The basic principle and structural design of 2 DOF tip/tilt laser scanner are introduced. Two different methods to measure the 2 DOF deflection angle of the scanner are discussed, including their mathematical models, computing expression and optical systems. The aspects of PSD output signal processing circuit and sample-hold circuit to eliminate the environmental noise are presented. Displacement calibration demonstrates that the system can reach a wide measurement range of 30° and angle resolution of 0.01° as well as fast response and high stability.