Diode-based additive manufacturing of metals using an optically-addressable light valve.

Selective Laser Melting (SLM) of metal powder bed layers, whereby 3D metal objects can be printed from a digital file with unprecedented design flexibility, is spurring manufacturing innovations in medical, automotive, aerospace and textile industries. Because SLM is based on raster-scanning a laser beam over each layer, the process is relatively slow compared to most traditional manufacturing methods (hours to days), thus limiting wider spread use. Here we demonstrate the use of a large area, photolithographic method for 3D metal printing, using an optically-addressable light valve (OALV) as the photomask, to print entire layers of metal powder at once. An optical sheet of multiplexed ~5 kW, 20 ms laser diode and ~1 MW, 7 ns Q-switched laser pulses are used to selectively melt each layer. The patterning of near infrared light is accomplished by imaging 470 nm light onto the transmissive OALV, which consists of polarization-selective nematic liquid crystal sandwiched between a photoconductor and transparent conductor for switching.

[1]  A. Rubenchik,et al.  Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones , 2015, 1512.02593.

[2]  J. Huignard,et al.  Liquid crystal light valve using bulk monocrystalline Bi22SiO20as the photoconductive material , 1982, IEEE Journal of Quantum Electronics.

[3]  J P Huignard,et al.  Nearly diffraction-limited laser focal spot obtained by use of an optically addressed light valve in an adaptive-optics loop. , 1998, Optics letters.

[4]  Manyalibo J. Matthews,et al.  Optics Recycle Loop Strategy for NIF Operations above UV Laser-Induced Damage Threshold , 2016 .

[5]  Konstantin Shcherbin,et al.  Infrared sensitive liquid crystal light valve with semiconductor substrate. , 2016, Applied optics.

[6]  Xiaoyu Zheng,et al.  Multiscale metallic metamaterials. , 2016, Nature materials.

[7]  K. Wegener,et al.  High temperature material properties of IN738LC processed by selective laser melting (SLM) technology , 2013 .

[8]  Matthias Markl,et al.  Multiscale Modeling of Powder Bed–Based Additive Manufacturing , 2016 .

[9]  R. Everson,et al.  Surface roughness analysis, modelling and prediction in selective laser melting , 2013 .

[10]  Sheldon Wu,et al.  Modulating laser intensity profile ellipticity for microstructural control during metal additive manufacturing , 2017 .

[11]  Justin Wolfe,et al.  A programmable beam shaping system for tailoring the profile of high fluence laser beams , 2010, Laser Damage.

[12]  Alexander M. Rubenchik,et al.  Denudation of metal powder layers in laser powder bed fusion processes , 2016 .

[13]  L. Froyen,et al.  Selective laser melting of iron-based powder , 2004 .

[14]  W. Krupke,et al.  Fiber lasers grow in power , 2002 .

[15]  J. Kruth,et al.  Residual stresses in selective laser sintering and selective laser melting , 2006 .

[16]  Justin Wolfe,et al.  Programmable beam spatial shaping system for the National Ignition Facility , 2011, LASE.

[17]  H. B. Brown,et al.  Application Of The Liquid Crystal Light Valve To Real-Time Optical Data Processing , 1978 .

[18]  J. Kruth,et al.  A study of the microstructural evolution during selective laser melting of Ti–6Al–4V , 2010 .

[19]  C. Kamath,et al.  Laser powder bed fusion additive manufacturing of metals; physics, computational, and materials challenges , 2015 .