Brian Bowe

White light interferometric surface profiler

We describe an optical system for 3-D profilometry based on the white light interferometer. Recently many different methods have been used to analyze the data obtained from white light interferometric profilers. Many commercially available white light profilers are also in use today. We detail a simple way to construct a profiler that uses two simple and efficient algorithms. It deals with the data in a fast and simple man- ner, thus reducing both the acquisition and analysis time. The system has a theoretically unlimited range and can profile both optically rough and smooth surfaces.

Dual in-plane electronic speckle pattern interferometry system with electro-optical switching and phase shifting

A dual in-plane electronic speckle pattern interferometry (ESPI) system has been developed for in situ measurements. The optical setup is described here. The system uses an electro-optical switch to change between the illumination directions for x and y sensitivity. The ability of the electro-optic device to change the polarization of the laser light forms the basis of this switch. The electro-optic device is a liquid-crystal layer cemented between two optically flat glass plates. An electric field can be set up across the layer by application of a voltage to electrodes. The speckle interferometry system incorporates two additional liquid-crystal devices to facilitate phase shifting, and the overall system is controlled by advanced software, which allows switching between the two perpendicular planes in quasi real time. The fact that there are no moving parts is an advantage in any ESPI system for which mechanical stability is vital.

Core Skills Assessment to Improve Mathematical Competency.

Many engineering undergraduates begin third-level education with significant deficiencies in their core mathematical skills. Every year, in the Dublin Institute of Technology, a diagnostic test is given to incoming first-year students, consistently revealing problems in basic mathematics. It is difficult to motivate students to address these problems; instead, they struggle through their degree, carrying a serious handicap of poor core mathematical skills, as confirmed by exploratory testing of final year students. In order to improve these skills, a pilot project was set up in which a ‘module’ in core mathematics was developed. The course material was basic, but 90% or higher was required to pass. Students were allowed to repeat this module throughout the year by completing an automated examination on WebCT populated by a question bank. Subsequent to the success of this pilot with third-year mechanical engineering students, the project was extended to five different engineering programmes, across three different year-groups. Full results and analysis of this project are presented, including responses to interviews carried out with a selection of the students involved.

Least squares algorithm for rapid analysis of Fabry-Perot fringe patterns

Accurate measurement and analysis of Fabry–Perot fringe patterns is essential in many areas of optical metrology. This paper presents a least squares, two dimensional method of interferogram acquisition and fringe analysis, which ensures highly accurate results together with rapid measurement. An experimental implementation is also described, using a conventional CCD camera to image fringes, demonstrating a measurement bandwidth of 25 Hz, and an estimated phase measurement accuracy of δ = ± (5 × 10−4).

An investigation of introductory physics students' approaches to problem solving

Abstract This paper outlines ongoing research investigating students’ approaches to quantitative and qualitative problem solving in physics. This is an empirical study, which was conducted using a phenomenographic approach to analyse and interpret data from individual semi-structured interviews with students from introductory physics courses. The result of the study thus far is a preliminary set of hierarchical categories that describe the students’ problem-solving approaches when faced with various physics problems. The findings from the research presented here indicate that many introductory students in higher education do not approach problem solving in a strategic manner and many do not try to link or use their physics knowledge in order to solve problems. Introduction In recent years two of the most significant drivers leading to transformations in science education have been education research and changes in student profile. The changes in student profile stem from mass education, dramatic changes in information technology and the decline of student numbers in science education (Institute of Physics 2002). These factors have led science educators in higher education to not only take a critical look at what is being taught but also how this is being taught. Therefore in the last thirty years the importance and need for science education research has led to the development of many research groups and projects undertaken to get a better understanding of how students learn and how educators can help students learn and develop. Education research, where the emphasis is on theory and practice, had already shown the importance of student-centred and lifelong learning, which has led to a paradigm shift in higher education. Science education research, where the emphasis is on how students learn and develop understanding was largely ignored among science educators for many years. In 2001 the School of Physics in the Dublin Institute of Technology set up the Physics Education Research Group to carry out research to inform curriculum development, teaching and assessment practices. Physics education research of student understanding in physics indicates that certain naive conceptions about the physical world are common among students entering higher-level education (Clement 1982; McDermott 1991; Hake 1998 Knight 2002; McDermott and Redish 1999). Research also shows there is often little or no change in conceptual understanding before and after formal instruction and that students are unable to apply the concepts that they have studied to the task of solving quantitative problems. It is widely accepted that physics graduates are required to be adept problem-solvers with the ability to conceptualise and transfer their understanding and knowledge, but research has shown that many students are not developing the necessary conceptual understanding (Van Heuvelen 1991). Some research has found that students cannot develop as problem-solvers without first

A Strategy for the Development of Lifelong Learning and Personal Skills throughout an Undergraduate Engineering Programme

For many years engineering programmes have placed a stronger emphasis on the development of technical knowledge, understanding and skills at the expense of personal skills such as initiative, creativity, communication, teamwork and lifelong self-directed learning. Recent changes in accreditation criteria call for greater competences in these skills to be achieved in the undergraduate programme. An argument is presented that this requires a change from the traditional approach to engineering education to a group-based project driven one as this is compatible with concurrent development of both technical and non-technical learning outcomes. Just as a clear path of progression exists from the fundamentals of science in stage one to the advanced engineering content in the final year so too should personal skills be developed in a progressive structured way. This paper presents a strategy that is currently being developed and implemented in the School of Electrical Engineering Systems in the Dublin Institute of Technology in a four year Bachelor of Engineering programme. In the group-based project-driven approach students practice communication and team work skills not in isolation to but integrated with the programmes technical content. The early stages of the programme focus on strongly developing the group learning process and introducing students to a reflective practice so they can observe and improve performance. Tutor observation fades in later years as students become more adept at managing group work and self-directed learning. This strategy is designed to progressively change a dependent freshman student into an independent graduate who is prepared for the challenges ahead.

Modernization of the Hilger & Watts gauge-block interferometer

The Hilger & Watts gauge-block interferometer was designed and manufactured commercially in the 1950s. The instrument uses isotope lamps as wavelength standards to perform absolute length calibration of gauge blocks (slip gauges) up to 100 mm in length, to an accuracy of approximately 1 ppm. It is entirely manually operated. In order to make the instrument more suitable for the modern laboratory, new hardware has been added, and a customized software package developed to automate the measurement process. This paper shows how interferograms may be imaged successfully at each of the eight available wavelengths, and the critical fringe fraction measurement automated, ensuring an accuracy better than ±0.05 fringe. To demonstrate the validity of the new system, representative data are presented alongside data obtained using the traditional method and from an external accredited laboratory.

Problem-based learning: an approach to enhancing learning and understanding of optics for first-year students

In this paper a model for the implementation of a problem-based learning (PBL) course for a typical year physics one programme is described. Reference is made to how PBL has been implemented in relation to geometrical and physical optics. PBL derives from the theory that learning is an active process in which the learner constructs new knowledge on the basis of current knowledge, unlike traditional teaching practices in higher education, where the emphasis is on the transmission of factual knowledge. The course consists of a set of optics related real life problems that are carefully constructed to meet specified learning outcomes. The students, working in groups, encounter these problem-solving situations and are facilitated to produce a solution. The PBL course promotes student engagement in order to achieve higher levels of cognitive learning. Evaluation of the course indicates that the students adopt a deep learning approach and that they attain a thorough understanding of the subject instead of the superficial understanding associated with surface learning. The methodology also helps students to develop metacognitive skills. Another outcome of this teaching methodology is the development of key skills such as the ability to work in a group and to communicate, and present, information effectively.

Investigation of the relationship between conceptual understanding and quantitative problem-solving in optics

This study outlines ongoing research within the area of physics education, namely the investigation of the relationship between conceptual understanding and quantitative problem-solving. Industry, society and research need graduates to be excellent problem solvers with an ability to conceptualise and transfer their understanding and knowledge. However recent research has shown that physics students are not developing the conceptual understanding necessary to become adept problem-solvers. Physics education tends to rely on the assumption that students will develop an understanding of the conceptual nature of physics by solving quantitative problems. Research has shown that this is not the case and students cannot develop as problem-solvers without first having the conceptual understanding. Many of these physics graduates go on to work in optics, in areas such as nanotechnology, photonics fabrication and optical sensing. This research involves an investigation of student learning in physics and the impact this has on conceptual understanding and their ability to solve quantitative and qualitative problems. It builds on research carried out in the United States in order to obtain a better understanding of how students learn physics and the difficulties they have developing an understanding of the conceptual nature of physics. It aims to develop a systematic way of identifying students’ misconceptions in physics and to assess the affect these have on student learning and the development of understanding. This research will inform teaching and assessment practices, not only in physics education but also in other disciplines so that third level education can produce better problem-solvers for industry, research and a knowledge-based society.

Holographic optical elements for combined holographic and digital speckle pattern interferometry

Holographically recorded diffractive optical elements are described, which can be used to implement very simple self-aligning electronic speckle pattern interferometers (ESPI) and holographic interferometers requiring only a laser source and a CCD camera in the optical set-up. The ESPI systems can utilize transmission or reflection holographic optical elements (HOEs). The HOEs are essentially amplitude beamsplitters and recombiners whose recording and reconstruction parameters can be adjusted to optimize the ratio of reference and object beams reconstruction so as to maximize subtraction fringe contrast. The HOEs are recorded using a 4-component photopolymer system. In addition the HOEs can be recorded at visible wavelengths but used in ESPI systems, which incorporate at diode laser. The diode can be wavelength modulated. In this way we can incorporate digital speckle pattern interferometry (DSPI) or amplitude and phase modulation of the optical path difference for time-averaged speckle interferometry.