# US 11,993,017 B2 · Methods and apparatus for tomographic additive manufacturing with a spatially coherent light source

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- Number: US 11,993,017 B2
- Document ID: US11993017B2
- Status: Granted
- Kind: B2
- Application number: 17/291,115
- Filed: 2019-11-05
- Published: 2021-12-09
- Granted: 2024-05-28
- Earliest claimed: 2018-11-06
- Assignees: Ecole Polytechnique Federale De Lausanne (Epfl)
- Applicants: Ecole Polytechnique Federale de Lausanne (EPFL)
- Inventors: Paul Delrot; Damien Loterie; Christophe Moser
- Web page: https://patentgrep.com/patent/US11993017B2

## CPC

- B29C 64/106: using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
- B29C 64/268: using laser beams; using electron beams [EB]
- B29C 64/135: the energy source being concentrated, e.g. scanning lasers or focused light sources
- B29C 64/282: of the same type, e.g. using different energy levels
- B29C 64/286: Optical filters, e.g. masks
- B33Y 10/00: Processes of additive manufacturing
- B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING

## Abstract

A method of fabricating a three-dimensional article comprises providing a spatially coherent light source (101, 201), generating from the light source (101, 201), patterns of light based on computed tomographic projections of the three-dimensional article, and projecting the patterns of light into a photoresponsive medium. The projecting is configured to define a three-dimensional dose distribution, thereby locally altering the phase of the photoresponsive medium and creating the article.

## Claims

### Claim 1

A method of fabricating a three-dimensional article with volumetric additive manufacturing by computed projections, sad method comprising:
providing a spatially coherent light source, wherein a beam-parameter product of the light source is less than 400 μm*rad or its etendue is lower than 0.16 mm2,
generating from said light source, patterns of light based on computed projections of said three-dimensional article, and
projecting said patterns of light into a photoresponsive medium, whereby the projecting is configured to define a three-dimensional dose distribution, thereby locally altering the phase of the photoresponsive medium and creating the article.

### Claim 2 (depends on 1)

The method according to claim 1, wherein a beam emitted from said light source has an intensity that varies less than 50% over an area of the beam.

### Claim 3 (depends on 1)

The method according to claim 1, wherein said patterns of light are generated by projecting a beam of light from said spatially coherent light source onto a light modulator.

### Claim 4 (depends on 1)

The method according to claim 1, wherein said photoresponsive medium is provided in an optically transparent vessel which defines a build region.

### Claim 5 (depends on 3)

The method according to claim 3, wherein projecting said patterns of light is carried out such that a print resolution in a center of a build volume in the range from 100 to 500 μm is obtained.

### Claim 6 (depends on 5)

The method according to claim 5, wherein the photoresponsive medium having a refractive index in the range from 1.20 to 1.60 is used and the beam-parameter product of the light source is less than 200 μm*rad.

### Claim 7 (depends on 1)

The method according to claim 1, wherein said spatially coherent light source comprises one or multiple lasers coupled into an optical fiber.

### Claim 8 (depends on 7)

The method according to claim 7, wherein with said optical fiber a light modulator can be illuminated with a light beam that has less than 15% intensity variation over an aperture of the light modulator.