Key Takeways:

  • Convex lenses, known for converging light rays towards a focal point, have diverse applications. Types like plano convex, double convex lens, and concave-convex serve specific purposes.
  • They’re crucial in eyeglasses for vision correction, microscopy for magnification, and cameras for focusing images.
  • They also power magnifying glasses for detailed inspection. Their versatility makes them indispensable across optics, ensuring clear vision and precise imaging.

Convex lenses play an essential role when it comes to optics. They have various applications, and people use them in their daily lives. However, most do not know how these items work or what they do. 

What is a Convex Lens?

A convex lens, also called a converging lens, joins parallel light rays. This lens is thick in the center and much thinner at the upper and lower ends, allowing the light to converge at the principal axis. Due to the shape of this lens, the rays of light passing through the upper and lower ends are curved inwardly and not outwardly. It is placed in front of the eye to sharply curve incoming light, thereby shortening the focal point and guaranteeing optimal retinal illumination. 

Typically, it may concentrate a beam of parallel rays onto a point on the other side. This distance from the optical center of the beam is used to determine the focal length of the lens.

Types of Convex Lenses

Various types of lenses reflect light in different ways depending on the shape of the lens. These lenses can be used to create a real or virtual image based on the type and use. Here are the types of convex lenses.

Plano-Convex Lens

It’s shape is rounded on both the left and right sides. Plano-Convex Lens possesses positive focal length components with one spherical and one flat face. Plano-Convex Lenses function best in non-critical settings where unlimited parallel light can be used. They are intended to be used as general-purpose focusing optics. You can also find them being used in pharmaceuticals, robotics, etc.

Convex Lenses, Plano Convex Lens, Double Convex Lens, Concave Convex Lens

Double Convex Lens

The sides in a double Convex lens are curved outwards, creating an outward curve. This convex shape is what gives rise to its multiple names, and its focal length is less than that of a similarlysized and shaped plano-convex lens. In order to function, many optical tools need longer focal lengths. Due to this, double convex lenses are the better options. 

Double Convex Lens has many applications, including projectors, monoculars, telescopes, cameras, and more. In addition, it is used for an optical illusion for the human eye, glass-cutting, real imaging for photography, and an optical sensor.

Convex Lenses, Plano Convex Lens, Double Convex Lens, Concave Convex Lens

Concave-Convex Lens

It curves outwards on one side and inwards on the other. It corrects for spherical aberrations, which occur because of other lens types. Also, it directs the laser beam. To put it simply, a concave-convex lens, or meniscus, consists of two lenses, one of which is the convex lens and the other of which is a concave lens.

A similar lens is a biconcave lens, which increases focal length or expands laser beams. Biconcave lenses can be applied in optical character readers, projection systems, etc.

Convex Lenses, Plano Convex Lens, Double Convex Lens, Concave Convex Lens

Why Is a Convex Lens Called a Simple Microscope?

A simple microscope is an optical equipment used to increase the apparent size of a tiny object to examine it better. But which lens is used in the microscope: convex or concave? Well, all microscopes use convex lenses, but why do we use a convex lens in a microscope? These lenses are used in microscopes because they magnify images, whereas concave lenses do not.

Some might call a convex lens a simple microscope because that is the only type of lens that can be used on this device. Keep in mind that there is a difference between a simple and a compound microscope. A simple microscope uses just one lens to magnify a distant object, while a compound microscope uses several lenses to increase magnification.

General Applications


Incorrect focusing of light onto the retina causes vision impairments such as farsightedness and nearsightedness. If you suffer from farsightedness, your lens concentrates on an image that is behind your retina.

Since your lens cannot properly focus the image on the retina, it becomes difficult for you to see near objects. Using a convex lens on your eye will correct the problem. This works because the convex lenses curve the ray of right correctly onto your retina, allowing the focal point to be shorter.


A convex lens is always used in a microscope because of its ability to magnify images. Convex lenses are ideal for use in microscopes because they enable the creation of highly magnified visuals of tiny objects. A simple microscope typically uses three lenses. However, only the lens at the end of the microscope creates a magnified image size; the other two do not.

Magnifying Glasses

The magnifying glass, which utilizes a convex lens, is the most common application of a convex lens. When light enters the magnifying glass’ convex lens, it is concentrated on a point directly in front of the lens’ optical center, thereby increasing magnification. In addition, to get the best magnification results, you need to position the magnifying glass at the optimum distance from the object.


A convex lens is generally used in cameras because it can both focus and enlarge the captured image. The camera’s lens is a combination of two convex lenses, one concave and one convex. The distance between the object and the first lens determines the degree of magnification.


A convex lens is a tool that converges parallel light rays into a focal point (principal axis). It can do this due to its oval shape, with the upper and low ends thinner than the middle. Although a simple item, a convex lens ensures that several apparatus work efficiently to produce results. Some of this equipment includes eyeglasses, cameras, and microscopes. Without a convex lens, using these tools would be challenging.

Please contact us if you’d like to schedule a free consultation or request for a quote on your next project.


Share this article to gain insights from your connections!