All about Optical lenses



All about Optical lenses

Light is the reason why we can see everything in this world. There is a certain phenomenon that takes place in the sphere of light. Lenses to light are like matchsticks to a flame. Optical physics is the strain of physics that deals with everything light and how it interacts with different particles of matter. Optical physics covers ground on many such interactions that we know by the name of reflection, refraction, dispersion, and more.

Dissecting a lens

The meaning of a lens for a kid is just a sphere of glass, for an adult a piece of glass cut in a particular way to refract light and for a science person or a scientist, it is an object of transmission supporting optical physics and dispersing light through a process called refraction.

Lenses are of many types. The first and the basic one is a single lens which is just a single piece of glass or transparent material that refracts light. The second type is a compound lens. A compound lens is a group of lenses that have different sizes yet are aligned to the same axis.

Lenses can be made out of a lot of elements and compounds like glass and plastics. They are shaped into any form as desired. When light passes through a lens they can actually manipulate the light ray, a prism only disperses without any control.

Types of single lenses

Single lenses are of two types, converging and diverging. A converging lens is also known as a convex lens while a diverging lens is called a concave lens. For simpler terms to remember, imagine making a “c” out of your left hand; the inner curve of “c” or the part that looks like a cave can be called a concave lens while the backhand or the obtruding part can be called the convex lens.

Converging lenses

Convex or converging lenses are thickest in the middle and starts tapering towards the top and the bottom, it is called converging due to its ability to converge or accumulate all the light rays that pass through it to a particular point of convergence. This length between this point (also called the focus) to the centre of the converging lens or point zero is called the focal length. In a converging lens since the point of convergence or focus is always beyond and in front of the lens, the distance is always positive.

Diverging lenses 

Concave or diverging lenses are thinnest in the middle and start getting thicker at ends, it is called diverging due to its ability to diverge light rays passing through it away from the centre. The focus of a diverging lens is imagined and traced back to behind the lens towards the source of light, this happens as the light rays never meet after going through the lens. Since the focus of a diverging lens is always imagined the length between the imaginary image and centre of the lens is always negative.

Utilizing these optic powers

Lenses are used in everyday life in different forms and equipment. Lenses are very interesting to work with and help us view the world from a new perspective; they help us see things that we cannot with our naked eyes.

Where do we put on the diverging lenses?

See the space and everything afar

Concave lenses are used in telescope and binoculars, this is because the use of these is to see things that are very far away and cannot be seen through the naked eye. Concave lenses magnify these objects to a certain degree of power depending on the focal length of the lens inserted. Concave lenses are inserted to extend the focal length of the telescope, while the convex lens helps converge the rays of light to see the object but blur it, here concave lenses help illuminate the area and straightens the image.

See the car driving down

Myopia or near-sightedness occurs when a person’s focal length is decreased due to the shape of his eye which in turn forms the image of a faraway object not on the retina but rather in front of it, this causes faraway objects to become blurry. Using a concave lens in spectacles helps lengthen the dispersion and corrects the error of falling short, thus a person with myopic vision sees more clearly.

Prevent the laser burns

Machines like a photocopier use lasers to scan and photocopy. In order to ensure that the lasers do not concentrate in one area resulting in a fault or the paper burning, concave lenses are used to scatter or diverge these laser beams evenly throughout the area.

Flash the light

Concave lenses are also placed in flashlights. Remember the bulging out lens at the frontal part of a flashlight that is a concave lens. We know by now that concave lenses diverge the ray of light or increases the field area of refracted light, now imagine a flashlight that converges all rays to a single point, in turn burning whatever it is flashed on and also failing to illuminate a space; an utter and complete disaster. Hence flashlights have a diverging lens so that the field of illumination increases by increasing the focal length.

Capture the moment

A diverging lens is used along a convex lens to capture images in a camera. The mechanism works very similarly to that of a telescope only here the image can actually be attained on a screen and the power of magnification is much less. The converging part of the mechanism blurs the image while the diverging part rectifies it.

Safety first

Concave lenses are also used in peepholes or safety holes fitted in the front doors. This is done by diverging the light rays and increasing the field of light scattered in, the lens offers a wider angle view or a panoramic view of the surroundings thereby making it a safety precaution to see who is at the door before you open it.

Where to put the converging lenses?

Zoom into the private investigator in you

A magnifying glass uses the phenomena of a converging all the light rays that pass through it to zoom in/ illuminate on one article. This results in distortion of articles and surfaces around it. For the maximum magnification of a particle to occur the glass must be put at an optimum distance to create the proper focal length.  A convex lens produces a virtual, magnified and an erect image in front of the object itself.

 Tune into microbiology

Just like the mechanism of the magnifying glass, a microscope uses the same mechanism to produce overtly zoomed in images of our very tiny cells. A typical microscope employs three convex lenses of varying radius to produce the magnitude to zo mint a one infinite of a speck of dirt to a size scalable with the naked eye.  An optical microscope makes use of the light around; converges these rays and illuminates that cell of an insignificant size. Without microscopes we would never learn biology and this proves how important lenses really are.

Read those books

Just like how we discussed that human eye can be myopic resulting into near-sightedness in the same way human eye can also suffer from hypermetropia resulting in far-sightedness. This disease usually happens with old age, in here the image formed by the eye forms beyond the retina. In order to shorten the focal length a convex length is placed in front of the human eye in form of spectacles. The convex lens corrects the fault of the eye by converging the light to the retina and not beyond.

Capturing the moment 2.0

It is not only the diverging lens that is necessary to assemble a camera and capture the beauty of moments rather a convex lens is also very vital to the camera. The structure of lenses in a camera reminds me of a grilled cheese with the convex lenses being the bread and the concave being the cheese.

There are two convex lenses present in a camera for the purpose of focusing on the subject and for controlling the level of magnification. The first lens placed before the diverging lens helps us zoom in and out by increasing the space between the lens and the concave lens. The second lens helps in focusing on the subject by converging the light rays onto the subject.

Now we know

The uses that we have discussed above prove to us the importance of lenses in everyday life. Without lenses a lot of branches of science and other things would have never existed. It is impossible to study microbiology, photography, astronomy, and more. Lenses have enabled people with error in the human eye to see normally like a normal person would. We wouldn’t have been able to carry out some of the mundane tasks of life without lenses let alone the complex ones. Lenses make life easier and the world seem like a smaller space than it is really is. With all these things lenses help us peer into the future of mankind, making it seem nearer than it would have been without them.

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