A Capstone Design Project Based on Optical Frequency Domain Reflectometry (OFDR): A Comprehensive Undergraduate Research Project

This research-to-practice paper presents a novel capstone project for electrical and computer engineering students. It encompasses a broad range of electrical and computer engineering, including lasers and fiber optics, signal processing, analog circuit design, python programming, metrology and measurement uncertainty, and remote instrument control using GPIB and/or LAN. This broad range of topics gave the students an excellent opportunity to demonstrate, expand, and solidify the knowledge and skills from their undergraduate coursework. In addition, it also introduced the students to undergraduate engineering research. Prior publications on undergraduate research have demonstrated that it is invaluable to student self-efficacy and future success. However, prior publications on undergraduate research have also demonstrated the challenges of inexperience, short time frames, and limited resources, which are often exacerbated by the limited research resources available at a teaching-focused institution. Another challenge is the lack of technical elective experience: students usually take most of their technical elective coursework immediately prior to graduation, and limited resource require that most institutions must rotate which technical elective courses are offered in each semester. Both factors make it unlikely that undergraduate students will have had the opportunity to take the relevant technical electives prior to embarking on their undergraduate research. In this work, those challenges were overcome using a combination of regular one-on-one faculty mentorship and independent study by the students, as recommended by prior publications on undergraduate research. Additionally, the project was shaped and informed by many years of faculty experience as a Research U ndergraduate Experience (REU) mentor to a large number of undergraduate students at a major national lab. In this project, students started with a comprehensive literature search to understand the state-of-the art in the field. The students had prior experience in literature searches for many of their courses, but this was the first time they had taken that information and incorporated into their own research project. The students created software to control the laser, and they designed, tested, and built detection and filtering circuitry. Additionally, the students implemented their knowledge of signal processing to convert the measured frequency-domain data to time-domain information. Finally, the students determined the uncertainty of their measurements by comparing measurements of a microscope slide to a standard reference (a physical caliper measurement). Although this project used an expensive tunable laser, that is not strictly required to implement this project, and this paper will also present ideas for a similar project implementation with inexpensive, commonly-available components, such as a white light source and smartphone camera.