Abstract:

Typically, the Optics Subjects of Science degrees are structured in three types of lessons: theoretical lectures, problem classes, and practical experimentation. The laboratory practice sessions are an important complement to the theory given in class and help students to understand the fundamental concepts.

Since 1999 the European Higher Education Area has been promoting the implementation of innovative teaching methodologies based on the use of new technologies. However, the Covid-19 pandemic has speeded up the need of using digital technologies in all universities around the world. In particular, the preventive measures against the Covid-19 virus adopted at the University of Alicante substantially limit the performance of laboratory practices with large groups of students (of more than 50 students). For example, to perform traditional laboratory experiences by the high number of students in Geometrical Optics implies many difficulties because there are not available individual optical assemblies for each student in a large laboratory. The motivation of the present work is to find a new teaching methodology that allows the students to experiment with the modification of different parameters of some optical systems.

The proposed approach has consisted in the use of free software: the JOptics “Ray Tracing” applet. This applet allows the student to get an intuitive and robust understanding of optical systems in general. Part of the students receive on-site teaching and the rest of the students followed the class connected by videoconference with the teacher. All of them reproduced in their own computers the optical systems that the teacher was preparing and explaining. This new teaching methodology has made it possible to easily visualize fundamental optical concepts such as the focus of a light beam through different positive and negative lenses. Furthermore, it has made it possible to compare the Ray Tracing obtained by means of the paraxial approximation of geometrical optics versus the Ray Tracing obtained by an exact calculation. In this sense, paraxial on-axis and off-axis images have been compared with aberrated images. At the end of the session the software is used to reproduce the ray tracing through different optical instruments such as: telescope, microscope, a telephoto lens, or zoom. The position of the cardinal elements of each optical system and the beam limitation through them (entrance pupil, exit pupil and field diaphragm) was also shown.

The results of the implementation of this new methodology will be evaluated qualitatively with the satisfaction of the students and quantitatively evaluated through the analysis of the marks obtained by the students in the final theory exam and in the report performed by each student. Although it is true that the experience acquired in the Optics Laboratory allows the students to improve certain skills, hard to be replaced, such as: the good alignment of optical systems and good procedures to obtain accurate experimental measurements, in the concise case of the Degree in Physics with a limited teaching load in Optics, the introduction of these kinds of computer tools in their practice lessons can allow them to understand fundamental concepts of Optics quickly, easily, autonomously, and safely.

Keywords:

Optics, Covid-19, Virtual Laboratory, Optical Instruments.