JPH03174109A - Designing method and working device for aspherical lens - Google Patents

Abstract

PURPOSE:To obtain the aspherical lens from which spherical aberrations are completely eliminated by determining the inclination of a curved surface in such a manner that the ray passing an arbitrary height from an optical axis passes a desired final pass point which is previously set after passing a lens. CONSTITUTION:The initial value of a first tracing ray R is set by an initial value setting means 11. The ray tracing is executed for this initial value by using a ray tracing means 12 and the pass point at the design curved surface is determined by an intersected point position determining means 15. In addition, the desired final pass point P0 at one point for the respective intersected points PT of the design curved surface is determined by a desired value setting means 13. The inclination T1 of the arbitrary curved surface at the intersected point PT is determined by a inclination setting means 14. The ray tracing at the inclination T1 of this curved surface is executed and the final pass point P1 of the ray is determined by a final pass point calculating means 16. The inclination T1 of the curved surface is determined as the desired inclination of the curved surface when the final pass point P1 and the desired final pass point P0 coincide. The lens from which the spherical aberrations are completely eliminated is easily produced in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for designing an aspheric lens, such as an intraocular lens or a contact lens, as a refractive correction means for the eye, and a manufacturing apparatus.

[Conventional technology]

In conventional technology, the asphericity of a lens is expressed as an even-order polynomial of the deviation from the spherical surface, ray tracing is performed while changing the coefficients of the polynomial, and aberrations are calculated and designed, or a special method is used instead of the polynomial. The most common method was to express the aspherical surface using an algebraic function and then design it by changing the coefficients.

However, with these methods, the expression of aspheric surfaces is limited to those that can be expressed by algebraic functions, and the degree of freedom in design is limited.For example, in the case of a refracting surface that is rotationally symmetrical about the optical axis,
The radius of curvature of that point is determined by the distance from the optical axis.

When the radius of curvature is expressed as an algebraic function of the distance from the optical axis,
The radii of curvature at two different points had a certain relationship depending on the shape of the algebraic function, and the radii of curvature at those points could not be changed independently.

For this reason, methods that use algebraic functions to express aspherical surfaces generally limit the degree of freedom in design, making it impossible, for example, to design intraocular lenses or contact lenses that completely eliminate spherical aberration.

[Problem to be solved by the invention]

In the ocular optical system, the image quality at the fovea of the macula affects visual acuity, so when designing intraocular lenses and contact lenses,
One of the important issues is how to control spherical aberration.The present invention provides an intraocular lens or contact lens that completely eliminates spherical aberration, or allows spherical aberration to be controlled arbitrarily. It is an object of the present invention to provide a lens designing method and manufacturing apparatus having arbitrary depth of focus and resolution.

[Means to solve the problem]

In the present invention, the shape of the refracting surface to be designed is not expressed using an algebraic function, but rather the inclination of the curved surface at a certain height from the optical axis of the refractive surface is determined, and the rays that use that height are determined as desired. A method is used in which the shape of the entire curved surface is designed from the height and the slope of the curved surface at that point. That is, (1) In the aspheric lens design method according to the present invention, in lens design using the ray tracing method, ray tracing is performed for a certain incident ray, and the intersection point of the ray and a specific refraction curved surface is determined. A step of determining the position (height from the optical axis and a position in the optical axis direction), a step of determining the desired final passing point PO where the tracing ray passing through the intersection point should pass after refracting the final refracting surface, and a step of determining the desired final passing point PO at the intersection point. a step of appropriately determining the slope T1 of the ray, a step of finding the final passing point P1 corresponding to Tl of the ray using the ray tracing method, a step of changing the slope at the intersection point to T2, and a step of determining the final passing point P1 corresponding to T2. determining the passing point P2 using a ray tracing method; Pl;
If neither P2 coincides with a specific point PO, finding a new slope by interpolation or extrapolation from the previous two slopes, two corresponding final passing points, and PO;
By repeating the step of finding the corresponding final passing point using the ray tracing method, the inclination is successively changed, and the final passing point P corresponding to the changed inclination is PO
If it agrees with , then the inclination is determined as the inclination of the refracting surface at the intersection point, and the step of repeating the same process as above for different intersection points by sequentially changing the height or angle of the incident ray. The present invention is characterized in that it includes a step of calculating the shape of a specific curved surface from the obtained intersection point and the slope at that point.

(2) Furthermore, in the lens design and manufacturing apparatus according to the present invention, in the lens design and manufacturing apparatus using a ray tracing method, ray tracing is performed for a certain incident ray, and the intersection of the ray and a specific refraction curved surface is determined. means for determining the position (height from the optical axis and position in the optical axis direction), and the desired final passing point PO where the tracing ray passing through the intersection should pass after refracting the final refracting surface.
, a means for appropriately determining the inclination TI of the curved surface at the intersection point, a means for finding the final passing point P1 corresponding to T1 of the ray using a ray tracing method, and changing the inclination at the intersection point to T2. means for determining the final passing point P2 corresponding to T2 using a ray tracing method; A method for successively changing the slope by repeating the steps of finding a new slope by interpolation or extrapolation and finding the corresponding final passing point using the ray tracing method. When the final passing point P coincides with PO, the inclination is determined as the inclination of the refracting surface at the intersection point, and the same process as above is performed for different intersection points by sequentially changing the height or angle of the incident ray. and a means for calculating the shape of a specific curved surface from the intersection point and the slope at that point, and a means for recording the calculated curved surface shape in a storage device, based on the information in the storage device. The lens is machined using a numerically controlled lathe device.

[Effect]

In the lens design method and manufacturing method of the present invention, the slope of the curved surface at a height h from the optical axis of a specific refracting surface is arbitrarily specified by the designer after a ray passing through the height h passes through the final refracting surface. is determined to pass through a specific point Po. The height or angle of the incident light ray is changed sequentially, and the slope of the curved surface at different heights h is determined sequentially, and the shape of the entire curved surface is calculated and designed from the slope value at each height h of the curved surface. Ru. That is, in the lens design method according to the present invention, a certain specific refractive curved surface of the optical system is selected as the designed curved surface, and the method according to the present invention is applied to that curved surface.

The incident rays are usually calculated from paraxial rays, and the following calculations are performed for each incident ray, with the ray height or angle increasing in small increments depending on the design objective. That is, the intersection point (height from the optical axis and distance in the optical axis direction) where the incident ray passes through the designed refraction curved surface is determined by ray tracing. The inclination of the refractive surface at this point of intersection is successively varied by the method presented by the present invention.

In other words, the first two inclinations are arbitrarily determined, and the third and subsequent inclinations are determined from the two preceding inclinations, the two corresponding final passing points obtained by ray tracing, and the desired final passing point.
The next slope is determined by interpolation or extrapolation.

In this way, the slopes of the curved surfaces at the intersection points are determined one after another. When the corresponding final passing point coincides with the desired passing point, the slope at that time becomes the slope of the curved surface.

As the slope of the curved surface at different heights h is determined by successively changing the incident light beam, the shape of the curved surface is also determined successively. In a design method in which the incident ray is started as a paraxial ray and the angle is gradually increased, the angle of the incident ray is gradually increased. The position of the intersection of the light beam and the designed curved surface in the optical axis direction changes according to the design. This change is calculated using the already designed curved surface shape and the following slope. A refractive surface designed in this way is designed so that the slope of the refractive surface from the optical axis always passes through the intended final passing point, making it possible to design lenses with various properties. For example, if the desired final passing point is chosen as one common point for each height, a lens that completely eliminates spherical aberration will be designed, and if the desired final passing point is chosen to be two points, a lens with bifocals will be designed. is designed.

〔Example〕

Hereinafter, a case will be described in which an embodiment of the present invention is applied to an intraocular lens that completely eliminates spherical aberration of an ocular optical system. FIG. 1 is a flowchart of the method according to the present invention, FIG. 2 is a schematic diagram of an eyeball with an intraocular lens inserted and symbols used in the flowchart, and FIG. 3 is a flowchart of the method according to the present invention. 1 is a block diagram of a device used for In FIG. 3, l is a computing device, 2 is a storage device, 3 is a display device, 4 is a keyboard, 5 is a storage device, and 6 is a numerically controlled lathe. The calculation device (2) is composed of a CPU and performs lens design according to a control program written in a memory (not shown).A specific file in the storage device is selected by selecting the keyboard, and the calculation device necessary for intraocular lens design is selected by the 10 successive means. The radius of curvature of the anterior and posterior surfaces of the cornea, the anterior and posterior surfaces of the intraocular lens, the distance between each refractive surface, the refractive index of the medium, information on which refractive surface is the target of the design, the initial value of the tracing ray, and the When changing the initial value, information such as whether the height from the optical axis changes, whether the angle changes, the pinch of change, or information for setting the target value is read. The desired final passing point of the ray for each intersection point of the designed curved surface is determined by the objective value setting means of No. 13. In this example, since an intraocular lens is designed with spherical aberration removed, the desired final passing point is a common point. Become. Ray tracing is performed on the first ray initial value of the tracing ray using the ray tracing means No. 12, and the passing point on the design curved surface (height h from the optical axis) is
and the position in the optical axis direction) are determined by the 15 intersection position determining means. The inclination of the refracting curved surface at the intersection point is successively changed by 14 inclination setting means based on the method according to the present invention, and the changed inclination is determined by using a ray tracing means, and the final passing point is determined by 16 final passing point calculation means. Desired.

It is checked whether this final passing point matches the target value by the determining means 1 of 17, and the slope setting means of 14 is repeatedly applied based on the method according to the present invention until failure occurs, and the slope changes one after another. The final passing point is calculated in each case. If the distance in the optical axis direction changes at that time, the change is determined by the intersection position determining means. When the final passing point matches the value determined by the target value setting means in this way, the inclination of the refraction curved surface at that time becomes the inclination of the curved surface to be determined. Inclinations at different heights h are successively determined by changing the initial value one after another, and the shape of the curved surface is determined one after another by the 18 curved surface shape calculation means.

This curved shape will be calculated after the following height.

The determining means 2 checks whether the shape of the curved surface is completely determined. When the shape is completely determined, the data of the curved surface shape is written into the storage device 5 by the writing means, and the numerical value 6 is written based on the data. The lens is processed under control.

〔Effect of the invention〕

According to the present invention, an intraocular lens that completely eliminates spherical aberration for a certain conjugate point can be easily designed and processed within the scope of geometrical optics. In addition, by changing the desired final passing point for each height h of the curve, it is possible to design and process an intraocular lens with the desired spherical aberration. It becomes possible to use intraocular lenses and contact lenses with In this way, according to the present invention, intraocular lenses and contact lenses that are clearly visible without spherical aberration can be produced, and bifocal and multifocal lenses can be precisely designed and processed.

[Brief explanation of the drawing]

FIG. 1 shows a flowchart of the method according to the invention. FIG. 2 shows the optical system of an eye with an intraocular lens inserted. PT is the intersection point, h is the height at the refraction surface, T is the slope of the surface at that point, PO is the desired final passing point, and P is T
This is the final passing point corresponding to . FIG. 3 is a block diagram of the equipment necessary for carrying out the present invention, in which 1 is a computing device, 2 is a storage device 3 is a display device, 4 is a keyboard, 5 is a storage device, and 6 is an NC lathe. 11 Bolt (I) Kanyuan (2) Figure 3 Voluntary procedure amendment dated February 15, 1991 1, Indication of the case, 1991 Patent application No. 313917 2, Title of the invention 3, Person making the amendment Case and connection of

Claims (1)

[Claims] (1) In lens design using the ray tracing method, ray tracing is performed for a certain incident ray, and the position of the intersection between that ray and a specific refraction surface (height from the optical axis and position in the optical axis direction)
a step of determining the desired final passing point P0 through which the tracing ray passing through the intersection point should pass after being refracted by the final refracting surface; a step of appropriately determining the slope T1 of the curved surface at the intersection point; using a ray tracing method to obtain a final passing point P1 corresponding to T2; If both P1 and P2 do not match a specific point P0, a step of finding a new slope by interpolation or extrapolation from the previous two slopes, two corresponding final passing points, and P0, and calculating the corresponding final passing point. By repeating the steps of determining the slope using the ray tracing method, the final passing point P corresponding to the changed slope is P0.
If it agrees with , then the inclination is determined as the inclination of the refracting surface at the intersection point, and the step of repeating the same process as above for different intersection points by sequentially changing the height or angle of the incident ray. A lens curved surface design method (2) comprising a step of calculating the shape of a specific curved surface from the obtained intersection point and the inclination at that point. A method for ray tracing an incident ray and determining the position (height from the optical axis and position in the direction of the optical axis) of the point of intersection between the ray and a specific refracting surface, and a means for tracing the ray that passes through that intersection to the final refracting surface. Desired final passing point P0 to pass through after refracting
, a means for appropriately determining the inclination T1 of the curved surface at the intersection point, a means for finding the final passing point P1 corresponding to T1 of the ray using a ray tracing method, and a means for changing the inclination at the intersection point to T2. means for determining the final passing point P2 corresponding to T2 using a ray tracing method; A method for successively changing the slope by repeating the steps of finding a new slope by interpolation or extrapolation and finding the corresponding final passing point using the ray tracing method; The final passing point P is P0
If it agrees with , there is a means to determine the inclination as the inclination of the refracting surface at the intersection, a means to repeat the same process as above for different intersections by sequentially changing the height or angle of the incident ray, and a method for determining the inclination in this way. means for calculating the shape of a specific curved surface from the intersection point and the slope at that point, means for recording the calculated curved surface shape in a storage device, and a numerically controlled lathe device based on the information in the storage device. Lens design and manufacturing equipment characterized by lens processing