Additive manufacturing method and manufacturing system for ophthalmic lenses

Abstract

A method for additive manufacturing of an ophthalmic lens. The manufacturing method includes creating at least one discontinuity that results in a discontinuity in refractive index change. The at least one discontinuity is less than 1 mm 3 and smaller than, for example, 1 / 12 mm 3 and smaller than. The at least one discontinuity is located deep within the ophthalmic lens or on the surface of the ophthalmic lens.

Description

Technical Field

[0001] Various aspects of the present disclosure generally relate to the field of additive manufacturing methods for ophthalmic lenses and to the field of manufacturing systems.

Background Art

[0002] Myopia can have a long-term and serious impact on the eyes that can even lead to blindness. It appears that in most subjects, especially children, the myopic condition of the eyes tends to worsen over time.

[0003] Therefore, since the severity as a result of myopia progression is related to the ultimate severity of myopia that the subject reaches, it is extremely important to suppress or prevent myopia progression.

[0004] To suppress or prevent myopia progression, a small lens, a scattering point, or a scattering region can be added to one surface of the two surfaces of the ophthalmic lens worn by the subject.

[0005] Additive manufacturing can be used to obtain ophthalmic lenses. However, there are limitations in the actual additive manufacturing methods and manufacturing systems, especially when the ophthalmic lens is designed to suppress myopia progression.

[0006] This is also known from the U.S. application reference (Patent Document 1). However, the marks on the lens are not intended to reduce the myopia progression of the wearer.

[0007] Therefore, there is a need for additive manufacturing methods and manufacturing systems for ophthalmic lenses without these limitations.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Means for Solving the Problem

[0009] The following presents a simplified overview for providing a basic understanding of various aspects of the present disclosure. This overview is not an extensive overview of all contemplated aspects, nor is it intended to identify key or essential elements of all aspects or to define the scope of any or all aspects. The sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that follows.

[0010] One aspect of the present disclosure is a method of additive manufacturing of an ophthalmic lens. The manufacturing method includes creating at least one interruption, where at least one interruption results in an interruption in the refractive index change. The at least one interruption is less than 1 mm 3 and, for example, less than 1 / 12 mm 3 The at least one interruption is located deep within the ophthalmic lens or on the surface of the ophthalmic lens.

[0011] Another aspect of the present disclosure is a manufacturing system configured to additive manufacture an ophthalmic lens. The manufacturing system is configured to create at least one interruption, where at least one interruption results in an interruption in the refractive index change. The at least one interruption is less than 1 mm 3 and, for example, less than 1 / 12 mm 3 The at least one interruption is located deep within the ophthalmic lens or on the surface of the ophthalmic lens.

[0012] To understand the description provided herein and its advantages in more detail, reference is now made to the following simplified explanation in connection with the accompanying drawings and detailed description, where like reference numerals represent like parts.

Brief Description of the Drawings

[0013]

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DETAILED DESCRIPTION OF THE INVENTION

[0014] The detailed description set forth below in connection with the appended drawings is intended as a description of various possible embodiments and is not intended to represent the only embodiment by which the concepts described herein can be carried out. The detailed description includes specific details to enable a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

[0015] This description applies more particularly to the manufacture of ophthalmic lenses. The ophthalmic lenses can be suitable for attachment to an eyeglass frame. The ophthalmic lenses are either already potentially manufactured in a shape adapted to be attached to an eyeglass frame or require further edging steps to reach the required shape.

[0016] The expression "additive manufacturing technique" means a manufacturing technique defined in the international standard ASTM 2792-12, which describes a process of joining materials to manufacture an object from 3D model data by stacking layers, in contrast to subtractive manufacturing methodologies such as conventional machining. Thus, a solid object is manufactured by juxtaposing volume elements (mainly layers of voxels or drops or droplets or in some cases even blocks of material). In the context of this description, the ophthalmic lenses are manufactured per volume element, also known as a voxel, preferably per layer.

[0017] The additive manufacturing technique can actually be stereolithography (SLA), digital light processing stereolithography (DLP-SLA) or polymer jetting or others. Polymer jetting is also known as the inkjet method or printing method. The additive manufacturing technique includes a process of creating an object according to a predetermined arrangement definable in a CAD (computer-aided design) file.

[0018] Stereolithography (SLA) and Digital Light Processing Stereolithography (DLP-SLA) both act by focusing light, most often ultraviolet light, onto a container of photopolymer liquid resin to form solid layers that are stacked to create solid objects. With respect to Stereolithography (SLA), the liquid resin is subjected to selective exposure to light by a laser beam that scans the printing area. Digital Light Processing Stereolithography (DLP-SLA) uses a digital projector engine to project an image of each layer across the entire surface of the resin. Since the successive images of each layer are perceptually composed of square pixels, layers are obtained that are formed from small rectangular bricks called voxels (the volume of which is defined by the square pixels or laser width for stereolithography and the layer thickness).

[0019] Alternatively, the pixels can have other shapes, such as hexagonal, rhombic, elongated, etc., depending on the technology used.

[0020] In polymer jetting technology, a print head, such as an inkjet print head, is used to jet, drip, or deposit droplets of a curable material onto a support or build platform. The curable material is cured by a light source, such as an infrared source or an ultraviolet source, and solidified to build the layers that form the final ophthalmic lens.

[0021] The curable material is, for example, a photopolymer resin, and the ophthalmic lens is cured by a photopolymerization process. As an example, the photopolymer resin contains a (meth)acrylate monomer together with a radical photoinitiator.

[0022] In practice, in many cases, the photopolymerization process can be characterized by the conversion rate Cv (or polymerization rate) of the curable material. The conversion rate Cv is associated with the physical state of the substance of the curable material. Prior to irradiation with curable energy, most often light, the curable material is liquid.

[0023] At the start of curing, the conversion rate Cv is considered to be near 0, despite the slight polymerization due to the aging of the curable material. Under irradiation of the curable material with curable surface energy, the curable material polymerizes and progressively switches from a liquid state to a solid state. The curable material experiences a plurality of states, particularly an intermediate state called the "gel state", and its corresponding conversion rate Cv depends on the curable material.

[0024] The intermediate state corresponds to a state of matter that is neither liquid nor solid, in between them. In particular, according to the methodology of Jacobs (Paul F. Jacobs, Fundamentals of stereolithography in International Solid Freeform Fabrication Symposium, 1992), it is not a solid, but the monomers have started to polymerize with each other and have begun to form parts of a polymer network. The conversion rate Cv of the intermediate state can be, for example, 20% - 80% for some acrylate monomers, or higher than 10% and / or lower than 67% for some others. The curable material is considered to be in a solid state when the conversion rate Cv is generally higher than 80%. For some acrylate monomers, the curable material is considered to be in a solid state when the conversion rate Cv is higher than 67%. Depending on the material, the curable material is considered to be in a solid state when the conversion rate is higher than a critical conversion rate that can be empirically determined to be about 60% - about 80%.

[0025] The conversion rates characterizing the intermediate state and the solid state are determined by the curing surface energy E (or light dose) induced from the light source, the absorption characteristics of the curable material, and the efficiency of the initiator that polymerizes the curable material.

[0026] Figure 1 represents a manufacturing system 1 adapted to manufacture an ophthalmic lens through a DLP - SLA process. This manufacturing system includes a forming unit 3, a container 10, a support 15, and a shifting means 20.

[0027] The forming unit 3 includes an energy source 2, an optical system 4, and a computer element 6. The forming unit 3 is adapted to implement a method for manufacturing an ophthalmic lens 100 when instructions are executed. In practice, the computer element 6 includes a processor and a memory (not shown). The processor is adapted to execute instructions for manufacturing the ophthalmic lens 100, and the memory stores these instructions. As an example, the computer element 6 is programmed to generate instructions regarding the magnitude of the curing surface energy of each successive step providing the curing surface energy and regarding the image pattern (or light pattern) projected onto the surface 55 of the curable material 50. These instructions are transmitted, for example, to the energy source 2 and / or the optical system 4.

[0028] Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, system on chips (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gate logic, discrete hardware circuits, tensor processing units (TPUs), and other suitable hardware configured to perform the various functions described throughout this disclosure.

[0029] The memory is a computer-readable medium. By way of example and without limitation, such computer-readable media can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage devices, magnetic disk storage devices, other magnetic storage devices, combinations of the types of computer-readable media described above, or any other medium that can be used to store instructions or data structures in a form accessible by a processor in the form of computer-executable code.

[0030] The energy source 2 is suitable for irradiating the surface 55 of the curable material 50 with curing surface energy. The energy source 2 provides a light beam, such as an ultraviolet light beam, towards the curable material 50 by means of the optical system 4.

[0031] The optical system 4 is adapted to project the light originating from the energy source 2 onto the surface 55 of the curable material 50. The optical system 4 includes a plurality of micromirrors 8 arranged in a grid pattern. The plurality of micromirrors 8 is also referred to as a digital micromirror device (DMD). The micromirrors 8 are separated from each other by gaps (since it is actually impossible to provide a perfect junction between two adjacent micromirrors). The micromirrors 8 are, for example, of a sensibly square shape with a size of 8 μm × 8 μm. The gaps are 1 - 10 μm, for example about 2.8 μm, for a pitch between micromirrors of about 10.8 μm. When projected onto the surface 55 of the curable material 50, the micromirrors 8 form a projected pixel having a given pitch, including the direct projection of the micromirrors and the gaps. For example, the pitch can be about 40 μm × 40 μm, and about 30 μm × 30 μm corresponds to the projection of the micromirrors separated by a gap of about 10 μm.

[0032] It should be noted that other combinations of the energy source and the optical system exist. For example, the formation of the image pattern can be entirely caused by the energy source using an LED or OLED (organic light emitting diode) screen, and the optical system only provides a positional effect and a focusing effect. Alternatively, the energy source can provide energy in a continuous or regular burst mode, and the optical system generates an image pattern in addition to the positioning effect and the focusing effect. This typically applies to MEMS (micro - electro - mechanical systems) and LCD systems. Furthermore, the size of the micromirrors or LCD or LED pixels or the projected pixels can vary from this example.

[0033] As shown in FIG. 1, the optical system 4 includes a projection system 7 adapted to direct an ultraviolet beam from the energy source 2 towards a plurality of micromirrors 8.

[0034] The curable material 50 is in a liquid state within the container 10. When polymerized, the curable material 50 forms an ophthalmic lens 100 carried by the support 15. In practice, the support 15 is partially immersed in the container 10 of the curable material 50 such that a portion of the liquid curable material 50 is on the support 15. Thus, the light beam provided by the energy source 2 is projected onto this portion of the curable material 50. Thus, when this portion polymerizes, a part of the ophthalmic lens 100 formed is on the support 15.

[0035] FIG. 2 depicts a manufacturing system 201 adapted to manufacture an ophthalmic lens 100 through polymer injection. The manufacturing system 201 includes · a support 15 on which the ophthalmic lens 100 is fabricated, the support 15 also being configured to move downward during the manufacture of the ophthalmic lens 100, the support 15 being sensibly flat and configurable to be in a horizontal position during the manufacturing process, the support 15; · a tank 202 configured to contain a curable material; · a print head 206 including a nozzle 205 connected to the tank 202 and configured to eject, drip, or deposit the curable material coming from the tank 202, the print head 206 being configured to move along a plane parallel to the support 15; · a curing unit 203 configured to cure the already ejected curable material and includes. The curing unit can be an imaging device or a non-imaging device (such as an LED light-emitting diode or UV light) like the DLP presented earlier.

[0036] The set including the tank 202 and the print head 206 forms a dispensing unit.

[0037] In some embodiments, the support 15 is fixed and the print head 206 can move in three dimensions.

[0038] In some embodiments, the print head 206 is fixed and the support 15 can move in three dimensions.

[0039] Optionally, the manufacturing system 201 can include a leveling blade 204 used to level the layer of curable material ejected by the nozzle 202.

[0040] During the manufacturing process, the nozzle 202 is used to eject a layer of curable material. This layer either rests on top of a previously manufactured layer of curable material 50 or directly on the support 15. The curable material 50 is cured using the curing unit 203. Once the material has been cured, the support 15 can be lowered to manufacture a new layer.

[0041] The manufacturing system of FIG. 2 can further include a computer element (not shown). As previously explained, the computer element includes a processor and a memory. The processor is adapted to execute instructions for manufacturing the ophthalmic lens 100, and the memory stores these instructions. As an example, the computer element 6 is programmed to generate instructions regarding the amount of curable material to be dropped onto each part of a given layer. To do this, the computer element 6 instructs the print head 206 and / or the support 15 to move to each position where curable material must be dropped, and instructs the nozzle 205 to drop a predetermined amount of curable material at different positions.

[0042] The computer element 6 also instructs the curing unit 203 to effect the curing of the layer. The manufacturing systems of FIGS. 1 and 2, more precisely the computer element 6, are configured to implement a manufacturing method. This manufacturing method enables the production of ophthalmic lenses.

[0043] As shown in FIG. 3, the manufacturing method includes step 301 of fabricating a plurality of discontinuity portions that result in a discontinuity in the refractive index change. The discontinuity portion includes a plurality of boundary surfaces. Each of the discontinuity portions is smaller than 1 mm 3 and, for example, smaller than 1 / 12 mm 3 . The discontinuity portion is located deep inside the ophthalmic lens or on the surface of the ophthalmic lens. When the discontinuity portion is inside the ophthalmic lens or flush with the surface of the ophthalmic lens, it is located deep inside the ophthalmic lens.

[0044] The manufacturing method of FIG. 3 further includes step 302 of fabricating one or more other portions adjacent to and / or at least partially surrounding the discontinuity portion.

[0045] Specifically in relation to U.S. Patent Application Publication No. 2015 / 0253585, which is a U.S. application, the discontinuity in refractive index change means that the discontinuity portion can exhibit an irregular and uncontrolled arrangement of layers as compared to the prior art arrangement.

[0046] The plurality of discontinuity portions and the other portions can be obtained using the same curable material. In contrast, in U.S. Patent Application Publication No. 2015 / 0253585, which is a U.S. application, the mark and the other portions of the lens are not obtained using the same curable material. Using the same material is advantageous because the manufacturing process is simplified by having only one material to handle.

[0047] The discontinuity in refractive index change causes scattering of light across at least one discontinuity portion.

[0048] The other portions surrounding the discontinuity portion are transparent and exhibit a substantially homogeneous and constant refractive index. The substantially homogeneous and constant refractive index is a refractive index that does not affect the optical quality of a portion of the ophthalmic lens having this substantially homogeneous and constant refractive index.

[0049] The discontinuity portion and the other portions form the ophthalmic lens.

[0050] The change in refractive index is, for example, from 0.0001 to 0.001.

[0051] Step 301 of creating the interrupted portion and step 302 of creating the other portions can be realized simultaneously or sequentially.

[0052] The manufacturing method of FIG. 3 can be executed using the manufacturing system of FIG. 1 or the manufacturing system of FIG. 2.

[0053] By using this method, the entire ophthalmic lens including the interrupted portion is manufactured using a single method. Therefore, this method is not more complex than other manufacturing methods as it avoids adding several complex steps. The method of this description also limits industrial problems (such as cost, accuracy consistency, etc.).

[0054] Since the interrupted portion is located deep within the ophthalmic lens, these portions do not need to be damaged, and the aesthetics of the ophthalmic lens are improved.

[0055] When varnish is applied to the ophthalmic lens after manufacturing, this localization of the interrupted portion also prevents the formation of a meniscus with a negative curvature at the contour of the interrupted portion, which may occur when the interrupted portion is located on the surface of the ophthalmic lens.

[0056] The interrupted portion scatters light, while the other portions do not scatter light or scatter light very little (for example, without co-polymerization as described later). When layers are created and cured according to conventional curing strategies, optical defects (part of the micro-optical element) are generated between the two cured layers.

[0057] In other words, the manufacturing method of the present disclosure uses the same curable material for the interrupted portion of the lens and the other portions of the lens surrounding the interrupted portion to provide light scattering in a controlled manner.

[0058] Using this method, inhomogeneity can be created on the substrate, and the propagating wavefront and scattered light can be deformed.

[0059] According to the following literature, due to the discontinuity (inhomogeneity, non-linear gradient) of the refractive index change, the wavefront is chaotically distorted and light scattering occurs. In the modeling of light by inhomogeneous refractive index materials, the following three references, namely, · 1998 (Tunick) Calculating the Microstructure of Atmospheric Optical Turbulence https: / / apps.dtic.mil / sti / pdfs / ADA358511.pdf · 2007 (Cheon Muschinski) Closed-form approximations for the angle-of-arrival variance of plane and spherical waves propagating through homogeneous and isotropic turbulence · 2018 (Voelz Xiao) Computer simulations of optical turbulence in the weak-and strong scattering regime angle-of-arrival fluctuations obtained from ray optics and wave optics https: / / doi.org / 10.1117 / 1.OE.57.10.104102 are used.

[0060] Figure 4 shows the manufacture of an ophthalmic lens 100 using the method of Figure 3. The ophthalmic lens 100 is formed of a discontinuity portion 401-a and other portions 401-b surrounding the discontinuity portion 401-a. Each of the discontinuity portions 401-a is less than 1 mm 3 less than, for example, 1 / 12 mm 3 less than. The discontinuity portions 401-a are located deep within the ophthalmic lens 100. The three dimensions (width, length, and height) of the discontinuity portions 401-a are, for example, 1 mm to 1 / 4 mm.

[0061] The method of FIG. 3 can include the step of manufacturing a plurality of layers of curable material to create at least one discontinuity 401-a. Different interfaces are located between each of the layers. The number of interfaces is determined by the number of layers and is equal to the number of layers minus one. The number of layers in each discontinuity is determined by the layer thickness and the thickness of the discontinuity.

[0062] In some embodiments, other portions 401b are also obtained by manufacturing a plurality of layers. The plurality of layers forming the other portion 401-b can be obtained simultaneously with the plurality of layers forming at least one discontinuity 401-a.

[0063] The layers among the plurality of layers can be substantially perpendicular or parallel to an axis orthogonal to the front surface of the ophthalmic lens 100 at the front vertex, for example, the optical axis of the ophthalmic lens 100. In other words, the layers have an orientation parallel or perpendicular to the general orientation of the front or back optical surface of the ophthalmic lens 100, or an orientation between an angularly parallel orientation and a perpendicular orientation. When the layer is perpendicular to the axis, the ophthalmic lens is constructed in the vertical direction, which is advantageous because the support 15 of the manufacturing system contacts the edge of the ophthalmic lens 100. By having an angle of 30° to 45°, it is possible to quickly perform the manufacturing method by enabling both sides of the ophthalmic lens 100 to face the bottom or top of the manufacturing system.

[0064] In a first example of the manufacturing method, the step of manufacturing a plurality of layers is · using a first image having a first contrast level to cure a first area of one of the plurality of layers, the first area being included in one of the discontinuities 401-a; and · using a second image having a second contrast level to cure a second area of the layer, the second area being different from the first area and the first contrast level is higher than a predetermined sharpness threshold, and the second contrast level is lower than a predetermined blur threshold.

[0065] The second area is part of the other portion 401-b that surrounds the discontinuity 401-a. Therefore, the second area is not included in one of the discontinuities 401-a.

[0066] The first image and the second image can form an overall image. This overall image is used to cure the first area and the second area in a single curing step.

[0067] The first image having a first contrast level higher than a predetermined sharpness threshold generates a first portion of a layer that results in a greater change in refractive index, while the second image having a second contrast level lower than a predetermined blur threshold generates a second portion of the same layer that results in a smaller change in refractive index.

[0068] Both the first image and the second image are generated using a DMD (Digital Micromirror Device) to generate a light beam of a desired shape for irradiating the curable material. In the process of using a DMD to photocure a resin, in the projection area onto the photocurable resin, the intensity of the projected light in the portion corresponding to the area of the micromirror itself is different from the intensity of the projected light in the portion corresponding to the area between adjacent micromirrors. Due to this, a slight difference occurs in the state of the photocurable resin between these two portions, and a periodic refractive index change corresponding to the two-dimensional array of micromirrors occurs in the cured layer of the photocurable resin. The first image is directly generated using a DMD, for example. In this first image, a high contrast level is obtained by the difference in intensity between the light projected by the area of each micromirror and the light projected by the area between adjacent micromirrors. To obtain a second image having a contrast level lower than that of the first image, the second image is passed through a diffusing element. To obtain a second image having a contrast level lower than that of the first image, the optical system 4 can also be put into a defocused state while displaying the second image.

[0069] In an embodiment, the image is a monochrome image, for example, a black and white image. The energy level of the image can be equal to or higher than a solid energy threshold described in the next part of this description.

[0070] Regarding other portions 401-b surrounding the discontinuous portion 401-a, the use of a second image having a contrast level lower than the contrast level of the first image is also called blurring. This blurring is used to obtain a certain uniform refractive index for this surrounding portion. This blurring enables the projection of light of substantially constant intensity onto the curable material. More precisely, the intensity of light projected by the area of each micromirror and the intensity of light projected by the area between adjacent micromirrors are approximately equal or at least more approximate compared to the case where no blurring is used. When a blurred image is used, curing becomes substantially the same for the entire portion cured by this blurred image. The cured product has a certain uniform refractive index.

[0071] FIG. 5 is a graph schematically showing the illumination energy provided by the first image and the second image.

[0072] Here, the illumination energy is defined as the surface dose of optical energy that can be expressed in mJ / mm 2 units.

[0073] The illumination energy provided by the first image is represented by curve 24, and the illumination energy provided by the second image is represented by curve 61.

[0074] Curve 24 has a high region 32 corresponding to the location where the first image is projected and a low region 33 corresponding to the location where the first image is not projected.

[0075] The high region 32 includes a series of terraces 25 and valleys 26 that are respectively the influence of the micromirrors of unit 16 and the influence of the spaces between these micromirrors.

[0076] The mesa part 25 defines a high energy level 27 which is the average maximum energy received by the area of the layer 21 onto which the first image is projected. These mesa parts are obtained at locations where the micromirrors are present.

[0077] The valley part 26 defines a low energy level 28 which is the average minimum energy received by the area of the layer 21 onto which the first image is projected. These valley parts are obtained at locations where the micromirrors are not present.

[0078] The low region 33 defines a minimum energy level 30 which is the average residual energy received by the area of the layer 21 onto which the first image 17 is not projected, and such average residual energy is considered to be zero here.

[0079] The curve 61 has a high region 34 corresponding to the location where the second image is projected and a low region 35 corresponding to the location where the second image is not projected.

[0080] The high region 34 is formed by a series of mesa parts 36 and valley parts 37 which are respectively the influence of the micromirrors of the unit 16 and the influence of the space between these micromirrors.

[0081] The mesa part 36 defines a high energy level 38 which is the average maximum energy received by the area of the layer 21 onto which the second image is projected. These mesa parts are obtained at locations where the micromirrors are present.

[0082] The valley part 37 defines a low energy level 39 which is the average minimum energy received by the area of the layer 21 onto which the second image is projected. These mesa parts are obtained at locations where the micromirrors are not present.

[0083] The low region 35 defines a minimum energy level 40 which is the average residual energy received by the area of the layer 21 onto which the second image 18 is not projected, and such average residual energy is considered to be zero here.

[0084] Curve 61 joins the high region 34 to the low region 35 respectively, and is a fading region 41 corresponding to the periphery of the second image 18, and further has a fading region 41 where the light energy gradually decreases.

[0085] Similar fading regions actually also exist in curve 24, but here, since the contrast level of the first image 17 is much higher than the contrast level of the second image 18, it can be ignored.

[0086] Another fact indicating the higher contrast level of the first image 17 with respect to the contrast level of the second image 18 is that the altitude difference between the mesa portion 25 and the valley portion 26 of curve 24 is larger than the altitude difference between the mesa portion 36 and the valley portion 37 of curve 61.

[0087] Taking the above into consideration, the contrast level of the image projected by the unit 16, for example, the first image 17 or the second image 18, can be defined by the following formula, that is, contrast level = (high energy level - low energy level) / (high energy level - minimum energy level).

[0088] As described above, in the case of the first image and the second image, the minimum energy level is the average residual energy received by the area of the layer 21 where the image is not projected, and can be regarded as zero.

[0089] Actually, this average residual energy is mainly a characteristic of the manufacturing system 1, and is actually close to 0 mW / cm 2 and, for example, is 0.12 mW / cm 2 This value of the average residual energy is usually given by the manufacturer of the manufacturing system 1.

[0090] By regarding the average residual energy as equal to zero, the above formula is simplified as follows, that is, contrast level = (high energy level - low energy level) / (high energy level).

[0091] Therefore, for the first image, the contrast level is (Level 27 - Level 28) / (Level 27).

[0092] Therefore, for the second image, the contrast level is (Level 38 - Level 39) / (Level 38).

[0093] This difference in contrast is obtained because the second image is passed through a diffusing element before being projected onto the curable material.

[0094] The predetermined sharpness threshold and the predetermined blur threshold may be determined by the composition and / or the inherent parameters of the curable material.

[0095] The predetermined blur threshold can be obtained by additive manufacturing a plurality of test elements representing the ophthalmic lens to be manufactured from the curable material, each test element being obtained at a respective different contrast level, and then each of these test elements is tested to determine the contrast level below which the diffraction effect is tolerated (or accepted), i.e., the blur threshold.

[0096] The test elements can be manufactured using a manufacturing system such as the system of FIG. 1.

[0097] Each test element can be tested by the shadowgraph method, for example, using an arc lamp to irradiate the test element and generate a shadowgraph that can be analyzed by the naked eye. The diffraction effect can be considered acceptable when it cannot be detected or can hardly be detected by the naked eye, or more generally, when it is low enough for ophthalmic applications.

[0098] Alternatively, or in addition, each test element can be tested by analyzing transmission characteristics such as the diffraction order generated by a laser or the transmittance in UV spectroscopy.

[0099] For example, for a given material containing acrylate and methacrylate monomers, a given blur threshold is about 3%, whereby a refractive index change of about 0.0001 is obtained.

[0100] More generally, for most given curable materials, it has been found that a cured product having an acceptable diffraction effect for obtaining a non-discontinuous portion can be obtained by using a second contrast level lower than a given blur threshold of 4% or preferably 2%.

[0101] The given sharpness threshold is higher than 60%, preferably 66%.

[0102] FIG. 6-a represents a first image used to create a discontinuity in a layer that results in a discontinuity in the refractive index change for one of the layers. FIG. 6-b represents a second image used to create a portion surrounding the discontinuity for the same layer. Both FIGS. 6-a and 6-b are used to create a layer that is substantially perpendicular to the axis orthogonal to the front surface of the ophthalmic lens 100 at the front vertex.

[0103] In a second example of the manufacturing method, the step of manufacturing a plurality of layers is · curing a first area of one of the plurality of layers, which is included in one of the discontinuities 401-a, using the first image without shifting the first image during curing; · curing a second area of the layer, which is different from the first area, using the second image by shifting the second image during curing and includes.

[0104] Generally, the shift of the second image is performed along the horizontal plane. Since the curable material is generally liquid, it means that the shift of the second image is realized along a plane parallel to the surface of the curable material. In other words, during the shift, the projection of the second image onto the surface of the curable material is moved along a plane parallel to the surface of the curable material. This shift is advantageously performed over a distance corresponding to the size of the gap between the micromirrors. For example, if this gap is 1 μm to 10 μm, the shift can be performed over 10 to 100 μm. This shift can be realized by moving the forming unit 3 along the horizontal plane, by moving the support 15 along the horizontal plane, or by moving both the forming unit 3 and the support 15 along the horizontal plane.

[0105] In this second example, by not shifting the first image, it becomes possible to create a plurality of boundary surfaces of the discontinuity portion 401-a. By shifting the second image, it becomes possible to create other portions 401-b surrounding the discontinuity portion 401-a, and these other portions 401-b have a certain uniform refractive index. Therefore, the second area is not included in one of the discontinuity portions 401-a.

[0106] The images of FIGS. 6-a and 6-b can also be used in this second example. The discontinuity portion 401-a is generated using a DLP projector for curing the material. As described above, DLP is composed of a DMD (micromirror lattice) that pixelates a light beam.

[0107] By shifting the second image used to create the other portions 401-b, the occurrence of defects that occur when curing the discontinuity portion is avoided.

[0108] Regarding the other portions 401-b surrounding the discontinuity portion 401-a, in order to obtain a certain uniform refractive index of the other portions 401-b, the blur of the first example or the shift of the second example is used.

[0109] The level of refractive index change discontinuity depends on various parameters, namely, · Type of hardening material · Size of pixels of the DLP projector · Distance separating pixels · Hardening parameters (light intensity, hardening time, etc.) · Thickness of the layer · Voxel stacking (The light scattering effect is determined by the size of the discontinuity. The size is determined by the size of the voxels in each layer, but is also determined by the layer stacking, for example, how many layers are used to create the discontinuity.) It is determined by

[0110] When the layers are fabricated sensibly parallel to the optical path, in other words, substantially parallel to the axis orthogonal to the front surface of the ophthalmic lens at the apex of the front surface, it is also possible to use the first and second examples of the steps of manufacturing a plurality of layers. In fact, the "black space" between the pixels is "propagated" deep into the printed layer, and when scattering occurs, a change in the refractive index change in the Z direction (the direction of the illumination axis for hardening) occurs, which helps to control myopia. In order to realize this fabrication using sensibly parallel layers, accordingly, the printing orientation of the ophthalmic lens is corrected.

[0111] FIG. 7-a represents another example of a first image that can be used to create a discontinuity 401-a of a layer that results in a refractive index change discontinuity for one of the layers. FIG. 7-b represents another example of a second image that can be used to create another portion 401-b surrounding the discontinuity 401-a for the same layer. Both FIGS. 7-a and 7-b are used to create layers that are substantially parallel to the axis orthogonal to the front surface of the ophthalmic lens at the apex of the front surface of the ophthalmic lens.

[0112] In a third example, or in combination with the first and second examples, the step of manufacturing a plurality of layers is · irradiating a first hardening surface energy that is above a solid energy threshold corresponding to an energy sufficient to harden the entire thickness of a first area, thereby hardening a first area of a first layer of the plurality of layers; · irradiating a second cured surface energy that is strictly lower than the solid energy threshold and higher than the induced surface energy to cure a second area of the first layer comprising After irradiating the first layer, the method further comprises · irradiating a first cured surface energy onto the surface of the curable material to cure a first area of the second layer, the first area of the second layer covering the first area of the first layer · using at least a third cured surface energy that is higher than the induced surface energy, the third cured surface energy irradiating both a second area of the second layer and at least a portion of the second area of the first layer, and the sum of the second cured surface energy and the third cured surface energy received by the second area of the first layer being sufficient to cure the second area of the first layer, and the second area of the second layer covering the second area of the first layer, to cure the second area of the second layer further comprising The first area of the first layer is included in one of the breaks 401-a. The first area of the second layer is included in the same break 401-a as the first area of the first layer. The second area of the first layer and the second area of the second layer correspond to the other part 401-b surrounding the break 401-a. Therefore, the second areas of the first layer and the second layer are not included in one of the breaks 401-a.

[0113] A curing step that enables curing of the second area of the first layer at a threshold lower than the solid energy threshold and supplies residual energy for polymerization during curing of a subsequently deposited layer is referred to herein as a subpolymerization process.

[0114] The solid energy threshold Ts can correspond to the energy sufficient to make solid over the entire thickness of the first area of the first layer or the first area of the second layer of the ophthalmic lens 100. Alternatively, the solid energy threshold Ts can correspond to the energy for having sufficient “green strength,” which means that the energy is solid enough to allow handling of the fabricated device, but lower than the energy required to fully cure the material of the layer or device, and is sufficient to cure the first area of the first layer or the first area of the second layer of the ophthalmic lens 100. The term “green” here refers to the initially formed photopolymerized ophthalmic lens, in contrast to the final ophthalmic lens, which undergoes additional thermal curing and / or UV post-curing after the additive manufacturing process. More details about this solid energy threshold Ts can be found in the paper “Polymers for 3D Printing and Customized Additive Manufacturing” of Samuel Clark Ligon, Robert Liska, Jirgen Stampfl, Matthias Gurr, and Rolf MCilhaupt, published Chemical Reviews 2017 117(15), 10212 - 10290, DOI: 10.1021 / acs.chemrev.7b00074.

[0115] The induction surface energy Ei is the curing surface energy E above which the polymerization process starts. If the curing surface energy E is lower than this induction surface energy Ei, the curable material remains liquid and polymerization does not occur.

[0116] Furthermore, the solid energy threshold Ts is strictly higher than the induction surface energy Ei, for example, higher than twice the induction surface energy Ei. This solid energy threshold Ts is sufficient to obtain a portion that is more solid than the still unpolymerized portion.

[0117] As an illustrative example, it can be considered that the curable material is based on an acrylate monomer having an experimentally determined value of the critical Jacobs energy Ec of 5 mJ and a light depth penetration value Dp of 200 μm. Thus, for constructing a layer having a thickness of 10 μm, the solid energy threshold Ts is 5.26 mJ. The solid energy threshold Ts is equal to the Jacobs energy Ej. Using the values from the previous section, the first curing energy can be equal to 6 mJ. The curable material can also be irradiated by a plurality of successive irradiations, for example, four successive irradiations each equal to 1.66 mJ. The second curing energy and the third curing energy can be equal to 3 mJ. The curable material can also be irradiated by a plurality of successive irradiations, for example, three successive irradiations each equal to 1 mJ. This initial set of pixels is projected onto the surface 55 of the curable material 50 above the support 15 to form an initial layer. In the first area, since the curable material is cured throughout its thickness, the first area becomes solid. In the second area, the curable material being irradiated does not become solid. The second layer is disposed to cover the initial layer. The second layer is irradiated and the first area is cured throughout its thickness. After irradiation, the second area of the second layer does not become solid. After irradiation, the second area of the initial layer becomes solid due to the irradiation received during the irradiation of the initial layer and the irradiation of the second layer.

[0118] In other words, in the third example, the discontinuity 401-a is produced using a part of the additive manufacturing method described above without using co-polymerization, i.e., as in the case of the first area described above. When curing a further new layer on the previously cured layer, the interface is produced with different material properties and thus different optical properties by polymerizing a part of the new layer until it becomes solid. By stacking these defects resulting from the process for each layer, a refractive index discontinuity occurs.

[0119] The other part 401-b surrounding the discontinuity 401-a is obtained using co-polymerization to have a homogeneous and constant refractive index.

[0120] To achieve curing using different energies, two different images can be used. The first image used to cure the discontinuity exhibits a high light density in the portion to be cured, meaning a white or near-white color. The second image is used to cure the portion surrounding the discontinuity. The second image exhibits a lower light density, meaning that a part of the image used for curing is darker than the portion of the first image.

[0121] The first image and the second image can be applied sequentially or simultaneously depending on the characteristics and configuration of the manufacturing system, for example, the number of curing devices.

[0122] When the first image and the second image are applied simultaneously, the first image and the second image must be integrated into a single image light beam projected onto the surface to be cured. Curing can also be achieved using a single image including the first image and the second image in grayscale mode to adjust the amount of light on the surface to be cured.

[0123] FIG. 8 shows a grayscale image used to cure a curable material using energy corresponding to the portion to be cured. The white portion of the image enables curing of the discontinuity 401-a, and the gray portion of the image enables curing of the other portion 401-b surrounding the discontinuity 401-a.

[0124] In a fourth example, by steps of manufacturing a plurality of layers, · the front surface of the ophthalmic lens 100, · the back surface of the ophthalmic lens 100, · the side surface of the ophthalmic lens 100, · and a plurality of protrusions extending from the front surface, the back surface, or one of the other surfaces in the direction of one of the other surfaces can be formed, The method is · a step of filling the curable material inside the ophthalmic lens 100, · and a step of polymerizing the curable material filled inside the ophthalmic lens further includes.

[0125] In other words, using the fourth example, by forming the front surface, the back surface, and the side surfaces, it becomes possible to form the skin of the ophthalmic lens 100. Further, substantially simultaneously with the production of the side surfaces of the ophthalmic lens, a plurality of protrusions are produced. The protrusions exhibit a refractive index discontinuity, and therefore, a method that enables achieving this refractive index discontinuity must be used to produce the protrusions. The side surfaces generally have a homogeneous and constant refractive index. To obtain the protrusions with a discontinuous refractive index and the side surfaces with a homogeneous and constant refractive index, the first embodiment, the second embodiment, and the third embodiment described above can be used.

[0126] FIG. 9 shows a cross-sectional view of the ophthalmic lens 100. 901 is one of the protrusions. 902 is a portion having a constant and homogeneous refractive index. 903-a is the back surface, 903-b is the side surface, and 903-c is the front surface.

[0127] Generally, the first, second, third, and fourth examples of the step of manufacturing a plurality of layers are used in the manufacturing system shown in FIG. 1, which is adapted to manufacture the ophthalmic lens 100 through a DLP-SLA process.

[0128] In the fifth example, the step of manufacturing a plurality of layers is · a step of ejecting a discontinuous layer of a curable material onto a first area of one of the plurality of layers, · a step of ejecting a continuous layer of a curable material onto a second area of the layer, · a step of curing the first discontinuous layer and the first continuous layer and includes. The first area is included in one of the discontinuity portions 401-a.

[0129] The method, after curing the first discontinuous layer and the first continuous layer, · Injecting a second discontinuous layer of curable material onto a first area of a second layer among a plurality of layers, the first area of the second layer covering the first area of the first layer; · Injecting a second continuous layer of curable material onto a second area of the second layer, the second area of the second layer covering the second area of the first layer; · Curing the second discontinuous layer and the second continuous layer; and further comprising.

[0130] The first area of the second layer is included in the same discontinuity 401-a as the discontinuity 401-a of the first area of the first layer.

[0131] The second area of the first layer and the second area of the second layer are included in other portions 401-b surrounding the discontinuity 401-a. Therefore, the second area is not included in one of the discontinuities 401-a.

[0132] The discontinuous layer of curable material is, for example, a layer in which less than 50%, preferably less than 30%, and even more preferably less than 10% is covered by the curable material.

[0133] The continuous layer of curable material is, for example, a layer in which more than 70%, preferably more than 80%, and even more preferably more than 90% is covered by the curable material.

[0134] Generally, the fifth example of the step of manufacturing a plurality of layers is used in a manufacturing system represented in FIG. 2, adapted to manufacture an ophthalmic lens by polymer injection.

[0135] In other words, in this fifth example, the interruption portion 401-a is manufactured by discharging a curable material (for example, using the print head 206) by means of a "multi-pass process". The multi-pass process consists of distributing a certain amount of material over a plurality of steps and curing the material after each discharge step. Defects are generated, resulting in light scattering that helps to control myopia. In the case of a normal "multi-pass process", only continuous layers of material are ejected. However, in the case of the fifth example, discontinuous layers of material are also ejected.

[0136] During the printing process, the ejection unit locally supplies the curable material 50 to form discontinuous layers. The ejected material is cured, and then the ejection unit supplies a second pass of additional material to form another discontinuous layer. Curing of the ejected material and the like is carried out until the desired level of light scattering is achieved and / or the layer is completed. In this way, a "matte effect" that causes light scattering is brought about.

[0137] When the curing unit 203 is a non-imaging device (for example, a conventional LED) that passes above the layer (for example, in the case of inkjet technology), the emitted light is the same for the entire layer.

[0138] FIG. 10-a and FIG. 10-b show two examples of discontinuous layers used to manufacture the interruption portion of the ophthalmic lens 100.

Description of the reference numerals

[0139] 1 Manufacturing system 3 Forming unit 4 Optical system 6 Computer element 7 Projection system 8 Micromirror 10 Container 15 Support 16 Unit 17 First image 18 Second image 20 Shifting means 21 Layer 24 Curve 25 Terrace part 26 Valley part 27 High energy level 28 Low energy level 30 Minimum energy level 32 High region 33 Low region 34 High region 35 Low region 36 Terrace part 37 Valley part 38 High energy level 39 Low energy level 40 Minimum energy level 41 Fading region 50 Hardening material 55 Surface 61 Curve 100 Ophthalmic lens 201 Manufacturing system 202 Tank 203 Hardening unit 204 Blade 205 Nozzle 206 Print head 901 Protrusion 902 Interior

Claims

1. A method for additive manufacturing of an ophthalmic lens (100), wherein the additive manufacturing method comprises - creating at least one interruption part (401-a) that causes an interruption in the refractive index change, wherein The at least one discontinuity portion (401-a) is less than 1 mm ３ and smaller than the at least one interruption part (401-a) is located deep within the ophthalmic lens (100) or on the surface of the ophthalmic lens (100), and light scattering occurs across the at least one interruption part due to the interruption in the refractive index change, the additive manufacturing method.

2. - further comprising manufacturing a plurality of layers of a curable material to create the at least one interruption part (401-a), the method according to claim 1.

3. The layer among the plurality of layers is substantially perpendicular or parallel to an axis orthogonal to the front surface of the ophthalmic lens (100) at the apex of the front surface, the method according to claim 2.

4. - using a first image having a first contrast level to cure a first area of one layer among the plurality of layers, the first area being included in the at least one interruption part (401-a), - using a second image having a second contrast level to cure a second area of the layer, the second area being different from the first area, wherein the first contrast level is higher than a predetermined sharpness threshold, and the second contrast level is lower than a predetermined blur threshold, the method according to claim 2 or 3.

5. - using the first image to cure a first area of one layer among the plurality of layers, the first area being included in the at least one interruption part (401-a), without shifting the first image during curing, - using the second image to cure a second area of the layer, the second area being different from the first area, by shifting the second image during curing, the method according to claim 2 or 3.

6. - irradiating with a first curing surface energy that is above a solid energy threshold corresponding to an energy sufficient to cure the entire thickness of the first area, to cure the first area of the first layer among the plurality of layers, - irradiating a second cured surface energy that is strictly lower than the solid energy threshold and higher than the induced surface energy to cure a second area of the first layer; further comprising; after said irradiation of the first layer; - irradiating the surface of the curable material with the first cured surface energy to cure a first area of a second layer that covers the first area of the first layer; - at least a third cured surface energy, wherein the third cured surface energy is higher than the induced surface energy, and the third cured surface energy irradiates both a second area of the second layer and at least a portion of the second area of the first layer, and the sum of the second cured surface energy and the third cured surface energy received by the second area of the first layer is sufficient to cure the second area of the first layer, and the second area of the second layer covers the second area of the first layer, curing the second area of the second layer using the third cured surface energy; further comprising; the first area of the first layer is included in the at least one discontinuity (401-a); the first area of the second layer is included in the at least one discontinuity (401-a); The method according to any one of claims 2 to 5, wherein the induced surface energy is a cured surface energy at which the polymerization process of the curable material starts when it is exceeded. **Claim 7** - injecting a discontinuous layer of the curable material onto a first area of one of the plurality of layers; - injecting a continuous layer of the curable material onto a second area of the layer; - curing the first discontinuous layer and the first continuous layer; comprising; The method according to claim 2 or 3, wherein the first area is included in the at least one discontinuity (401-a). **Claim 8** the layer is a first layer, the discontinuous layer is a first discontinuous layer, the continuous layer is a first continuous layer, when curing the first discontinuous layer and the first continuous layer, the method - injecting a second discontinuous layer of the curable material onto a first area of a second layer among the plurality of layers, the first area of the second layer covering the first area of the first layer; - Injecting a second continuous layer of the curable material onto a second area of the second layer that covers the second area of the first layer; - Curing the second discontinuous layer and the second continuous layer; further comprising The method according to claim 7, wherein the first area of the second layer is included in the at least one discontinuity (401-a).

9. By manufacturing the plurality of layers, - The front surface (903-c) of the ophthalmic lens (100); - The back surface (903-a) of the ophthalmic lens (100); - The side surface (903-b) of the ophthalmic lens (100); - At least one protrusion (901) extending in a direction from the front surface (903-c), the back surface (903-a), or the side surface (903-b) to one of the other surfaces; can be formed, The method comprises - Filling the interior (902) of the ophthalmic lens (100) with the curable material; - Polymerizing the curable material filled in the interior (902) of the ophthalmic lens (100); The method according to claim 2 or 3, further comprising.

10. A manufacturing system (1; 201) configured to additively manufacture an ophthalmic lens (100), the manufacturing system (1; 201) being configured to create at least one discontinuity (401-a) that results in a discontinuity in the refractive index change, The at least one discontinuity (401-a) is less than 1 mm ３ and smaller than The at least one discontinuity (401-a) is located deep within the ophthalmic lens (100) or on the surface of the ophthalmic lens (100), A manufacturing system (1; 201) in which scattering of light occurs across the at least one discontinuity due to the discontinuity in the refractive index change.

11. The manufacturing system (1; 201) according to claim 10, further configured to manufacture a plurality of layers of curable material to create the at least one discontinuity (401-a).

12. - Using a first image having a first contrast level to cure a first area of one of the plurality of layers, the first area being included in the at least one discontinuity (401-a); - Using a second image having a second contrast level to cure a second area of the layer, the second area being different from the first area; further configured as The manufacturing system (1; 201) according to claim 11, wherein the first contrast level is lower than a predetermined blur threshold value, and the second contrast level is higher than a predetermined sharpness threshold value.

13. - Without shifting the first image during the hardening, using the first image, hardening a first area of one of the plurality of layers, the first area being included in the at least one discontinuous portion (401-a); - By shifting a second image during the hardening, using the second image, hardening a second area of the layer, the second area being different from the first area. The manufacturing system (1; 201) according to claim 11, further configured as described above.

14. - Irradiating a first curing surface energy that is a first curing surface energy and is equal to or higher than a solid energy threshold value corresponding to an energy sufficient to cure the entire thickness of the first area, thereby curing the first area of the first layer of the plurality of layers; - Irradiating a second curing surface energy that is a second curing surface energy and is strictly lower than the solid energy threshold value and higher than the induced surface energy, thereby curing a second area of the first layer. Further configured as described above, After the irradiation to the first layer, the method includes: - By irradiating the first curing surface energy to the surface of the curable material, curing a first area of a second layer, the first area of the second layer covering the first area of the first layer; - At least a third curing surface energy, the third curing surface energy being higher than the induced surface energy, the third curing surface energy irradiating both the second area of the second layer and at least a part of the second area of the first layer, and the sum of the second curing surface energy and the third curing surface energy received by the second area of the first layer is sufficient to cure the second area of the first layer, and the second area of the second layer covers the second area of the first layer, using the third curing surface energy to cure the second area of the second layer. Further including: The first area of the first layer is included in the at least one discontinuous portion (401-a). The manufacturing system (1; 201) according to claim 11, wherein the first area of the second layer is included in the at least one discontinuity (401-a).

15. - Injecting a first discontinuous layer of the curable material onto a first area of a first layer among the plurality of layers, - Injecting a first continuous layer of the curable material onto a second area of the first layer, - Curing the first discontinuous layer and the first continuous layer, further configured to be like this, the first area of the first layer is included in the at least one discontinuity (401-a), when the manufacturing system (1; 201) cures the first discontinuous layer and the first continuous layer, - Injecting a second discontinuous layer of the curable material onto a first area of a second layer, which is the first area of the second layer covering the first area of the first layer, - Injecting a second continuous layer of the curable material onto a second area of the second layer, which is the second area of the second layer covering the second area of the first layer, - Curing the second discontinuous layer and the second continuous layer, further configured to be like this, The manufacturing system (1; 201) according to claim 11, wherein the first area of the second layer is included in the at least one discontinuity (401-a).

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