DEVICE AND METHOD FOR CREATING THREE-DIMENSIONAL STRUCTURES

Abstract

The present invention relates to a device as well as a method for creating three-dimensional structures consisting of a material to be consolidated, in particular a material containing organopolysiloxane, by way of locally selective consolidation of the latter as a result of light-induced organic cross-linking. The device is characterized by a movable focusing optical system for the formation of one or a plurality of laser foci, wherein either the laser beam of a laser source can be introduced into the material to be consolidated through the material container and a movable carrier unit is arranged in said container or the focusing optical system is immersed into the material bath and the laser beams can be introduced into the material to be consolidated via a beam exit area of the focusing optical system. In the method, a focusing optical system that is movable in at least one plane is used for the formation of at least one laser focus, and a movable carrier unit is positioned in the material to be consolidated in one embodiment.

Claims

1. A device for creating three-dimensional structures consisting of a material to be consolidated, in particular a material containing organopolysiloxane, by way of locally selective consolidation of the latter as a result of light-induced organic cross-linkage, comprising a laser source, a movable focusing lens to form one or a plurality of laser foci and a material container for the material to be consolidated, wherein the laser source and the focusing lens are formed to create laser pulses or laser pulse sequences which trigger a two- or multiphoton polymerization of the material to be consolidated in their focal point, and wherein the focusing lens comprises a numerical aperture of greater than 0.25 and is set up such that the distance between the focus range and the bath bottom is at least 0.1 mm, wherein the material container consists at least partially of a material that is permeable for the used laser beam and is or can be arranged in the beam path in such a way that the laser beam can be introduced into the material to be consolidated through the material container, wherein the material container acts as optically defined interface and wherein a carrier unit is arranged in the material container which can be positioned opposite to the latter.

2. A device for creating three-dimensional structures consisting of a material to be consolidated, in particular a material containing organopolysiloxane, by way of locally selective consolidation of the latter as a result of light-induced organic cross-linkage, comprising a laser source, a movable focusing lens to form one or a plurality of laser foci, wherein the laser source and the focusing lens are formed for creating laser pulses or laser pulse sequences, which trigger a two- or multiphoton polymerization of the material to be consolidated in their focal point, and wherein the focusing lens comprises a numerical aperture of greater than 0.25, wherein the focusing lens is impermeable to the material to be consolidated and configured to be arranged immersible in the material to be consolidated such that a beam exit area of the focusing lens itself is configured to form an optically defined interface with the material to be consolidated.

3. A device according to claim 1, characterized by further comprising a container for the material to be consolidated.

4. A device according to claim 1, characterized in that the focusing lens is movable at least in the horizontal (X-Y) plane.

5. A device according to claim 1, characterized in that the focusing lens (3) has a numerical aperture of greater than 0.5.

6. A device according to claim 1, characterized in that the working distance between the object lens of the focusing lens (3) and the associated laser focus is between 0.1 and 100 mm.

7. A device according to claim 1, characterized in that it comprises a lens for the three-dimensional splitting of the laser beam and for the creation of at least two laser foci or intensity maximums arranged at a three-dimensional distance from each other.

8. A device according to claim 1, additionally comprising an optical detection system.

9. A device according to claim 8, characterized in that the detection system comprises a light source as well as an electronic registration system.

10. A device according to claim 9, characterized in that the detection system at least partially detects the topography of the carrier unit and is connected with a control system used to register surface points potentially deviating from the target value in such a way that they are activated in an optically correct manner.

11. A device according to claim 1, additionally comprising a dispenser system for the in situ deposition of the material to be consolidated.

12. A method for creating three-dimensional structures consisting of a material to be consolidated, in particular material containing organopolysiloxane, by way of locally selective consolidation of the latter as a result of light-induced organic cross-linking based on laser radiation, wherein the material to be consolidated is or will be arranged in a material container, the material container is permeable for the used laser at least in some areas, a laser pulse or a laser pulse sequence is positioned through the material container into the material to be consolidated onto at least one laser focus by means of a movable focusing lens having a numerical aperture of greater than 0.25 in such a way that the material container forms an optically defined interface via which the laser is introduced into the material to be consolidated, wherein the laser pulse or the laser pulse sequence triggers a two- or multiphoton polymerization of the material to be consolidated in its focal point such that consolidation conditions are only achieved in the immediate vicinity of at least one laser focus due to the intensity present there, such that one volume element of the material to be consolidated is consolidated per focus for the duration of the laser pulse or the laser pulse sequence, characterized in that a carrier unit is positioned in the material to be consolidated relative to at least one laser focus, that the material to be consolidated accumulates on the carrier unit or on consolidated material that has already accumulated on the carrier unit during the consolidation, wherein the carrier unit is positionable relative to the material container, wherein the focusing lens is set up such that the distance between the focus range and the bath bottom is at least 0.1 mm.

13. A method for creating three-dimensional structures consisting of a material to be consolidated, in particular material containing organopolysiloxane, by way of locally selective consolidation of the latter as a result of light-induced organic cross-linking based on laser radiation, wherein a laser pulse or a laser pulse sequence is positioned into at least one laser focus in the material to be consolidated via a movable focusing lens having a numerical aperture of greater than 0.25, wherein the laser pulse or the laser pulse sequence triggers a two- or multiphoton polymerization of the material to be consolidated in its focal point such that consolidation conditions are only achieved in the immediate vicinity of at least one laser focus due to the intensity present there, such that one volume element of the material to be consolidated is consolidated per focus for the duration of the laser pulse or the laser pulse sequence, characterized in that the focusing lens is or will be immersed into the material to be consolidated, such that an exit area of the focusing lens forms an optically defined interface with the material to be consolidated via which the laser pulse or the laser pulse sequence is introduced into the material to be consolidated.

14. A method according to claim 13, wherein the material to be consolidated is or will be arranged in a material container.

15. A method according to claim 12, characterized in that the focusing lens can be moved at least in the horizontal (X-Y) plane and in the case of the immersed focusing lens, in all three directions of space (X, Y, Z).

16. A method according to claim 12, characterized in that a laser beam is split into at least two sub-beams and/or that at least two laser foci or intensity maximums arranged three-dimensionally apart from each other are created.

17. A method according to claim 12, characterized in that the material to be consolidated is added to the material container in situ via a dispenser system.

18. A method according to claim 13, characterized in that the carrier unit is a carrier path, unreeled from a roll, pulled in one direction (X-direction) through the material to be consolidated and wound up again after the removal of subsequently created three-dimensional structure(s), wherein the pulling motion occurs discontinuously or continuously.

Description

[0063] Other characteristics and advantages of the invention can be derived from the following exemplary description of particularly preferred embodiments based on the figures. In the figures:

[0064] FIG. 1 shows a schematic illustration of a device according to the prior art,

[0065] FIGS. 2 to 4 show schematic illustrations of first embodiments of devices according to the invention with exposure of the material containing organopolysiloxane through a material container,

[0066] FIGS. 5 to 7 show schematic illustrations of second embodiments of devices according to the invention with exposure of the material containing organopolysiloxane through a focusing optical system immersed in the material,

[0067] FIGS. 8 and 9 show schematic illustrations of third embodiments with the use of elements for three-dimensional beam shaping and

[0068] FIGS. 10 and 11 show schematic illustrations of fourth embodiments having a positioning system with a rotational axis.

[0069] FIG. 12 shows a motion unit for the focusing optical system.

[0070] FIG. 13 shows an illustration of the optical detection of an anchor point.

[0071] FIG. 14a and b show two three-dimensional structures produced according to the invention with very different sizes, of which the latter can be used as “scaffold” (the distance from one of the large square openings to the other is approximately 300 μm).

[0072] FIG. 1 contains a schematic illustration of a device used to explain part of the invention. The device according to this figure comprises a laser source 1, a deflection mirror 2 as component of a beam guide as well as a focusing optical system 3. The unfocused laser beam 4 exiting the laser source 1 is guided to the focusing optical system 3 through the deflection mirror 2. There, it is focused into a focus 5.

[0073] Material to be consolidated 6 is arranged below the focusing optical system 3, between a lower carrier 7 and an upper carrier 8. As implied schematically in FIG. 1, the material retainer consisting of lower carrier 7 and upper carrier 8, together with the material to be consolidated 6 placed in between, can be positioned in X- and Y-direction relative to the focus 5 and the focusing optical system 3, while the focusing optical system 3 can be positioned in Z-direction relative to the material 6.

[0074] FIG. 1 shows an arrangement of the focusing optical system 3 relative to the material to be consolidated 6 at the start of a consolidation cycle. The focus 5 borders directly on the lower carrier 7 such that material consolidated in the focus area accumulates on the carrier 7. This initial positioning is required in order to consolidate material within the scope of the further consolidation in a fixed position or else no defined structures can be built up. In order that said initial positioning of the focus can be approached, the distance between the respective top side of the lower carrier 7 and upper carrier 8 has to be smaller than the working distance 9 of the focusing optical system 3. Otherwise, it is impossible to position the focus 5 on the lower carrier 7 and to accumulate consolidated material there. In the event of an initial accumulation at the underside of the upper carrier 8, the distance between the lower carrier 7 and upper carrier 8 could indeed be greater than the working distance 9 of the focusing optical system 3. However, in this case, the consolidation would only be possible with a limited distance to the upper carrier 8, corresponding to the working distance 9 less the thickness of the upper carrier 8. As a result, the geometry and size of producible structures are restricted in an undesirable manner.

[0075] FIG. 2 shows a first embodiment of the invention in which the exposure of the material to be consolidated is achieved through a material container 10. In the illustrated case, the exposure is conducted through the bottom 11 of the material container 10 from below, by directing an unfocused laser beam 4 created in the laser source 1 via a deflection mirror 2 to a focusing optical system 3 arranged underneath the material container 10. The deflection mirror 2 can be designed positionable. The beam is focused by the focusing optical system in the material to be consolidated 6 in the material container 10. Similar to the device according to FIG. 1, the maximum depth at which the focus can be immersed into the material to be consolidated 6 is limited by the working distance 9 of the focusing optical system 3. In order to prevent the resulting size restriction of the producible structures, the device illustrated in FIG. 2 comprises a carrier unit 12 that can be positioned opposite the material container 10. The carrier unit 12 is immersed in the material to be consolidated 6 in the material container 10. In the illustrated example, the carrier unit 12 is positionable in Z-direction, while the focusing optical system is positionable in X- and Y-direction.

[0076] FIG. 2 again contains an exemplary illustration of the start of the creation of a structure. In the process, the carrier unit 12 is positioned relative to the material container 10 and focus 5 in such a way that the focus is adjacent to the lower surface area of the carrier unit 12. Material that has consolidated in the vicinity of the focus 5 is deposited at the underside of the carrier unit 12 and adheres to it. Matching the dimensions of already consolidated volume elements, the carrier unit 12 can be positioned in Z-direction in such a way that the focus comes to rest at an interface of already consolidated material and subsequently consolidated material is deposited on already consolidated material and adheres to it. The position of the consolidation in X- or Y-direction is determined with the positioning of the focusing optical system 3 in X- as well as Y-direction and with the corresponding introduction of laser pulses. The carrier unit positionable in Z-direction and the corresponding travel guide makes it possible to consolidate structures whose dimensions are independent and in particular larger than the working distance 9 of the used focusing optical system 3.

[0077] FIG. 5 shows a further schematic illustration of a different embodiment of the invention. The device again comprises a laser source 1, wherein an unfocused laser beam 4 emitted by it is aimed at a focusing optical system 3 via a deflection mirror 2. Moreover, it comprises a material container 10 containing material to be consolidated 6 as well as a carrier unit 12. In the illustrated example, the latter is not mobile, but it can be positionable in one or a plurality of directions. The laser beam is introduced into the material to be consolidated 6 via the focusing optical system 3 immersed in the material to be consolidated 6.

[0078] In the illustrated example, the focusing optical system 3 comprises a case 14 with a beam output area 13 and is positionable in the three directions of space X, Y and Z. With the immersion of the focusing optical system 3, the beam output area 13 forms a defined interface with the material to be consolidated 6, thus enabling a defined and accurate introduction of the laser beam into the material to be consolidated 6.

[0079] FIG. 5 again shows the device at the start of the structuring process, in which the focusing optical system 3 is arranged relative to the carrier unit 12 at the working distance 9 such that the focus 5 borders on the surface of the carrier unit 12. The consolidation and accumulation in X- and Y-direction is determined with the corresponding positioning in X- as well as Y-direction. After the initial consolidation on the carrier unit 12, the structuring can be performed with the corresponding positioning of the focusing optical system 3 in Z-direction, matching the strength of the already consolidated material adhering to the carrier unit 12. With this embodiment, the height of the producible structures is not restricted either by the working distance 9 of the focusing optical system 3.

[0080] Preferably, the present invention is using a focusing optical system 3 with high NA for all possible embodiments, at least with an NA of greater than 0.25 in order to achieve the desired high resolution or small voxels. The working distances 9 of the objective lenses preferably range between 0.1 and 100 mm, more preferably between 1 and 10 mm. We would like to point out that the focus range 5 of the focusing optical system obviously has to be inside the bath 10. Therefore, the thickness of the transparent bath bottom which has to be penetrated also needs to be considered in the selection of the proper working distance. It is favorable if the thickness of the bath bottom is selected in the range of 0.1 and 20 mm, preferably in the range of 0.5 and 5 mm. Values of 0.1 to 2 mm are best for the distance between the focus range 5 and the bath bottom. With lower values, there is a risk that the material consolidates directly on the bottom and adheres there. As a consequence, the removal of the carrier unit 12 would be impaired. Values above the favorable range may result in increasing imaging errors (mainly spherical aberrations). Since the focusing optical system is moved at least in one plane according to the invention (usually the horizontal, i.e., the X-Y plane), the size of the selected NA is not necessarily relevant, especially with a minimum value of 0.25.

[0081] A high-NA object lens with NA=1.4 and a working distance of 200 μm is used in one example of the invention, which is designed in such a way that an ideal focus is formed if a 170 μm thick container bottom is used, immersion oil is applied between the exit pupil and the container bottom and the distance of the object lens is selected such that the focus is directly above the inner side of the container bottom, namely such that the created voxel cannot adhere to the container bottom.

[0082] According to the invention, the laser beam is preferably coupled into the focusing optical system by way of a system of mirrors as illustrated in FIG. 12.

[0083] FIG. 8 shows an embodiment of the invention, the design of which essentially corresponds to the embodiment according to FIG. 5. As an additional element, a beam shaping element 15, for example in the form of a phase or amplitude mask, is arranged in the beam path between the deflection mirror 2 and the focusing optical system 3. With the use of the beam shaping element 15, the laser beam is focused into a plurality of foci 5a, 5b and 5c via focusing optical system 3 in such a way that material to be consolidated 6 can be consolidated at several positions simultaneously. In the process, the number of consolidation positions corresponds to the number n of created foci (parallelization). FIG. 9 shows a corresponding use of a beam shaping element 15 within the scope of a device according to the exemplary embodiment of FIG. 2. Reference is made to the description of FIG. 2 above.

[0084] Other devices with parallelization are illustrated in FIGS. 3, 4, 6 and 7. In them, the parallelization is achieved with the use of a semi-permeable deflection mirror 16, used to split the unfocused laser beam 4 exiting the laser source 1 into two sub-beams 17a, 17b, each of which are aimed at an independent focusing optical system 3.

[0085] The devices according to FIGS. 3 and 6 comprise two carrier units 12a and 12b immersed into the material to be consolidated 6, which can be positioned in Z-direction jointly or independently from each other. Structures with different geometries can be created simultaneously with said devices, with the corresponding approach of the positioning axes. FIGS. 4 and 7 show devices in which it is possible to record at several positions on a carrier unit 12 simultaneously by means of parallelization, said carrier unit being immersed in the material to be consolidated.

[0086] Another embodiment of the invention is illustrated in FIGS. 10 and 11. In it, a rotary table 18 that allows a rotational positioning e.g. around a rotational axis 19 additionally or alternatively to a linear positioning is used instead of only a single linearly positionable carrier unit 12. The rotary table 18 illustrated in FIG. 10 serves the positioning of a foil-shaped carrier unit with material to be consolidated 6 relative to the focus 5.

[0087] In the device illustrated in FIG. 11, a carrier unit 12 which can be rotated around a rotational axis 19 and can be positioned linearly in Z-direction is immersed in a bath of material to be consolidated. The focusing optical system 3 can be positioned linearly in X- and Y-direction. The focus position is set such that material 6 is consolidated, deposited and virtually rolled up on the carrier unit 12.

REFERENCE LIST

[0088] 1 Laser source

[0089] 2 Deflection mirror

[0090] 3 Focusing optical system

[0091] 4 Unfocused laser beam

[0092] 5 Focus

[0093] 6 Material to be consolidated

[0094] 7 Lower carrier

[0095] 8 Upper carrier

[0096] 9 Working distance

[0097] 10 Material container

[0098] 11 Bottom

[0099] 12 Carrier unit

[0100] 13 Beam output

[0101] 14 Case

[0102] 15 Beam formation element

[0103] 16 Semi-permeable deflection mirror

[0104] 17a,b Sub-beams

[0105] 18 Rotary table

[0106] 19 Rotational axis