The multi-function surgical instrument for facilitating corneal surgery by laser includes lower and upper rings. The apparatus includes a manifold head with a manifold surface having a plurality of conduits configured to generate a fluid meniscus on a substrate surface when positioned proximate the substrate. Different types of wobbles are formed on the grooves of either the user data area or the lead-out area, thereby preventing an optical pickup that performs recordingreproduction from deviating from the user data area. A magnetic bearing assembly rotationally supports the shaft relative to the housing in response to a magnetic bearing command. Thus, the GaN single crystal substrate suitable for manufacture of a GaN-based semiconductor device having a small variation of characteristics can be obtained.