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The Zoom Lens

A Case Study in Geometrical Optics


Alan Cheville
Department of Electrical Engineering
Bucknell University
Misa Scepanovic
Department of Electrical Engineering
Oklahoma State University


A motion picture company (circa 1950) is having problems with antiquated equipment. The director, actors, and crew all want the CEO of the company, who is notorious for being tight with money, to invest in a newly developed zoom lens. Students are asked to take the part of an engineering design team and design a zoom lens that meets certain specifications. They first write a proposal for the project, then build the lens in the lab.  The final activity is a written report with supporting data, models, and measurements.  The case was developed for use in an undergraduate laboratory course sequence in photonics for junior and senior level students.


  • To provide a means for students to apply basic principles of geometrical optics (refractive index, Huygen's, Fermat's, Fresnel's laws); images (formation, real vs. virtual); thin and thick lens equations; mirrors; imaging with multiple lens systems; magnification; ABCD matrix formalism; aberrations (causes, types, and effects; techniques for minimizing aberrations; aperture stops or pupils; and basic optical systems (telescopes and microscopes) to a real-world situation.
  • To create a relevant laboratory exercise to stimulate the students’ desire to learn.
  • To mimic the environment found in academic and industrial research laboratories in order to give the students a sense of what real research entails.
  • To provide exercises in teamwork and written communication.


Zoom lens; optics; Huygen's law; Fermat's law; Fresnel's law; aberration; aperture; image

Topical Areas


Educational Level

Undergraduate upper division



Type / Methods




Subject Headings

Electrical Engineering  |   Physics  |  

Date Posted


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