Optical method and apparatus for fabricating a structured object

• US 10,442,133 B2
• Filed: 08/17/2018
• Issued: 10/15/2019
• Est. Priority Date: 02/17/2016
• Status: Active Grant

• Current Assignee: Hochschule Fuer Angewandte Wissenschaften Aschaffenburg
• Original Assignee: Hochschule Fuer Angewandte Wissenschaften Aschaffenburg
• Inventors: Trautmann, Anika, Hellmann, Ralf
• Primary Examiner(s): Wathen, Brian W
• Assistant Examiner(s): McMenemy, Brian T
• Application Number:
  US16/104,603
• Publication Number:
  US 20190047224A1
• Time in Patent Office: 424 Days
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29C 64/273 pulsed; frequency modulated
• CPC Class Codes: B29C 64/277 using multiple radiation means, e.g. micromirrors or multiple light-emitting diodes [LED]
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: G02B 27/106 for splitting or combining a plurality of identical beams or images, e.g. image replication
• CPC Class Codes: G02B 27/40 Optical focusing aids
• CPC Class Codes: G02B 5/003 Light absorbing elements

Abstract

A method and an apparatus for fabricating a structured object wherein a photo-curing material, which is cured by being irradiated with light, within successive layers is irradiated with light providing energy, which is transformed by absorption to internal energy of the photo-curing material for curing, thereby forming the object. Within each individual layer of the successive layers coarse structures of the object and fine structures of the object are identified. A first light beam is directed, which provides a single photon energy that matches the energy gap of the photo-curing material for absorption, to first focus positions within the photo-curing material. The first focus positions being associated with the coarse structures of the object within a first individual layer of the successive layers, to cure the photo-curing material at the first focus positions thereby forming the coarse structures of the object within the first individual layer.

Claims

1. A method of fabricating a structured object wherein a photo-curing material, which is cured by being irradiated with light, within successive layers is irradiated with light providing energy, which is transformed by absorption to internal energy of the photo-curing material for curing, thereby forming the object, the method comprising:

identifying within each individual layer of the successive layers coarse structures of the object and fine structures of the object;

directing a first light beam, which provides a single photon energy that matches the energy gap of the photo-curing material for absorption, to first focus positions within the photo-curing material, the first focus positions being associated with the coarse structures of the object within a first individual layer of the successive layers, to cure the photo-curing material at the first focus positions thereby forming the coarse structures of the object within the first individual layer;

directing a second light beam, which provides a single photon energy less than the energy gap of the photo-curing material for absorption, to second focus positions within the photo-curing material, the second focus positions being associated with the fine structures of the object within the first individual layer to cure the photo-curing material at the second focus positions by multiple photon absorption, thereby forming the fine structures of the object within the first individual layer, and

repeating the steps of directing the first light beam to the first focus positions and the second light beam to the second focus positions within a next and at least one remaining individual layer of the successive layers.

2. The method according to claim 1, wherein at least one of the first light beam and the second light beam is split into a plurality of light beams directed to focus positions within the photo-curing material, thereby forming multiple structures of the object and/or multiple objects in parallel.

3. The method according to claim 1, wherein an intensity of the first light beam or the second light beam is controlled during fabrication of the object, and/or wherein the phase, the polarization or the intensity of the first light beam or the second light beam is spatially modulated during fabrication of the object.

4. The method according to claim 1, wherein the first light beam and the second light beam are focused via light focusing optics.

5. The method according to claim 1, wherein the first light beam is generated by the second light beam with a second harmonic generation process.

6. The method according to claim 1, wherein the first light beam is generated by a diode laser, the diode laser emitting ultraviolet light.

7. The method according to claim 1, wherein the second light beam is generated by a pulsed laser, the pulsed laser emitting infrared laser pulses.

8. The method according to claim 1, wherein the individual layers of the successive layers each have a thickness between 10 μ

m and 100 μ

m, and/or wherein the coarse structures comprise structural elements having a size between 10 μ

m and 100 μ

m, and/or wherein the fine structures comprise structural elements having a size between 100 nm and 500 nm.

9. An apparatus via which a photo-curing material, which is cured by being irradiated with light, within successive layers is irradiated with light providing energy, which is transformed by absorption to internal energy of the photo-curing material for curing, thereby forming the object, the apparatus comprising:

a light source section comprising a light generator that generates a first light beam, which provides a single photon energy that matches an energy gap of the photo-curing material for absorption, and that generates a second light beam, which provides a single photon energy less than the energy gap of the photo-curing material for absorption to cause a multi photon absorption phenomenon in the photo-curing material;

a container for containing the photo-curing material;

a first light director adapted to direct the first light beam to first focus positions within the photo-curing material;

a second light director adapted to direct the second light beam to second focus positions within the photo-curing material; and

a controller adapted;

to identify within each individual layer of the successive layers coarse structures of the object and fine structures of the object,

to control the first light director for directing the first light beam to first focus positions associated with the coarse structures of the object within a first individual layer of the successive layers to cure the photo-curing material at the first focus positions, thereby forming the coarse structures of the object within the first individual layer,

to control the second light director for directing the second light beam to second focus positions associated with the fine structures of the object within the first individual layer to cure the photo-curing material at the second focus positions by multiple photon absorption, thereby forming the fine structures of the object within the first individual layer, and

to repeat the steps of directing the first light beam to first focus positions and the second light beam to second focus positions within a next and at least one remaining individual layer of the successive layers.

10. The apparatus according to claim 9, wherein the first light director for directing the first light beam to first focus positions or the second light director for directing the second light beam to second focus positions comprises at least one beam splitting element to split the first and/or the second light beam into a plurality of light beams, and wherein the controller is further adapted to control the first light director for directing the first light beam and/or the second light director for directing the second light beam to form multiple structures of the object and/or multiple objects in parallel.

11. The apparatus according to claim 9, wherein the first light director for directing the first light beam to first focus positions or the second light director for directing the second light beam to second focus positions comprises at least one controllable intensity modulator, and wherein the controller is further adapted to control the intensity of the first light beam and/or of the second light beam during fabrication of the object via the at least one intensity modulator.

12. The apparatus according to claim 9, wherein the first light director for directing the first light beam to first focus positions or the second light director for directing the second light beam to second focus positions comprises a controllable spatial light modulator, and wherein the controller is further adapted to control the phase, the polarization or the intensity of the first light beam and/or of the second light beam via at least one spatial modulator.

13. The apparatus according to claim 9, wherein the first light director for directing the first light beam to first focus positions or the second light director for directing the second light beam to second focus positions comprise light focusing optics.

14. The apparatus according to claim 9, wherein the light source section comprises a diode laser adapted to generate the first light beam, particularly of ultraviolet light, or wherein the light source section comprises a pulsed laser adapted to generate pulses of the second light beam, particularly of infrared light.

15. The apparatus according to claim 9, wherein the light source section comprises a second harmonic generator adapted to generate the first light beam by the second light beam by a second harmonic generation process.