1.

INTRODUCTION

In College of Optical Science and Engineering, Zhejiang University, the curriculum includes the following modules: general education courses, professional education courses, personality courses, practice courses and other courses. Applied Optics, Applied Optics Lab and Computer Aided Optical System Design ^[1] belong to the series of courses in the fields of geometrical optics and optical system design. The undergraduate students who have studied the knowledge of geometrical optics, principles of classical optical systems and aberrations in spring-summer semester will have an engineering practice training in two weeks in summer vocation. How to design the practice training to let the students combine what they have learned, to build engineering idea, and to understand the procedure of optical design, there were what we thought in many years.

In order to grow students’ abilities for solving optical design problems independently by using their knowledge of related fields, the students will learn to develop simple software with the functions of ray tracing and aberration calculating as programmers, to understand the principles of optimization design on optical systems, and will use optical software to design a photographic lens as designers. It is very important for the students to become optical designer.

Before 2015, we offered Computer Aided Optical System Design course in the autumn-winter semester. This practice course lasted for 8 weeks in that time. Although every week we had only one afternoon or 4 hours, but the students have much time to continue their work after class. Since 2016, the time of this practice course has been moved to the short term in summer, and lasts only 10 workdays. In 2017, ITMO University reported educational programs in optical design and engineering oriented for different background level, “such are: introduction into optical engineering, introduction into applied and computer optics, Optical system design, Image modeling and processing, Design of optical devices and components.”^[2] This program lasts 4 weeks. Undoubtedly, the period of 10 workday gives us a great challenge. In this paper the teaching design, difficulties and strategies are presented.

2.

PROJECT-BASED TEACHING DESIGN

3.

DIFFICULTIES AND STRATEGIES

For the students, this practice course means a new learning model, and some difficulties have been appeared in the implementation process, mainly in the following:

1. The period is only 2 weeks, and the task is challenging and not experienced for the students

At the beginning, over 40% of the students feel difficult. In order to help them to complete the task, we establish the minimum standards. We give outstanding students the space to show their abilities, and enable most students to complete the practice. The program design requires cooperation of every student in one group, and each student must at least design a lens that meets the technical requirements. Our goal is mainly to let the students experience the whole process of optical design by cooperation. Every year, the difficulty of the task is controlled by the instructors, and the task is decided in such way, that is the students can complete the practice by efforts. There are 4 or 5 instructors and 2 teaching assistants for about 120 students. If any students are in great trouble, instructors and teaching assistants will help them and teach them step by step. In Figure 1, a professor is teaching the students how to design an optical system. In Figure 2, an instructor and 2 teaching assistants are showing how to draw optical system and optical elements.

Figure 1.

Professor Zhaofeng Cen is instructing students to design their optical systems.

Figure 2.

A instructor and two teaching assistant are demonstrate the method of drawing (from left to right in front row: teaching assistant Minli Chen, teaching assistant Anqi Jiang, instructor and engineer Lingying Jiang; back row: 5 students).

2. Some students underestimate the difficulties. In the first few days they do not hurry, and in the following days they work from day to night

This is not a good learning habit. So every year we implement the practice project according to the following practice plan in Table 1. The students must complete the work at each time node, or they will lose some of their score. This helps these students complete the practice successfully.

Table 1.

Practice plan

As shown in table 1, the whole period of the course is divided into 6 stages. Every stage needs one to three days. The instructors check the achievements of each student group at the end of the 2rd to 5th stage. This plan improves the abilities of time management of the students, and actually they can finish their work on time. Figure 3 shows two interfaces of the software developed by a student group within 3 days.

Figure 3.

The interfaces of the software developed by a student group (a) input interface (b) spherical aberration curve

4.

PLURALISTIC EVALUATION SYSTEM

As the project includes several parts with different requirements, a pluralistic evaluation system is needed. Our evaluation system consists of four parts: software development, optical system design, optical system and element drawing, report presentation and defense. This evaluation system shown in Table 1 has been implemented more than 10 years, and now the percentage of each part has been changed gradually to a reasonable value that is approved by the instructors and students according to our poll each year.

In the last day of the practice term, every student group will present the design result in our class. After the defense, the other groups will give the score of this group in each item in Table 2. Finally the highest score and the lowest score are deleted, and the average score is calculated as shown in Figure 4. After the instructors has reviewed the design reports, the scores of all the student group will be given. Then the group leader will assign the score to the group members in accordance with their contributions in the project.

Figure 4.

The student groups are scoring each other

Table 2.

Pluralistic evaluation system

This pluralistic evaluation system has implemented for many years, and reviewing of the reports of the whole class and the daily record of the practice term indicates that the evaluation system keeps the students’ to get their scores in justice.

5.

CONCLUSION

This practice course has become a comprehensive training in growing the abilities of our students, includes not only theoretical courses, software development, optical system design, drawings, design reports and defense, but also a very good training in leadership, cooperation spirit, and the ability to complete work in a short period.

This practice is both competitive and cooperative, and is named by the students as “the most memorable short semester”. Most of the students are satisfied with their experiences in the short period. The following are some feelings and experiences of the students in their reports:

“I am very like this course. It is a process of independent learning. Teachers help us very kindly and answer my questions timely. We have a large space for personal promotion.”

“This design task drives us to think more about how to divide our work and how we can maximize everyone’s capabilities when completing projects in the future.”

“In this short semester we have learned a lot of professional knowledge. The practice opens the door of optical engineering for us, not only let us see what the future work is like, but also let me recognize the sense of life. These days, though bitter, but the bitter is worth! Hope that in the future I can correct shortcomings and improve myself.”

“This practice gives us a sense of accomplishment and the joy of beyond words. On the other hand, the tasks not only integrate the knowledge I have learned, but also greatly stimulate my enthusiasm for learning. Now I recognize the pleasure of being an engineering student.”

“I believe this course is an unforgettable experience for everyone in our group. We worked together to complete an optical software that we never thought we would complete, and completed a lens design. It is hot this summer, and the sense of accomplishment is also exciting. Thank you very much to my team members, as well as to the teachers and teaching assistants who have been very helpful during the course. I believe this experience will bring great help in our learning and working in future.”