Additive manufacturing systems and methods

Abstract

Additive manufacturing systems and methods utilizing an optical light valve configured to spatially modulate the intensity of a laser beam, in conjunction with a writing and erasing sub-system configured to repeatedly write and erase patterns in the optical light valve to repeatedly vary the spatial modulation of the laser beam. In some implementations, the systems and methods may also employ additional laser beams or other energy sources that are not spatially modulated by the optical light valve. In some implementations, the systems and methods may employ additional laser beams or other energy sources configured to reduce surface roughness of the powder or other material being used for additive manufacturing.

1 . A laser energy delivering system for an additive manufacturing system, comprising:
 an optical light valve;   a writing and erasing sub-system configured to repeatedly write and erase patterns in the optical light valve;   a first laser beam, the optical light valve configured to spatially modulate an intensity of the first laser beam based on a pattern written into the optical light valve;   a second energy beam, the second energy beam not being spatially modulated by the optical light valve; and   a manufacturing material;   wherein the manufacturing system is configured to apply the modulated first laser beam and the non-modulated second energy beam to the manufacturing material to increase temperature in a build area to at least a first temperature that is at or above the melting temperature of the manufacturing material.   
     
     
         2 . The system of  claim 1 , wherein the system is configured to apply the non-modulated second energy beam to the manufacturing material to increase temperature in a non-build area to a second temperature that is below the melting temperature of the manufacturing material. 
     
     
         3 . The system of  claim 2 , wherein the system is configured to apply the modulated first laser beam and the non-modulated second energy beam to the manufacturing material to increase temperature in the non-build area to the temperature below the melting temperature of the manufacturing material. 
     
     
         4 . The system of  claim 2 , wherein the system is configured to simultaneously apply the first laser beam and the second energy beam to both the build area and the non-build area. 
     
     
         5 . The system of  claim 2 , wherein the difference between the first and second temperatures is 5% or more. 
     
     
         6 . The system of  claim 1 , wherein the first increased temperature in the build area spatially varies. 
     
     
         7 . The system of  claim 1 , further comprising a third laser beam, and a second optical light valve configured to spatially modulate an intensity of the third laser beam, the system configured to apply the modulated third laser beam to the manufacturing material to increase temperature in a portion of the build area to third temperature that is above the first temperature. 
     
     
         8 . The system of  claim 1 , wherein the second energy beam is a second laser beam. 
     
     
         9 . The system of  claim 8 , wherein the first laser beam has a first pulse duration and the second laser beam has a second pulse duration, the first pulse duration being shorter than the second pulse duration. 
     
     
         10 . The system of  claim 9 , wherein the system is configured such that:
     W> 2( Dt   1 ) 1/2      in which W is a required precision length for an object to be manufactured from the manufacturing material, D is a thermal diffusivity property of the manufacturing material, and t 1  is the first pulse duration.   
     
     
         11 . The system of  claim 9 , wherein the system is configured such that:
   2( Dt   2 ) 1/2   >W> 2( Dt   1 ) 1/2      in which W is a required precision for an object to be manufactured from the manufacturing material, D is a thermal diffusivity property of the manufacturing material, t 1  is the first pulse duration, and t 2  is the second pulse duration.   
     
     
         12 . The system of  claim 9 , wherein the first pulse duration is 10 ns or less and the second pulse duration is longer than 10 ns. 
     
     
         13 . The system of  claim 1 , wherein the first laser beam comprises a first fluence and the second energy beam comprises a second fluence, wherein the second fluence is higher than the first fluence. 
     
     
         14 . The system of  claim 13 , wherein the second fluence is at least 80% of the total fluence applied on the material comprised of the first and the second fluence. 
     
     
         15 . The system of  claim 1 , wherein the first beam comprises a first cross-sectional area and the overlapping second energy beam comprises a second cross-sectional area, wherein the second cross-sectional area is at least as large as the first cross-sectional area. 
     
     
         16 . The system of  claim 1 , further comprising a third laser beam, the third laser beam not being spatially modulated by the optical light valve, the system configured to apply the third laser beam to the manufacturing material at an angle that is non-normal to an upper surface of the manufacturing material. 
     
     
         17 . The system of  claim 16 , wherein the third laser beam is configured to decrease a surface roughness attribute of the manufacturing material. 
     
     
         18 . The system of  claim 1 , wherein the optical light valve comprises an all-optical light valve including a photoalignment layer that is not electrically conductive. 
     
     
         19 . A laser additive manufacturing system, comprising:
 a particulate manufacturing material or material mixture;   a first laser beam; and   a second laser beam, the manufacturing system configured to apply the second laser beam to the manufacturing material at an angle that is non-normal to an upper surface of the manufacturing material;   wherein the manufacturing system is configured to apply the first laser beam and the second laser beam to the manufacturing material to increase temperature in a build area of the manufacturing material to at least a first temperature that is at or above the melting temperature of the manufacturing material;   wherein the manufacturing system is configured to apply the second laser beam to the manufacturing material to decrease a surface roughness attribute of the manufacturing material.   
     
     
         20 . The manufacturing system of  claim 19 , wherein the system is configured to spatially modulate an intensity of the first laser beam. 
     
     
         21 . The manufacturing system of  claim 19 , wherein the manufacturing system is configured to apply the first laser beam to the manufacturing material at a normal angle. 
     
     
         22 . The manufacturing system of  claim 19 , wherein the manufacturing system is configured to apply pulses of the first and second laser beams to the manufacturing material simultaneously or to apply at least some pulses of the first laser beam before pulses the second laser beam. 
     
     
         23 . The manufacturing system of  claim 19 , further comprising:
 a third laser beam;   an optical light valve configured to spatially modulate an intensity of the first laser beam based on a pattern written into the optical light valve; and   a writing and erasing sub-system configured to write and erase patterns in the optical light valve;   wherein the second and third laser beams are not modulated by the optical light valve.   
     
     
         24 . The manufacturing system of  claim 23 , wherein the optical light valve comprises an all-optical liquid crystal light valve including a photoalignment layer that is not electrically conductive. 
     
     
         25 . The manufacturing system of  claim 23 , wherein the manufacturing system is configured to apply the modulated first laser beam and the non-modulated second and third laser beams to the manufacturing material to increase temperature in a build area of the manufacturing material to at least a first temperature that is at or above the melting temperature of the manufacturing material and to increase temperature in a non-build area of the manufacturing material to a second temperature that is below the melting temperature of the manufacturing material. 
     
     
         26 . The manufacturing system of  claim 25 , wherein the first laser beam has a first pulse duration, the second laser beam has a second pulse duration, and the third laser beam has a third pulse duration, wherein the first and second pulse durations are shorter than the third pulse duration. 
     
     
         27 . The manufacturing system of  claim 19 , further comprising an additional laser beam, the manufacturing system configured to apply the additional laser beam to the manufacturing material at an angle that is non-normal to an upper surface of the manufacturing material and that is different from the angle of the second laser beam. 
     
     
         28 . A laser additive manufacturing system, comprising:
 (a) an all optical liquid crystal beam shaper;   (b) an all optical writing and erasing sub-system configured to write, erase, and rewrite a plurality of optical patterns in the optical liquid crystal beam shaper;   (c) a laser beam source that produces a known and repeatable intensity profile on the locations of the all optical liquid crystal beam shaper;   (d) laser beam transport and imaging optics configured to project the image of the optical patterns in the optical liquid crystal beam shaper onto an unprocessed material layer; and   (e) a beam steering mechanism configured to control the position of the projected laser beam optical patterns on to the unprocessed material layer.   
     
     
         29 . The laser additive manufacturing system of  claim 28 , wherein the all optical liquid crystal beam shaper comprises:
 (i) a first alignment layer that is photo-switchable and is located on an inner surface of the first transparent substrate;   (ii) a second alignment layer having a fixed alignment state and is located on an inner surface of a second transparent substrate;   (iii) a liquid crystal material contained between the two alignment layers and transparent substrates; and   (iv) a polarizer that reflects a first polarization state and transmits a second complimentary polarization state.   
     
     
         30 . The laser additive manufacturing system of  claim 29 , wherein the photo-switchable alignment layer comprises at least one from the group of materials including PESI-F, SPMA:MMA 1:5, SPMA:MMA 1:9, or SOMA:SOMA-p:MMA 1:1:6. 
     
     
         31 . The laser additive manufacturing system of  claim 29 , wherein the fixed alignment layer comprises either an inherently permanently aligned layer produced by rubbing or other physical processes or a write-once photoalignment layer that has been permanently oriented using polarized UV light with a maximum wavelength of 380 nm. 
     
     
         32 . The laser additive manufacturing system of  claim 31 , wherein the fixed alignment layer is a buffed Nylon 6/6 or a write-once photoalignment material. 
     
     
         33 . The laser additive manufacturing system of  claim 29 , wherein the first and second transparent substrates comprise any optical material that exhibits practically no absorption during operation of the system. 
     
     
         34 . The laser additive manufacturing system of  claim 29 , wherein the liquid crystal material of the beam shaper includes partially saturated liquid crystals, fully saturated liquid crystals, partially fluorinated liquid crystals, or per-fluorinated liquid crystals. 
     
     
         35 . The laser additive manufacturing system of  claim 34 , wherein the liquid crystal material of the beam shaper includes phenylcyclohexanes, cyclo-cyclohexanes, or a material including per-fluorinated alkyl side chains. 
     
     
         36 . The laser additive manufacturing system of  claim 28 , wherein the all optical writing and erasing sub-system is configured such that writing an optical pattern into the photo-switchable alignment layer causes a localized change in configuration of the liquid crystals, such that a laser beam passing through the liquid crystal beam shaper undergoes a localized change in polarization state. 
     
     
         37 . The laser additive manufacturing system of  claim 36 , wherein the optical writing and erasing sub-system comprises:
 a coherent or incoherent light source with an operating wavelength less than 500 nm and matched to a peak absorption wavelength of the photo-switchable alignment material;   wherein the light source is coupled to either (i) a spatial light modulator configured to write an optical pattern on the photo-switchable alignment layer;   or (il) an optical system that provides a raster-scanned light spot configured to write the optical pattern on the photo-switchable alignment layer.   
     
     
         38 . The laser additive manufacturing system of  claim 36 , wherein the optical writing and erasing sub-system is configured to erase the written optical pattern by application of
 (i) incident light of wavelength less than 500 nm and having a different polarization state than the incident light used to write the optical pattern, or   (ii) application of visible light.   
     
     
         39 . The laser additive manufacturing system of  claim 28 , wherein the laser beam source is operating at a wavelength that is larger than 500 nm 
     
     
         40 . The laser additive manufacturing system of  claim 28 , wherein the laser beam transport and imaging optics include:
 (i) fixed optical elements to control beam divergence, beam direction and beam polarization state and/or,   (ii) adaptive optical elements to reduce or eliminate beam wavefront distortions and/or,   (iii) active optical elements to control the location of beam direction or compensate for drifting during system operation.   
     
     
         41 . The laser additive manufacturing system of  claim 28 , wherein the optically transparent substrates, the photo-switchable alignment layer, the fixed alignment layer, and the liquid crystal mixture have an N-on-1 laser induced damage threshold using small beam damage testing configuration exceeding:
 (i) 40 J/cm 2  at 1053 nm and 1500 ps pulse width, or   (ii) 5 J/cm 2  at 1053 nm and 100 ps pulse width, or   (iii) 1 J/cm 2  at 1053 nm and 10 ps pulse width, or   (iv) 0.8 J/cm2 at 1053 nm and 0.6 ps pulse width.   
     
     
         42 . The laser additive manufacturing system of  claim 28 , wherein the photo-switchable alignment layer and the fixed alignment layer are electrically non-conductive. 
     
     
         43 . The additive manufacturing system of  claim 28 , wherein the liquid crystals comprise an absorption edge of less than 330 nm.