Linear Fresnel lens
Linear Fresnel lens
Fresnel lenses are light compared to generic lenses. The Fresnel lenses have 3 merits. Maximum lens size is 1800* 1500mm for sheet type and 1520mm width for Film type can be produced indefinitely. Sheet type thickness is 0.4mm to 10mm. Film is a water um. Therefore, the weight of the lens is very light and it is more economical when mass-producing products than optical glass.
Precautions when manufaturing
- Specification design suitable for intended use (Thickness, Focal distance)
- Material quality selection
- Fresnel quality management (Pitch value, Osteoplastic type, Center level of completioin)
Fresnel Factory has various application experiences ranging from optical design, mold design, and fabrication of Fresnel lens. Links to optical and mold design, fabrication design and tooling
The Fresnel lens is an optical component of continuous concentric grooves etched in plastic. Thin and light, available in small and large sizes, for a wide variety of applications with excellent light collection. Frennel lenses are most commonly used for light collection applications such as condenser systems and emitter/detector setup. In addition, in lighting systems and image forming applications, it can be used like a magnifying glass or projection lens.
Frennel lenses are a replacement of the curved surface of conventional optical lenses with a series of concentric grooves. This appearance acts like an individual refractive plane, bending parallel light to a typical focal length (Figure 1). As a result, even though the lens is physically narrow, it can focus light similarly to conventional optical lenses, giving it more advantages over thicker similar lenses.
Figure 1: Fresnel lens profile
Fresnel Lens Theory
Behind the concept of the Fresnel lens is the driving principle that the direction of light propagation does not change within the medium (unless scattered). Instead, light only deviates from the surface of the medium. As a result, most materials at the center of the lens will only serve to increase weight and absorbance in the system.
To utilize such a physical attribute, physicists from 18th century started to work on creating optical components what is now known as Fresnel lens today. At that time, to make the profile of the curved surface ring, you had to cut the grooves into pieces of glass. The profiles of these curves form conventional spherical lenses, either spherical or non-spherical, through extrusion (Figure 2). Optical properties similar to conventional optical lenses can provide slightly improved focusing performance depending on the application. In addition, a higher density of the grooves produces a better image of quality, whereas a lower density of the grooves provides better efficiency (required for light applications). Nevertheless, if high-precision imaging is required, it should be noted that conventional single, dual, or non-spherical optical lenses are still best suited.
Figure 2: Plano-Convex (PCX) Lens vs. Fresnel Lens side profile comparison
French physicist Augustin-Jean Fresnel (1788-1827) was not a pioneer of Fresnel lens’ concept, however, he did demonstrate an ability to popularize it by combining Fresnel lens to a lighthouse. Since then, we have been able to use Fresnel lenses in a wide range of applications ranging from light collimation and light collection to zooming. Easy to collate – on the Finite-conjugate system, the grooves face of the Fresnel lens must face the longer conjugate (Figures 3 - 4) for best performance.
Figure 3: Demonstrating light from a light source using a Fresnel lens.
Cohesion of light
One of the applications that utilize the Fresnel lens the most is the light collection of sunlight, which is almost like an infinite-conjugate system. The light collection lens is ideally used to condense light onto the photovoltaic cells or to heat the surface. For example, you can use a Fresnel lens for home use, such as heating a home or heating a swimming pool. In this case, the amount of light collected is determined by the overall surface of the lens.
Figure 4: Concentrating the light of a collimated light source using a Fresnel lens.