What is a microscope? In our understanding, microscopes allow us to peek into the world that cannot be seen clearly with the naked eye. Telescopes can take us to understand the earth’s world and detect stars and planets in the night sky. The light beams from lighthouses can be projected to very far away places. Let the boats drifting on the sea see the direction clearly. Glass (becomes a lens), in the following article we will explain what a lens is and how it works.
What are optical lenses?
A lens, we can call it, is a piece of glass or plastic with at least one concave and convex surface. Its name comes from the Latin word for “lentil”. Except for the more conventional convex lens that looks like a lentil, the others are not very similar.
Classification of optical lenses
We are mainly divided into two types of lenses. Converging lenses are also called convex lenses, and diverging lenses are also called concave lenses. I believe there are many applications in the reflection of physical light. I draw pictures based on the principles of convex lenses and concave lenses.
Convex lense
In a convex lense (sometimes called a positive lens), the glass (or plastic) surface bulges outward in the center, creating a classic lentil-like shape. A convex lense is also called a converging lens because it causes parallel rays of light passing through it to bend inward and meet (converge) at a point outside the lens (called the focus).
Concave lense
A concave lense, on the other hand, has its outer surface curved inward, so it bends or diverges parallel light rays outward. This is why concave lenses are sometimes called divergent lenses.
Compound lense
By combining convex and concave lenses, lenses with more complex behavior can be created. Lenses that use two or more simpler lenses in this way are called compound lenses.
How to measure the power of a lense?
Lenses are optical devices that can magnify or shrink the apparent size of an object. One important characteristic used to evaluate the performance of a lense is the focal length. The focal length of a lense is the distance from the center of the lens to the point where light is focused. A shorter focal length indicates a more powerful lens that can bring objects into closer view.
Focal length can be measured in ordinary length units, such as meters or millimeters. Alternatively, it can be expressed in diopters, which is a unit of optical power. The diopter measurement of a lense is the reciprocal of the focal length in meters (1 divided by the focal length). For example, a lens with a focal length of 0.5 meters would have a power of 2 diopters.
In terms of image brightness, larger lenses are capable of collecting more light compared to smaller lenses. This is particularly relevant when choosing a lense for a camera, as the amount of light gathered by the lens affects the appearance of the captured image. Camera lenses are often rated using the f-number, which is the ratio of the focal length to the diameter of the lens opening. Generally, a lens with a smaller aperture (larger f-number) will produce a brighter image. Lenses with higher f-numbers also have a greater depth of focus, meaning that more of the photographed object and its surroundings will appear in focus simultaneously.
While focal length is an important characteristic of a lens, it is not the sole factor to consider. Other factors such as lense construction, optical quality, and special coatings can also significantly impact the performance and image quality of a lense.