Layer thickness control for stereolithography utilizing variable liquid elevation and laser focal length
First Claim
1. A method of fabricating an object comprising at least one layer using stereolithography, comprising:
- providing a vertically stationary, horizontal surface disposed in a reservoir;
raising a volume of curable liquid above the surface to a first selected depth approximating a thickness of a first layer of the object, wherein raising the volume of curable liquid comprises moving at least a portion of the reservoir with respect to the vertically stationary horizontal surface; and
selectively curing portions of the first selected depth of curable liquid above the surface to at least a semisolid state to define at least portions of the first layer.
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Accused Products
Abstract
An apparatus and method for controlling the surface level of a liquid residing within a relatively vertically stationary workpiece support platform disposed within a reservoir for use in stereolithographic processes wherein a layered object or structure is formed by selectively curing portions of the liquid to at least a semisolid state in multiple, at least partially superimposed layers. Providing precise control of liquid depth over the vertically stationary platform as well as focusing of a laser beam for curing the liquid at the varying surface levels thereof relative to the vertically stationary platform is effected using a laser range finder system controlled by a computer used to control the stereolithographic process in a closed loop fashion.
104 Citations
24 Claims
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1. A method of fabricating an object comprising at least one layer using stereolithography, comprising:
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providing a vertically stationary, horizontal surface disposed in a reservoir;
raising a volume of curable liquid above the surface to a first selected depth approximating a thickness of a first layer of the object, wherein raising the volume of curable liquid comprises moving at least a portion of the reservoir with respect to the vertically stationary horizontal surface; and
selectively curing portions of the first selected depth of curable liquid above the surface to at least a semisolid state to define at least portions of the first layer. - View Dependent Claims (2, 3, 4, 8, 9)
selectively curing portions of the second selected depth at least partially superimposed on portions of the first layer to define at least portions of the second layer.
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3. The method of claim 1, further comprising curing the curable liquid by traversing a beam of electromagnetic radiation in a selected pattern over the surface.
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4. The method of claim 3, further comprising determining a distance between a surface level of the curable liquid at the first selected depth and a reference point above the surface;
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adjusting a focal length of the beam of electromagnetic radiation to coincide with the surface level of the curable liquid at least in part responsive to the determining a distance.
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8. The method of claim 1, wherein raising the volume of curable liquid above the surface to a first selected depth approximating a thickness of a first layer of the object comprises raising the reservoir with respect to the surface.
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9. The method of claim 1, wherein raising the volume of curable liquid above the surface to a first selected depth approximating a thickness of a first layer of the object comprises one of raising a plate comprising a bottom of the reservoir and moving at least one side wall of the reservoir.
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5. A method of fabricating an object comprising at least one layer using stereolithography, comprising:
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providing a vertically stationary, horizontal surface;
raising a volume of curable liquid above the surface to a first selected depth approximating a thickness of a first layer of the object;
selectively curing portions of the first selected depth of curable liquid above the surface to at least a semisolid state to define at least portions of the first layer;
first determining a distance between the surface and a reference point above the surface before raising the volume of curable liquid thereabove;
second determining a distance between a surface level of the curable liquid at the first selected depth and a reference point above the surface after raising the volume of curable liquid thereabove; and
verifying that the depth of the curable liquid over the surface comprises the first selected depth from a difference between the first and second distance determinations. - View Dependent Claims (6, 7)
increasing the depth of the curable liquid above the surface to a second selected depth wherein a difference between the first selected depth and the second selected depth approximates a thickness of a second layer of the object;
third determining a distance between a surface level of the curable liquid at the second selected depth and a reference point above the surface after raising the volume of curable liquid thereabove;
verifying that an increased depth of the curable liquid over the first layer of the object approximates the thickness of the second layer of the object from a difference between the second and third distance determinations; and
selectively curing portions of the second selected depth at least partially superimposed on portions of the first layer to define at least portions of the second layer.
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7. The method of claim 5, further including:
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increasing the depth of the curable liquid above the surface to a second selected depth wherein a difference between the first selected depth and the second selected depth approximates a thickness of a second layer of the object;
third determining a distance between a surface level of the curable liquid at the second selected depth and a reference point above the surface after raising the volume of curable liquid thereabove;
verifying that the depth of curable material over the surface comprises the second selected depth from a difference between the first and third distance determinations; and
selectively curing portions of the second selected depth at least partially superimposed on portions of the first layer to define at least portions of the second layer.
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10. An apparatus for forming a structure comprising a plurality of layers, comprising:
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a platform having a vertically fixed, horizontally oriented upper surface disposed in a reservoir for containing a curable liquid;
a source of electromagnetic radiation for generating, focusing and traversing a beam of electromagnetic radiation effective to at least partially cure the curable liquid to at least a semisolid state; and
a liquid displacement structure selectively movable into and out of a volume of the curable liquid in the reservoir to selectively vary a surface level of the curable liquid within the reservoir relative to the vertically fixed, horizontally oriented upper surface of the platform. - View Dependent Claims (11, 12, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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13. An apparatus for forming a structure comprising a plurality of layers, comprising:
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a platform having a vertically fixed, horizontally oriented upper surface disposed in a reservoir for containing a curable liquid;
a source of electromagnetic radiation for generating, focusing and traversing a beam of electromagnetic radiation effective to at least partially cure the curable liquid to at least a semisolid state; and
a portion of the reservoir configured to be movable with respect to the platform to selectively vary a surface level of the curable liquid within the reservoir relative to the vertically fixed, horizontally oriented upper surface of the platform. - View Dependent Claims (14, 15)
a lift mechanism for selectively raising and lowering the reservoir with respect to the platform.
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15. The apparatus of claim 13, wherein the portion of the reservoir configured to be movable comprises one of a plate comprising a floor of the reservoir and at least one side wall of the reservoir.
Specification