METHOD FOR THE PRODUCTION OF AN OPTICAL GLASS ELEMENT

Abstract

A method for the production of an optical glass element, with the following process sequence: a) applying a liquid embossing material on an embossing die, b) embossing the embossing material at a temperature of less than 500° C., c) hardening the embossing material, d) sintering the embossing material and thus executing the primary forming of the optical glass element. In addition, an optical glass element that is produced with the method, a device for implementing the method, and a use of this device are disclosed.

Claims

1-14. (canceled)

15. A method for the production of an optical glass element, comprising: a) applying a liquid embossing material on an embossing die, embossing the embossing material at a temperature of less than 500° C., c) hardening the embossing material, d) sintering the embossing material and thus executing the primary forming of the optical glass element, whereby a reduction of the surface roughness of the optical glass element take place during the sintering, and e) removing gases and/or additives generated before and/or during the sintering such that a final concentration of the gases and/or additives is lower than 100 ppm.

16. The method according to claim 15, wherein the embossing is carried out in step b) at a temperature of less than 400° C.

17. The method according to claim 15, wherein after step a), a degree of coverage of the liquid embossing material on an embossing die surface of the embossing die is more than 20%.

18. The method according to claim 15, wherein the embossing material is applied in the form of multiple small, distributed drops on an embossing die surface of the embossing die.

19. The method according to claim 15, wherein the embossing of the embossing material is carried out in step b) by converging said embossing die and a second embossing die.

20. The method according to claim 19, wherein said embossing die is a lower embossing die and the second embossing die is an upper embossing die.

21. The method according to claim 15, wherein the hardening of the embossing material is carried out in step c) by a thermal method, whereby heat is transported to the embossing material, and a polymerization process of the embossing material starts above a critical temperature T.sub.k, the critical temperature T.sub.k being between 0° C. and 1,000° C.

22. The method according to claim 15, wherein the hardening of the embossing material is carried out in step c) by an electromagnetic method, whereby the embossing material is irradiated by an electromagnetic radiation.

23. The method according to claim 22, wherein the electromagnetic radiation is UV light.

24. The method according to claim 22, wherein a wavelength range of the electromagnetic radiation is between 1 nm and 10,000 nm.

25. The method according to claim 15, wherein steps a), b) and c) are performed in an embossing device, and the sintering is performed in step d) in a sintering device that is separated from the embossing device.

26. The method according to claim 15, wherein the sintering is carried out in step d) by microwave radiation.

27. The method according to claim 15, wherein the sintering is carried out in step d) in a furnace, whereby the temperature during sintering is greater than 50° C.

28. The method according to claim 27, wherein the furnace is a continuous furnace.

29. The method according to claim 15, wherein the embossing material has at least one of the following components: Polyhedral oligomeric silsesquioxane (POSS), Polydimethylsiloxane (PDMS), Tetraethyl orthosilicate (TEOS), and Poly(organo)siloxane silicone.

30. An optical glass element produced with a method according to claim 15.

31. A device for implementing a method according to claim 15.

32. Use of the device according to claim 31 for the production of an optical glass element.

33. The method according to claim 15, wherein the embossing is carried out in step b) at a temperature less than 300° C.

34. The method according to claim 15, wherein the embossing is carried out in step b) at a temperature less than 200° C.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0065] FIG. 1a a diagrammatic cross-sectional depiction of a first process step of an exemplary embodiment of the method according to the invention,

[0066] FIG. 1b a diagrammatic cross-sectional depiction of a second process step of an exemplary embodiment of the method according to the invention,

[0067] FIG. 1c a diagrammatic cross-sectional depiction of a third process step of an exemplary embodiment of the method according to the invention,

[0068] FIG. 1d a diagrammatic cross-sectional depiction of a fourth process step of an exemplary embodiment of the method according to the invention,

[0069] FIG. 1e a diagrammatic cross-sectional depiction of a fifth process step of an exemplary embodiment of the method according to the invention,

[0070] FIG. 2 a diagrammatic cross-sectional depiction of an optical glass element according to an exemplary embodiment,

[0071] FIG. 3a a magnified, diagrammatic cross-sectional depiction of a substrate according to an exemplary embodiment before the sintering process,

[0072] FIG. 3b a magnified, diagrammatic cross-sectional depiction of a substrate according to another exemplary embodiment before the sintering process,

[0073] FIG. 3c a magnified, diagrammatic cross-sectional depiction of an optical glass element according to an exemplary embodiment after the sintering process.

[0074] In the various figures, the same parts are always provided with the same reference numbers and are therefore in general also in each case named or mentioned only once.

DETAILED DESCRIPTION OF INVENTION

[0075] FIG. 1a shows a diagrammatic depiction of a first process step of an exemplary embodiment according to the invention, in which an embossing material 4 is dispensed by a dispensing unit 5 onto the embossing die surface 1o of the lower embossing die 1. The embossing material 4 can be applied by a so-called pool deposition (puddle dispense). In this case, embossing material 4 is deposited on the embossing die surface 1o by the dispensing unit 5 until the embossing material 4 covers the majority of the embossing die surface 1o. It is also conceivable that a complete covering is carried out only in an additional process step. The embossing material can be applied in particular by centrifugal enameling processes and/or spray-enameling processes. During dispensing, the degree of coverage of the embossing die surface 1o is more than 20%, preferably more than 40%, more preferably more than 60%, most preferably more than 80%, and with utmost preference 100%.

[0076] By further processes such as, for example, the centrifugal enameling (spin coating), the degree of coverage can again be increased or the embossing material layer thickness t can be homogenized relative to the site. An application of the embossing material 4 on the embossing die surface to by a spray enameling device (spray coater) is also conceivable. In another embodiment, not depicted, the embossing material 4 is not applied as a pool, but rather in the form of multiple small, distributed drops, which have, however, sufficient embossing material 4 to agglomerate in subsequent processes and to form a corresponding monolithic substrate. The advantage of the application of drops in this case lies primarily in the possibility of a more homogeneous distribution of the embossing material 4. Also, the drops of embossing material 4 distributed by the application of drops can be distributed by a subsequent centrifugal enameling process over the embossing die surface 1o and can agglomerate as early as in this process step. The deposition of individual drops is also conceivable, however, in order to emboss optical units that are separated from one another. Such a process is described in the publication WO2013/178263A1.

[0077] In an exemplary second process step, depicted in FIG. 1b, a second embossing die 2 is aligned with the first embossing die 1. In this case, the alignment of the two embossing dies is preferably carried out via multiple (not indicated) alignment marks on the embossing dies 1 and 2. Two alignment marks, opposite in each case, at at least two different positions that lie preferably as far as possible on the edge are aligned with one another by corresponding alignment units.

[0078] In an exemplary third process step that is depicted in FIG. 1c, an embossing of the embossing material 4 is carried out by a converging of the two embossing dies 1 and 2. In this case, the embossing material 4 is pressed into the embossing forms 3 of the upper embossing die 2 and/or the lower embossing die 1. In another exemplary process step that is depicted in FIG. 1d, a hardening of the embossing material 4 is carried out between the two embossing dies 1 and 2. In this case, the hardening can be carried out either by means of heat, photons, electric current, chemicals such as acids and bases, or any other type of chemical and/or physical exposure. Thermal and electromagnetic methods are especially preferred.

[0079] With the thermal method, heat is transported via the upper embossing die 2 and/or the lower embossing die 1 to the embossing material 4. The thermal initiators within the embossing material 4 start the polymerization process of the embossing material 4 above a critical temperature T.sub.k. In this case, the critical temperature is greater than ambient temperature, preferably greater than 100° C., more preferably greater than 200° C., most preferably greater than 300° C., most preferably greater than 400° C., and even more preferably greater than 500° C.

[0080] In an electromagnetic method, the embossing material 4 is illuminated by an intensive electromagnetic radiation, in particular UV light. In this case, the electromagnetic radiation shines through the upper embossing die 2 and/or the lower embossing die 1. The transilluminated embossing die 1 and/or embossing die 2 must accordingly be transparent for the electromagnetic radiation. The preferred wavelength range of the electromagnetic radiation lies between 1 nm and 10,000 nm, preferably between 10 nm and 1,000 nm, more preferably between 100 nm and 500 nm, and most preferably between 200 nm and 500 nm.

[0081] After the hardening of the embossing material 4, a dimensionally stable, solid embossing material 4′ is already present in the form of a monolithic substrate 6. The monolithic substrate 6 is sintered again for converting the embossing material 4′ into the glass material 7. FIG. 1e shows a fifth process step of an exemplary embodiment. The sintering is preferably done outside of the embossing device 8. According to the invention, a separation of the embossing process and the sintering process is thus also performed, which can have a positive effect on the throughput. Especially preferably, namely the embossing device 8 is always used only for embossing, and a corresponding sintering device 9 is used only for sintering. The sintering device 9 is, for example, a furnace, even more preferably a continuous furnace. Especially preferably, the sintering unit 9 uses a microwave source 10. The microwave source 10 is used to heat either the material 4′ of the monolithic substrate 6 directly or a structural element 11, in particular a specimen holder 11, which is thermally coupled as efficiently as possible to the monolithic substrate 6. The thermal coupling exists either via direct contact of the monolithic substrate 6 to the structural element 11 or via a gas that conducts heat as efficiently as possible. In special embodiments, it may be useful to combine the embossing device 8 and the sintering device 9 with one another. As a result, it is possible according to the invention to perform the embossing process and the sintering process in one and the same unit.

[0082] FIG. 2 shows an exemplary embodiment of an optical glass element 13 that is comprised of multiple optical subcomponents 12. In special cases, the optical subcomponents 12 are biconvex lenses. The optical subcomponents 12 could, however, just as well be, for example, biconcave, convex-concave or concave-convex lenses. In addition, it is conceivable that the optical subcomponents 12 are diffraction lattices, any other type of optical element, or any other type of glass structural element.

[0083] In each case, FIGS. 3a and 3b show a magnified depiction of an exemplary monolithic substrate 6 before the sintering process. FIG. 3c shows an exemplary optical glass element 13 that is comprised of glass material 7 after the sintering process with an almost ideal surface 13o. The monolithic substrates 6 are comprised of the dimensionally stable but not yet sintered material 4′. FIG. 3a shows a magnified depiction of a monolithic substrate 6 with a statistically roughened surface 6o. FIG. 3b shows a magnified depiction of another monolithic substrate 6 with a well-defined surface 6o that deviates systematically from the ideal form 13o. The surface 6o could be produced, for example, as a negative of an embossing form 3 of an embossing die 1 or an embossing die 2. Provision can be made in particular for suitably designing and building the surfaces 3o of the embossing forms 3 namely in the middle of the desired form but for configuring their short-range ordering in steps.

[0084] The shrinkage process results in an in particular light smoothing of the surface 6o or the stepped structuring 6o of the substrate 6. It is therefore a preferred aspect according to the invention to influence the shrinkage process by the structuring of the surface 6o, in particular by a stepped structuring. Preferably, the structuring of the surface 6o influences the shrinkage process to the extent that as smooth as possible a surface 13o″ is produced according to FIG. 3c. This smoothing is a surface effect of the compressing of the material 4′ that takes place in particular throughout the volume.

LIST OF REFERENCE SYMBOLS

[0085] 1 Lower embossing die [0086] 1o Embossing die surface of the lower embossing die [0087] 2 Upper embossing die [0088] 3 Embossing form [0089] 4, 4′ Embossing material [0090] 5 Dispensing unit [0091] 6 Monolithic substrate [0092] 6o Surface [0093] 7 Glass material [0094] 8 Embossing device [0095] 9 Sintering device [0096] 10 Microwave source [0097] 11 Structural element [0098] 12 Optical subcomponent [0099] 13 Optical element [0100] 13o Surface