I. Introduction
The development of the components and devices of precision manufacturing and inspection system is important for increasing product competition. Metrology technology is always the vital factor of the precision engineering. After the laser applications are popular and the progress of optoelectronic technologies grows rapidly, there are many optical methods for dimensional metrology [1], such as laser interferometer for large range displacement [2], laser triangular method [3] and its combination with diffraction grating [4], confocal chromatic method [5], and the simultaneous measurement of linear and angular displacement using laser interferometer and four-quadrant photodiode [6].