Development of an atomic force microscope (AFM) with laser optical feedback = Desarrollo de un microscopio de fuerza atómica (AFM) de bajo coste basado en realimentación óptica láser

Abstract

This project aims to develop and manufacture a low-cost atomic force microscope (AFM), enabling measurements with a performance comparable to those of a commercial microscope. This type of microscopy is based on monitoring the deflection of a probe, acquiring images within the nanometer scale. The developed prototype employs an Optical Pick-up Unit (OPU) as the head of the microscope. Additionally, piezoelectric buzzers are used as actuators, thus driving the sample motion. During this master's thesis, the instrument's electronics have been designed and assembled, being capable of generating and adapting the different signals needed for its operation. In addition, the structure of the microscope has been manufactured using a 3D printer. Furthermore, an isolation system has been built, protecting the measurements against external noise sources i.e. vibrations and air flows. On the other hand, the control software which manages the different components of the microscope has been designed and programmed. This software design was made considering a previous study about microcontrollers, therefore aiming to identify the most suitable microcontroller which meets the requirements of this instrument. Moreover, the software also has a graphical user interface (GUI), allowing the user to easily control the prototype using keyboard and mouse. Furthermore, the different manufactured components as well as the developed software have been verified. Thus, having a suitable performance to obtain high resolution measurements. In this way, an instrument capable of acquiring three-dimensional profiles with sub-micron resolutions has been designed. Being this device based on the laser optical feedback from the optical pick-up unit. Finally, once the project is finished, all the electronics, software and hardware designs will be published on Open Source platforms. Therefore, providing the opportunity to replicate this prototype without charge. Thereby supporting those companies and research groups that cannot afford the purchase of a commercial AFM