## 1 Introduction  
As nanoscale science, technology, and engineering have grown phenomenally over the past few decades, awareness of nanotechnology and nanoscience concepts and implications is increasingly important in education. Scanning Probe Microscopy (SPM), proclaimed to be the key to enabling discovery for nanotechnology, has evolved into a series of profound techniques for interdisciplinary research at the nanoscale. Atomic Force Microscopy (AFM) [1], a family member ofSPM, is one of the most versatile techniques for surface analysis. Over the past three decades, it has evolved into a powerful tool used to image and measure interatomic or intermolecular forces, for a wide range of surfaces including those encountered in the semiconductor and biomaterial industries. Recent advances have paved the way for atomic level insight into various surfaces such as semiconductors [2; 3; 4], insulators [5; 6], and metal oxides [7; 8], which has strongly contributed to the understanding of surface structure and chemical composition. Moreover, the ability of AFM to operate under a liquid environment makes it an indispensable tool for studies of solid-liquidinterface [9; 10]. It is perceivable that AFM offers an effective educational tool in nanoscience and nanotechnology. For educational purposes, students and beginners oftenfind it hard to comprehend some of the original literature. It would therefore be helpful to begin with some introductory topics onfundamental principles and basic instrumental aspects [11; 12; 13].  
In recent years, institutions have taken initiatives to incorporate AFM into teaching laboratories. For instance, a macroscopic model of AFMs wasdemonstrated to explain operating principles on a macroscopic scale [14; 15]. An AFM model without electronic detection and utilized modified phonograph stylus was created [16]. [PERSON] et al. presented a conceptual AFM model built with the LEGO MINDSTORMS which was able to produce three-dimensional surface graphs [17]. Using specialized interdigitated cantilever, [PERSON] et al. designed a low-cost system that was able to perform imaging in constant-height mode withmeasurement of Boltzmann's constant [18]. Another low-cost AFM setup was developed by [PERSON] et al. [19]. This system used the Fabry-Perot interferometer as a detecting device and also operated in constant-height mode. However, the system suffered from signal ambiguity problem for features of height exceeding 158 nm. An optical beam deflection (OBD) based AFM was presented by [PERSON] and [PERSON] [20]. Many parts used for the AFM were off the shelf and the system was capable of measuring features on the submicron scale.  
In this paper, an OBD based AFM designed for the undergraduate engineering laboratory is presented. The purpose of this work is to utilize existing resources that are available from the undergraduate laboratory and build a cost-effective AFM as a teaching instrument. Even though an educational platform and low-cost components are used, the test results show that the developed system is capable of performing imaging in constant-force mode with reasonable resolution and scanning speed. While the performance does not approach that of a commercial AFM, it is adequate to serve as a teaching instrument for undergraduates.  
The rest of this paper is organized as follows. In Section 2 the detection method and system setup design are presented along with details of the electronics and software for the controller. Cost considerations are also briefly discussed here. Section 3 details the results of imaging in constant force mode under feedback control along with discussions. Section 4 concludes thepaper.