Lenses Research Paper Example | Topics and Well Written Essays - 1250 words

Lenses - Research Paper Example Whenever a lens is surrounded by air, refraction of light takes place from the air into the lens, crossing through the lens and then refracting back into the air. Each refraction can lead to a change in the direction of light travel. There are two types of lenses, converging lenses, and diverging lenses. A converging lens is one that causes light rays that were initially parallel to the central axis to converge, while a diverging lens is one that causes such light rays to diverge. When an object is placed in front of any of the two types of lenses, light rays that can refract either into or out of the lens from the object to produce an image of the object. A lens can produce an object image only because it can bend light rays, but it can only do this only if its refraction index is different from that of the surrounding medium (Halliday, Resnick & Walker, 936). The single spot to which light rays that have been refracted by a lens are converging is known as the focal point. The dista nce from the lens to the focal point, often denoted by the letter f, is called the focal length. Every lens has its own focal length that forms its defining characteristic. A lens can have either a positive or a negative focal length, depending on the side of the lens on which an object is placed. When the focal point of a lens is on the opposite side of the lens from where an object is placed, the resulting focal length is positive. On the other hand, when the focal point is on the same side as the object, the focal length is negative. While these terminologies are useful convections used by scientists and engineers to characterize lenses as well as mirrors, they contain no real physical meanings (Kirkpatrick & Gregory, 367). Both converging and diverging lenses form different types of images, depending on where the object is placed. When an object is placed inside the focal point, the lens forms a virtual image that is on the same side of the lens as the object, and having the sam e orientation. Thus, a converging lens can form two types of images, real or virtual, depending on whether the object is placed inside or outside of the focal point. In the case of a diverging lens, the image formed is virtual that is on the same side of the lens as the object, and contains the same orientation. This is regardless of the object distance and whether it is placed inside or outside of the focal point. Just like in the case of mirrors, when the image is real the image distance is taken to be positive while when the image is virtual it is taken to be negative. However, the location from lenses of real and virtual images are the reverse of those belonging to mirrors. Real images form on the lens side that is opposite the object, while virtual images form on the side that the object is located (Benenson, 358). There are lens systems that are arrangements of a correction of lenses that have a common optical axis, and are mostly applied in the correction of image defects tha t are present in single lenses. If the positions of the principal planes of the single lens are known together with their total focus, then it is possible for an optical image to be constructed for a lens system. The image construction is similar with that of thick lens if there are only two principal planes. In addition to lens systems, there are lenses with