Method of manufacturing a mould for an optical element

Abstract

A method is provided for manufacturing a mould for an optical element. The method comprises manufacturing, by means of a first manufacturing technology, in accordance with a first dataset, a first part of a first master piece, the first master piece being at least a partial representation of the optical element manufacturing, by means of a second manufacturing technology, in accordance with a second dataset, a second part of a first master piece and joining, on a first substrate area, the first part of the first master piece and the second part of the first master piece for forming the first master piece. The method further comprises providing at least one mould piece comprising a cavity having a shape corresponding to a shape of the first part of the first master piece joined with the second part of the first master piece.

Description

[0001] Title: Method of manufacturing a mould for an optical element

[0002] TECHNICAL FIELD

[0003] The various aspects and implementations thereof relate to manufacturing of optical elements and moulds for casting such optical elements.

[0004] BACKGROUND

[0005] Printing a master piece for manufacturing of a mould for an optical element, for example as presented in unpublished patent application PCT / NL2022 / 050215, is a time consuming and expensive process.

[0006] EP 4 119 321 Al discloses A method for forming a mould insert includes forming a stamp, a surface of the stamp including a plurality of inverted microstructures formed thereon; and pressing the stamp into a medium disposed on a surface of a first mould insert to form a microstructured film, the microstructured film including a plurality of microstructures formed on a surface of the microstructured film based on the plurality of inverted microstructures, the plurality of microstructures being complementary to the plurality of inverted microstructures.

[0007] SUMMARY

[0008] It is preferred to provide a more efficient printing process of masters for manufacturing of a mould. This is particularly preferred if certain parts of the optical element are custom made, like prescription glasses for a virtual reality display and other parts of the optical element are standard, like a mounting of the glasses in the display.

[0009] A first aspect provides a method of manufacturing a mould for an optical element. The method comprises manufacturing, by means of a first manufacturing technology, in accordance with a first dataset, a first part of a first master piece, the first master piece being at least a partial representation of the optical element manufacturing, by means of a second manufacturing technology, in accordance with a second dataset, a second part of a first master piece and joining, on a first substrate area, the first part of the first master piece and the second part of the first master piece for forming the first master piece. The method further comprises providing at least one mould piece comprising a cavity having a shape corresponding to a shape of the first part of the first master piece joined with the second part of the first master piece. Hence, the cavity has a shape defined by both a first part shape of the first part of the first master piece and a second part shape of the second part of the first master piece, which first part of the first master piece is joint with the second part of the first master piece. The first part and the second part may both be provided on the first substrate area while being joined.

[0010] This aspect allows for increase flexibility of manufacturing moulds for optical elements and other objects. Firstly, the first part of the first master piece may be manufactured using a first manufacturing technology and the second part of the first masterpiece may be manufactured using a second manufacturing technology. The first manufacturing technology may be the same as or different from the second manufacturing technology. In this way, each part may be manufactured using an optimal manufacturing technology, based on, for example, a trade off between accuracy and cost. Additionally, or alternatively, durability of materials may be taken into account.

[0011] Second, either or both of the first part of the first master piece or the second part of the first master piece may be used with other parts, for use in other moulds. This means that in other cases, not all of the master piece has to be manufactured every time, but only the first part or the second part of a manufacturing piece. This may reduce manufacturing time, may increase stock flexibility, may reduce a number of total parts in stock and may in such ways reduce cost. It is noted that more than two parts may be provided for providing a single master piece.

[0012] In an implementation, providing the at least one mould piece comprises providing, on the first substrate area, a first formwork around the first master piece, providing a first amount of mould substance in the first formwork, allowing the first amount of mould substance to settle, thus forming a first mould; and removing the first formwork. This implementation allows for convenient and efficient way of providing the mould.

[0013] In a further implementation, the first part of the first master piece is a representation of a first part of the optical element that provides the main optical functionality of the optical element. Optical elements generally require different tolerances, either higher or lower, depending on applications, than other parts of the element to be manufactures - and there may be other differences in manufacturing and product requirements. This implementation addresses those differences.

[0014] In again a further implementation, the second part of the first master piece is a representation of a second part of the optical element that provides, in use, at least one of support for optical functionality of the first part of the optical element, mechanical support for the first part of the optical element and an aesthetical function. Parts other to those providing an optical function may provide a function supportive to the optical functionality.

[0015] In another implementation, the first part of the first master piece has a shape of at least part of a lens and the second part of the first master piece is at least part of a support member arranged to surround at least part of the lens. A common example of an optical element is a lens. The part at least partially supporting the lens may for example be used for mounting of the lens in a larger system. Such system may be used for virtual reality or augmented reality applications. Yet another implementation further comprises depositing a filler substance at at least part of an interface between the first part of the first master piece and the second part of the first master piece. The first part and the second part of the master piece are preferably manufactured such that when joined, they form a substantially contiguous - seemingly monolithic - element. However, due to mechanical tolerances due to various reasons, there may be very small spaces, like trenches or gaps, between the first part and the second part. This may result in ridges or other protrusions in the moulds - which is all but preferred, as this will end up in a final product. This implementation addresses this issue.

[0016] In yet a further implementation, the filler substance deposited is the same as one of the first part of the first master piece and the second part of the first master piece. This implementation provides a master piece with parts having all substantially similar or even the same material properties, like mechanical thermal coefficients. This reduces mechanical stress in case of temperature changes.

[0017] In again another implementation, the filler substance comprises at least one material comprised by at least one of the first part of the first master piece and the second part of the first master piece. This implementation provides a master piece with parts having all substantially similar or even the same material properties, like mechanical thermal coefficients. This reduces mechanical stress in case of temperature changes.

[0018] In another implementation, the first part of the first master piece and the second part of the first master piece predominantly comprise the same one or more materials. This implementation provides a master piece with parts having all substantially similar or even the same material properties, like mechanical thermal coefficients. This reduces mechanical stress in case of temperature changes.

[0019] In again another implantation, the first manufacturing technology and the second manufacturing technology comprise at least one of printing, casting, milling, pressing, and injection moulding. With printing, deposition of material is meant, which commonly referred to a s three-dimensional printing. With such technology, objects may be manufactured with very high tolerances - small variations or errors in dimensions. Such technology is relatively expensive. Milling and in particular injection moulding are significantly cheaper and may be different tolerance, in particular injection moulding. However, of a first of the first part and the second part, lower tolerances may be acceptable, whereas for a second of the first part and the second part of the master piece, high tolerances are required. A trade off, for example between tolerance, manufacturing cost and manufacturing time, may be made for each part independently.

[0020] In yet another implementation, the first manufacturing technology and the second manufacturing technology are the same. In some cases, it may be efficient to use the manufacturing technology for both parts.

[0021] In a again a further implementation, the first manufacturing technology has a higher resolution than the second manufacturing technology. As indicated, for some part, a higher tolerance - or resolution - may be required, depending on the functionality of the corresponding part of the final object.

[0022] In yet a further implementation, the second part of the first master piece at least partially surrounds the first part of the first master piece. This allows the second part to support the first part.

[0023] A further implementation further comprises, prior to providing the first amount of mould substance, providing a master mould skeleton as an example of an insert around the deposited amount of master substance. A preferred material for the mould is an elastomer, like silicon rubber. Such materials and elastomers in general - but also other materials - may not provide sufficient rigidity to make the mould suitable for casting with a desired tolerance. This implementation addresses that issue. In another implementation, the master mould skeleton comprises at least one of an organic polymer and a metal.

[0024] In yet a further implementation, the first mould amount comprises an elastomer, for example silicon rubber. Such materials allow for relative cheap and simple manufacturing of the insert.

[0025] A second aspect provides a method for manufacturing an optical element. The method comprises manufacturing a first production mould part according to a method according to any one of the preceding claim s, wherein the first production mould comprises a first cavity that is complementary shaped to the first master piece, the first master piece representing a first part of the optical element, manufacturing a second production mould part according to a method according to any one of the preceding claims, wherein the second production mould comprises a second cavity that is complementary shaped to a second master piece, the second master piece representing a second part of the optical element, combining the first production mould with the second production mould, such that cavities of the first production mould and the second production mould face one another, thus forming a product cavity, providing a product substance in the product cavity, allowing the product substance to settle thus forming the optical element and removing the first production mould part and the second production mould part from the optical element.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The various aspects and implementations thereof will now be discussed in further detail in conjunction with drawings. In the drawings,

[0028] Figure 1: shows a flowchart;

[0029] Figure 2: shows optical master pieces printed on a substrate;

[0030] Figure 3: shows optical master pieces joined with mechanical master pieces; Figure 4: shows joined master pieces with a formwork;

[0031] Figure 5: shows moulds for manufacturing of an optical element;

[0032] Figure 6: shows the moulds for manufacturing of an optical element joined to form a product cavity; and

[0033] Figure 7: shows an optical element.

[0034] DETAILED DESCRIPTION

[0035] The various aspects and implementations thereof will be discussed in conjunction with a flowchart 100 shown by Figure 1 and with drawings showing products of the various parts of the flowchart 100, shown by Figure 2 through Figure 7. In the list below, brief summaries of the various parts of the flowchart 100 are provided.

[0036] 102 start procedure

[0037] 104 receive data optical piece

[0038] 106 print optical piece

[0039] 108 receive data mechanical piece

[0040] 110 print mechanical piece

[0041] 112 apply mechanical piece to optical piece

[0042] 114 seal boundaries

[0043] 116 surface treatment

[0044] 118 apply skeleton

[0045] 120 apply pins

[0046] 122 apply form work

[0047] 124 cast mould material

[0048] 126 allow mould to settle

[0049] 128 remove form work

[0050] 130 remove print and substrate

[0051] 132 all done? 134 combine moulds

[0052] 136 provide product substance

[0053] 138 allow product to settle

[0054] 140 remove mould

[0055] 142 end

[0056] The procedure starts in a terminator 102 and proceeds to step 104 by receiving data by a three-dimensional printer that is arranged to deposit a fluid material on a substrate 202. Figure 2 shows an isometric view and a cross-section of the substrate 202. On the substrate 202, a first amount of master substance forming a first optical master piece 204 and a second amount of master substance forming a second optical master piece 206 are deposited, in step 106. The master substance is deposited using a three- dimensional printing process. Preferably, UV curable substance is used as a master substance. In the configuration shown by Figure 2, two master pieces are printed on the substrate 202. In another example, one or more than two master pieces are provided on the substrate 202.

[0057] In the context of this application, a three-dimensional printing process is a process of deposition of a fluid in small controlled amounts by means of a dispensing head. Movement of the dispensing head may be controlled, based on the data received by the printing process. This allows the three-dimensional printer to accurately deposit small amounts of fluid at specific locations on the substrate and on already deposited fluid. After deposition, the master substance is allowed to settle, for example by means of curing under influence of one or more of UV-radiation and thermal energy. In another example, the master fluid is solidified while losing thermal energy.

[0058] In step 108, the three-dimensional printer receives data on mechanical master pieces to be printed. The mechanical master pieces are printed in step 110. Figure 3 A shows a first mechanical master piece 214 and a second mechanical master piece 216. Figure 3 B shows the first mechanical master piece 214 and the second mechanical master piece 216 provided around the first optical master piece 204 and the second optical master piece, respectively, as a result of step 112. It is noted that additionally or alternatively, further mechanical master pieces may be provided as partially surrounding optical master pieces. Additionally or alternatively, mechanical master pieces may be provided on top of the optical master pieces.

[0059] In this example, the first optical master piece 204 and the second optical master piece 206 as well as the first mechanical master piece 214 and the second mechanical master piece 216 are printed using a three- dimensional printer as discussed above. In another example, at least one of the mechanical master pieces and the optical master pieces are manufactured using one or more of printing, casting, milling, pressing, injection moulding, other or a combination of two or more thereof. The mechanical master pieces may be manufactured using one or more processes that are different from one or more processes that are used for manufacturing of the optical master pieces.

[0060] The first optical master piece 204 and the second optical master piece 206 may provide representations of a front and back side of a prescription lens. In another example, the first optical master piece 204 and the second optical master piece 206 provide either back sides or front sides of left and right prescription lenses. Whereas Figure 2 shows two amounts of master substance deposited on the substrate 202, it is noted that the various aspects and examples thereof may also be used with only one amount of master substance deposited on the substrate 202.

[0061] For optical elements, smoothness and tolerances with respect to dimensions may be more critical than for mechanical parts. From that perspective, the manufacturing method for manufacturing of the mechanical master pieces may have a lower resolution than the manufacturing of the optical master pieces. For example, the optical master pieces may be manufactured using three-dimensional printing, whereas the mechanical master pieces may be manufacturing using injection moulding or milling.

[0062] After the mechanical master pieces have been joined with the optical master pieces on the substrate 200, boundaries between the mechanical master pieces and the optical master pieces are sealed in step 114. An aim of the sealing is filling any trenches or other spaces between the optical master pieces and the mechanical masterpieces. The sealing is preferably executed by depositing a material at the boundary, which material may trickle down to fill any trench or gap between the optical master pieces and the mechanical masterpieces. Additionally or alternatively, a gasket is provided between the master pieces. As such, the sealing of any space that may - unintentionally or unwanted - exist between the master pieces may be sealed by providing a fluid, preferably liquid, or solid sealing as a filler.

[0063] The material used for the sealing may be the same as that of the optical master pieces or the same as that of the mechanical masterpieces. It is noted that the optical master pieces and the mechanical masterpieces may be manufactured using the same material. In one example, by virtue of the sealing, optical master pieces may form one contiguous body with mechanical master pieces with which they are joined.

[0064] After applying the sealing, the joined pieces may be provided with a surface treatment.

[0065] Such surface treatment may comprise the application of a coating. Such coating may provide scratch protection to the joined master pieces. Alternatively or additionally, such coating may enhance smoothness of a surface of the joined master pieces. Additionally or alternatively, the coating may enhance other or more properties of the joined master pieces. Additionally or alternatively, the joined master pieces may be subjected to a corona treatment, for example by means of a flame. The sealing of boundaries may be executed by means of applying a coating or other surface treatment.

[0066] In step 118, a mould skeleton 242 is provided around the joined master pieces, as shown in the right part of Figure 4. The mould skeleton 242 comprises an open structure that may be provided as a cage around the joined master pieces. The mould skeleton 242 is open to a fluid that may be used for forming a mould, as will be discussed below. The mould skeleton 242 may enhance stiffness of a mould to be formed. To that purpose, the mould skeleton 242 may comprise an organic polymer, like PETG - Polyethylene terephthalate glycol -, PE - polyethylene -, other, or a combination of two or more thereof. In another implementation, the mould skeleton 242 may comprise one or more metals, like iron, chromium, vanadium, magnesium, copper, other, or a combination of two or more thereof. In another implementation, the mould skeleton 242 comprises one or more metals and one or more organic polymer substances.

[0067] The mould skeleton 214 is in this example an inner skeleton, provided as an example of an insert for the mould, which mould is discussed below. In another implementation, the skeleton 214 may be provided as an exoskeleton, that may at least partially be provided outside a mould, which mould is discussed below.

[0068] In the substrate 202, substrate holes 208 (Figure 2) are provided. In this example, holes are provided at each corner of the rectangular substrate 202. Furthermore, additional holes are provided near the centre of the long sides of the rectangular substrate; one at each side of the centre of each long side. In step 120, rods 242 or pins are provided in the substrate holes 208. The rods 242 comprise steel, a single metal composition like aluminium or iron or another composition of metals. In another implementation, the rods 242 comprise an organic polymer. In step 122, a formwork 244 or casting box is provided around the mould skeleton 242.

[0069] In this example, the formwork 244 comprises a barrier between the first joined master piece provided by the first optical master piece 204 and the first mechanical master piece 214 on one hand and the second joined master piece provided by the second optical master piece 206 and the second mechanical master piece 216.

[0070] The formwork 244 has in this example a footprint that is about the same as the footprint of the substrate 202 and larger than the first mechanical master piece 214 and larger than the second mechanical master piece 216. More in particular, each of the two spaces provided by the copy formwork 244 has a footprint larger than an area defined by the four holes 208 in each space of the copy formwork 244.

[0071] By providing the barrier, a first working mould 252 may be provided based on the first copy piece 234 and a second working mould 254 may be provided based on the second copy piece 236, as shown by Figure 5. The first working mould 252 and the second working mould 254 are provided in step 124 by casting moulding substance in the space provided by the copy form work 244 and the working copy 230.

[0072] In step 124, a mould substance is provided in the casting box thus provided. As mould substance, preferably an elastomer like silicon rubber is used. However, another elastomer or another substance may be used as well - as long as it is a substance to which the master substance is resistant, once the master substance has settled.

[0073] After casting, the mould substance is allowed to settle in step 126, for example by means of curing under influence of one or more of UV- radiation and thermal energy. In another example, the mould substance is solidified while losing thermal energy. In again another example, the mould substance is solidified as a result of chemical reactions between two materials. In step 128 the form work is removed from the first working mould 252 and the second working mould 254. In step 130, the substrate 202, with the first optical master piece 204, the second optical master piece 206, the first mechanical master piece 214 and the second mechanical master piece 216 are removed from the first working mould 252 and the second working mould 254. In the first working mould 252, a first cavity 256 is left and in the second working mould 254, a second cavity 258 is provided. The first cavity 256 is complementary to a first joined master piece provided by the first optical master piece 204 and the first mechanical master piece 214. The second cavity is complementary to a second joined master piece provided by the second optical master piece 206 and the second mechanical master piece 216.

[0074] Optionally, the copy rods 242 are removed from the first working mould 252 and the second working mould 254 as well. If that is the case, mating mould rods 262 are provided in holes of the first working mould 252 and the second working mould 254. The holes in the first working mould 252 and in the second working mould 254 are shaped by means of the rods 242. The mating rods 262 enable precise alignment of the first working mould 252 and the second working mould 254 while combining the mould parts in step 134, as shown by Figure 8.

[0075] In step 136, a product substance is cast in a cavity 270 provided by the first working mould 252 and the second working mould 254 for manufacturing of the optical element 290, as shown by Figure 9. The product substance is preferably a transparent resin. In step 138, the product substance is allowed to settle and in step 140, the optical element 290 is removed from the first working mould 252 and the second working mould 254. The procedure ends in terminator 142.

Claims

Claims1. Method of manufacturing a mould for an optical element, the method comprising: manufacturing, by means of a first manufacturing technology, in accordance with a first dataset, a first part of a first master piece, the first master piece being at least a partial representation of the optical element; manufacturing, by means of a second manufacturing technology, in accordance with a second dataset, a second part of the first master piece; joining, on a first substrate area, the first part of the first master piece and the second part of the first master piece for forming the first master piece; providing at least one mould piece comprising a cavity having a shape corresponding to a shape of the first part of the first master piece joined with the second part of the first master piece.

2. The method according to claim 1, wherein providing the at least one mould piece comprises: providing, on the first substrate area, a first formwork around the first master piece; providing a first amount of mould substance in the first formwork; allowing the first amount of mould substance to settle, thus forming a first mould; and removing the first formwork.

3. The method according to any one of claim 1 and claim 2, wherein the first part of the first master piece is a representation of a first part of the optical element that provides the main optical functionality of the optical element.

4. The method according to any one of the preceding claims, wherein the second part of the first master piece is a representation of a second part of the optical element that provides, in use, at least one of support for optical functionality of the first part of the optical element, mechanical support for the first part of the optical element and an aesthetical function.

5. The method according to claim 4, wherein the first part of the first master piece has a shape of at least part of a lens and the second part of the first master piece is at least part of a support member arranged to surround at least part of the lens.

6. The method according to any one of the preceding claims, further comprising depositing a filler substance at at least part of an interface between the first part of the first master piece and the second part of the first master piece.

7. The method according claim 6, wherein the filler substance deposited is the same as one of the first part of the first master piece and the second part of the first master piece.

8. The method according to any one of claim 6 and claim 7, wherein the filler substance comprises at least one material comprised by at least one of the first part of the first master piece and the second part of the first master piece.

9. The method according to any one of the preceding claims, wherein the first part of the first master piece and the second part of the first master piece predominantly comprise the same one or more materials.

10. The method according to any one of the preceding claims, wherein the first manufacturing technology and the second manufacturing technology comprise at least one of the following: printing; casting; milhng; pressing; injection moulding.

11. The method according to any one of the preceding claims, wherein the first manufacturing technology and the second manufacturing technology are the same.

12. The method according to any one of the preceding claims, wherein the first manufacturing technology has a higher resolution than the second manufacturing technology.

13. The method according to any one of the preceding claims, wherein the second part of the first master piece at least partially surrounds the first part of the first master piece.

14. The method according to anyone of the preceding claims, further comprising, prior to providing the first amount of mould substance, providing a master mould skeleton around the deposited amount of master substance.

15. The method according to claim 14, wherein the master mould skeleton comprises at least one of an organic polymer and a metal.

16. The method according to any one of the preceding claims, wherein the first mould amount comprises an elastomer, for claim silicon rubber.

17. A method for manufacturing an optical element, the method comprising: manufacturing a first production mould part according to a method according to any one of the preceding claim s, wherein the first production mould comprises a first cavity that is complementary shaped to the first master piece, the first master piece representing a first part of the optical element, the first production mould comprising a first cavity; providing a product substance in the first cavity; allowing the product substance to settle thus forming the optical element; and removing the first production mould part from the optical element.

18. The method according to claim 17, further comprising: manufacturing a second production mould part according to the method according to any one of the preceding claims, wherein the second production mould comprises a second cavity that is complementary shaped to a second master piece, the second master piece representing a second part of the optical element; combining the first production mould with the second production mould, such that cavities of the first production mould and the second production mould face one another, thus forming a product cavity; providing a product substance in the product cavity, the product cavity having a shape equivalent to that of the optical element..

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