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

Abstract

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.

Mechanical Metamaterials and Their Engineering Applications

“…However, the energy beam is focused on a continuous stream of powder or wire which is deposited directly onto the substrate . While both PBF and DED suffers from slow printing rates, researchers from Lawrence Livermore National Laboratory (LLNL) have developed a novel method to solve this problem by using an optically‐addressable light valve (OALV), which consists of polarization‐selective nematic liquid crystal sandwiched between a photoconductor and transparent conductor, as a photo‐mask to print an entire layer of metal powder at once . High power laser diode arrays are used to multiplex an optical sheet and switched laser pulses are used to selectively melt each powder layer.…”

One-step volumetric additive manufacturing of complex polymer structures

“…Although DLW and DIW allow some capability to build out-of-plane unsupported structures, it is highly limited and still requires serial deposition of 0D or 1D elements. In a number of recent reports, including projection micro-stereolithography (PμSL) ( 8 , 9 ), continuous liquid interface printing (CLIP) ( 10 ), and diode AM (DiAM) ( 11 ), complete 2D layers are formed in a single operation.…”

Diode area melting single-layer parametric analysis of 316L stainless steel powder

“…No details have been reported on how many laser multi-spots have been integrated into this new Fraunhofer machine, nor has information been disclosed detailing its processing performance or quality of produced samples. Matthews et al recently demonstrated a diode-based additive manufacturing (DiAM) system [7]. The laser diode sources used within the DiAM method are comprised of a set of four 1.25 kW continuous wave (CW) stacked diode arrays (60 individual bars each) giving a total of 4.8 kW power from a combined incoherent beam at 150 A.…”