Development of a large-range atomic force microscope measuring system for optical free form surface characterization

Abstract

In this paper, a large-range atomic force microscope (AFM) measuring system is developed for optical free form surface characterization. Based on the self-sensing tuning fork probe, a compact AFM head is developed, which is easy to combine with a scanning stage. Depending on the probe's unique structure and the usage of dynamic working mode, the tip–sample interaction force is reduced, improving the system's dynamic response performance. A two-platform structure is applied in the system, which combines a PZT stage with a motor driving platform. A dual feedback strategy is applied to ensure a measuring range up to 25 mm × 25 mm × 5 mm. The system includes three laser interferometers to make the measuring data traced to the ‘meter’ definition. A standard one-dimensional grating is tested to show the performance of the system. A millimeter scale optical free form surface with a sinusoidal structure array is measured relying on the two-platform structure implemented. The high frequency information and low frequency information of the sample are separated automatically, which represent the profile and roughness, respectively.