Development of a nanometer resolution flatness measurement system for the ceramic surface by using Blue-ray optical pickup

This study proposes a new type of measurement system for the flatness of ceramic surface. The system proceeds the measurement with the optical pickup head of blue ray. It used the light source emitted from the optical pickup head which reflected by the ceramic surface and the reflective light was received by the photo diodes in the optical pickup head then to be calculated into focusing error signal. Then, we can automatically lock focus and analyze the data on the measurement surface by the program to get the flatness of the ceramic surface. The advantages of this measuring method are that no need to use expensive interference system, easier to set up and operate, the over-all cost of detection devices is low, the size of components is small, and the measurement accuracy can up to sub-micron level. The resolution of this measurement system is up to 20 nm.