drum lens

optics

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Last updated

June 25, 2026

Quick Summary

The term "drum lens" in optics refers to a type of lighthouse lens developed in 1836 by William Cookson. This lens is cylindrical in shape and concentrates light into an all-around fan beam. While not as efficient as rectangular Fresnel lenses, drum lenses provide a steady, consistent light source.

Modern drum lenses are often made from plastic, making them lighter and more affordable than their glass predecessors. They are commonly used in buoys and beacons, where their compact size and robustness are advantageous. These smaller drum lenses often eliminate the need for rotating mechanisms, with their lights being flashed on and off electronically.1

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Rectangular and drum lenses
…principle by producing a cylindrical drum lens, which concentrated the light into an all-around fan beam. Although not as efficient as the rectangular panel, it provided a steady, all-around light. Small drum lenses, robust and compact, are widely used today for buoy and beacon work, eliminating the complication of a…
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…principle by producing a cylindrical drum lens, which concentrated the light into an all-around fan beam. Although not as efficient as the rectangular panel, it provided a steady, all-around light. Small drum lenses, robust and compact, are widely used today for buoy and beacon work, eliminating the complication of a…
Read More