What is the difference between a Fresnel lens and a convex lens?

A Fresnel lens, also known as a ribbed lens, is typically a thin sheet molded from polyolefin materials; glass versions are also available. One side of the lens surface is smooth, while the other is engraved with concentric circles that gradually increase in diameter. The lens’s surface texture is designed based on the principles of light interference and diffraction, as well as specific requirements for relative sensitivity and acceptance angle.

A Fresnel lens, also known as a ribbed lens, is typically a thin sheet molded from polyolefin materials; glass versions are also available. One side of the lens surface is smooth, while the other is engraved with concentric circles of gradually increasing diameter. The lens’s surface texture is designed based on the principles of light interference and diffraction, as well as specific requirements for relative sensitivity and acceptance angle.

When a conventional convex lens is used, the edges and corners tend to appear dimmer and blurrier. This is because light refraction occurs only at the interface between different media; in a thick convex lens, the portion of the light that travels in a straight line through the glass leads to attenuation. If the straight-line propagation segment could be eliminated and only the refracting curved surface retained, substantial material could be saved while still achieving the same focusing effect. Fresnel lenses operate on precisely this principle. Although they look like a piece of glass etched with countless concentric rings—known as Fresnel zones—they deliver the same optical performance as a conventional convex lens. When the incident light is collimated, the lens can focus it so that the brightness remains uniform across the entire image.

Key words:

Fresnel lens,Threaded lens