Optical metrology tool, LX530, is designed for high throughput and dense sampling metrology in semiconductor manufacture. It can inspect the dose and focus variation in the process control based on the critical dimension (CD) and line edge roughness (LER) measurement. The working principle is shown with a finite-difference-time-domain (FDTD) CD simulation. Two optical post lithography wafers, including one focus-exposure-matrix (FEM) wafer and one nominal wafer, are inspected for CD, dose and focus analysis. It is demonstrated that dose and focus can be measured independently. A data output method based on global CD uniformity (CDU), inter CDU and intra CDU is proposed to avoid the data volume issue in dense sampling whole wafer inspection.