WO2021058077A1

WO2021058077A1 - Production process of an isolated monolithic micro optical component

Info

Publication number: WO2021058077A1
Application number: PCT/EP2019/075469
Authority: WO
Inventors: Gabi GRÜTZNER; Susanne GRÜTZNER; Arne Schleunitz; Johannes Wolf
Original assignee: Micro Resist Technology Gesellschaft Für Chemische Materialien Spezieller Photoresistsysteme Mbh
Priority date: 2019-09-23
Filing date: 2019-09-23
Publication date: 2021-04-01

Abstract

A production process of an isolated monolithic micro optical component comprising one or two convex curvatures using an additive manufacturing method as well as an isolated monolithic micro optical component comprising one or two convex curvatures obtainable by the method.

Description

Production process of an isolated monolithic micro optical component

TECHNICAL FIELD:

The present invention relates to a production process of an isolated monolithic micro optical component comprising one or two convex curvatures using an additive manu- facturing method as well as an isolated monolithic micro optical component comprising one or two convex curvatures obtainable by the inventive method.

PRIOR ART:

For the manufacture of isolated polymeric micro optical components, such as diffrac- tive-refractive micro optical components or biconvex refractive micro lenses, different ap- proaches are known to the skilled person. Such isolated polymeric micro optical compo- nents may be manufactured using a replication process, such as injection molding. This process may be advantageous for the manufacture of large quantities of the same micro optical components. Nevertheless, injection molding requires post-processing of the mi- cro optical component in order to remove the hardened material comprised in the filling nozzle, which increases manufacturing time and, thus, costs as well as makes the pro- duced micro optical components susceptible to defects.

Furthermore, injection molding requires time and, thus, cost intensive alignment of the optical axes using the two parts of the injection die. In addition, change of the optical design of the micro optical component requires change and new manufacturing of the injection die and is, thus, time and cost intensive. Other suitable methods for the manufacture of isolated polymeric micro optical com- ponents relate to embossing and imprinting, which are also suitable to provide isolated micro optical components. Nevertheless, they are also time and, thus, cost intensive when aligning the optical axes of the isolated micro optical component and require changes of the processing tools when a change of optical design of the micro optical component is required.

On the other hand, methods, such as pure inkjet printing of polymers for optical ap- plications, facilitate individualizing the refractive power of a micro optical component de- pendent on the amount of optical material applied. This method is presently used to pro- duce integrated micro optical components into numerous devices, such as light emitting diodes, photodiodes and micro-opto-eletro-mechanical systems (MEOMS) and are not used to produce isolated micro optical components.

In order to enable, however, system-level optical packaging, such as hybrid-optical building blocks, e.g. for collimating light into on-chip level waveguides, there exists a need to provide a production process for isolated micro optical components. In addition, as isolated micro optical components with individualized optical properties are needed, a production process is needed, which facilitates individualization of the micro optical com- ponents. The production process for micro optical components should preferably be time and cost-saving already at small production numbers of micro optical components.

Accordingly, the aim of the present invention is to provide a

- production process for isolated micro optical components,

- production process for micro optical components facilitating individualization of an isolated micro optical component, and/or

- wherein the production process is time and, thus, cost-saving already at small production numbers of the micro optical components.

BRIEF DESCRIPTION OF THE INVENTION:

The aforementioned aim is solved at least in part by means of the claimed inventive subject matter. Advantages (preferred embodiments) are set out in the detailed descrip- tion hereinafter and/or the accompanying figures as well as in the dependent claims.

Accordingly a first aspect of the invention relates to a production process of an iso- lated monolithic micro optical component comprising one or two convex curvatures. The inventive process comprises or consists of a) forming or providing a mold master with an opening, wherein the mold master rep- resents the negative structure of the isolated micro optical component, with the proviso that the mold master does not represent a negative structure of the or one of the convex curvatures of the isolated monolithic micro optical component, b) adding a suitable amount of an optical material through the opening to the mold master using an additive manufacturing technique so that the monolithic micro op- tical component comprising the one or two convex curvatures is formed, whereby the convex curvature, which is not comprised as negative structure in the mold master, is formed by self-organizing the optical material in the opening, wherein the radius of the convex curvature is dependent on the amount and the surface energy of the optical material and the mold master, c) optionally curing the monolithic micro optical component comprising the one or two convex curvatures formed in step b) and d) demolding the monolithic micro optical component comprising the one or two con- vex curvatures of step b) or c) to form the isolated monolithic micro optical compo- nent comprising the one or two convex curvatures.

A second aspect of the invention relates to an isolated monolithic micro optical com- ponent comprising one or two convex curvatures obtainable by the inventive production process.

The inventive aspects of the present invention as disclosed hereinbefore can com- prise any possible (sub-)combination of the preferred inventive embodiments as set out in the dependent claims or as disclosed in the following detailed description and/or in the accompanying figures, provided the resulting combination of features is reasonable to a person skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 shows a general overview on the inventive production process for an isolated monolithic diffractive-refractive micro optical component.

Figs. 2a), 2b) and 2c) show photographs of the initial master substrate (a) and its replicas made of UV-PDMS KER-4690 in the first step (b) and made of OrmoClear®FX on polycarbonate foil in the second replication step (c). Fig. 3 shows a SEM micrograph of two inventive isolated monolithic diffractive-refrac- tive micro optical components with laminar grating as diffractive pattern, fabricated with the additive process variant #1 .

Fig. 4 shows a screen photograph of the 0th and +/-1st diffraction orders generated by the diffraction grating and focused by the micro-lens.

Fig. 5 shows a general overview on the inventive production process for an isolated monolithic biconvex refractive micro lens.

Figs. 6a), 6b), 6c) and 6d) show SEM micrographs of inventive isolated monolithic biconvex refractive micro lens.

Fig. 7 shows a SEM micrograph of an inventive isolated monolithic plan-convex re- fractive micro lens.

DETAILED DESCRIPTION OF THE INVENTION:

As set out in more detail hereinafter, the inventors of the different aspects of the present invention have found out that the inventive production process is suitable for producing one or more isolated micro optical components comprising one or two convex curvatures, which may be used in particular for system-level optical packaging. In par- ticular the isolated micro optical components can be produced substantially defect free as set out in detail in the Example section and Figures 3, 6a) to 6d) and 7. The additive manufacturing technique for forming the inventive micro optical component also facili- tates an easy and quick auto-adjustment of the optical axes by the optical material used.

Moreover, the inventive production process also facilitates individualization of the one or more isolated micro optical component in particular in view of refractive power of the convex curvature, which is formed by self-organizing the optical material in the open- ing, as the radius of the convex curvature is dependent on the amount and the surface energy of the optical material and the mold master (see Figures 3, 6a) to 6d) and 7). Thus, the inventive production process allows for a highly versatile production routes in particular for prototyping and, thus, a high degree of design flexibility.

In addition, the inventive production process allows an easy and fast fabrication of mold master and micro optical components and, thus, is time and cost-efficient already at small production numbers of the micro optical components and, thus, is in particular suitable for prototyping. Moreover, the mold master does not need to be changed in order to change the refractive power of the convex curvature, which is formed by self- organizing the optical material in the opening, as the refractive power is dependent on the amount and surface energy of optical material applied and surface energy of the mold master.

Thus, the inventive production process provides a cost-effective implementation of tailor-made optical design in micro optical components.

In the context of the present invention the term “isolated" in expressions such as “isolated monolithic micro optical component’ means that the inventive (monolithic) mi- cro optical component produced or obtainable by the inventive process is a stand-alone component or lens and does not form an integrated device.

In the context of the present invention the term “individualized’ in relation to in ex- pressions such as “individualized monolithic micro optical component’ means that the inventive production process facilitates changing the optical property of each of the com- ponents, in particular of the refractive power thereof, by adjusting either the amount of the optical material and/or by selecting an optical material exhibiting a different surface energy. Preferably, the mold master does not need to be changed, when adjusting the optical design.

In the context of the present invention the expression “micro optical component’ or “micro lens" is used interchangeably to “isolated monolithic micro optical component’ or “isolated monolithic micro lens" and generally covers respective components or lenses in the micro to millimeter range. In particular, the diameter of the inventive micro optical components can generally range from 10 pm to 10 mm, or 50 pm to 7 mm, or 1 mm to 4 mm, or any other intermediate range. The total thickness, i.e. the thickness of the inventive micro optical component at its widest dimension, can generally range from 1 pm to 5 mm, or 10 pm to 2 mm, or 100 pm to 600 pm, or any other or any other inter- mediate range. The radius of curvature for the one or more convex curvatures of the inventive micro optical component can independently from each other be selected from the range of 10 pm to 8 mm, or 50 pm to 6 mm, or 600 pm to 3 mm or 750 pm to 2 mm.

In the context of the present invention the expression “micro optical component comprising one or two convex curvatures" means that the micro optical component com- prises one or two refractive lenses, which are formed respectively by the one or two convex curvatures. Due to the additive manufacturing step, the inventive process facili- tates an easy and fast auto-adjustment of the optical axes in comparison to the prior art techniques.

In the context of the present invention, the expression “optical material·’ means a material suitable optical application. According to the present invention, the “optical material·’ is suitable for application to the mold master by additive manufacturing tech- niques.

In the context of the present invention, the expression “mold master with an opening, wherein the mold master represents the negative structure ol· the isolated micro optical component, with the proviso that the mold master does not represent a negative structure ol· the or one ol· the convex curvatures ol· the isolated monolithic micro optical component’ means, that the mold master includes the negative form of the outer structure of the inventive micro optical components with the exception that the outer structure of the or one of the convex curvatures, i.e. refractive lenses, is not represented by the mold master. Generally, the mold master is replicated as a hollow negative form into a repli- cation material into which the optical material is dispensed. The opening of the mold master generally exhibits a cross-sectional area, which represents the cross-sectional area of the convex curvature forming the (see Figure 7) or one of the refractive lenses (see Figures 3, and 6a) to 6d)).

In the context of the present invention, the expression “whereby the convex curvature, which is not comprised as negative structure in the mold master, is tormed by sell·- organizing the optical material in the opening" means that the optical material is not formed by the mold master to build the convex curvature, but instead is in contact with the air or any other suitable environment and automatically forms the convex curvature dependent on its added amount and its surface energy. As the remaining part of the optical material is comprised in the mold master, the surface energy of the mold master material also influences the shape of this convex curvature.

In the context of the present invention, the expression “an additionally or alterna- tively further preferred embodiment” or “an additionally or alternatively preferred embod- iment” or “an additional or alternative way of configuring this preferred embodiment” means that the feature or feature combination disclosed in this preferred embodiment can be combined in addition to or alternatively to the features of the inventive subject matter including any preferred embodiment of each of the inventive aspects, provided the resulting feature combination is reasonable to a person skilled in the art.

According to the first aspect, the inventive production process of an isolated mono- lithic micro optical component comprising one or two convex curvatures is characterized in that the process comprises or consists of a) forming or providing a mold master with an opening, wherein the mold master rep- resents the negative structure of the isolated micro optical component, with the proviso that the mold master does not represent a negative structure of the or one of the convex curvatures of the isolated monolithic micro optical component, b) adding a suitable amount of an optical material through the opening to the mold master using an additive manufacturing technique so that the monolithic micro op- tical component comprising the one or two convex curvatures is formed, whereby the convex curvature, which is not comprised as negative structure in the mold master, is formed by self-organizing the optical material in the opening, wherein the radius of the convex curvature is dependent on the amount and the surface energy of the optical material and the mold master, c) optionally curing the monolithic micro optical component comprising the one or two convex curvatures formed in step b) and d) demolding the monolithic micro optical component comprising the one or two con- vex curvatures of step b) or c) to form the isolated monolithic micro optical compo- nent comprising the one or two convex curvatures. e) component comprising the one or two convex curvatures.

The mold master of step a) may generally represent any suitable form in cross- sectional view, such as a round form, in particular a circular form, ellipse form or a cir- cular ring form; or an angular form, such as a triangular form, a square form, pentagonal form, hexagonal form, octagonal form etc. The mold master may be formed on a solid carrier substrate, such as a Si-wafer, or on a flexible carrier substrate, such as a poly- carbonate foil. Accordingly, the resulting template is rigid when using a solid carrier sub- strate and bendable, when using a flexible carrier substrate. Flexible carrier substrates may enhance defect free demolding of the inventive isolated micro optical components comprising one or more convex curvatures.

According to an additionally or alternatively preferred embodiment of the first in- ventive aspect, the additive manufacturing technique in step b) is selected from the group consisting of i) melting of a suitable amount of solid optical material, such as applying a suitable amount of an optical material in solid phase, melting the optical and self-organization of the material to form the convex curvature in the opening; and ii) dispensing a suitable amount of liquid optical material optionally comprising one or more solvents and self-organization of the optical to form the convex curvature in the opening, such as dispensing by inkjet-printing, pico-dispensing and super inkjet-printing. The liq- uid optical material used for dispensing generally exhibits a suitable viscosity required for the respective dispensing method, such as preferably in the range of 5 to 25 mPas dynamic viscosity for inkjet printing, and > 5 mPas for the remaining dispensing tech- niques, such as pico dispensing or super inkjet printing. The respective viscosity may be adjusted as necessary by addition of suitable additives, such as one or more sol- vents. However, it is preferred to keep the amount of additives as low as possible in order to reduce or avoid process steps, such as evaporation of solvents.

Correspondingly, the solid optical material for use in the melting process is prefera- bly selected from the group consisting of thermoplastic polymers suitable for optical ap- plications, such as cycloolefin copolymers (COC) and cycloolefinpolymers (COP), and inorganic materials suitable for optical applications, such as solid glass or solid glass- like materials. The liquid optical material for use in the dispensing process is preferably selected from the group consisting of liquid glass or liquid glass-like inorganic materials suitable for optical applications and liquid optical polymer materials suitable for optical applications, such as organic-inorganic hybrid polymers, in particular organic-inorganic hybrid polymers comprising one or more (meth) acrylate based organic units connected to an inorganic Si-O-Si-network, and epoxy based resins, in particular based on phenol and having a pure organic network.

Optionally, the liquid optical material, preferably the liquid optical polymer material may comprise one or more additives for adjusting the viscosity, such as solvents, reac- tive diluents etc.. The liquid optical material, preferably the liquid optical polymer mate- rial is preferably repeatedly dispensed in one, two, three or more parts to the mold mas- ter in step b). The one or more viscosity adjusting additives, such as solvents may evap- orate prior to the subsequent addition. In this case, the added part of the liquid optical material, preferably liquid optical polymer material can be further processed, such as heated, prior to the subsequent addition step in such a way, that at least part of the one or more viscosity adjusting additives, such as solvents evaporate from the added liquid optical material. The evaporation of one or more solvents facilitates to reduce shrinking of the optical material in particular during curing. Evaporation of the viscosity adjusting additives, such as solvents is preferably conducted at suitable increased temperatures, such as at 100°C, more preferably for more than 20 minutes, preferably for 1 hour. Ac- cording to another alternative of the present invention, the optical material is substan- tially free of solvent, which need to evaporate prior to finalization of the isolated mono- lithic micro optical components. In this case, the optical material does not need to be applied repeatedly interrupted by an evaporation step.

In order to design permanent optical applications, inkjetable compositions compris- ing organic-inorganic hybrid polymers, more preferably organic-inorganic hybrid poly- mers comprising one or more (meth) acrylate based organic units connected to an inor- ganic Si-O-Si-network, such as InkOrmo (from microresist technology GmbH) are pre- ferred. Organic-inorganic hybrid polymers comprising one or more (meth) acrylate based organic units connected to an inorganic Si-O-Si-network, such as InkOrmo, are in particular preferred, as they exhibit glass-like properties after UV curing, excellent optical properties, such as high transparency (non yellowing) or no birefringence, exhib- its high temperature stability up to 270 °C and high chemical and physical stability (pass- ing Telcordia test), exhibits excellent replication fidelity for mastering.

In order to design waveguide applications, inkjetable epoxy resins, preferably based on phenol and having a pure organic network, such as InkEpo (from microresist tech- nology GmbH), are preferably used. The epoxy resins exhibit a high transparency (neg- ligible yellowing), a temperature stability up to 180 °C, a high chemical and physical stability, and excellent replication fidelity for mastering.

According to an additionally or alternatively preferred embodiment of the first in- ventive aspect, the mold master is formed using a micro-structuring and/or nano-struc- turing technique to form a micro- and/or nano-structured and optionally pre-patterned mold structure and replicating the mold structure with replicating material one or more times to form the mold master. This combination of structuring and replication technique allows easy and fast production and at the same time reliable production of individual- ized mold masters. In case the inventive micro optical component shall represent a bi- convex micro lens, then the micro-structuring technique may be further complemented with an additive manufacturing technique, as set out above, prior to replication. In this case, a suitable material for additive manufacturing, which does not need to be suitable for optical applications, is added to the top surface of the mold structure produced above. The required convex curvature, which corresponds to the structure of the second refractive lens element of the biconvex lens, is formed by self-organization of the applied material dependent on the amount and surface energy of the applied material as well as of the mold material. When replicating the mold structure with or without convex cur- vature, the master mold exhibits the corresponding negative form of the second refrac- tive lens. Combining the micro-structuring technique with the additive manufacturing technique is preferred, as is provides an easy and quick and at the same time reliable production of adjusting the convex curvature corresponding to the second refractive lens for each isolated micro optical component, in particular isolated biconvex micro lens independently from each other.

According to an additionally or alternatively further preferred embodiment of the first inventive aspect, the micro-structuring and/or nano-structuring technique is / are se- lected from the group consisting of i) lithography, such as UV lithography, E-beam li- thography, nanoimprint lithography, laser lithography; ii) ablative processing, such as chipping, preferably by milling, turning, or grinding; eroding, preferably by sinking or wire eroding; and iii) etching, preferably by dry etching or wet etching, and iv) 3D printing. Further preferred are the lithography processes, more preferably the UV lithography and/or nano imprint lithography processes are preferred as they provide an easy and quick and at the same time reliable structuring of the mold master.

Correspondingly, i) the structuring material suitable for forming the mold master by lithography is preferably selected from the group consisting of positive photo resists, such as resin based resists, in particular novolak based resists; negative photo resists, such as resin based resists, in particular novolak based resists, or epoxy based resists, such as SU-8, or dry films of resin based resists, in particular acrylate based resists, or epoxy based resists, such as SU-8; polymeric material for imprint lithography, such as duroplast and thermoplastics; ii) the material suitable for ablative processing is prefera- bly selected from the group consisting of metals, such as Ni, Al, Au, alloy steel and/or other alloys; and inorganic materials, such as glass; and/or plastics, such as polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), polypropylene (PP); iii) the mate- rial suitable for etching is preferably selected from the group consisting of semiconduc- tors, such as silicon, and plastics, such as duroplast, acrylate and epoxy based poly- mers; and iv) the material suitable form 3D printing is preferably selected from the group consisting of thermoplastic material, such as poly(methyl methacrylate) (PMMA), poly- styrene, poly lactic acid (PLA), acrylonitrile butadiene styrene (ABS), cycloolefine poly- mer (such as Zeonex^®); or composite material, such as conductive inks, photopolymers including metal oxides.

In general, the mold material does not need to be selected from an optical material, as it is typically only used in view of its structuring purposes.

According to an additionally or alternatively further preferred embodiment of the first inventive aspect, the one or more replication steps are independently from each other selected from the group consisting of i) casting and UV curing, thermal curing or chem- ical hardening; ii) injection molding, iii) embossing and UV or thermal curing, iv) ther- moforming or v) electroplating.

Correspondingly, i) the material suitable for casting is preferably selected from the group consisting of soft material, i.e., after replication the material is soft and bendable, such as polydimethylsiloxane; or hard materials, i.e. after replication the material is hard and not bendable, such as cycloolefin copolymers (COC), cycloolefinpolymers (COP), organic-inorganic hybrid polymers, in particular inorganic-organic hybrid polymer com- prising one or more (meth) acrylate based organic units connected to an inorganic Si- O-Si-network, metals, such as Ni, or glass or glass-like materials; ii) the material suitable for injection molding is preferably selected from the group consisting of thermoplastic polymers, such as cycloolefin copolymers (COC), cycloolefinpolymers (COP), polypro- pylene (PP), polyethylene terephthalate (PET); iii) the material suitable for embossing is preferably selected the group consisting of polystyrene, polycarbonate (PC), and poly(methyl methacrylate) (PMMA); and iv) the material suitable for thermoforming is preferably selected from the group consisting of thermoplastic foils, such as polyeth- ylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), and high impact poly- styrene; v) the material suitable for electroplating is selected from the group consisting of metals such as Ni. Preferably the mold master is formed by a soft replication material as listed above, more preferably UV curable polydimethylsiloxane (synonym: UV-PDMS). In case the mold master is made of soft replication material, demolding of the inventive isolated monolithic micro optical components is enhanced. According to an additionally or alternatively preferred embodiment of the first in- ventive aspect, an array comprising two or more individual mold masters is provided in step a). The inventive production process is in particular preferred, as it allows individu- alizing the design of each mold master independently from each other and, thus, pro- vides a higher degree of individualization, as also optical properties of further parts of the micro optical components can be designed. In other words, one array comprising two or more mold masters may exhibit two or more optical designs. Moreover, producing the mold masters in parallel reduces production time and, thus, costs. More preferably, the additive manufacturing technique in step b) is configured to independently adjust selection of optical material and/or predetermined amount of the optical material for each micro optical component. The combination of production methods of step a) and step b) allows to independently adjust all optical properties for each isolated micro opti- cal component.

According to a preferred embodiment, the inventive isolated monolithic micro optical components may comprise a part, also called edge, for enhancing handling and clamp- ing. Generally, it is advantageous in case the height of the edge material is as small as possible and necessary. As an example, the height can range from 10 pm to 500 pm and may be 150 pm as shown in Figures 3, 6a) to 6d) and 7.

According to an additionally or alternatively preferred embodiment of the first in- ventive aspect, the isolated monolithic micro optical component is an isolated monolithic diffractive-refractive micro optical component. The inventive production process prefer- ably comprises or consists of the following process steps: forming the mold master with the opening according to step a) of the first inventive aspect by i) providing a carrier and adding a structuring material, which is nanostructured using a nano-structuring method to form a pre-patterned mold comprising a negative form of the diffractive structure of the isolated diffractive-refractive micro optical component, ii) optionally adding a confining resist layer, which is structured using a micro-structuring technique to form a micro-structured pre-patterned mold, iii) replicating the pre-patterned mold of step i) or the micro-structured pre-patterned mold of step ii) with a first replication material to form a mold comprising a positive form of the diffractive structure of the isolated diffractive-refractive micro optical com- ponent and demolding the mold, iv) replicating the mold formed in step iii) with a second replication material to form a mold master comprising a negative form of the diffractive structure of the isolated diffractive-refractive micro optical component and demolding the mold master, adding the suitable amount of the optical material through the opening to the mold master to form the monolithic diffractive-refractive micro optical component according to step b), optionally curing the monolithic diffractive-refractive micro optical component according to step c) and demolding the monolithic diffractive-refractive micro optical component formed according to step b) or cured according to step c) to form the isolated monolithic diffractive-refractive micro optical component.

According to a preferred or alternative embodiment of the production process of a diffractive-refractive monolithic micro optical component, one or more release agents may be added during production, in particular a release agent may be added to a micro- structured, pre-patterned mold, more preferably by vapor phase deposition. Such a coating improves demolding of the replicated mold from the micro-structured, pre-pat- terned mold. Alternatively or in addition, a release agent may be added to the replicated mold structure after demolding and prior to the second replication step in order to im- prove demolding of the mold master after second replication. The inventive production of the diffractive-refractive micro optical component is a cost-effective way to generate prototypes and small batches of hybrid micro-optical components. According to a further preferred embodiment thereof, UV-molding is com- bined with inkjet printing techniques.

Thus, the inventive production process enables the integration of diffractive and re- fractive optical elements into one isolated monolithic micro optic component and, thus, facilitates the implementation of tailor-made optical designs. Furthermore, it produces lenses with a high lens transparency and provides a high pattern fidelity even after at least four replication steps.

According to an additionally or alternatively preferred embodiment of the first in- ventive aspect, the isolated monolithic micro optical component is an isolated monolithic plan-convex refractive micro lens. The inventive production process comprises or con- sists of the following process steps: forming the mold master with the opening according to step a) by i) providing a carrier and adding a confining resist layer, which is structured using a micro-structuring technique to form a micro-structured mold comprising a positive form of the plane surface of the isolated plan-convex refractive micro lens, ii) replicating the micro-structured mold of step i) with a replication material to form a mold master comprising a negative form of the plane surface of the isolated plan- convex refractive micro lens and demolding the mold master, adding the suitable amount of the optical material through the opening to the mold master to form the monolithic plan-convex refractive micro lens according to step b), optionally curing the monolithic plan-convex refractive micro lens according to step c) and demolding the monolithic plan-convex refractive micro lens formed according to step b) or cured according to step c) to form the isolated monolithic plan-convex refractive micro lens.

The inventive production process basically differs from the production of isolated monolithic diffractive-refractive micro optical components only in that the step of nano- structuring to form a pre-patterned mold is not conducted and one instead of two repli- cation steps is used to form the mold master. With respect to the remaining features, all preferred embodiments, as set out with respect to the production of the isolated mono- lithic diffractive-refractive micro optical component, can also be applied for production of the isolated monolithic plan-convex refractive micro lens.

According to an additionally or alternatively preferred embodiment of the first in- ventive aspect, the isolated monolithic micro optical component is an isolated monolithic biconvex refractive micro lens. The inventive production thereof preferably comprises or consists of the following process steps: forming the mold master with the opening according to step a) by i) providing a carrier and adding a confining resist layer, which is structured using a micro-structuring technique to form a micro-structured mold and subsequently adding a suitable amount of a material onto an upper surface of the micro-structured mold using an additive manufacturing technique thereby forming a micro-structured mold comprising a convex curvature on top of the micro-structured mold or ii) providing a carrier and adding a polymeric material, which is embossed to form an embossed mold comprising a convex curvature on top of the embossed mold, iii) replicating the mold of step i) or ii) with a replication material to form a mold master comprising a negative form of the convex curvature of the mold of steps i) and ii) and demolding the mold master, adding the suitable amount of the optical material through the opening to the mold master to form the second convex curvature of the monolithic biconvex refractive micro lens ac- cording to step b), optionally curing the monolithic biconvex refractive micro lens according to step c) and demolding the monolithic biconvex refractive micro lens formed according to step b) or cured according to step c) to form the isolated monolithic biconvex refractive micro lens.

Production step i) of the inventive production process of the isolated monolithic bi- convex refractive micro lens differs from the inventive production process of the isolated monolithic plan-convex refractive micro lens only in that an additive manufacturing tech- nique is used to form the convex curvature on top of the micro-structured mold, which may also be called pedestal. Suitable additive manufacturing techniques and materials are described hereinbefore with respect to step b) of the inventive production process. However, as the formed mold structure is not used for optical applications, the materials used for additive manufacturing can accordingly be selected from a wider variety. The additive manufacturing process facilitates to adjust the convex curvature of the pedestal by adjusting the amount of material added without amending the micro-structuring pat- tern.

In contrast thereto step ii) describes an alternative production of the mold compris- ing the convex curvature by embossing. In case the convex curvature shall be adjusted, the embossing tool needs to be newly designed. Thus, production step i) is preferred in case the convex curvature is subject of adjustments.

The further production steps are generally the same as for the production process of the isolated monolithic plan-convex refractive micro lens. Thus, with respect to the remaining features, all preferred embodiments as set out with respect to the production of the isolated monolithic plan-convex refractive micro optical component can also be applied for production of the isolated monolithic plan-convex refractive micro lens.

All features and embodiments disclosed with respect to the first aspect of the pre- sent invention are combinable alone or in (sub-)combination with the second aspect of the present invention including each of the preferred embodiments thereof, provided the resulting combination of features is reasonable to a person skilled in the art.

According to the second aspect of the present invention an isolated monolithic micro optical component comprising one or two convex curvatures is provided, which is ob- tainable by an inventive production process.

According to a preferred embodiment, the inventive isolated monolithic micro optical component is selected from a diffractive-refractive micro-optical component, synony- mously also called hybrid micro components. The inventive diffractive-refractive micro- optical components may correct aberrations present in pure chromatic and spherical biconvex refractive lenses. Furthermore, the inventive diffractive-refractive monolithic micro-optical components can enable higher compactness / integration in comparison to the use of a separate diffractive optical element, such as a beam splitter, and a sep- arate refractive lens. According to the present invention, the diameter of the inventive hybrid micro lens can generally range from 10 pm to 10 mm, or 50 pm to 7 mm, or 1 mm to 4 mm, or any other intermediate range. The total thickness, i.e. the thickness of the inventive hybrid micro lens at its widest dimension, can generally range from 1 pm to 5 mm, or 10 pm to 2 mm, or 100 pm to 600 pm, or any other or any other intermediate range. The radius of the convex curvature of the inventive hybrid micro lens can be selected from the range of 10 pm to 8 mm, or 50 pm to 6 mm, or 600 pm to 3 mm or 750 mhh to 2 mm. Furthermore, the diffractive pattern of the inventive hybrid micro lens may generally exhibit a laminar grating, such as 100 nm to 1 pm line and space, 100 nm to 2 pm depth.

According to an alternatively preferred embodiment, the inventive isolated mono- lithic micro optical component is selected from a plan-convex refractive micro lens (see Fig. 7). Generally, the diameter of the inventive plan-convex refractive micro lens can generally range from 10 pm to 10 mm, or 50 pm to 7 mm, or 1 mm to 4 mm, or any other intermediate range. The total thickness, i.e. the thickness of the inventive plan-convex refractive micro lens at its widest dimension, can generally range from 1 pm to 5 mm, or 10 pm to 2 mm, or 100 pm to 600 pm, or any other or any other intermediate range. The radius of the convex curvature of the inventive plan-convex refractive micro lens can be selected from the range of 10 pm to 8 mm, or 50 pm to 6 mm, or 600 pm to 3 mm or 750 pm to 2 mm. The plan-convex refractive micro lens shown in Fig. 7 has a diameter of 1 mm and a total thickness of approximately 250 pm, and a radius of curva- ture of 750 pm.

According to a further alternatively preferred embodiment, the inventive isolated monolithic micro optical component is selected from a biconvex refractive micro lens, more preferably wherein the biconvex refractive micro lens comprises two different con- vex curvatures (see Figures 6a) to 6d)). Generally, the diameter of the inventive bicon- vex refractive micro lens can generally range from 10 pm to 10 mm, or 50 pm to 7 mm, or 1 mm to 4 mm, or any other intermediate range. The total thickness, i.e. the thickness of the inventive biconvex refractive micro lens at its widest dimension, can generally range from 1 pm to 5 mm, or 10 pm to 2 mm, or 100 pm to 600 pm, or any other or any other intermediate range. The radius of the convex curvatures of the inventive biconvex refractive micro lens can be selected from the range of 10 pm to 8 mm, or 50 pm to 6 mm, or 600 pm to 3 mm or 750 pm to 2 mm. The biconvex refractive micro lens shown in Fig. 6a has a diameter of 1 mm and a total thickness of approximately 450 pm, and a radius of curvature of 750 pm for the left refractive lens and a radius of curvature of 600 pm for the right refractive lens. Although the description of the present invention encompasses inventive embodi- ments of isolated monolithic diffractive-refractive micro optical components, isolated monolithic plan-convex refractive micro lenses and isolated monolithic biconvex micro lenses, it is also apparent that the invention can be separated in each of the alternative inventive embodiments. In this case the general description may relate to each of the alternative inventive embodiments independently. In other words, it is also disclosed that the claims may be directed solely to the production of isolated monolithic diffractive- refractive micro optical components or isolated monolithic plan-convex refractive micro lenses or isolated monolithic biconvex micro lenses or any sub-combination.

The present invention is described in the following on the basis of exemplary em- bodiments, which merely serve as examples and which shall not limit the scope of the present protective right.

EXAMPLES

Further characteristics and advantages of the present invention will ensue from the following description of example embodiments of the inventive aspects with reference to the accompanying drawings.

All of the features disclosed hereinafter with respect to the example embodiments and / or the accompanying figures can alone or in any sub-combination be combined with features of the two aspects of the present invention including features of preferred embodiments thereof, provided the resulting feature combination is reasonable to a per- son skilled in the art.

Example 1: Preparation of inventive isolated monolithic diffractive-refractive micro optical components

Fig. 1 shows a general overview on the inventive production process for an isolated monolithic diffractive-refractive micro optical component. At first, the carrier substrate is nano-structured by nanoimprint lithography (step 1 ) and micro-structured with SU-8 or an appropriate dry film alternative by UV-lithography as a confining layer (step 2). The micro-structured confining layer formed in step 2 may be at least partly coated with a release agent in order to improve demolding in the subsequent replication step 3. The release agent may be applied by any suitable technique, such as vapor phase deposi- tion. A laminar grating with 500 nm half pitch and groove depth as diffractive nano- pattern is used, while the overlying micro-pattern defined by UV-lithography has a cup shape with 1 mm in diameter. This micro-structured pre-patterned mold (synonym: master wafer) is then repli- cated twice: firstly with mold material “A” (step 3), secondly with mold material “B” to form the mold master (step 4). The mold master does not comprise the negative struc- ture of the convex curvature of the diffractive-refractive micro optical component. The applicable mold and substrate materials and their combinations are listed in Table 1.

Table 1 : Mold and substrate materials used for replication and the resulting template properties

This fabricated mold master is an exact copy of the master with several cavities in which the commercially available inks InkOrmo (inkjetable composition comprising inor- ganic-organic hybrid polymer comprising one or more (meth) acrylate based organic units connected to an inorganic Si-O-Si-network, micro resist technology GmbH, Ger- many) or InkEpo (inkjetable composition comprising epoxy resins, preferably based on phenol and having a pure organic network, micro resist technology GmbH, Germany) are dispensed via inkjet printing with a frequency of 100 Hz (step 5). The solvent is evaporated after each inkjet printing application on a hotplate at 90-100 °Cfor 60’. Since the polymer inks contain a considerable percentage of solvent, several inkjet printing and evaporation cycles are repeated until the desired shape of the final lens is reached. Finally, the components are UV-cured and separated from the mold (step 6). Appling a hard bake step at 150°C (InkOrmo) or 140°C (InkEpo) improves the mechanical stability of the optical components.

Since the first replication step from the initial master wafer is challenging due to high release forces and wetting issues, the first replication step of process variants #1 to #3 are made with the soft UV-curable material polydimethylsiloxane (UV-PDMS KER-4690, Shin-Etsu Japan). With this generated soft stamp, the final mold for inkjet printing can be fabricated in different materials on different substrates. The proof of concept was shown in OrmoComp® and OrmoStamp® (compositions respectively comprising inor- ganic-organic hybrid polymers comprising one or more (meth) acrylate based organic units connected to an inorganic Si-O-Si-network, micro resist technology GmbH, Ger- many) on rigid silicon wafers as a carrier. To enhance the detachment capabilities, we further use bendable polycarbonate (PC) foils as a carrier substrate and the more flexi- ble and low shrinkage polymer OrmoClear®FX (composition comprising inorganic-or- ganic hybrid polymer comprising one or more (meth) acrylate based organic units con- nected to an inorganic Si-O-Si-network, micro resist technology GmbH, Germany) as mold material. Besides UV-molding applied in variant #1 and #2, our third variant is to make a thermal imprint (CNI Tool from NIL Technology ApS, Denmark) into the thermo- plastic cyclic olefin-copolymer TOPAS® 8007 (COC, Tg=78 °C, TOPAS Advanced Pol- ymers GmbH, Germany) bulk material without a carrier substrate. In process variant #4 the master wafer is replicated by electroplating of nickel with a thickness of 500pm. Although the master wafer is sacrificed by this variant, the so generated nickel stamp is very durable and able to be replicated with UV-PDMS.

The photographs depicted in Fig. 2a) to 2c) are showing the entire samples of the initial master substrate (Figure 2a) and of the first (Figure 2b, UV-PDMS) and the second generation copy (Figure 2c), OrmoClear®FX on PC-foil). In Fig. 2a) the replicated area with nanoimprinted diffractive structure and microscopic confining layer is framed. Each replica substrate contains approx. 20 pedestals (first replication step) or cavities (second replication step) with 1000 pm in diameter which are filled via inkjet printing with InkOrmo 18 mPas or InkEpo 25 mPas subsequently. The replication fidelity of the master wafer replicas is high, sidewalls of the cavities are measured to be vertical (>88°) and the diffractive nano-structure is replicated till the edge of the confining structure in both replication steps. Since only hard molds are rep- licated with soft stamp materials and vice versa, the demolding procedure is easy to apply. Prior to demolding, the optical components are UV-cured and thermally treated. ADDITIVE MANUFACTURING OF OPTICAL COMPONENTS

With the process variants described above, we fabricated prototypes of inventive isolated micro optical components, in particular diffractive-refractive micro optical com- ponents (synonym: hybrid micro-components), which include an edge for handling and clamping (Fig. 3). The specific property of each variant enables to easily adapt the man- ufacturing to the available equipment, component and material needs. The replication fidelity of the diffractive nano-pattern is guaranteed by the accuracy of the mold and the defined shrinking of the used polymer for the optical application. The resulting focal length of the inkjet printed micro-lenses is well controlled by the number of printed drops. Lens footprint is confined by the diameter or shape of the cavity. The shape of the self- organized refractive lens was verified by interferometry and was measured to have a mean deviation from a subtracted spherical fit of 4.1 nm rms for InkOrmo and of 5.2 nm rms for InkEpo (field of view 105 pm x140 pm).

OPTICAL CHARACTERIZATION

For optical characterization, the inventive hybrid micro optical components (diffrac- tive optical element combined with the refractive micro-lens) were illuminated with a collimated, expanded laser beam of 543 nm wavelength A microscope objective, placed in the focal plane of the micro-lens, was used to generate an enlarged image on the screen, making the footprint of the lens and the focused orders of diffraction (-1st, 0th and +1st order) visible (Fig. 4).

CONCLUSION

The example embodiments of Example 1 described hereinbefore relating to the in- ventive isolated monolithic diffractive-refractive micro optical component demonstrate the technological gain accomplished by combining UV-molding and nano-pattern-repli- cation with inkjet printing as additive manufacturing technique. In particular, it is shown that a cost-effective prototyping of diffractive-refractive micro-components with the pol- ymer inks of organic-inorganic hybrid polymers, such as InkOrmo and epoxy based ma- terial, such as InkEpo, on flexible substrates and in soft molds is possible. This enables a non-destructive detachment of the fabricated inventive hybrid micro optical compo- nents. The performed qualitative and quantitative characterizations prove their function- ality. Example 2: Preparation of inventive isolated monolithic biconvex refractive micro lenses

Fig. 5 shows a general overview on the inventive production process for an isolated monolithic biconvex refractive micro optical component. At first, the carrier substrate is micro-structured with SU-8 or an appropriate dry film alternative by UV-lithography as a confining layer (step 1). The micro-structured confining layer formed in step 1 may be at least partly coated with a release agent or treated with oxygen plasma in order to just the surface energy of the carrier substrate including micro-structure. This influences the wetting properties in the subsequent application of a convex curvature (step 2) by inkjet printing of InkEpo (inkjetable composition comprising epoxy resins, preferably based on phenol and having a pure organic network, micro resist technology GmbH, Germany). This micro-structured pre-patterned mold (synonym: master wafer) is then replicated with UV-PDMS (step 3). The mold master comprises one negative curvature of the two convex curvatures of the biconvex refractive micro optical component. This fabricated mold master is an exact copy of the master with several cavities in which the commercially available inks InkOrmo (inkjetable composition comprising inor- ganic-organic hybrid polymer comprising one or more (meth) acrylate based organic units connected to an inorganic Si-O-Si-network, micro resist technology GmbH, Ger- many) or newly developed additive manufacturing optimized prototype inks based on hybrid polymers or epoxies are dispensed via inkjet printing with a frequency of 100 Hz (step 4). The solvent is evaporated 60’ after each inkjet printing application on a hotplate at 90-100 °C. Since the polymer inks contain a considerable percentage of solvent, sev- eral inkjet printing and evaporation cycles are repeated until the desired shape of the final lens is reached. Finally, the components are UV-cured and separated from the mold (step 5). Appling a hard bake step at 150°C improves the mechanical stability of the optical components.

With the process described above, prototypes of inventive isolated micro optical components, in particular biconvex refractive micro lenses were fabricated, which in- clude an edge for handling and clamping having a height of e.g. 150 pm and with circular form and 1 mm in diameter (Fig. 6a), with circular form and 4 mm diameter (Fig. 6b), with circular ring form and 4 mm diameter (Fig. 6c) and with hexagonal form with 1 mm length of two parallel sides (Fig. 6d). Example 3: Preparation of inventive isolated monolithic plan-convex refrac- tive micro lenses

The inventive production process for an isolated monolithic plan-convex refractive micro lens is included in steps 1 , and 3 to 5 of the general process overview depicted in Fig. 5. In other words, step 2 is not conducted, when preparing a plan-convex refractive micro lens. Accordingly, the same process steps as set out in Example 2 are carried out for producing the inventive plan-convex micro lenses.

With this process, prototypes of inventive isolated micro optical components, in par- ticular plan-convex refractive micro lenses were fabricated, which include an edge for handling and clamping having a height of e.g. 150 pm and with circular form and 1 mm in diameter (Fig. 7) and a radius of curvature of 750 pm.

Claims

Claims:

1 ) Production process of an isolated monolithic micro optical component comprising one or two convex curvatures, characterized in that the process comprises or consists of a) forming or providing a mold master with an opening, wherein the mold master rep- resents the negative structure of the isolated micro optical component, with the proviso that the mold master does not represent a negative structure of the or one of the convex curvatures of the isolated monolithic micro optical component, b) adding a suitable amount of an optical material through the opening to the mold master using an additive manufacturing technique so that the monolithic micro op- tical component comprising the one or two convex curvatures is formed, whereby the convex curvature, which is not comprised as negative structure in the mold master, is formed by self-organizing the optical material in the opening, wherein the radius of the convex curvature is dependent on the amount and the surface energy of the optical material and the mold master, c) optionally curing the monolithic micro optical component comprising the one or two convex curvatures formed in step b) and d) demolding the monolithic micro optical component comprising the one or two con- vex curvatures of step b) or c) to form the isolated monolithic micro optical compo- nent comprising the one or two convex curvatures. 2) Production process according to claim 1, wherein the additive manufacturing tech- nique in step b) is selected from the group consisting of i) melting of a suitable amount of solid optical material, such as applying a suitable amount of an optical material in solid phase, melting the optical and self-organization of the material to form the con- vex curvature in the opening; and ii) dispensing a suitable amount of liquid optical material optionally comprising one or more solvents and self-organization of the opti- cal to form the convex curvature in the opening, such as dispensing by inkjet-printing, pico-dispensing and super inkjet-printing.

3) Production process according to claim 2, wherein the solid optical polymer material is selected from the group consisting of thermoplastic polymers suitable for optical ap- plications, such as cycloolefin copolymers (COC) and cycloolefinpolymers (COP), and inorganic materials suitable for optical applications, such as solid glass or solid glass- like materials; and liquid optical material is selected from the group consisting of liquid glass or liquid glass-like inorganic materials suitable for optical applications and liquid optical polymer materials suitable for optical applications, such as organic-inorganic hybrid polymers, in particular organic-inorganic hybrid polymers comprising one or more (meth) acrylate based organic units connected to an inorganic Si-O-Si-network, and epoxy based resins, in particular based on phenol and having a pure organic network.

4) Production process according to claim 2 or 3, wherein the liquid optical material is repeatedly dispensed in one, two, three or more parts to the mold master in step b) and optionally in case the liquid optical polymer material comprises one or more vis- cosity adjusting additives, the added part of the liquid optical polymer material is pro- cessed prior to the subsequent addition step in such a way, that at least part of the one or more viscosity adjusting additives evaporate from the added liquid optical ma- terial.

5) Production process according to any one of claims 1 to 4, wherein the mold master is formed using a micro-structuring and/or nano-structuring technique to form a micro- and/or nano-structured and optionally pre-patterned mold structure and replicating the mold structure with replicating material one or more times to form the mold master. 6) Production process according to claim 5, wherein the micro-structuring and/or nano- structuring technique is / are selected from the group consisting of i) lithography, such as UV lithography, E-beam lithography, nanoimprint lithography, laser lithography; ii) ablative processing, such as chipping, preferably by milling, turning, or grinding; erod- ing, preferably by sinking or wire eroding; and iii) etching, preferably by dry etching or wet etching, and iv) 3D printing.

7) Production process according to claim 6, wherein i) the material suitable for forming the mold master by lithography is selected from the group consisting of positive photo resists, such as resin based resists, in particular novolak based resists; negative photo resists, such as resin based resists, in particular novolak based resists, or epoxy based resists, such as SU-8, or dry films of resin based resists, in particular acrylate based resists, or epoxy based resists, such as SU-8; polymeric material for imprint lithography, such as duroplast and thermoplastics; ii) the material suitable for ablative processing is preferably selected from the group consisting of metals, such as Ni, Al, Au, alloy steel and/or other alloys; and inorganic materials, such as glass; and/or plas- tics, such as polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), polypro- pylene (PP); iii) the material suitable for etching is preferably selected from the group consisting of semiconductors, such as silicon, and plastics, such as duroplast, acrylate and epoxy based polymers; and iv) the material suitable form 3D printing is preferably selected from the group consisting of thermoplastic material, such as poly(methyl methacrylate) (PMMA), polystyrene, poly lactic acid (PLA), acrylonitrile butadiene sty- rene (ABS), cycloolefine polymer; or composite material, such as conductive inks, photopolymers including metal oxides

8) Production process according to any one of claims 5 to 7, wherein the one or more replication steps are independently from each other selected from the group consist- ing of i) casting and UV curing, thermal curing or chemical hardening; ii) injection molding, iii) embossing and UV or thermal curing, iv) thermoforming or v) electroplat- ing.

9) Production process according to claim 8, wherein i) the material suitable for casting is selected from the group consisting of soft material, such as polydimethylsiloxane; or hard materials, such as cycloolefin copolymers (COC), cycloolefinpolymers (COP), organic-inorganic hybrid polymers, in particular inorganic-organic hybrid polymer com- prising one or more (meth) acrylate based organic units connected to an inorganic Si- O-Si-network, metals, such as Ni, or glass or glass-like materials; ii) the material suit- able for injection molding is selected from the group consisting of thermoplastic poly- mers, such as cycloolefin copolymers (COC), cycloolefinpolymers (COP), polypropyl- ene (PP), poly-ethylene terephthalate (PET); iii) the material suitable for embossing is selected the group consisting of polystyrene, polycarbonate (PC), and poly(methyl methacrylate) (PMMA); and iv) the material suitable for thermoforming is selected from the group consisting of thermoplastic foils, such as thermoplastic foils, such as poly- ethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), and high impact polystyrene; v) the material suitable for electroplating is selected from the group con- sisting of metals such as Ni. 10) Production process according to any one of claims 1 to 9, wherein in step a) an array comprising two or more individual mold masters is provided, and optionally in step b) the additive manufacturing technique is for each micro optical component to be formed independently adjustable in relation to selecting a predetermined optical material and/or adding a predetermined amount of the selected optical material.

11 )Production process according to any one of claims 1 to 10, wherein the isolated mon- olithic micro optical component is an isolated monolithic diffractive-refractive micro optical component and the production process thereof comprises or consists of the following process steps: forming the mold master with the opening according to step a) by i) providing a carrier and adding a structuring material, which is nano- or micro-struc- tured using a nano- or micro-structuring method to form a pre-patterned mold com- prising a negative form of the diffractive structure of the isolated diffractive-refractive micro optical component, ii) optionally adding a confining resist layer, which is structured using a micro-structuring technique to form a micro-structured pre-patterned mold, iii) replicating the pre-patterned mold of step i) or the micro-structured pre-patterned mold of step ii) with a first replication material to form a mold comprising a positive form of the diffractive structure of the isolated diffractive-refractive micro optical com- ponent and demolding the mold, iv) replicating the mold formed in step iii) with a second replication material to form a mold master comprising a negative form of the diffractive structure of the isolated diffractive-refractive micro optical component and demolding the mold master, adding the suitable amount of the optical material through the opening to the mold master to form the monolithic diffractive-refractive micro optical component according to step b), optionally curing the monolithic diffractive-refractive micro optical component according to step c) and demolding the monolithic diffractive-refractive micro optical component formed according to step b) or cured according to step c) to form the isolated monolithic diffractive-refractive micro optical component.

12)Production process according to any one of claims 1 to 10, wherein the isolated mon- olithic micro optical component is an isolated monolithic plan-convex refractive micro lens and the production process thereof comprises or consists of the following process steps: forming the mold master with the opening according to step a) by i) providing a carrier and adding a confining resist layer, which is structured using a micro-structuring technique to form a micro-structured mold comprising a positive form of the plane surface of the isolated plan-convex refractive micro lens, ii) replicating the micro-structured mold of step i) with a replication material to form a mold master comprising a negative form of the plane surface of the isolated plan- convex refractive micro lens and demolding the mold master, adding the suitable amount of the optical material through the opening to the mold master to form the monolithic plan-convex refractive micro lens according to step b), optionally curing the monolithic plan-convex refractive micro lens according to step c) and demolding the monolithic plan-convex refractive micro lens formed according to step b) or cured according to step c) to form the isolated monolithic plan-convex refractive micro lens.

13)Production process according to any one of claims 1 to 10, wherein the isolated mon- olithic micro optical component is an isolated monolithic biconvex refractive micro lens and the production process thereof comprises or consists of the following process steps: forming the mold master with the opening according to step a) by i) providing a carrier and adding a confining resist layer, which is structured using a mi- cro-structuring technique to form a micro-structured mold and subsequently adding a suitable amount of a material onto an upper surface of the micro-structured mold using an additive manufacturing technique thereby forming a micro-structured mold compris- ing a convex curvature on top of the micro-structured mold or ii) providing a carrier and adding a polymeric material, which is embossed to form an embossed mold comprising a convex curvature on top of the embossed mold, iii) replicating the mold of step i) or ii) with a replication material to form a mold master comprising a negative form of the convex curvature of the mold of steps i) and ii) and demolding the mold master, adding the suitable amount of the optical material through the opening to the mold master to form the second convex curvature of the monolithic biconvex refractive micro lens ac- cording to step b), optionally curing the monolithic biconvex refractive micro lens according to step c) and demolding the monolithic biconvex refractive micro lens formed according to step b) or cured according to step c) to form the isolated monolithic biconvex refractive micro lens. 14)lsolated monolithic micro optical component comprising one or two convex curvatures obtainable by a production process according to any one of claims 1 to 13.

15) Isolated monolithic micro optical component according to claim 14, wherein the mon- olithic micro optical component is selected from a diffractive-refractive micro-optical component, a plan-convex refractive micro lens, a biconvex refractive micro lens, pref- erably wherein the biconvex refractive micro lens comprises two different convex cur- vatures.