Study on liquid crystal polymer molding for off-axial aspherical reflective grating optical element by injection molding process

This study aims to investigate the effect of polymers and mold temperature on the micro-structure of off-axial aspherical reflective grating optical element (OAA-RGOE) by injection molding (IM) process. The IM process combines a micro vibratile (MV) and varithermo mold temperature (VMT) methods. In this study, three polymers including liquid crystal polymer (LCP), polycarbonate (PC), and polyphenylene sulfide (PPS) have been used to produce OAA-RGOE for the structured optical elements. Results show that the surface topography of the micro-structure of LCP is much smoother than those made by PC and PPS. The measurement results also present that the micro-structure filling ratio (MSFR) has increased with higher mold temperature. The structure height of OAA-RGOE is around 0.45 µm and MSFR has been achieved around 91.22 % at mold temperature of100 °C. The LCP material has provided a high applicability for OAA-RGOE in IM process. This study can be further applied to manufacture micro-structure of reflective optical element for integrated spectrometer by LCP material.