Fresnel Lenses Theory

Fresnel Lenses Theory and Its Usage Today


The demand for energy is increasing exponentially over the world, while Fossil fuel reserves begin to deplete. To sustain development, the supply of energy continuously required. Finding new regenerative energy sources, such as biomass, geothermal energy, or solar energy, etc. and cannot deplete with time. Amongst all, solar energy is essential and fulfills the future needs of energy. Several developed technologies solar energy for domestic use like Fresnel lenses. Fresnel Lenses were actually for concentrating solar energy. The Fresnel lenses theory is not new, and its popularity is growing due to an increase in its applications and improvements in material and manufacturing techniques.

The invention of Fresnel Lenses

Fresnel lenses offer high optical efficiency with low cost and weight and us as solar concentrators. From the 1960s, the Fresnel lens concentrators are useful in solar energy. Due to this feature, the development of Fresnel lenses in commercial solar energy is still widespread and ongoing. That’s why its use is expanding rapidly, and found in highly sophisticated optical. Fresnel lenses solved many severe optical problems and introduced new designs consideration. Although the Fresnel lenses theory is not new, their popularity is growing due to improvements in material and manufacturing techniques.

Working Principle of Fresnel Lenses

The principle behind the Fresnel lenses’ concept is that the direction of propagated light, unless scattered, cannot change in the medium. Instead, the rays of light deviate at the surface of the medium. The material in the center of lenses only increases the weight and volume of the system. For creating annual rings of the curved profile, grooves are cut into the glass pieces, and on releasing becomes conventional. Due to this function, when conventional optical lenses compared to Fresnel lenses, Fresnel lenses offer better-focusing performance. Furthermore, higher groove density allows the more excellent image quality, while lower density provides better efficiency. 

frensel lens

Fresnel Lenses Making

Georges-Louis Leclerc de Buffon proposed the idea of Fresnel lenses in 1748. The approach was later adopted by Augustine-Jeans in 1827 and used in 1823 for the first time. Where the refraction occurs, it maintained the curved surface. Fresnel lenses made up of several concentric rings etched into the plastic. The thin and light-weighted construction of lenses is available in different sizes. Because of their ability to gather excellent light, there are useful in various applications. Fresnel lenses consist of simple lens elements, and concentric rings appropriately assembled on a flat surface to provide short focal lengths. Methods of designing Fresnel lenses are easy to process and have excellent optical performance. Fresnel Lenses Theory widely used.

How Are Fresnel Lenses Better than other lenses?

While comparing different lenses, observation reveals that the Fresnel lens is cheaper than any other lens and can be made with a considerable area. The circular section of the Fresnel lens has the same curved surface as the normal lens. But the correspondence present in the normal lens is removed from the Fresnel lens, to make the Fresnel lens flat. The focus point of every ring in the Fresnel lens is the same as the core of the ring in the normal lens. As a result, the Fresnel lens produces the same image as the normal lens created. Most of the area of Fresnel lenses can be made appropriately by plastic.

Uses and Advantages of Fresnel Lenses

Light Gathering Applications

Fresnel lenses are mostly useful for light gathering applications, emitter or detector setups, and condenser systems. Fresnel lenses are useful as image formulation, projection, or magnifier lenses in the illumination system. It is helpful for searchlights and lighthouses to concentrate light I relatively narrow beams. Because of the thickness and weight, large scale beacon lenses of solid glass are almost impossible to manufacture. The lightest Fresnel lenses usually polished and assembled from the appropriate glass.

Home Maintenance and Photovoltaic Cells

One of the most common uses of Fresnel lenses is the collection of Sunlight. Concentration with these lenses is ideal on the heating surface and photovoltaic cells. For instance, Fresnel lenses are used for home maintenance, such as pool and home heating, depending on the amount of collected light. Collection of light is common in all solar applications, but the Fresnel lenses are cheaper, thinner, and lightweight than others, so they are more suitable. Fresnel lenses are unique optical lenses, making it an ideal tool for providing a variety of optical designs.

fresnel-lenses-and its uses

Useful in Light Houses

Modern Fresnel lenses consist of refractive elements. Many of the lighthouses have both reflecting and refracting elements. The inner components are the sections of refraction, and the outer elements of sections are reflections. Because of the reflection of the silvered mirror, the internal reflection is useful for avoiding the light loss.

Cheaper in cost and lighter in weight

Fresnel lenses have many advantages, like reducing the lens thickness and reduce the material cost; similarly, the weight reduction results in less assembling and mounting expenses. High aperture lenses give high-value design freedom, and large diameter lenses (up to 50 “) can be replaceable with expensive conventional mirrors. Fresnel Lenses Theory widely used.

Useful in Overhead Projectors

Fresnel lenses are most useful at a specific distance, and when they are mostly aspheric. Every overhead projector (OHP) uses a large Fresnel lens to focus the light rays from a substage to collect the light through the flashed transparency. The Fresnel lens gives the same light on all areas, and the transparency directly sits on the Fresnel lens.


For magnification purposes

 Fresnel lenses can use anywhere that a large area shaft of insensitive quality is required, while the small size of the plastic, Fresnel lenses magnifies the area for reading the fine print, and they are much lighter than other kinds of the glass lens.

For the lighting system in TVs and Cameras

Fresnel lenses are of great use in lighthouses where no other optics give excellent performance. So, fresnel lenses have many applications like usage in traffic lights and TVs, photography with a compact camera, lightweight, and hand-held magnifier lenses. Fresnel Lenses Theory widely used.

For Making Good Quality Glasses

 It is also useful in glasses, Polyvinyl chloride (PVC) membrane commonly used to correct strabismus, eye condition, work as a high power lens. Also used for children with severe eye problems, because of lightweight it is suitable for children and adults. It can capture more light from the light source, and allow the light from the lighthouse over the greater distance. Fresnel Lenses Theory widely used.

Advantages of using Chlorine Gas for Disinfecting Water

Advantages of using Chlorine Gas for Disinfecting Water

In the 13th century, a chemist in Sweden named Carl Wilhelm Scheele prepared pure chlorine gas for the first time. He prepared the chlorine gas (Cl2) by simply heating manganese dioxide (MnO2) with hydrochloric acid (HCl). Sir Humphry Davy, in 1810 did some reactions of the chlorine and found that chlorine is an element as this gas cannot be separated. Based on the color of the gas that is yellowish-green, Davy named it chlorine derived from the Greek word “chloros” means yellow-greenish. Chlorine is present in the form of compounds everywhere, as it is very reactive. Usually, it combines with sodium, forming sodium chloride (table salt) that occurs as rock salt in the earth’s crust. Advantages of using chlorine gas discussed.

Properties of Chlorine

Chlorine is a very reactive element and quickly binds with other elements. The reaction property of the chlorine is just like other halogen elements as the halogens react with the metal to form the salt. So, in the periodic table, it is placed in the column of halogens (fluorine, bromine, iodine, and astatine. Each atom of chlorine contains 17 electrons moving around the nucleus within three shells. According to the rule, the innermost shell consists of 2 electrons.

The next contains 8 electrons, and the last shells contain 7 electrons. The outer shell has one electron less for making it stable, and thus the charge on chlorine is -1. For becoming stable, it makes a covalent bond with other chlorine atoms, thus making Cl2 or with any other element. Depending on the element with which it combines, it can make the most reactive substance like hydrochloric acid or most stable substance like sodium chloride (salt).

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Advantages of using chlorine gas discussed.

Uses of Chlorine

Chlorine has a significant role in the field of science. It is used as a component in many medicines. A large number of drugs that we use contain chlorine or made by the help of by-products that contain chlorine. It naturally occurs in the herbs that are useful for medical purposes. Chloroform (CHCl3) also contains chlorine, that is the medicine that is used for anesthesia purpose during surgery. In the chemical industry, there is also a high usage of chlorine. There are thousands of products manufactured in chemical industries that contain chlorine in them. Few products that contain chlorine are paints, anti-freezing agents, pesticides, and PVCs. A large amount of chlorine is used in papermaking that is the most popular product.

The invention of Water Chlorination

In 1990’s Centers for Disease Control and Prevention and Pan American Health Organization developed a system named Safe Water System. The development of the Safe Water System was due to the spread of cholera in Southern America. The treatment involves chlorination of water with dilute sodium chloride solution. The people were guided through adding one bottle cap of sodium hypochlorite solution in clean water filled in a sizeable standard-size container. Use this water for drinking purposes after 30 minutes to kill all the microorganisms.

Advantages of using chlorine gas discussed.

Chlorine as a disinfecting Agent

The concept of using disinfectants for health care purposes started in the 19th century when, for the first time, Luis Pasteur discovered that microorganisms cause many diseases and infections. Chlorine widely used as a disinfecting age all over the world. It deactivates the activity of pathogenic microorganisms. Before the discovery of chlorine, no one knows that the cause of the diseases are microorganisms. Chlorine deactivates the microbes and pathogens that are present in drinking water, swimming pools, and wastewater. Chlorine generally used for disinfecting houses and hospitals area for health care purposes. Dr. Oliver Wendel Holmes, in 1835 first time started the process that the midwives after the childbirth will wash their hands with hypochlorite to avoid midwives fever. Chlorine thus has a significant role in increasing the humans’ expected life period.

Advantages of using chlorine gas discussed.

Water Purification through Chlorination

During the water treatment process, chlorination can be done at any time. At every point of chlorination, chlorine removes different contaminants. Pre-chlorination a process in which the chlorine applied to the water just as the water entered the treatment facility. This first chlorine used directly to the raw water for removing algae and other aquatic organisms, so they will be removed from passing into the next stages. At the stage of pre-chlorination, the color and smell of the water removed, stop the organism’s growth in water.

Iron and manganese oxidized in the presence of chlorine and thus removed during sedimentation and filtering stages. Chlorination also done in the last stage of the water treatment process. At this stage, the chlorine added to disinfect the water and maintain the chlorine remain in the water so they can move to the distribution system. The chlorinated water is cheaper than any other water purification technique. The chlorination process requires less concentration of chlorine and less time to purify the water. For supporting the presence of chlorine residual in the distribution unit, the re-chlorination of water usually done. The re-chlorination process maintains the chlorine during the whole system of distribution.


Advantages of using chlorine gas discussed.

Increase in population and water demand

With the increase in population, the water demand has also increased. To cope with this water demand, recycling wastewater is becoming a necessity. Wastewater treatment plants work in the same as water purification plants. The most crucial process activated sludge process is to remove the organic waste. The chlorine required for wastewater treatment is in more meaningful content than the quantity of chlorine used for portable water purification. The number of pathogens and organic waste is higher in the wastewater; therefore, proper water purification plant design and proper operations required to make the purification very useful.

According to the World Health Organization (WHO), in the standard drinking water, 2 to 3 milligrams of chlorine is necessary for satisfying disinfection. The maximum level of the chlorine that can be used for the disinfection process is up to 5 milligrams per liter. Exceeding 5 milligrams becomes harmful, so in case more effective disinfection required, add the amount of free chlorine after 30 minutes at the pH below 8. Chlorine widely used as a disinfectant in almost all countries because of its low cost and disinfecting properties.

global warming and CO2 emission


Global warming and CO2 emission are serious issues. The gases present in the atmosphere acts as the blockage to the escaping infrared radiations. These radiations capturing gases can change the climate system. The atmospheric gases that capture radiations include; carbon dioxide (CO2), methane (CH4) and water vapors (H2O) mainly. In 1859, British scientist named Joseph Tyndall called these gases “greenhouse gases”. The greenhouse gases prevent the escape of harmful radiations that heat the earth surface. The heating process of earth is called global warming. The global warming results in the melting of glaciers, increase in rainfall, and increase in acidification level.

Climate Warming During Cretaceous

According to geological time scale variations in the amount of atmospheric CO2 is the root cause of climate change. On a geological timescale, the carbon cycle regulates the atmospheric CO2 from more than the last 106 years. The carbon cycle is caused by geological processes. Processes like weathering of silicates, precipitation of carbonate rocks, mantle degassing, and many others. During Phanerozoic, the era, the period of middle to late Cretaceous is known as the warmest period.

global warming and polar bear
High resolution digital image depicting a single, sad, dirty polar bear, floating on a dwindling chunk of ice, in the center of vast ocean garbage patch. Image is intended to illustrate themes like environmental degredation, ocean pollution, habitat loss, global warming, and climate change in general.

The global temperature at that time was 60C greater than today. Anoxic oceans that are warmer supported the burial of organic carbon, with no polar ice in that period due to extremely high temperatures. In the Cretaceous period, the phenomenon of seafloor spreading was occurring globally. The rate of seafloor spreading at that time was twice as compared to today. In the middle Cretaceous period, oceanic basalts were produced due to the fast movement of continents and the ocean floor widening. This continent and ocean pattern is the primary reason for climate change in the Cretaceous time.

Thus, it is proved that the warm climate at the time of Cretaceous is due to the tectonic forces. That caused active metamorphism processes, volcanism and mantle degassing maintaining the CO2 level.

Global warming and CO2 emission are serious issues.

Tectonic plates

Plate tectonics of Cretaceous played a vital role in the creation and modification of oceanic gateways and seaways. The African plate rotated in east direction, translated away from South America, enlarging the connection between North and South Atlantic Ocean. The anti-clockwise movement of Iberia connected North Atlantic with Tethys sea, due to which the Betic seaways deepened and opened the pathways through Bays of Biscay. During the late Cretaceous, the connection between the Pacific Ocean and the Arctic ocean closed in the north. All these paleogeographic modifications strongly impacted global oceanic circulations for a time scale of millions of years. The middle Cretaceous period shows the significant changes in Tethys-Atlantic oceanography that provided the new way in evolving global Oceanic systems. These changes occur as the climate becomes warm in mid-Cretaceous. And the reason for raising the temperature in Cretaceous time is due to the Plate-tectonic configuration.


Green House Gas Emission Promoting Global Warming

A few years back, most people deny the concept of global warming and consider this topic prediction or just the fears that will never happen. The scenario changed suddenly when the year 2018 was the hottest.  As the whole World is familiar that with the increase in industrialism, the rate of CO2 release in the atmosphere is very high, this results in instability in climate all around the World. The consumption of these harmful gases causes a rise in global temperature. Globally, the storms become more robust; the period of droughts extended the ice sheets become thin, Glaciers melt at a higher pace than predicted.


Methane is one of the most hostile greenhouse gases that is destroying our atmosphere. Carbon dioxide gas is a non-poisonous, fragrance-free, and colorless gas. It usually generates by the burning of fossil fuel and during cement manufacturing. The property of carbon dioxide gas is to absorb radiation and do not let the heat escape from the atmosphere of the earth. This heat blockage results rise in heat in the atmosphere and depletion of the ozone layer. This trapped heat disrupts the patterns of weather. In 1956, David Keeling from Scripps Institute of Oceanography started measuring the samples from different locations, and the result shows that there is a 2 ppm/yr. An increase in CO2 is the result of human activities. Global warming and CO2 emission are serious issues.

Proof of climate change

This long-term CO2 is reliable for 100 and even more years, and this is the best proof of climate change.  Change in weather and rise of temperature about 2% in total, can cause the extinction of about 30% species. The rise in temperature due to greenhouse gas emissions has seen (Figure 1). As the whole World is familiar that with the increase in industrialism, the rate of CO2 release in the atmosphere is very high, this results in instability in climate all around the World. Climate change is a global matter that everyone is facing, and the consequences will affect the whole population of the World. So, all the countries of the World must adopt some measures in controlling greenhouse gas emissions.

Two main strategies to reduce greenhouse gas emissions discuss in the present research; one is the adoption of the carbon tax method, and second is setting the goal to reduce greenhouse gas emissions each year.


Coronavirus – Nature’s Message

Despite many drawbacks of Coronavirus, there are some positive impacts also that we are ignoring.  On one side, people are considering it a curse of God, but if we observe this pandemic’s positivity, we can call it the “Nature’s Message,” as said by the United Nations environment chief. Climate change remained the hottest issue in the United Nations for the past few years, as it became a global issue. Representatives of different countries united on the United Nations platform to solve the problem of climate change.

Global warming and CO2 emission are serious issues.

But there was no significant change as industrialism is at its peak in this era, and it is difficult to stop as we are entirely dependent on our industries for everything. But the Coronavirus is successful in the reduction of CO2 emission as the whole World locked down. All the industries and transport systems shut down these days to avoid the epidemic spread. This shutdown stopped the fossil fuel burning worldwide, causing a temporary drop in CO2 emission.

Drop-in Air Pollution due to lock down

There is a clear drop in the air pollution in atmosphere due to present situation. As the pandemic spread started from the Wuhan city of China, the city completely locked down. As a result of this lockdown the public activities completely banned, limiting the people to their homes. NASA did an experiment on the air of China, to check the pollution rate. According to their observation there was a considerable drop in air pollution in China after the spread of coronavirus. Fri Liu, one of the researchers at NAS states in the magazine that “This is for the first time I have seen such a dramatic drop over such a wide area for a specific event”.

Not only in China but also in other cities there is a clear drop in the air pollution. In Spain, there is a drop of 14% traffic this year, this drop-in traffic decreases the air pollution. According to the research of Stanford University named Marshall Burke, the quality of air in China enhanced. The decrease in air pollution saved the lives of many children under 5 years age and old people of more than 70 years age. And an estimate revealed that this decrease in air pollution saved the lives twenty times more than the deaths due to coronavirus.

Global warming and CO2 emission are serious issues.

Reduced Emission of Green House Gases

During the recession of 2007 to 2009, the rate of CO2 emission reduced but after that year the CO2 emission doubled. The increase in CO2 emission after the great recession was due to increased burning of fossil fuel to cope with energy demand. In the present situation many industries shutdown due to which the CO2 emission has reduced. Oil demand has fallen worldwide because oil is not in use these days. World oil prices dropped below zero due to which many countries shut down their oil wells. Such drop decreases the rate of fossil fuel burning and, as a result, reduced the price of CO2 emission. The European countries where the traffic increased in recent years might also be a drop-in carbon dioxide emission as governments ordered lockdown these days.

The positive impact on our atmosphere is not just for these days. As the Simon Evans of Carbon Brief said, “Obviously there are almost certainly going to be further impacts on emissions. ” Still, it will be more protracted and more beneficial. This pandemic conveys us the message that we can control environmental pollution. If we start taking it sincerely and avoid fossil fuel burning at such a high pace.