Fresnel Lens

DCS Code: 6A65.70 Last Updated: March 27, 2026
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Purpose

Show how Fresnel lenses use concentric grooves to achieve the focusing power of a conventional thick lens with drastically reduced thickness and weight. Students examine the groove structure and verify focal lengths using standard image formation.

Large octagonal Fresnel lens propped upright and smaller square Fresnel lens lying flat, with a wooden ruler and small white cube for scale
Figure 1: Large octagonal Fresnel lens (f ≈ 70 cm) and smaller square overhead-projector Fresnel lens (f ≈ 30 cm). Concentric groove structure is visible on both.