An optically addressable liquid crystal spatial light modulator (SLM) is used for dynamic laser beam shaping used in a unique, fast metal additive manufacturing process (3D printing) [1]. We address challenges of using our SLM exposed continuously to high power kW-MW lasers. Control of liquid crystals is coupled to the optical-response of the photoconducting insulators that affects contrast, switching speed, and laser power handling. We compare liquid crystal materials laser damage rationalized based on their thermal properties, and highlight device-level stresses via computational modeling. Key areas of liquid crystals and semiconductor properties are presented that impact optically addressed SLM for power switching applications.
[1] https://www.seurat.com/area-printing
An optically addressed light valve is described for high-speed laser beam shaping used in rapid metal additive manufacturing [1]. The resulting Area Printing™ delivers shaped high-power pulses to a metal powder bed that locally sinters and melts to consolidate into a fully dense metal part. This technology and device enable scaling, cheaper additive manufacturing with high spatial resolution and greater efficiency with minimal spatter defects. We address here the unique optoelectronic properties and challenges related to optically addressed photoconducting insulator that control the switching dynamics under high intensity laser irradiation. Further description is presented of the device-level thermomechanical analysis from parasitic absorption of the laser at kW to MW power levels.
[1] https://www.seurat.com/area-printing
Our study analyzed the laser-damage threshold of liquid crystal alignment materials, including photoaligned azobenzene, rubbed polyimide, and rubbed nylon. We found that the presence of liquid crystal was necessary to observe variation in damage thresholds among alignment materials. Nylon outperformed photoalignment, which outperformed polyimide. We also investigated the polarization dependence of the damage threshold in ordinary and extraordinary modes at a near-infrared wavelength and found that only the photoalignment material demonstrated polarization sensitivity at our statistical power level. Our results can inform the design of high-power beam-shaping devices for various applications, including fusion, 3-D printing, and defense systems.
An optically addressable light valve is used for high repetition rate dynamic laser beam shaping used in a unique metal additive manufacturing process [1]. The resulting Area Printing™ delivers high power pulses - each with an individually controlled shape - to a metal powder bed that locally sinters and melts to consolidate into a fully dense metal part. This technology and device enable scaling cheaper additive manufacturing with high spatial resolution, while capable of printing part features beyond reach of conventional manufacturing, and with greater efficiency and minimal spatter defects. We address here the unique optoelectronic properties needed from the optically addressable photoresistor that controls the dynamic beam shaping for high density, high-resolution laser 3D printing. Further description is presented of the device-level thermomechanical analysis from parasitic absorption of the laser at kW to MW power levels. We thus highlight key areas of semiconductor properties challenging the performance capabilities in optically addressed light valves used in high power switching applications.
[1] https://www.seurat.com/area-printing
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