Development of electromagnetic scanning stage for astigmatic profilometer

As the well-grown of technology, manifold detecting functions have been developed on the surface measurement. By using diverse physical/chemical effects, the 3D surface profile measurement can be developed to detect the sample surface structure. Through the delicate optical configuration, the astigmatic pick-up head can achieve the nano-scale measurement resolution. Furthermore for realizing a profilometer, the scanning performance also plays a significant function to detect the sample profile. This paper is to present our developed astigmatic profilometer integrated with a coplanar and biaxial electromagnetic scanning stage and an astigmatic pick-up head. The electromagnetic scanning function is based on the moving-coil principle which utilizes the Lorentz force to drive the coil attached to the elastic membrane. Each scanning axis possesses two opposite-working electromagnetic actuators with the pull-push actuation method to symmetrically create large actuating force. It has been experimentally verified that the coplanar and biaxial scanning stage can achieve the scanning range over 1 mm. The astigmatic profilometer can scan an surface area of 1 mm × 1 mm (500 pixels × 500 pixels) at the scanning rate of 20 Hz. Its maximum scanning speed is equivalent to 40 mm/s.