Design and implementation of an all-digital atomic force microscope controller

A digital controller for an Atomic Force Microscope is designed and implemented. The traditional analogue Proportional Integral control loop is replaced with a digital one. Prior to describing the experimental work in this area, a short review of AFM is given, with emphasis on the requirements for the controller.;The controller is used to acquire an image of a diffraction grating. This image is compared with similar data acquired by a commercially available AFM controller and recommendations are made regarding further development and improvement of the digital Atomic Force Microscope controller.;The controller is built around a Motorola 56001 Digital Signal Processor interfaced to an 80386-based Personal Computer and to a custom Printed Circuit Board. The Digital Signal Processor rasters the scanning tip over the sample surface, maintaining a constant force between the tip and the surface as it does so. As the experimenter's means of controlling the Digital Signal Processor, the Personal Computer runs a mouse-based graphical user interface program. The custom Printed Circuit Board enables communication between the analogue Atomic Force Microscope and the digital Personal Computer and Digital Signal Processor.