An introduction to concave lens

What are concave Lens?

A concave lens is a transparent medium having concave surfaces. The lens curve is the best indicator of whether or not it is a concave lens. Since the parallel beams on their surface tend to diverge from their paths, they are known as diverging lenses. 

Since they diverge light rays away from their path, concave lenses cannot produce a real image of anything. As a result, the light rays will not physically converge and meet at a specific point. 

Uses of the concave lens

Flashlights

A primary goal of a flashlight’s beam is to light a large area. The concave lens diverges the light from the bulb, resulting in a wider beam of light. Some flashlights’ beam radius changes by adjusting the distance between the concave lens and bulb.

Binoculars

Binoculars use a convex and concave lens combination to magnify distant things and make them appear closer. Convex lenses magnify while concave lenses focus on the image.

Telescope

Binoculars and telescopes both operate on the same principle. The solar system’s planets and distant objects are visible through telescopes, and they also have a convex and concave lens combination. Convex lenses are for magnification, and concave lenses are for the eyepiece.

Camera

The concave and convex lenses in cameras produce images. The concave lens combines with a convex lens because it can diffract light into different directions.

Eyeglasses

Concave lenses correct myopia or nearsightedness. Myopia occurs when the eye cannot focus the image onto the retina. Pictures formed in front of the retina rather than on the retina result in blurred distant images. A diverging lens focuses the image directly on the retina.

Peepholes

Peepholes provide a large areal view. Combining concave and convex lenses provides a broad view.

CD/DVD players

CD/DVD players use laser technology. They have a concave-lens Laser device.

Scanners

Scanners also use lasers with concave lenses.

Phoropter

Professionals in eye care use phoropters (also known as refractors) to correct vision, and a phoropter manually tests your vision and corrects it. An eye specialist manually changes the lenses and asks for your responses after each change.

Lighting application

LED lighting can use concave lenses for special effects.

Concave lens formula

The concave lens formula determines the concave lens’s image type. It also identifies the image’s position. The concave lens formula is as follows:

1/f=1/v -1/u

Where,

f=focal length

v = image distance from centre

u= the distance of an object from the centre

Difference between concave and convex lenses

• A concave lens diverges light rays parallel to its principal axis, distinguishing it from a convex lens. It is the opposite of the convex lenses that converges light in the opposite direction of the lens’s principal axis.
• Depending on the lens’s properties, light rays that pass through it either converge or diverge. Concave lenses diverge, whereas convex lenses converge.
• The shape of these two lenses also differentiates them. The thin middle portion and thick edges of a concave lens give it a cave-like structure. However, the edges of the convex lens are thinner than concave lenses.
• Negative focal length polarity in concave lenses and positive in convex ones. Hence the diverging lenses are negative lenses and the converging one a positive one.
• A convex lens creates a real image, whereas a concave lens creates a virtual and erect picture.
• Concave lenses treat myopia, while convex lenses treat hypermetropia.
• Concave lenses are in the human eye, while convex lenses are in microscopes and telescopes. But convex lenses are in lasers, car flashlights, and door peepholes.
• An object near a concave lens appears distant and smaller than it is. However, when placed in front of a convex lens, an object appears closer and larger than it actually is.

Concave mirrors

Spherical mirrors have curved reflecting surfaces that look similar to a sphere. A convex mirror is a sphere whose reflecting surface curves outward and in concave mirror reflecting surface curves inward. Mirrors with concave surfaces reflect and focus light rays (parallel) at a specific point, known as the focus point. The image type depends on the object’s distance from the reflecting surface. Science and technology use both mirrors. Concave mirrors are in headlights, torches, solar furnaces, microscopes, telescopes, and so on.

Concave mirrors: facts and information.

• Concave mirrors are in satellite dishes and bomb detectors.
• Uses for concave mirrors include searchlight reflectors. These mirrors help focus on intense collimated beams over long distances.
• Concave mirrors collimate beams. A moving coil galvanometer uses a concave mirror.
• The edges of the concave mirror concentrate the beams at a point slightly farther from the original focal point, yet concave mirrors may focus light from faraway sources. That is spherical aberration. Reflecting telescopes face the same problem and slightly distort the image of an object due to this aberration.
• With a concave mirror, you can get a wide range of images based on your object’s distance from it. It’s possible to enlarge or reduce some, making concave mirror devices very sensitive.

Conclusion

Nearsightedness glasses have concave lenses. Nearsighted people can’t see distant objects clearly because the distance between the lens and the retina in their eyes is longer than it should be. Concave lenses reduce light refraction and lengthen the focal length, enabling the retina to form the image.

In most optical devices there is a convex and concave lens combination. For example, combining a convex and concave lens provides better detail viewing of distant objects. It is because the convex lens condenses the light and the concave lens refracts it into parallel light once more. This arrangement enabled Galileo to create the Galilean telescope in the 17th century.