Optical Engineering II

Miniaturized Optical system engineering

With the increasing amount of material which must be taught during a university degree course, the time for laboratory courses often becomes too short. Hence the newly implemented laboratory course contains different elements: Ex. cathedra and practical work. The basic idea is to discuss applications and to realize simple measurement setups in the classroom. Such a course concept is challenging and needs careful preparation. The advantage is that students have the possibility to see the theory applied to a practical application. The main objective is to familiarize the student with basic design and manufacturing problems in realizing miniaturized optical systems. A theoretical introduction is followed by experiments and analysis of the results in form of a report to be delivered by the students. A modular experimental system is used that contains basic optical components and serves as experimental kit. The design of the experiments to fit into a short time slot of only 3-5 h was most challenging. The outcome are students that gather practical experience on subjects in optical micro-engineering which would not be accessible elsewhere and difficult to teach without “hands on”. An important aspect is the link between measurements and its evaluation by suitable software. We used MATLAB as the standard software within the course and all results were analyzed with MATLAB scripts that were provided to the students. Beside the theoretical and practical part there was always an analysis part based on software use. Students were familiarized with basic features of the software and whenever possible methods to improve measurement quality by software treatment (averaging for example) were introduced to show the link between these two parts of an experiment. 
Course content
The general topic of “Design and technology of miniaturized optical systems” is taught in 6 subjects:
Objectives and keywords
Introduction, Imaging
Collimation and focussing, Magnification
Laser beam collimation, minimal focus, Basic imaging equation, focal length measurement, F# number
Detector noise
Electronic noise
Noise influence: gain and exposure, full field, edge
Focalization of different sources, solid angle, spectral properties
Multimode fibres
Fibre optics
Skewed rays, NA measurement and coupling
Monomode fibres
Fibre optics, Modes
NA measurement, Visualization of modes, Compare the coupling for different sources
Pinhole camera
Resolution, MTF and contrast, intensity over the field
Spectral analysis
Grating spectrometer setup (compact disk grating), calibration (colour edge filter), LED measurement
Michelson interferometer alignment, fringe contrast and spectral width (coherence), phase shifting interferometry
Speckle sensor
Spatial noise
Speckles, autocorrelation, motion sensor, crosscorrelation
Microlens imaging, field curvature, distortion and chromatic aberrations, aberration corrections
Diffractive optics and FFT (Digital holography)
Diffraction and propagation
Diffraction at different objects (pinhole, slit, square ), Grating diffraction, Simulation of diffraction patterns via FFT
Wavefront analysis
Microlens imaging, Shack Hartman sensor, wavefront measurement



Didactical principle of the course

Students have to be educated in theoretical and practical matters. Only one of them does not allow attacking complex problems in research, development, and management. After their study students should be able to design, construct and analyze technical problems at highest levels. Who never experienced the difficulty of setting up measurements will not be able to understand, plan and manage such complex tasks in future careers. The course was given to beginners in the field with a very inhomogeneous background. Two aspects had to be considered – strengthen their fundamental knowledge on system design and allow hands on to “see” and “feel” the optical effects and their specific sensibilities. The course was based on concrete actions (enactive) to be done by the students, a synthesis of their work by writing a report (considered as the iconic part) and inputs from the teacher to generalize the findings and link it to a possible complete abstract description (symbolic). Intensive tutoring allowed an intermodal transfer between these categories

Course format
Twelve subjects were taught in lectures and practical work.
• Introductory lecture of 15 min
• Practical work of 120 min
• Groups of two students
• Report of 5-8 pages from each group of students for each subject
• Personal feedback to each students on report results
• Language of instruction: English

Didactical material and scripts
A set of opto-mechanical components was specifically designed for beginners without particular pre-knowledge.


Laboratory set of opto-mechanical components which were provided to the students to conduct the individual experiments.
Scripts of 20-30 pages were distributed to the students for each subject. Each script chapter contained the following information:
 • Introduction and description of the technical basics
• Detailed description of work with illustrations
• Summary of tasks to accomplish
• Preparatory and final questions
Documentation: Copies in English


Grading of student’s performance

The evaluation of the student’s performance during the course was based on reports. One report per group is delivered and corrected. A personalized debriefing in is given to each group after report correction.

Responsible teacher: Toralf SCHARF