A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications...A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications, was selected as a model pattern. The prism pattern is 50 μm in pitch and 108° in the vertical angle. The overall size of the plate was 335 mm×213 mm and the thickness of the plate varied linearly from 2.6 mm to 0.7 mm. The prism pattern was firstly machined on the nickel plated core block using micro diamond tool and this machined pattern core was installed in a mold for injection molding of prism patterned plate. Polymethyl methacrylate (PMMA) was used as a molding material. The pressure and temperature of the melt in the cavity were measured at different positions in the cavity and the replication of the pattern was also measured at the same positions. The results show that the pressure or temperature profile through the process depends on the shape and the size of the plate. The replication is affected by the temperature and pressure profiles at the early stage of filling, which is right after the melt reaches the position to be measured.展开更多
In optics,the refractive index of a material and its spatial distribution determine the characteristics of light propagation.Therefore,exploring both low-and high-index materials/structures is an important considerati...In optics,the refractive index of a material and its spatial distribution determine the characteristics of light propagation.Therefore,exploring both low-and high-index materials/structures is an important consideration in this regard.Hollow cavities,which are defined as low-index bases,exhibit a variety of unusual or even unexplored optical characteristics and are used in numerous functionalities including diffraction gratings,localised optical antennas and low-loss resonators.In this report,we discuss the fabrication of hollow cavities of various sizes(O.2-5μm in diameter)that are supported by conformal dielectric/metal shells,as well as their specific applications in the ultraviolet(photodetectors),visible(light-emitting diodes,solar cells and metalenses),near-infrared(thermophotovoltaics)and mid-infrared(radiative coolers)regions.Our findings demonstrate that hollow cavities tailored to specific spectra and applications can serve as versatile optical platforms to address the limitations of current optoelectronic devices.Furthermore,hollow cavity embedded structures are highly elastic and can minimise the thermal stress caused by high temperatures.As such,future applications will likely include high-temperature devices such as thermophotovoltaics and concentrator photovoltaics.展开更多
基金Project supported by Development of Large Surface Micro-Machining System Technology of Ministry of Knowledge Economy, Korea
文摘A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications, was selected as a model pattern. The prism pattern is 50 μm in pitch and 108° in the vertical angle. The overall size of the plate was 335 mm×213 mm and the thickness of the plate varied linearly from 2.6 mm to 0.7 mm. The prism pattern was firstly machined on the nickel plated core block using micro diamond tool and this machined pattern core was installed in a mold for injection molding of prism patterned plate. Polymethyl methacrylate (PMMA) was used as a molding material. The pressure and temperature of the melt in the cavity were measured at different positions in the cavity and the replication of the pattern was also measured at the same positions. The results show that the pressure or temperature profile through the process depends on the shape and the size of the plate. The replication is affected by the temperature and pressure profiles at the early stage of filling, which is right after the melt reaches the position to be measured.
基金the Materials,Components,and Equipment Research Program of Gyeonggi-do(AlCT-004-T1)the National Research Foundation of Korea through the Basic Science Research Program(2020R1A2B5B01002261)the Nano Material Technology Development Program(2021M3D1A2049865 and 2022M3H4A1A02085336).
文摘In optics,the refractive index of a material and its spatial distribution determine the characteristics of light propagation.Therefore,exploring both low-and high-index materials/structures is an important consideration in this regard.Hollow cavities,which are defined as low-index bases,exhibit a variety of unusual or even unexplored optical characteristics and are used in numerous functionalities including diffraction gratings,localised optical antennas and low-loss resonators.In this report,we discuss the fabrication of hollow cavities of various sizes(O.2-5μm in diameter)that are supported by conformal dielectric/metal shells,as well as their specific applications in the ultraviolet(photodetectors),visible(light-emitting diodes,solar cells and metalenses),near-infrared(thermophotovoltaics)and mid-infrared(radiative coolers)regions.Our findings demonstrate that hollow cavities tailored to specific spectra and applications can serve as versatile optical platforms to address the limitations of current optoelectronic devices.Furthermore,hollow cavity embedded structures are highly elastic and can minimise the thermal stress caused by high temperatures.As such,future applications will likely include high-temperature devices such as thermophotovoltaics and concentrator photovoltaics.
