Journal for Geometry and Graphics 29 (2025), No. 2, 255--265
Copyright by the authors licensed under CC BY SA 4.0
Self-Image Multiplicity in a Concave Cylindrical Mirror
Thach A. Nguyen
University of South Florida, Tampa, U.S.A.
thachn@usf.edu
Kaitlyn S. Yasumura
Scripps College, Claremont, U.S.A.
kyasumur1040@scrippscollege.edu
Duy V. Tran
University of Technology, Ho Chi Minh City, Vietnam
duy.tran0null@hcmut.edu.vn
Trung V. Phan
Scripps and Pitzer Colleges, Claremont Colleges Consortium, Claremont, U.S.A.
tphan@natsci.claremont.edu
Concave mirrors are fundamental optical elements, yet some easily observed behaviors, such as the formation of multiple reflected images, are rarely addressed in standard textbooks. Here we investigate self-imaging -- where the observer is also the observed object -- using a concave cylindrical mirror. We predict the number of self-images visible from different observation points and classify the observation space into regions by image count. We then test these predictions with an inexpensive stainless-steel concave cylindrical mirror commonly found in teaching labs. This activity links geometrical optics principles to direct observation and provides a ready-to-use classroom demonstration and student exercise.
Keywords: Geometrical optics, reflections, image formation, optics education.
MSC: 78A05
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