Oblique ultrasonic vibration-assisted polishing for grating structures of BK7 optical glass

Abstract

As a classical optical structure, grating is widely applied in semiconductor, biomedicine, and optical communication fields. However, the existing machining methods are difficult to accommodate the increasing requirements. A novel polishing method of optical glass BK7 was proposed based on ultrasonic vibration-assisted polishing with polishing oblique angle θ. It has better machining accuracy compared to common polishing. Finite element static analysis was performed to investigate the effect of polishing oblique angle on the processing of grating structures, and the feasibility and advantages of this method were illustrated theoretically. Meanwhile, the path corner profile, material removal rate, material removal depth, and surface roughness were analyzed. A series of single-factor experiments were performed to verify the feasibility of the proposed method. The experimental results indicate that a better grating corner profile and a higher material removal rate can be obtained with ultrasonic vibration. The introduction of polishing oblique angle can significantly improve the accuracy of grating corner profile and material removal rate calculation. This paper can provide useful insight and guidance to facilitate high-efficiency and high-precision machining of grating structures.