Numerical simulations and experiments about contamination mechanism of solid immersion lens system concerning hole and geometries of lens holder

The air flow field around a conical type solid immersion lens (SIL) system is simulated numerically and confirmed with experiment using a micro-particle image velocimetry (PIV) system. Jt is found that the back-flow from the downstream of the SIL is a major candidate for the contamination of the SIL. Five modifications are proposed to suppress the particle conveying mechanism, the back-flow. Among these modifications a method using two flow-bypasses reduces the back-flow most effectively, which connects the top surface of the SIL system and two side-holes of the lens holder where the static pressure is the minimum.