Boundary effect of the glass microlens array in partial-filling hot embossing

Partial-filling hot embossing (PFHE) is a flexible and rapid method to fabricate the glass microlens array (GMLA) with high efficiency and mass production. However, the sidewall of the microhole mold strongly affects the deformation modes and optical performance of the GMLA during PFHE. The microholes of a mold fabricated by electrical discharging machining (EDM) and focused ion beam (FIB) were employed for hot glass embossing to reveal the boundary effect of the GMLA in PEHE. The detailed characterizations were implemented for 3 × 3 microhole arrays by white-light interfering profilometer and scanning electron microscope to highlight the anomaly in the sidewall topography of different mold cavities. Also, the three-dimensional topography and optical quality of the GMLA were measured by a white-light interfering profilometer, parallel light system, and ultraviolet spectrophotometer. Experimental results indicated that the sidewall of the mold cavity significantly affected the filling modes, appearance, and optical quality of the GMLA. The phenomenon of sidewall slip occurs at the edge of the GMLA in the FIB-mold. The sidewall quality of the EDM-mold strongly affects deformation modes and light transmittance of the GMLA. The work provides a better understanding of fabricating the GMLA in PFHE.