Method for making optical lenses using 3D printed functional wafers

Abstract

An injection molding method for making an optical thermoplastic lens using a 3D printed functional wafer is disclosed. The wafer and the base lens are made of different materials with different glass transition temperatures.

Description

Technical Field

[0001] The present invention generally relates to additive manufacturing and injection molding methods for producing optical articles. Background Art

[0002] Fused deposition modeling (FDM, sometimes called fused filament fabrication or FFF) is the most widely used 3D printing technology for producing thermoplastic parts. FDM 3D printers build parts by extruding thermoplastic filament from a heated nozzle. The printer continuously moves the nozzle, depositing the molten material layer by layer at the predetermined location.

[0003] One major drawback of FDM 3D printing is that it cannot manufacture parts at resolutions high enough for optical quality parts. The FDM layering method involves repeatedly applying or building up multiple voxels of polymer filament material. The step-by-step buildup process produces numerous multiple edges or small holes on the surface of the manufactured part. Each of these numerous edges provides an area through which light can scatter. The end result is a manufactured part with a rough surface and an opaque appearance that significantly scatters transmitted light.

[0004] Another disadvantage of FDM 3D printing is that the manufactured parts often exhibit poor mechanical strength. Voxels of polymer filament material are laid down adjacent to each other. The voxels are welded to each other along their perimeter to form a solid part. Poor interdiffusion between adjacent voxels results in poor inter-strand adhesion. The end result of the large number of deposited filament material voxels is poor mechanical strength and poor impact strength of the manufactured parts.

[0005] Due to the inherent disadvantages associated with FDM 3D printed parts, current FDM methods are unsatisfactory for manufacturing ophthalmic lenses or lens components. In order for FDM to be useful in the ophthalmic industry, the optical quality and mechanical strength of the manufactured parts must be improved.

[0006] Wafers are polymer films that can be applied to the surface of a lens in order to impart some type of functionality to the lens. Examples of wafer functionality include color enhancement, reduced transmittance of desired wavelengths of light, and photochromism. One method for manufacturing thermoplastic lenses with surface-bound functional wafers is injection overmolding. In the injection overmolding process, a functional wafer is provided in a lens molding cavity and the cavity is subsequently filled with molten lens material. Due to their poor optical quality and mechanical strength, FDM 3D printed wafers are not ideal candidates for injection overmolding. Summary of the invention

[0007] The inventors have examined a variety of methods for incorporating FDM 3D printing into an ophthalmic lens manufacturing process. The inventors have discovered that selecting a wafer material having a glass transition temperature (Tg) greater than or equal to about 100°C below the base lens material Tg and less than or equal to about 15°C below the base lens material Tg can address the poor optical quality and mechanical strength issues associated with FDM 3D printed wafers. Selecting a wafer material Tg greater than or equal to about 100°C below the base lens material Tg and less than or equal to about 15°C below the base lens material Tg ensures that the wafer material is sufficiently softened to undergo viscoelastic deformation during injection molding. Viscoelastic deformation of the wafer reduces the surface roughness of the rough light scattering surface of the wafer. Viscoelastic deformation increases the interdiffusion of adjacent deposited filament strands. This increases interstrand adhesion, as well as adhesion to the injected lens material.

[0008] Some aspects of the present disclosure relate to a method for producing an optical article by overmolding an additively manufactured functional wafer onto a convex surface of a base lens to produce an ophthalmic lens. In some embodiments, the additively manufactured functional wafer is a non-optical quality 3D printed wafer having a surface roughness greater than 50 nm RMS. The overmolding process is performed using an injection molding apparatus and includes the steps of attaching the functional wafer to a concave surface of a mold cavity of the molding apparatus and filling the mold cavity with molten base lens material. In some embodiments, the glass transition temperature (T g,wafer ) is greater than or equal to less than the base lens material (T g,lens ) has a glass transition temperature of about 100°C and is less than or equal to about 15°C lower than the glass transition temperature of the base lens material.

[0009] T g，lens -100℃≤T g，wafer ≤T g，lens -15℃ (I)

[0010] In some aspects, overmolding is performed at a cavity temperature (T cavity ) is executed.

[0011] T g，wafer -10℃≤T cavity ≤T g，wafer +10℃ (II)

[0012] T g，wafer -5℃≤T cavity ≤T g，wafer +5℃ (III)

[0013] In some embodiments, the injection molding apparatus mold cavity is heated to a constant temperature prior to providing the mold with molten base lens material.The overmolding apparatus may include steel or glass mold inserts.

[0014] When the overmolding process is performed within the constraints given above, non-optical quality 3D printed wafers can be used. In some aspects of the overmolding process, the functional wafer is viscoelastically deformable. In some embodiments, the viscoelastic deformation deforms the functional wafer and reduces the surface roughness of the convex surface of the functional wafer. In some aspects, the viscoelastic deformation templates the texture of the concave surface of the mold cavity onto the convex surface of the functional wafer. In some aspects, the template produces an ophthalmic lens with an optically smooth convex surface having a roughness of less than 20nm RMS, preferably less than 17nm RMS. The heat and pressure provided by the injection molding equipment and the molten lens material transfer or template the smooth lens material convex surface onto the wavy concave surface. In some embodiments, the functional wafer includes at least one UV cutoff, blue light cutoff, color enhancement, near infrared cutoff, time cutoff (chronocut), and / or photochromic dye or filter.

[0015] In some embodiments, the functional wafer material is selected from the group consisting of polyamide, polyester, polyester alloy, polyethylene, polyethylene terephthalate, polysiloxane, polyimide, polyurethane, polypropylene, polyetheretherketone, polyetherarylalkanone, perfluoroalkoxy, polytrifluorochloroethylene, polyolefins such as cycloolefin polymers, polyacrylic acids such as polymethyl methacrylate (PMMA), poly(meth)acrylate, polyethylene(meth)acrylate, polybutyl(meth)acrylate, and polyisobutyl(meth)acrylate, polythiourethane, polycarbonate (PC), alicyclic polycarbonate, polyolefins, polyetheretherketone, polyetherarylalkan ... Polypropylene, polyphenylene sulfide, polyethylene, polyarylenes, polyoxides, polysulfones, fluorinated ethylene propylene, polytetrafluoroethylene, ethylene-tetrafluoroethylene, polyvinylidene fluoride, ethylene-trifluorofluoroethylene, polystyrene, polyacrylonitrile, such as styrene acrylonitrile, styrene methyl methacrylate, styrene butadiene methyl methacrylate, acrylonitrile butadiene styrene, methyl methacrylate acrylonitrile butadiene styrene and styrene maleic anhydride and other styrene copolymers, polyimide, polyetherimide, polypentene, triacetyl cellulose, their copolymers, and combinations thereof. Suitable polyamides include aliphatic nylon polyamides, such as nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 10, nylon 10-10, nylon 11, nylon 12, their copolymers, or derivatives or mixtures thereof.

[0016] In some embodiments, the functional wafer material and the base lens material are selected to be compatible with each other. Thermoplastic materials that diffuse into each other in the molten state are said to exhibit compatibility or be compatible with each other. Examples of such wafer / lens pairs include, but are not limited to: PMMA / PC, copolyester / PC, polyester alloy / PC, and alicyclic polycarbonate / PC.

[0017] Some aspects of the present disclosure relate to an optical article including an ophthalmic lens. The ophthalmic lens includes a base lens and an additively manufactured functional wafer attached to a convex side of the base lens. In some embodiments, the ophthalmic lens is produced by injection overmolding a molten base lens material onto the additively manufactured functional wafer. In some aspects, the glass transition temperature of the material of the additively manufactured functional wafer is greater than or equal to about 100°C below the glass transition temperature of the base lens material and less than or equal to about 15°C below the glass transition temperature of the base lens material.

[0018] According to the present disclosure, an "ophthalmic lens" is defined as a lens adapted to be mounted in a pair of glasses, the function of which is to protect the eyes and / or correct vision. This lens may be afocal, monofocal, bifocal, trifocal or a progressive lens. The ophthalmic lens may be corrective or non-corrective. The glasses in which the ophthalmic lens is to be mounted may be a conventional frame comprising two different ophthalmic lenses (one for the right eye and one for the left eye), or a mask, visor, helmet sight or goggles, in which one ophthalmic lens faces both the right eye and the left eye. The ophthalmic lens may be produced with a conventional geometric structure that is round or may be produced to fit the intended frame.

[0019] Any embodiment of any disclosed composition and / or method may consist of or consist essentially of—rather than comprise / include / contain / have—any of the described elements and / or features and / or steps. Thus, in any claim, the term "consisting of" or "consisting essentially of" may replace any of the open-ended linking verbs described above in order to alter the scope of a given claim from what it would otherwise be using the open-ended linking verb.

[0020] The term "substantially" and its variations are defined as being largely, but not necessarily completely, as understood by one of ordinary skill in the art, and in a non-limiting embodiment substantially refers to within 10%, within 5%, within 1%, or within 0.5%. The term "about" or "approximately" or "substantially unchanged" is defined as being close to what one of ordinary skill in the art understands, and in a non-limiting embodiment, these terms are defined as within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0021] When used in conjunction with the term "comprising" in the claims and / or description, the use of the words "a" or "an" may mean "one", but also conforms to the meanings of "one or more", "at least one" and "one or more than one".

[0022] The phrase "and / or" means "and" or "or". For illustration, A, B, and / or C includes: A alone, B alone, C alone, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C. In other words, "and / or" serves as an inclusive "or".

[0023] As used in this specification and in one or more claims, the words “comprising” (and any forms of comprising, such as “comprise” and “comprises”), “having” (and any forms of having, such as “have” and “has”), “including” (and any forms of including, such as “includes” and “include”), or “containing” (and any forms of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0024] The compositions and methods for their use may "comprise," "consist essentially of," or "consist of" any ingredient or step disclosed throughout the specification. With respect to the transition phrase "consist essentially of," in one non-limiting aspect, the fundamental and novel features of the compositions and methods disclosed in this specification include a method for injection overmolding a 3D printed functional wafer onto a base ophthalmic lens.

[0025] Other objects, features and advantages of the present invention will become clear from the following detailed description. However, it should be understood that the detailed description and examples, although indicating specific embodiments of the present invention, are still given by way of illustration only. In addition, it is expected that changes and modifications within the spirit and scope of the present invention will become clear to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of an FDM 3D printer.

[0027] Figure 2 An illustration of an FDM 3D printed functional wafer. The wafer has a rough, light-scattering surface, which is an inherent result of the FDM 3D printing process.

[0028] Figure 3 is a schematic diagram illustrating the injection overmolding process. The process bonds a functional wafer to the convex surface of an injection molded ophthalmic lens. DETAILED DESCRIPTION

[0029] The various features and advantageous details are explained more fully with reference to the non-limiting embodiments shown in the drawings and described in detail in the following description. However, it should be understood that the detailed description and specific examples, while indicating embodiments, are given by way of illustration only and not by way of limitation. Various substitutions, modifications, additions and / or rearrangements will be apparent to those of ordinary skill in the art in light of this disclosure.

[0030] In the following description, numerous specific details are provided to provide a thorough understanding of the disclosed embodiments. However, one of ordinary skill in the relevant art will recognize that the invention may be practiced without one or more of the specific details or with other methods, components, materials, etc. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0031] A wafer is defined as a structure with certain desired optical properties, such as selective transmittance, reflectivity or absorbance, polarization properties, color, photochromic, electrochromic, etc. The wafer structure is produced by an additive manufacturing process. The process involves the deposition of multiple filament voxels adhered or otherwise fixed to each other. An optically smooth surface refers to a transparent object surface with a roughness less than 20nm RMS, preferably less than 17nm RMS. Non-optical quality refers to a transparent object with a surface roughness greater than 50nm RMS.

[0032] As used herein, "voxel" refers to a volume element. A voxel is a distinguishable geometric structure that is part of a three-dimensional space. The diameter, width or thickness of a voxel is typically in the range of 0.1 to 500 μm. Voxels include elongated shapes, such as strands, and therefore, the length of a voxel does not necessarily include an upper limit. The voxel length may be 0.1 μm, 100 μm, 0.1 cm, 100 cm, greater than 100 cm, or any length therebetween. "Voxel" may refer to a single element that, in combination with other voxels, may define a line, layer, or other predetermined shape or pattern in a three-dimensional space. Depending on the technology and manufacturing process conditions used, the voxel formed may be of any desired shape. When arranged, a plurality of adjacent voxels or a collection of adjacent voxels may create or define a line or layer, and may constitute an optical element. A specific voxel may be identified by the x, y, and z coordinates of a selected point (such as an angle, a center) of the geometric structure of the shape or by other means known in the art. The boundary of a voxel is defined by the outer surface of the voxel. Such a boundary may be very close, with or without contact.

[0033] As used herein, "additive manufacturing" refers to a manufacturing technique as defined in the international standard ASTM 2792-12, which describes the process of connecting materials to make 3D solid objects from 3D digital models. This process is called "3D printing" or "material printing" because successive layers are laid on top of each other. Printing materials include liquids, powders, filaments and sheet materials, and a series of cross-sectional layers are constructed from these liquids, powders, filaments and sheet materials. These layers corresponding to the virtual cross-sections from the CAD model are connected or automatically melted to create a solid 3D object. Additive manufacturing includes, but is not limited to, the following manufacturing methods: such as stereolithography, mask stereolithography, mask projection stereolithography, polymer jetting, scanning laser sintering (SLS), scanning laser melting (SLM), and fused deposition modeling (FDM). Additive manufacturing technology includes a number of processes that create 3D solid objects by juxtaposing multiple volume elements or particles according to a predetermined arrangement typically defined in a CAD (computer-aided design) file. "Juxtaposition" is understood to be a sequential operation, including building a material layer on top of a previously built material layer and / or positioning a material volume element next to a previously deposited material volume element. The term "part" refers to any part built using layer-based additive manufacturing technology, and includes 3D parts and support structures built using layer-based additive manufacturing technology. The exemplary part disclosed herein is a functional wafer.

[0034] The term "polymer" refers to a polymer material having one or more monomer species, including homopolymers, copolymers, terpolymers, etc. As used herein, "thermoplastic" is understood to be a polymer resin that can melt when exposed to heat, and is preferably optically clear and optical grade.

[0035] As used herein, "interdiffusion" and derivatives refer to the movement of at least one molecule, a portion of a molecule, or a portion of a polymer chain from the space occupied by one voxel to the space occupied by juxtaposed physically contacting voxels. Interdiffusion can occur spontaneously or be induced by mechanical, physical or chemical treatments. For example, mechanical treatments include stirring, such as by exposure to ultrasonic energy, high-frequency vibration devices, etc., which promote mixing at voxel boundaries. Macroscopic diffusion is a mechanical method in which voxels are blended or "smeared" by stage vibration, especially when such vibration occurs during deposition, thereby producing close voxel-to-voxel contact. Exemplary physical treatments include thermal treatments by exposure to radiation such as heat, infrared, microwaves, etc. Thermal treatments raise the temperature to a glass-liquid transition point (Tg) above the high viscosity domain in the voxel and promote interdiffusion. Exemplary chemical treatments include chemical reactions between reactive species of the composition. The molecular weight of the polymer present in the voxel can be reduced, such as by two-pathway chemistries or reversible reactions, in order to promote interdiffusion.

[0036] FDM is one of the most cost-effective methods for producing custom thermoplastic parts and prototypes. Figure 1 ) builds a part by extruding a thermoplastic filament from a heated nozzle. Generally, the filament 12 is fed to an extruder 14, which includes a heater block 16 and a heated nozzle 18. The molten filament is delivered to a print bed 20 through the heated nozzle 18. The molten filament is applied to the XY plane to produce the first layer. Once the first layer is completed, the platform is lowered in the Z-axis direction and the second layer is printed. Repeat the above steps until the part is manufactured. The hot strands are welded to each other to form a solid part. A major disadvantage of FDM 3D printing is that it cannot produce high-resolution optical quality parts. The FDM layering method results in many light scattering edges and poor inter-filament diffusion and adhesion.

[0037] However, opportunities do exist for the application of FDM in the ophthalmic lens industry. Because 3D printing is more cost-effective for small volumes and rapid prototyping tasks, FDM can be used to produce functional wafers from thermoplastic filaments with specific dyes and / or filters. Examples include UV cutoff, blue light cutoff, NIR cutoff, color enhancement, time cutoff, and photochromic filters. The resulting functional wafer can then be integrated onto the front surface of an ophthalmic lens via an injection overmolding process (or a membrane insert molding process).

[0038] Conventional injection overmolding processes were examined, however, despite the high heat and pressure provided by the injection molding equipment, these processes were still unable to produce optical quality lenses. In conventional injection overmolding processes, the entire injection overmolding cycle is performed at a constant cavity temperature (T cavity) is carried out under the condition that the cavity temperature is significantly lower than the glass transition temperature (T g,wafer ).

[0039] The glass transition temperature characterizes the secondary transition of an amorphous polymer from a brittle, glassy solid to a viscous or rubbery substance. cavity Must be less than T g,wafer , so that the functional wafer maintains its shape when inserted into the cavity. Further, T cavity must be less than the glass transition temperature (T g,lens ), so the resulting lens is in a solid form that is rigid enough to be ejected without deformation. The most common, T cavity ≤T g,lens -20°C. The wafer and the lens are typically made of the same material to provide compatibility between the wafer and the lens for a good bond. In this case, T g,wafer =T g,lens .

[0040] One reason why conventional injection overmolding processes cannot produce optical quality lenses using 3D printed functional wafers is because the convex surface temperature of the wafer is maintained at a temperature well below its Tg. The convex surface remains solid throughout the injection overmolding process and retains the surface ridges created by the voxel deposition ( Figure 2 ). The glass transition temperature (T g,wafer ) is greater than or equal to the glass transition temperature (T g,lens ) is about 100°C and less than or equal to about 15°C below the glass transition temperature of the base lens material (i.e., T g,lens -40℃≤T g,wafer ≤T g,lensThe wafer material can be about 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 60, 70, 80, 90 or 100°C lower than the glass transition temperature of the base lens material, or any temperature therebetween. Within this temperature range, the wafer material is able to undergo viscoelastic deformation under high heat and high injection pressure. The concave surface of the wafer melts as it is strongly pressed by the molten lens material. The total contact surface area between the wafer and the base lens material increases, the wafer material and the lens material diffuse into each other at a microscopic level at the surface interface, and the adhesion between the wafer and the base lens material increases. The convex surface of the wafer undergoes viscoelastic deformation at high temperature and high injection pressure to replicate the surface of the concave insert. Finally, adjacent voxels within the wafer interdiffusion into each other to improve intravoxel adhesion and overall mechanical strength. Lenses manufactured according to the criteria set forth above have an optically smooth front surface with reduced roughness from the original surface of the wafer.

[0041] refer to Figure 3 The injection molding apparatus includes two mold halves and two opposing inserts. The concave insert and the convex insert are each located in the mold halves to form a cavity. In some embodiments, during the entire process, the cavity temperature T cavity Maintain at T g,wafer The constant mold temperature method benefits from shorter production cycle times and uses simpler mold designs than molds used in hot / cold processes.

[0042] In step I, the mold is opened to access the insert surface. In step II, the functional wafer is inserted. The wafer is attached to the concave insert surface. In step III, the two mold halves are joined to close the mold and form an injection molding cavity. The cavity space is a template of the shape of the lens to be molded. In step IV, molten lens material is injected into the mold cavity and the molten lens material becomes fused to the wafer. In step V, the mold halves are separated and the lens is ejected.

[0043] Example

[0044] Example 1

[0045] Base lens material 1 - UV-stable polycarbonate (Sabic OQ3820) as the base lens material. This PC resin has a glass transition temperature of 150°C and a UV cutoff of about 380 nm, as measured through a 2 mm thick lens.

[0046] Functional wafer 1 - a high heat resistant PMMA wafer material (Evonik hw55) with 1.0% UV absorber ( 326) compounded and extruded into 1.75 mm filament. A 4-base flat wafer with a diameter of 76 mm and a thickness of 1.0 mm was FDM 3D printed using the filament.

[0047] The functional wafer 1 is applied to the base lens material 1 using the key parameters listed in Table 1 below.

[0048] Table 1

[0049]

[0050] The resulting semi-finished (SF) lens with a thickness of 10 mm was optically clear, had a smooth front surface, and exhibited a UV cutoff of 402 nm after surface treatment to 2 mm flat. In addition, the blue light cutoff performance BVC B' was measured to be approximately 30%.

[0051] Example 2

[0052] Functional wafer 2 - a copolyester resin (SK Chemical) having a glass transition temperature of 110°C and a UV cutoff of about 320 nm as measured through a 2 mm thick lens. T110) with 1.0% UV absorber ( 326) compounded and extruded into 1.75 mm filament. A 4-substrate flat wafer with a diameter of 76 mm and a thickness of 1.0 mm was FDM 3D printed using the filament.

[0053] The resulting wafer was opaque with a rough surface. To produce an ophthalmic lens with a UV cutoff above 400 nm while providing blue light protection, a functional wafer 2 was applied to a base lens material 1 using the key parameters listed in Table 2 below.

[0054] Table 2

[0055]

[0056]

[0057] The resulting 10 mm thick SF lens was optically clear, had a smooth front surface, and exhibited a UV cutoff of about 402 nm after surface treatment to 2 mm flat. The blue light cutoff performance, BVC B', was measured to be about 30%.

[0058] In the method disclosed herein, the glass transition temperature of the functional wafer material is greater than or equal to 100°C lower than the glass transition temperature of the base lens material and less than or equal to about 15°C lower than the glass transition temperature of the base lens material. Because of this difference, the heat provided by the mold cavity and the molten lens material and the pressure provided by the injection molding equipment cause viscoelastic deformation of the wafer. The smooth surface of the concave insert is transferred to the convex surface of the viscoelastic deformed wafer, thereby reducing its surface roughness. The pressurized molten lens material melts the concave surface of the wafer, thereby creating an optically transparent interface by fusion. In this way, the 3D printed wafer can be used in an injection overmolding process because its initial rough surface is smoothed during the molding process.

[0059] The claims should not be interpreted as including means-plus-function or step-plus-function limitations unless such limitations are expressly recited in a given claim using one or more of the phrases "means for" or "step for," respectively.

Claims

1. A method for producing an optical article, the method comprising overmolding an additively manufactured functional wafer onto a convex surface of a base lens to produce an ophthalmic lens, wherein: The overmolding comprises: attaching the functional wafer to a concave surface of a mold cavity of a molding device; and filling the mold cavity with molten base lens material; The glass transition temperature of the functional wafer material is greater than or equal to at least 40°C lower than the glass transition temperature of the base lens material and less than or equal to 15°C lower than the glass transition temperature of the base lens material, so that T g，lens -40℃≤T g，wafer ≤T g，lens -15℃.

2. The method of claim 1, wherein: The additively manufactured functional wafer is a non-optical quality wafer with a surface roughness greater than 50 nm RMS.

3. The method of claim 1, wherein: The overmolding causes the functional wafer to viscoelastically deform.

4. The method of claim 3, wherein: The viscoelastic deformation templates the texture of the concave surface of the mold cavity onto the convex surface of the functional wafer.

5. The method of claim 4, wherein: The templating produces an ophthalmic lens with an optically smooth convex surface having a roughness less than 20 nm RMS.

6. The method of claim 1, wherein: The functional wafer includes at least one UV cut, blue light cut, color enhancement, near infrared cut, time cut, and / or photochromic dye or filter.

7. The method of claim 1, wherein: The functional chip material is selected from the group consisting of: polyamide, polyester, polyester alloy, polyethylene, polyethylene terephthalate, polysiloxane, polyimide, polyurethane, polypropylene, polyetheretherketone, polyetherarylalkanone, perfluoroalkoxy, polytrifluorochloroethylene, polyolefin, polyacrylic acid, polyacrylate, polythiourethane, polycarbonate (PC), alicyclic polycarbonate, polyallyl, polyphenylene sulfide, polyethylene, polyarylene, polyoxide, polysulfone, fluorinated ethylene propylene, polytetrafluoroethylene, ethylene-tetrafluoroethylene, polyvinylidene fluoride, ethylene-trifluorofluoroethylene, polystyrene, polyacrylonitrile, styrene copolymer, polyimide, polyetherimide, polypentene, triacetyl cellulose, and their copolymers, derivatives and mixtures.

8. The method of claim 7, wherein: The functional wafer material is selected from the group consisting of cycloolefin polymers, polymethyl methacrylate (PMMA), poly(meth)acrylate, polyethylene (meth)acrylate, polybutyl (meth)acrylate, and polyisobutyl (meth)acrylate, styrene acrylonitrile, styrene methyl methacrylate, styrene butadiene methyl methacrylate, acrylonitrile butadiene styrene, methyl methacrylate acrylonitrile butadiene styrene, and styrene maleic anhydride.

9. The method of claim 1, further comprising heating the molding cavity to a constant temperature prior to providing the mold with the molten base lens material.

10. The method of claim 1, wherein: The molding equipment includes steel or glass mold inserts.

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