DE19526928A1 - Optical gradient elements made from glass or plastic by spin casting - in process separating materials of differing molecular weight to produce a refractive index gradient along any required axis to make lightweight lenses or prisms for optical systems - Google Patents

Abstract

This optical gradient element shows refractive index variation perpendicular to one or more of its axes. The refraction is altered throughout the volume of the material. The variation extends from one axis radially outwards, spread evenly over a plane in all directions. The optical component is mfd. from the blank by mechanical operations, e.g. cutting and grinding, in which the location of the optical axis lies in the direction of a specified straight line, with a defined gradient of refractive index.

Description

The invention relates to gradient optical components, their use and a Method and device for its production from the liquid state.

The new type of optical components make it comparatively simple built optical systems with low weight and improved Imaging properties.

According to DE 42 14 259 a method is known with the optical glass material can be produced that has a refractive index gradient along a coordinate and for which Use as gradient optics is suitable.

The process involves mixing a mixture of different substances in a crucible Brought melt and after melting in the crucible until solidification be centrifuged. Centrifuging the melt leads to segregation, see above that a predetermined refractive index curve is realized.

The refractive index gradients and other properties that can be achieved with this method are not very reproducible and meet the requirements for optical components Not often.

With the melting of the batch there is a reduction in the volume of the Starting material connected. The melting pot is then no longer to the edge filled, which leads to the fact that the melted starting material by the action the centrifugal force is thrown outwards from the center of rotation. Plane-parallel plates with a refractive effect are used as optical components, Graduated filter or gray filter called.  

According to DE 36 31 660 a collimator lens is known which has an index change area that changes in the axial direction, but not at right angles to it.

An ion exchange takes place in an oxide glass plate, which leads to a gradient of the Refractive index leads. At least one spherical surface is attached to the glass plate worked on.

The invention is intended to be the process described in DE 42 14 259 for producing a Develop gradient optics so that optical material is reproducible in one Mass production process is inexpensive to manufacture.

Novel optical components or optical devices known per se are intended Components with novel properties can be created. The spherical and chromatic aberration should be easy to correct.

The object is achieved by gradient optical components with the Features of claim 1 or claim 2 solved. The sub-claims 3 to 12 are advantageous embodiments of the main claims.

According to the invention, the object is achieved by using gradient optics Components solved with the features of claim 13. The subclaim 14 is an advantageous embodiment of main claim 13.

According to the invention, the object is achieved by a production method Gradient-optical components with the features of claim 15 solved. The Subclaims 16 to 21 are advantageous embodiments of main claim 15.

The object is achieved by a device with the features of Claim 22 or claim 24 solved. The sub-claim 23 is an advantageous one Structure of main claim 22.  

The invention relates to methods for producing gradient optical Components made of a liquid material under the influence of gravity during the solidification of the material used to separate various Leads material components and causes a refractive index gradient in the material.

The invention relates to gradient optical components in which the refractive index changes continuously in the entire volume of the material in at least one coordinate. Gradient-optical components are determined according to DE 42 14 259 in that in a direction perpendicular to at least one axis of the component Refractive index changes in the entire volume of the material, the change being one Axis starting in one plane in all directions, radially outwards done evenly. At least one lies in the production of the blank Rotation axis in the area of the blank or outside of the blank.

According to the invention, the optical component is made from the blank in a first case can be produced by mechanical processing (e.g. cutting, grinding), the Position of the at least one optical axis in the direction of a predetermined straight line with a defined refractive index gradient.

In a second case, the optical component is formed by reshaping can be produced in the plastic state (e.g. pressing) of the blank, the position of the at least one optical axis in the direction of a predetermined straight line with a defined refractive index gradient.

If the surface quality obtained is not sufficient, the optical surfaces are used Example can be processed by lapping and / or polishing.

The gradient optical components are characterized in that the position of the optical axis is predetermined in the gradient medium.  

The refractive index in the medium has a defined initial value on the optical axis and in one case changes continuously along this axis. The gradient rises or falls. At right angles to the optical axis, the gradient is "zero" or it rises or falls also continuously preferably orthogonal to the optical axis with the distance of this.

In another case, the gradient along the optical axis is "zero" and the refractive index changes preferably at right angles to the optical axis. The Refractive index rises or falls from a defined initial value.

The refractive index changes in the volume of the material in a direction perpendicular to optical axis of the component, the change starting from an edge wedges, lenses for spectacle lenses or Layered lenses. In the production of the blank, the axis of rotation lies outside the Area of the blank.

A cylindrical lens is created when the refractive index changes from one Effective area of the optical component to another effective area of the optical Component out and preferably at a right angle with respect to an axis. In the production of the blank, its axis of rotation and the later optical one Axis of the component at a right angle to each other.

Are two or three preferably orthogonal in the manufacture of the blank Superimposed on the axes of rotation, the refractive index changes over the entire volume of the Material in several spatial directions of the optical component. Arise Components with a two- or three-dimensional course of the refractive index gradient. For example, a blank can be produced as a ball that has a radial center Refractive index has. The ball or part of the ball is an optical component usable.  

An optical component (lens) with one in the direction of the optical axis changing refractive index curve arises when in the manufacture of the cylindrical Blank two orthogonal axes of rotation are superimposed such that one axis of rotation is the cylinder axis of the blank and the other axis of rotation at a distance of the cylinder top surface is. A part of the cylindrical material becomes a gradient optical component manufactured. This is preferably the piece of material selected from the blank that is on the remote from the second axis of rotation Cylinder top surface lies.

The blank can be cylindrical, rectangular, triangular or one have any other shape. The whole blank can be used as a gradient optical Component or sections (cutouts, circular sections, Disks) with a predetermined refractive index curve are made from the blank selected.

Either the entire raw part is processed as an optical component or a certain part of the raw part is separated and further processing fed.

The invention relates to a method for the production of optical Material with a refractive index gradient in which a melted material is more homogeneous Composition via a pouring spout into a melting point of the Material preheated form is given, the shape around at least one axis is rotatably mounted and in the area of a vertical axis of a sprue is arranged. The shape is rotated about the at least one axis transferred. After the molten material has been filled in completely, the Form while maintaining the rotary motion cooled and defined Rotational movement is maintained until at least one plastic state of the material has been reached.  

The open form is used particularly where the rotary movement by one vertical axis and the filler neck essentially upwards (skyward) is directed. There can also be several fillers and air outlet openings be present if it is ensured that the material is rotated is not thrown out of shape.

The invention further relates to a method for producing optical material with refractive index gradients, in which a melted material homogeneous composition in a to melting temperature of the material preheated form is given. The form filled with the liquid material becomes dense completed. Then the mold rotates around at least one axis transferred. While maintaining the rotary motion, the shape is cooled and defined maintain the rotation until at least one plastic state of the Material has been achieved.

As the liquid material cools, its volume changes dramatically. Form is therefore designed so that the volume change can be compensated. To a wall of the form consists of a and acting in one dimension movable pressure surface that follows the volume change of the material. The closed form is preferably used where there is a rotation around there are several axes that are orthogonal to each other, for example. The geometry of the shape corresponds to the geometry of the blank to be produced. The Shape can take almost any shape. It just has to be in the design care should be taken to ensure that the material fills all areas of the mold and that air is in the Pouring the liquid glass can escape.

In the case of a closable mold, all must be filled in after filling Openings are closed.

The shape has a design that produces a semi-finished product from the liquid glass to Example in the form of a plate, block or rod.  

The form also has an education that raw parts in the form of, for example Lenses or prisms can be produced.

It is not necessary to leave the material in the mold until it solidifies rotate. The material can be removed from the mold in its plastic state and further processing, e.g. B. a pressing operation. The set refractive index gradient no longer changes in the plastic state.

The invention further relates to a method for producing gradient optics Components made of polymerizable liquids. The gradient optical Components are in particular plastic lenses for visual aids. It will be essentially carried out the procedures described above, with the difference that the Mold does not have to be preheated to a melting temperature and none Cooling process takes place, but a chemical reaction in which the inserted Material undergoes a transition from the liquid state to the solid state. The chemical reaction is, for example, a polymerization reaction of a casting resin. The crosslinking reaction of the molecules is triggered by the reaction of a cast resin hardener. (Catalyst) mixture triggered. By rotating during the Polymerization is followed by segregation of the homogeneous liquid resin hardener Mixture. The heavy molecules accumulate outside in relation to the axis of rotation, the lighter molecules inside. Due to the progressive solidification of the mixture the distribution of the molecules of different weights is "frozen". This distribution of the molecules creates a refractive index gradient in the material, which in the runs at right angles to the axis of rotation.

A one-component system can also be used. The Crosslinking reaction, which leads to solidification of the liquid resin, takes place in this Case triggered by energy supply. In one case, this is done by heat by the Form is heated.  

In another case, this is done by UV radiation if the shape or part the shape is made of a UV-permeable medium. For example, the liquid acrylic resin naftolan is used. The resin, the Catalysts (and possibly the retarder) are in a relationship with each other mixed so that a homogeneous liquid is formed. The mixture is in the Given lens shape. The shape is completed with a movable lid so that volume equalization can and will take place until a conclusion of the Curing reaction of the resin-hardener mixture is set in a rotary motion.

The invention is explained below with reference to figures. Show it:

Fig. 1 gradient-components with an outgoing from a rotational axis, radially outwardly directed refractive index gradient,

Fig. 2 representation of possible refractive index gradient in lenses according to Fig. 1,

Fig. 3 gradient-components with an outgoing from a side surface, directed towards a different side face of a refractive index gradient,

Fig. 4 gradient-components from parts of a cylinder with a running in the direction of a rotation axis of the refractive index gradient,

Fig. 5 with a lens extending in the direction of the optical axis of the refractive index gradient,

Fig. 6 lenses with different refractive index gradient which results from the different position of the axis of rotation,

Fig. 7 closed and open device for the production of gradient optical components.

Fig. 1 shows six basic lens shapes with differently shaped optical surfaces 1 and 2 , in which the optical axis 3 of the lens is the axis of rotation 4 of the blank. Starting from the center of the lens (optical axis 3 ), the refractive index increases continuously up to the outer diameter d. Show it:

FIG. 1a biconcave lens,

FIG. 1b biconvex lens,

Fig. 1c plano-convex lens,

Fig. 1d plano-concave lens,

Fig. 1e convex-concave lens,

Fig. 1f concave-convex lens.

This position of the axis of rotation 4 , which is identical to the later optical axis 3 , results in a center-radial refractive index curve that begins from the optical axis 3 (n = n₀) and rises continuously in all directions perpendicular to the optical axis 3 until the maximum Refractive index (n = n _max ) is reached at the lens edge. The course of the change can be linear (curves a in FIG. 2) or have a curve shape that is parabolic (curve b) or another shape that has a continuously increasing course starting from the pivot point 4 (curve c). The shape of the curve of the refractive index curve is dependent on the speed during the change in the state of the liquid-solid state, the material composition and the temperature curve during cooling and can be varied within wide limits. For example, with an optical medium of a certain composition and viscosity at n = 200 rpm, raw part diameter (mold diameter) 200 mm, a refractive index gradient .DELTA.n to 0.4 is achieved depending on the size of the temperature gradient. Plastic types and glass types are used as optical media, the components of which have a different size and weight. The components of the materials must be demixable under the influence of centrifugal force (or even just gravity).

Fig. 3 shows optical components in which the axis of rotation 4 of the blank is outside the surfaces 1 and 2 of the optical component. The axis of rotation 4 lies against an edge of the component or is at a distance a from it.

The distance a can be chosen from zero to infinity, whereby the technical and technological requirements and possibilities set limits. In order to obtain an almost constant refractive index in planes parallel to the axis of rotation 4 , the distance a should be large compared to the dimensions of the optical component. Fig. 3a shows a wedge with increasing with decreasing thickness refractive index. With this deflection wedge, the refractive index gradient acts against the dispersion (subtraction of the effect of the wedge angle and the refractive index). FIG. 3b shows a wedge of increasing thickness with increasing refractive index. With this deflection wedge, the refractive index gradient acts in the dispersion, a broad spectral band being generated (addition of the effect of the wedge angle and the refractive index).

Fig. 3c shows a circular or rectangular plate whose refractive index increases from a starting edge to another edge. The blank of the plate is rotated around the axis 4 during casting outside the later optical surfaces. The plate acts like a lens.

In further processing steps, shaped optical surfaces can be produced on the surfaces of the plate (as in FIG. 1).

A preferred application of the invention is that lenses for visual aids are manufactured (see Fig. 6). The production can take place as a blank from the melt or by further processing the above-described plate with refractive index gradients.

Components with a non-center radial refractive index curve are obtained that the blank is cast with a center-radial refractive index course and away only part of the cylinder is processed. The cylindrical blank can be divided, quartered or cut into strips. This will make cylindrical lenses receive.  

Fig. 4 shows cylindrical lenses that result from a section being cut out of the cylindrical blank along its axis. Fig. 4A shows a cylindrical-shaped blank with a radial refractive index profile. In Figs. 4b-4e different possibilities are shown, in which the blank is cut:

• b) a cut through the blank
• c) two cuts through the blank
• d) two cuts through the blank, symmetrical to the axis of rotation
• e) cuts that provide a segment of a circle.

Each type supplies parts with a specific position and a specific course of the refractive index gradient. For example, a plano-convex cylindrical lens ( FIG. 4f) can be produced from the part according to FIG. 4d by working on a radius on an optical active surface.

Fig. 5b shows a lens in which the cylindrical blank 5 ( Fig. 5a) was rotated liquid-tight around two axes during the change in the state of matter. An axis of rotation lies in the cylinder axis of the blank and a second axis is at a distance a from the end that is to be processed into a gradient lens. After the casting, spinning and solidification of the blank 5 , the section 6 of the blank 5 which has the refractive index gradient of interest is separated.

The section 6 can be an end piece or cut out of the cylinder. The optical surfaces 1 and 2 are then worked onto the section 6 . The lens according to Fig. 6b has a directed in the direction of the optical axis of the refractive index gradient in the volume of the material.

Optical devices of FIGS. 3, 4 and 5 can also be produced in that radial center blanks are molded as a cylinder, and only parts of the cylinder are further processed into optical devices by the blank takes place, the processing from the plastic state. In particular, the fine pressing of lens blanks is provided immediately after the plastic state of the raw part has been reached (after casting). By choosing the section of the cylinder, very variable refractive index curves can be mass-produced.

Fig. 6 shows gradient-components which are used as lens use. The differences in the schematic representation of the refractive index gradient in the lenses shown in FIGS. 6a, 6b (radial refractive index profiles) and 6c result from the different distance b of the axis of rotation 4 from the optical axis 3 . If the distance between the axis of rotation 4 and the optical axis 3 is large compared to the dimensions of the lens, the refractive index gradient is almost constant in parallel planes ( FIG. 6c).

Fig. 7a shows an apparatus for producing gradientenoptischer components in principle. The volume of the mold is lockable. It consists of a crucible made of a material that is resistant to the liquid optical medium. After the optical medium has been poured in, the crucible can be sealed with a lid. However, the cover is movable in the vertical direction and is pressed onto the optical medium by a force F. This compensates for the change in volume. FIG. 7b shows another device for producing gradient optical components in principle. The volume of the mold cannot be locked. It consists of a shape made of a material that is resistant to the liquid optical medium and has a vertical, skyward pouring spout. The sprue is located close to the axis of rotation.

Reference list

1 optical surface
2 optical surface
3 optical axis
4 axis of rotation
5 blank
6 section

Claims (24)

1. Gradient-optical components in which are in a direction perpendicular to at least one axis of the component the refractive index in the entire volume of Material changes, the change starting from an axis in a plane in all directions, radially outwards and evenly the optical component by mechanical processing (e.g. cutting, grinding), can be produced from the blank, the position of the at least one optical axis in the direction of a predetermined straight line with a defined refractive index gradient lies. 2. Gradient-optical components in which are perpendicular in one direction one axis of the component, the refractive index in the entire volume of the material changes, the change starting from one axis in one plane to all Directions, radially outwards and evenly the optical component by reshaping it in the plastic state (e.g. pressing) Blank can be produced, the position of the at least one optical axis in Direction of a predetermined straight line with a defined refractive index gradient. 3. gradient optical components according to claim 1 or claim 2, characterized characterized in that the whole blank or a predetermined part of the blank can be used.   4. gradient optical components according to claim 1 or claim 2, characterized characterized in that the position of the optical axis is such that the refractive index along this axis is one has a defined initial value and the gradient is "zero" or rises or falls, and / or that the refractive index is preferably at right angles to the optical axis has a defined initial value and the gradient is "zero" or increases or falls. 5. gradient optical components according to claim 1 or claim 2, characterized characterized in that in the production of the blank from the liquid state, an axis of rotation in the Area of the blank or outside of the blank and optionally other Axes of rotation in other spatial directions are superimposed. 6. gradient optical components according to claim 5, characterized in that the axis of rotation of the blank is the optical axis of the later component and the refractive index gradient along the optical axis is "zero". 7. gradient optical components according to claim 5, characterized in that the refractive index in a direction perpendicular to an axis of the component total volume of material changes, changing from one edge to another another edge of the component takes place, that is, in the manufacture of the Blank, the axis of rotation is outside the area of the blank.   8. Gradient-optical components according to claim 5, characterized in that the refractive index changes in one direction of an axis of the component in the entire volume of the material, the change starting from an active surface ( 1 ) of the optical component to another active surface ( 2 ) of optical component and preferably at a right angle with respect to this axis, that is, in the manufacture of the blank, the axis of rotation ( 4 ) of the blank and later optical axis ( 3 ) of the component are at a right angle. 9. gradient optical components according to claim 5, characterized in that in the production of the blank two or three, preferably orthogonal Axes of rotation are superimposed and the refractive index in the entire volume of Material changes in several spatial directions of the optical component. 10. gradient optical components according to claim 9, characterized in that
in the manufacture of the cylindrical blank, two axes of rotation are orthogonally superimposed such that
one axis of rotation is the cylinder axis of the blank and the other axis of rotation is at a distance from the cylinder top surface, from the adjacent material of which the gradient optical component can be produced and which has a refractive index curve which changes in the direction of the optical axis. 11. Gradient-optical components according to claim 1 or claim 2, characterized characterized in that the blank is cylindrical, rectangular, triangular or any other Has shape and the whole blank can be used as a gradient optical component or sections with a predetermined refractive index curve from the blank are selectable. 12. Gradient-optical components according to claim 1 or claim 2, characterized characterized in that the subsequent optical surfaces by final lapping and / or polishing are producible. 13. Use of gradient optical components in which the refractive index changes in the entire volume of the material in a direction perpendicular to an axis of the component, the change starting from one axis taking place in one plane in all directions, radially outwards uniformly (that is , in the manufacture of the blank, the axis of rotation ( 4 ) lies in the area of the blank or outside the blank) as optical lenses for use as a visual aid (spectacle lens). 14. Use of gradient optical components according to claim 13, characterized in that the axis of rotation ( 4 ) lies at the edge of the spectacle lens or outside the spectacle lens or in the spectacle lens. 15. Process for producing gradient optical components from a liquid Material under the influence of gravity during the controlled solidification of the Material that leads to the segregation of different material components and one Refractive index gradients in the material. 16. A method for producing gradient optical components according to claim 15, characterized in that

• - A liquid material of homogeneous composition is placed in a mold with a pouring spout, the pouring spout being close to an axis of rotation of the mold and remaining open
• the mold is rotated about at least one axis,
• - The liquid material solidifies after it has been completely filled into the mold while maintaining the rotational movement.

17. A method for producing gradient optical components according to claim 15, characterized in that

• - put a liquid material of homogeneous composition in a mold and
• - The form completely filled with the liquid material is still sealed
• the mold is rotated about at least one axis,
• - The liquid material solidifies in a defined manner while maintaining the rotary movement.

18. The method according to claim 17, characterized in that the change in volume of the solidifying material by at least one in at least one dimension of the movable wall of the mold is given.   19. The method according to claim 16 or claim 17, characterized in that

• - The liquid material is a plastic material that, when admixed with a substance that triggers the polymerization (hardener, catalyst) or supply of energy (heat, UV radiation), reacts chemically and solidifies under the action of the rotary movement, and is polymerized, in particular defined.

20. The method according to claim 16 or claim 17, characterized in that a defined lumen of liquid material under the influence of a rotary movement solidified, the refractive index is measured at at least one location in the lumen and the rotational movement when a certain refractive index or a certain one is reached Refractive index gradient is stopped. 21. The method according to claim 16 or claim 17, characterized in that

• - A melted material (plastic material, glass) of homogeneous composition is placed in the mold preheated to the melting temperature of the material and
• - The shape after the complete filling of the melted material while maintaining the rotational movement cooled and defined
• - The rotational movement is maintained until at least a plastic state of the material has been reached.

22. Device for the production of gradient optical components, consisting from a shape resistant to the optical medium in dimensions of the raw part to be produced, which can be sealed with at least one cover, wherein the at least one wall is movable in at least one direction and the change in volume of the optical medium can be compensated for, the shape being at least one axis of rotation is rotatably supported.   23. The device according to claim 22, characterized in that the lid is movable and is pressed onto the optical medium with a force. 24. Device for producing gradient optical components consisting of a shape resistant to the optical medium in the dimensions of the producing blank with a pouring spout that is in relation to the environment skyward open, closest to an axis of rotation of the form and in the direction of Axis of rotation is lying, the shape being rotatably mounted about the axis of rotation.