0.01 Θ1.21 1.21 30th 14.02 15.87 0.04 1.86 1.85 35 14.04 16.77 Table V 2.76 2.72

Refractive index = 1.56
Refractive Index Increment = -0.0050
Distance from the center of rotation «25.0 mm
axial strength = 14.0O diopters

diaper Sagittal
strength Tangentials
strength S.
failure t
failure Astigma
tism index 5 13.87 13.91 -0.14 -0.10 0.04 1.5550 10 13.73 13.90 -0.28 -0.11 0.17 1.5500 15th 13.58 13.97 -0.42 -0.04 0.38 1.5450 20th 13.44 14.13 -0.57 0t12 0.69 1.5400

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Sagittal
strength Tangentials
strength S.
failure t
failure 2707601 1.535O angle
A ° 13.29 14.40 _Z 6.71 0.39 Astigma index
tism 1.5300 25th 13.15 14.80 -0.85 0.79 1, 10 1.5250 30th 13.01 15.37 -0.99 1, 36 1.64 35 Table VI 2.35

Index = 1.56 and tapers from the midpoint towards the edge down to.

Distance from the center of rotation «25.0 mm axial thickness = 14,000 diopters

angle
A ° Sagittal
strength Tangentials
strength S.
failure t
failure Astigma
tism index 5 13.96 14.01 -0.04 0.00 0.04 1.5585 10 13.84 14.01 -0.17 0.01 0.17 1.5541 15th 13.61 13.99 -0.39 -0.01 0.38 1.5460 20th 13.32 14.00 -0.68 -0.01 0.68 1.5358 25th 12.96 14.01 -1.04 0.01 1.05 1.5232 30th 12.52 14.02 -1.48 0.01 1.5O 1.5078 35 12.O1 14.02 -2.00 0.01 2.01 1.49OO

Table IV shows what can happen to the off-axis aberration in a constant refractive index lens from the center to the edge when, for example, the on-axis Thickness is 14.00 diopters and has a concave curvature of -3.50 diopters and an average thickness of 11 mm. the Sagittal power remains almost constant from the center to the edge of the lens, i.e. from 0 ° to 35 ° of angle A, during the tangential strength increases in value to a point where it amounts to nearly 3.00 diopters at 35 °. Of the resulting astigmatism at 35 ° rotation in the eye is 2.72 diopters.

Table V with the same corrective lens of 14.0O diopters axial strength shows the improvement as it can be achieved according to the invention with a refractive index increasing over increments. This example results in the increment of the Refractive index by decreasing 0.05 for every 5 ° eye rotation away from the center of the lens. You can see that here-

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the less important sagittal strength errors have increased somewhat, but the more important tangential strength errors have been significantly reduced. At 35 ° the tangential power error is to approximately 2.0 diopters and the Astigmatism has accordingly been reduced to about 2.00 diopters.

By employing a non-linear index of refraction gradient as shown in Table VI, one can essentially constant tangential strength (almost 0 ° tangential error) can be achieved. It will be understood that, although a tangential strength error is generally considered to be more serious than a sagittal strength error is considered, so it does not necessarily have to be reduced to 0 at the expense of a considerable amount of the sagittal power error. Thus, in essence, Table VI is intended to show that an additional control of the off-axis correction according to the invention can be achieved in that the gradient of the Refractive index not only in predetermined increments, but rather, it is changed in a non-linear manner.

The examples in Tables I to VI serve to explain the subject matter of the invention when it is used under conditions where the usual value of 28.5 mm of the rotation center distance (CR) for general corrective lenses and a value of 25 mm for CR for corrective lenses with high plus value (i.e. star lenses) is. It is understood, however, that the astigmatism and the curvature of field (power error) are essentially eliminated, i.e. on Negligible values can be reduced for other rotation center distances (CR) taking into account the following explanations:

Tables VII and VIII explain control of astigmatism and power error, such as by grading the refractive index with a lens that has an anterior surface curvature of + 8.64 diopters, a posterior surface curvature of - 6.0 diopters, an average thickness of 3.84 mm and an index of refraction of 1.56 on its axis under Form an axial thickness of 3.00 diopters. The refractive index here increases radially from the center point in the direction of the edge of the Lens to.

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Table VII Refractive index = 1.56

Center of rotation distance = 25.0 mm axial strength = 3.00 diopters

angle
A ° Sagittal tangentials s
Strength strength failure 3.00 -0.00 t
failure Table VIII Astigma
tism index 5 3.00 3.01 0.00 -0.00 0.00 1.5600 10 3.00 3.02 0.00 0.01 0.01 1.5630 15th 3.00 3.04 -0.00 0.03 0.02 1.5660 20th 3.00 3.06 0.01 0.04 0.04 1.5700 25th 3.01 3.08 0.01 0.06 0.06 1.5785 30th 3.01 3.10 0.02 0.08 0.07 1.5885 35 3.02 0.10 0.08 1.6025

Refractive index = 1.56

Center of Rotation Distance ■ 32.0mm axial thickness - 3.00 diopters

angle Sagittal
strength Tagentials
strength S.
failure t
failure Astigma
tism index 5 2.99 3.00 -0.00 -0.00 0.00 1.5600 10 3.00 3.00 -0.00 -0.00 0.00 1.5630 15th 2.99 2.99 -0.01 -0.01 0.00 1.5660 20th 2.98 2.98 -0.02 -0.02 0.00 1.5700 25th 2.98 2.97 -0.02 -0.03 0.00 1.5785 30th 2.97 2.96 -0.03 -0.04 0.01 1.5885 35 2.97 2.94 -0.03 -0.06 0.03 1.6025

Referring to Tables IX and X, the numerical values are the same as to the construction of the lens, but without any gradation Refractive index reproduced in order to show the corresponding corrections of the field curvature (strength errors), which can be found under Apply the gradation of the refractive index according to Tables VII and VIII have been achieved.

Comparison of Tables VII and IX shows that the curvature of field (sagittal and tangential error) mainly due to the gradation the refractive index is decreased (Table VII). For the condition of a center of rotation distance of 25 mm, i.e. with con-

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With a constant index of refraction (Table IX), the s error amounts to -0.20 and the t-error to -0.14 at 35 °, while at the gradation the refractive index (labeHe ¥ 11) the s error down to 0.02 and the t error amounts to 10.

Similarly, comparison of Tables VIII and X shows a very considerable correction of the field curvature for the distance from the center of rotation of 32 mm. For the viewing angle of 45 ° there is the s error from -0.25 to -0.03 and the t error from -0.30 has been reduced to -0.06.

Table IX

Refractive Index - 1.56

Center of rotation distance = 25.0 mm
axial strength = 3.00 diopters

angle Sagittal
strength Tangentials s
Strength failure -0.00 t
failure astigmatism 5 3.00 3.00 -0.01 -0.00 0.00 10 2.99 3, OO -0.03 -0.00 0.01 15th 2.97 2.99 -0.06 -0.01 0.02 20th 2.94 2.98 -0.09 -0.02 0.04 25th 2.91 2.96 -0.14 -0.04 0.05 30th 2.86 2.92 -0.20 -0.08 0.06 35 2.80 2.85 Table X -0.14 0.05

Refractive Index - 1.56

Center of rotation distance = 32.0 mm
axial strength = 3.00 diopters

angle Sagittal
strength Tangentials
strength S.
celebration t
failure astigmatism 5 2.99 3.00 -0.00 -0.00 0, OO 10 2.98 2.98 -O, O2 -0.02 0.00 15th 2.96 2 ₇ 96 -0.04 -0.04 O, OO 20th 2.92 2.92 -0.08 -0.08 0.00 25th 2.88 2.87 -0.12 -0.13 O, O1 30th 2.82 2.8O -0.18 -0.20 0.02 35 2.75 2.70 -0.25 -0.30 0.05

All of the above examples are based on applying a lens to the has a refractive index of 1.56 at its center.

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It is understood, however, that major and minor indices of refraction can be used to avoid excessive decrease or increase in the index of refraction at the edges of the lenses.

The above explanations show the advantages that result from the fact that ophthalmic lenses in the manner according to the invention with Gradients of the refractive index are provided, which are used here in a special way as "tools" for the correction of off-axis Aberrations are applied. The numerical values according to the various examples in Tables I to VIII are mediated conventional calculations by the relevant person skilled in the art for the course of the rays using programmable computer technology been obtained, although the latter does not have to be used, but for the relevant person skilled in the art as proves extremely useful. The numerical values in Tables I to VIII have been selected for the purpose of explaining the basic principle of the subject matter of the invention, comparable information can be obtained in a simple manner depending on the circumstances the practically unlimited number of corrective lenses, regardless of whether they are spherical lenses with a single field of vision or lenses with multiple focal points, or whether these are in each case a cylinder correction exhibit.

Details regarding the application of the beam path, as is customary in the field, can be found in the üS-PSen 3,434,781 and 3,169,247 and / or one or more of the publications listed above.

As stated above, the procedure according to the invention can be used the correction of off-axis aberrations in ophthalmic lenses with a controlled gradation of the refractive index apply to provide aspherical surfaces, or such gradation can be used in and / or with aspherical lenses in order to achieve an even better "fine-tuning", i.e. corrector of the oblique gabberations.

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In all cases of calculation or design of lenses including the inventive application of the gradation of the refractive index, a base curve is carefully selected, and under Applying a gradient of the refractive index to replace the need for off-axis correction by means of aspheric Curvature, the base curve can be chosen so that the astigmatism is kept as small as possible and the gradient of the refractive index so It is assumed that the field curvature (strength error) is also kept as small as possible.

In the case of "fine-tuning" applying an aspheric Surface, special care can be exercised to the effect that a third off-axis aberration is corrected, a distortion regardless of whether it is of the so-called "barrel" or "pin cushion" type. In this case, the Selection of the base curve can be done more specifically in pursuit of a reduction in distortion and surface asphericity is chosen so that the astigmatism is kept as small as possible. The refractive index gradient was chosen and applied that the curvature of field (strength error) is reduced. The latter aspect has been shown above. details regarding the hadholding of the base curves and applying surface asphericity for a reduction in off-axis Abberations can be found in US patent application Ser.No. 494,784 and / or U.S. Patent 3,169,247.

The subject of the invention relates in particular to the application a gradient of the refractive index in ophthalmic lenses as a "tool" for correcting off-axis aberrations and is applicable to lens blanks that have a gradient of the refractive index from the center towards the edge, regardless of how the lens blanks are manufactured, treated or otherwise provided with the gradient of the refractive index. Appropriate procedures for making such Lens blanks are shown in FIGS. These working methods communicated here are only for example to understand.

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Referring to Figures 5 and 6, a blank 10 is made Lens material, e.g., optical glass, with a diametrical dimension equal to or greater than that provided by the US Pat corresponds to the largest required transverse dimension of an ophthalmic lens to be produced therefrom. The blank 10 is immersed in a salt 12 which contains alkali metal ions, causing an ion exchange between the ions in the glass and gives those in the salt in amounts which gradually penetrate radially into the blank 10.

Details of such ion exchange processes in lens blanks can be found in U.S. Patents 3,650,598 and 3,827,785.

A certain period of time occurs in the salt 12 Ion exchange that occurs over a predetermined distance in the direction of and / or to the axis of the Blank 10 runs, resulting in a change in the refractive index depending on the gradation with which the ion exchange has taken place. The resulting exchange of monovalent alkali metal ions of one size in salt 12 carries the ions of a different size in the blank 10 progressively radially inwardly with respect to the blank to a varying density of the Material of the material of the blank 1O, resulting in corresponding changes in the refractive index. Even if not in As shown in FIG. 5, the opposite ends of the blank 10 are preferably provided with a protective coating or the like, one ion exchange in directions axial with respect to the blank 10 prevented.

After the blank 10 is treated in this way in the salt 12 has been, the removal of the same from the salt 12 and cleaning leads to an interruption of the ion exchange process, and thus the blank 10 can be cut transversely into sections 14, see FIG. 6, with a thickness and diameter as it is for the formation of the lenses, such as the lens L of Fig. 4 are required. The meniscus configuration of the lens L is imparted conventional grinding and polishing processes.

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As shown by the hatching and the arrow 16 according to FIG. 4, the lens L is provided with a gradient of the refractive index from the axis outwards in the direction of arrow 16. the The density or the refractive index can also be chosen so that a decrease takes place in the direction of arrow 16 or vice versa.

In FIG. 7, an optional procedure for producing lens blanks which have a graded refractive index is described. Here, a blank 10 ^{1 is produced} from a central rod 18 with a preselected refractive index and successive, closely fitted sleeves 20, each of which has a predetermined different refractive index. The arrangement can have more or less than the five concentrically arranged components shown here, ie the gradation of the refractive index extending over increments starting from the rod radially outwards can have any desired step function, namely either increasing or decreasing.

The components 18 and 20 of the blank 10 'are normally heated and / or fused to one another in some other way on a unit and then on the transverse side with respect to the lens blank 22 cut to desired thickness. The fusion of the components 18 and 20 and the transverse cutting of the blank 10 ′ to form the lens blank 22 may be followed by irradiation or other treatment of the lens blank 22 being forming an intermingling or mutual merging the gradation of the refractive index of one of the components 18 and 20 with an adjacent component. It will further contemplated that components 18 and 20 may be surface treated prior to assembly Immersion in a diffusing agent, such as heated silver chloride, is experienced, causing a graded transition in the refractive index results in the individual parts with respect to the finished arrangement. Forming a gradation of the refractive index by means of Irradiation and / or diffusion are well known in the relevant field. Find details of how this works in the ÜS-PSs 3 610 924 and 3 563 057.

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Another way of working for producing a blank 10 * with The graduated refractive index, from which corresponding lens blanks can be cut, is shown in FIG. A multi-chamber glass furnace 24 is provided here, which has a plurality of concentric openings through each of which a lens material with a preselected refractive index can be fed, whereby the composite blank 13 "is formed. Im Following the formation of the blank 10 "and cooling of the same A transverse cutting along the lines 28 leads to the lens blanks 30 in a solid state. Instead of the glass furnace 24 can of course also be a plastic dispenser with multiple openings (i.e. ophthalmic plastic). step.

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Claims (20)

Claims 1. Procedure for correcting off-axis errors in the Manufacture of ophthalmic lenses, in addition to forming the lens with convex and concave opposing sides predetermined curvatures a specific thickness at the center of the lens and a predetermined refractive index adjacent to that Lens axis is formed, characterized in that a gradation of the refractive index in the material of the Lens is formed radially from the axis in the direction of the edge of the lens. 2. The method according to claim 1, characterized in that that the radial gradation of the refractive index is chosen so that an increase in the directions away from the lens axis he follows. 3. The method according to claim 1, characterized in that that the radial gradation of the refractive index is chosen so that a decrease in the directions away from the lens axis he follows. 4. The method according to claim 1, characterized in that that the radial gradation of the index of refraction is carried out in steps between the axis and the edge of the lens. 5. The method according to claim 1, characterized in that that the radial gradation of the refractive index in the form of a continuous change in value between the Axis and the edge of the lens. 6. The method according to claim 4, characterized in that that the radial gradation of the refractive index is chosen so that an increase in the directions away from the lens axis he follows. 7. The method according to claim 4, characterized in that that the radial gradation of the refractive index is chosen so that a decrease in the directions away from the lens axis he follows. 709840/0666 - 20 - 8. The method according to claim 5, characterized in that that the radial gradation of the refractive index is chosen so that an increase in the directions away from the lens axis he follows. 9. The method according to claim 5, characterized in that that the radial gradation of the refractive index is chosen so that a decrease in the directions away from the lens axis he follows. 10. The method according to claim 1, characterized e t that aspherical correction is carried out on at least one of the opposite sides of the lens. 11. Corrected, ophthalmic lens with optical convex and concave opposing side surfaces with preselected curvatures and a specific average thickness and index of refraction adjacent to the axis thereof, characterized in that a gradation of the refractive index in the There is material of the lens that extends in directions radially from the axis to the edge of the lens. 12. Ophthalmic lens blank with at least one curved Side surface, characterized in that there is a gradation of the refractive index in the material of the lens blank extends inward from the edges of the same. 13. Ophthalmic lens according to claim 11, characterized in that the radially graded refractive index in Directions away from its axis increases. 14. Ophthalmic lens according to claim 11, characterized in that that the radially graded index of refraction decreases in directions away from the axis thereof. 15. Ophthalmic lens blank according to claim 12, characterized in that the gradation of the refractive index decreases in directions from the edge towards the inside. - 21 709840/0686 16. Ophthalmic lens blank according to claim 12, characterized in that that the gradation of the refractive index increases in directions from the edge inward. 17. Ophthalmic lens according to claim 11, characterized in that the gradual gradation of the refractive index is gradual between the axis and the edge of the lens. 18. Ophthalmic lens according to claim 11, characterized in that g e k e η η ζ e i c hn e t that the radial gradation of the refractive index in the form of a continuous change between the axis and the edge of the lens. 19. Ophthalmic lens blank according to claim 12, characterized in that the gradation of the refractive index is gradually inward from the edge of the blank. 20. Ophthalmic lens blank according to claim 12, characterized in that the radial gradation of the Refractive index is in the form of a continuous change in directions from the edge of the lens blank inward. 7098U) / 0656