Sistema de microscopía de fuerza atómica basada en una unidad de lectura óptica digital y un escáner-zumbador

Abstract

An astigmatic detection system (ADS) based on a compact disk/digital-versatile-disk (CD/DVD) astigmatic optical pickup unit (OPU) is presented. It can achieve a resolution better than 0.3 nm in detection of the vertical displacement and is able to detect the two-dimensional angular tilt of the object surface. Furthermore, a novel scanner design actuated by piezoelectric disk buzzers is presented. The scanner is composed of a quad-rod actuation structure and several piezoelectric disks. It can be driven directly with low-voltage and low-current sources, such as analogue outputs of a data acquisition (DAQ) card and enables a sufficient scanning range of up to 15 $\mu$m. In addition, an economic, high-performance streamlined atomic force microscope (AFM) was constructed, using the buzzer-scanner to move the sample relative to the probe, and using a CD/DVD OPU to detect the mechanical resonance of a microfabricated cantilever. The performance of the AFM is evaluated. The high sensitivity and high bandwidth of the detection system makes the equipment suitable for characterizing nanoscale elements. An AFM using our detection system for detecting the deflection of microfabricated cantilevers can resolve individual atomic steps on graphite surfaces.