Great lens for survival kits. x5 magnification
What is Fresnel Lens
The Fresnel lens was invented by French physicist Augustine Fresnel, the Augustin Fresnel first used this lens design to build a glass Fresnel lens - lighthouse lens in 1822.
The Fresnel lens is a thin, flat optical lens which consists of a series of small narrow concentric grooves on the surface of a lightweight plastic sheet in order to reduce the thickness, weight and cost. Each groove is at a slightly different angle than the next and with the same focal length in order to focus the light toward a central focal point. Every groove can be considered as an individual small lens to bend parallel Fresnel light waves and focus the light. The lens actually eliminates some spherical aberration.
The Fresnel lens is a special optical lens. It can now be made from plastic such as acrylic fresnel lens, PMMA, polyvinyl cholride (PVC), polycarbonate (PC) and HDPE. A traditional glass convex lens would be thick, heavy and very expensive, but a plastic Fresnel lens is a thin, flat, lightweight and low cost alternative.
A high groove density has a better quality projection image. The Fresnel lens is a good solution for quality image and efficiency at a significantly lower cost. The Fresnel lens is usually corrected for spherical aberration.
Size: 52mm x 82mm
Groove pitch: 0.2mm
Focal length: 160mm