“…This is caused by the PSD's inherent PIN structure and inhomogeneous distribution of P-type layer resistivity [11,12], that is, so called PSD bordering effect (when the spot goes on bordering, the detecting accuracy decrease gradually). Limit to the length of the paper, only the result of the above typical point in square detecting area of (2,2),(2,2) xy ∈−∈− is presented. Actually, the stability is better than ±2μm in the whole square area.…”