Osaka Electro-communication University

Demands for long mechanical and optical parts which have high straightness or flatness are increasing. Examples are seen in a flat panel for liquid crystal display, a throttle die for thin film production and machine elements of semiconductor equipments. Although the length of the parts exceeds 1 m, the requirement for their figure accuracy is higher than 0.1mm. However, there is no useful method to evaluate precisely the figure accuracy of the long parts. The reasons are inevitable difficulties in manufacturing long tangible datum and prevention of deformation due to gravity and environment. Therefore, developing the ultra-precision measuring machine for long parts is an urgent need. A possible method for the purpose described above is differential laser auto-collimation (DLAC). The principle of figure measuring with DLAC is the accumulation of difference angle in inclination measured by laser auto-collimation between two points along a straight line on the surface to be measured. However, the figure accuracy measured by the method is influenced by the in alignment error of the devices in the measuring system. IN-SITU SELF CALIBRATION LASE