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Flat Lenses Formed by Photonic and Electromagnetic Crystals
Published in Filippo Capolino, Applications of Metamaterials, 2017
Pavel A. Belov, Constantin R. Simovski, Pekka Ikonen
In 1972, R. Silin in [29] theoretically revealed the all-angle negative refraction in periodic artificial lattices of holes in the high-ε material at microwaves (following to the modern terminology this effect refers to electromagnetic crystals). This idea was later developed in papers [30,31], where the flat aberrationless lenses were discussed for the optical range (i.e., for photonic crystals). Though these results of Radio Engineer Silin did not attract much attention of opticians, they were, in fact, very important for the integrated optics. Usual concave and convex lenses are evidently not applicable in this branch of optical engineering that allows only low-profile (as flat as possible) and thin (compared to the transverse size) lenses. Such lenses were invented by Fresnel in the beginning of nineteenth century. As a rule, one surface of the Fresnel lens is flat, and the other one is corrugated (not periodically). The shape of these corrugations is quite complex and they have sharp edges. Though these lenses are widely used in the integrated optics, they have serious shorts. The main shorts are the high aberration level and very high optical losses both associated with the morphology of corrugations. The strong parasitic scattering implies the great optical imprecision. These drawbacks together with the high cost limit the use of Fresnels lenses considerably. Therefore, aberrationless lenses with higher optical quality (and the same cost) are a very prospective alternative to Fresnel lenses even today. Moreover, it was so in 1970s.
Lenses
Published in Abdul Al-Azzawi, Photonics, 2017
A Fresnel lens replaces the curved surface of a conventional lens with a series of concentric grooves molded into the surface of a thin, lightweight glass or plastic sheet, as shown in Figure 10.15. The grooves act as individual refracting surfaces, like tiny prisms, when viewed in cross section, bending parallel rays in a very close approximation to a common focal length. Because the lens is thin, very little light is lost by absorption compared to conventional lenses. Fresnel lenses are a compromise between efficiency and image quality. High groove density allows higher quality images (as needed in projection), while low groove density yields better efficiency (as needed in light gathering applications). Fresnel lenses are most often used in light gathering applications, such as condenser systems or emitter/detector setups. Fresnel lenses can also be used as magnifiers or projection lenses.
Optofluidic devices and their applications
Published in Guangya Zhou, Chengkuo Lee, Optical MEMS, Nanophotonics, and Their Applications, 2017
Figure 14.18a shows a bulk lens where light refracts only at the surface of a bulk lens and the lens material in the middle (shown in the darker color) makes no contribution to the steering of incoming light. Thus, a bulk lens can be broken down into smaller subsections, where the curved surfaces in each section are replaced with flat surfaces of varying angles (Figure 14.18b). As a result, a Fresnel lens significantly reduces the lens material and cost, while offering a large aperture size. However, since conventional Fresnel lenses are made from solid materials (e.g., glass or plastic), their optical performance, such as a focal length, is fixed once the lens material and geometry has been designed. To provide a degree of tunability for a Fresnel lens, Park's group proposed an arrayed form of the liquid prisms where each prism is individually controlled by electrowetting to replicate the subsections of a solid Fresnel lens [84]. The set of discontinuous prisms in a Fresnel lens steers light through steep prism angles at the edges and incrementally smaller angles for intermediate prisms (see Figure 14.18c). By individually controlling each prism using electrowetting, they have achieved 3D focal control along the longitudinal (263 mm ≤ flong ≤ ∞) as well as the lateral (0 ≤ flat ≤ 30 mm) directions. The optofluidic tunable Fresnel lens presented here would become a leading technology in compact and tunable optical systems, with applications ranging from imaging and motion tracking to multicollector solar systems.
Investigation of effect of the Fresnel lens on the performance of the double slope single basin solar still
Published in International Journal of Ambient Energy, 2021
V. Sriram, Venkatesh Kondraganti, Charan Tejeswar Reddy Lokireddy, Jeya Jeevahan, G. Britto Joseph, R. B. Durai Raj, G. Mageshwaran
A Fresnel lens can capture more oblique light from a light source, thus allowing the light from a lighthouse equipped with one to be visible over greater distances. Fresnel lenses are usually made of glass or plastic; their size varies from large (old historical lighthouses, meter size) to medium (book-reading aids, OHP viewgraph projectors) to small. In many cases, they are very thin and flat, almost flexible, with thicknesses in the 1–5 mm (0.039–0.197 inch.) range. In this, the reading is initially taken by using contaminated water and therefore results are taken. After that the reading is taken by using industrial waste water. Two sets of reading are taken. Firstly, the readings are taken without the use of the Fresnel lens and hence its corresponding reading and graphs are made. Secondly, the readings are taken using the Fresnel lens (Figure 6).
Experimental investigation of a box-type solar cooker incorporated with Fresnel lens magnifier
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Gulsavin Guruprasad Engoor, S. Shanmugam, AR. Veerappan
A Fresnel lens is an optical component that can be used as a cost-effective, lightweight alternative to conventional continuous surface optics (Davis and Kühnlenz 2007). The Fresnel lenses are concentrating solar collectors that transmit energy to a line or a point. In normal case Fresnel lenses are fixed on a particular stand and the solar insolation falling on it is transmitted to the focus of the lens were the object that is to be heated is placed. Fresnel lenses are lightweight and low cost and have very high optical efficiency. These lenses can achieve very high concentration ratios (Haddock and Mckee 1991). The preeminent properties of Fresnel lens manufactured with PVC materials were stressed by (Oshida 1961), since these materials are highly economical and can be easily produced in large numbers. These lenses have the advantage of having density that is half of that of glass, ability to mold into any desired shape and size, high durability, and greater resistance to wear. The paper also discussed about the demerits of the lenses such as low heat retention capacity, scattering of light, etc. Investigations showed the output of the Fresnel lens in relation to its size had good performance and could be used for high-temperature applications (El-Ladan et al. 2013). Fresnel lens was employed in a solar integrated collector storage using phase change materials for heating domestic water (Senthil and Cheralathan 2012).
Experimental and theoretical analysis of thermoelectric energy generating system collecting concentrated solar energy
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Ali Murat Mahmat, Yavuz Köysal, Yusuf Yakut, Tahsin Atalay, Seyda Özbektaş
Fresnel lenses are produced as point type with very high concentration power or as linear type with less concentration power (Huang et al. 2021). Fresnel lenses have been used for a variety of applications and in a variety of fields, including optics, lighting, imaging, and aerospace. Fresnel lenses have an almost flat structure and their weight is negligible due to their material structure. On the other hand, they also act like spherical lenses. Solar concentrator Fresnel lenses are generally designed for Concentrating Photovoltaic (CPV) applications. Their configuration is designed to collect parallel light onto a line (Köysal, E, and Atalay 2018) or a spot (Köysal 2019). In the previous work with Fresnel lens (Atalay et al. 2022), the solar rays were concentrated on a copper surface and obtained thermal values provided the source for the thermoelectric generators to be used in electrical energy generation. One another work is belong to Ho et al. (2021). In their work, they used a Fresnel lens to control the light distribution in the 3D printing system they developed. With the system they developed two-layered woodpile structures were successfully fabricated in a very short time. Jumaily and Kaysi (Al-Jumaily and Al-Kaysi 1998) used two flat linear Fresnel lenses and two absorbers that are connected in series. They measured the efficiency of Fresnel lenses by mounting the system to a two-axis solar tracking system. Hussain et al. (Hussain, Ali, and Lee 2015) compared linear and spot-type Fresnel lenses in terms of performance used for greenhouse heating. Their systems were accompanied by a two-axis solar tracking system. They found that the spot-type Fresnel lens performed 7–12% more than the linear-type Fresnel lens. In the literature, there are large number of experimental (Huang et al. 2021; Köysal, E, and Atalay 2018) and theoretical studies (Moghimi, Craig, and Meyer 2015) with the Fresnel lenses.