The lens is a transparent glass body, which is bounded by a spherical or cylindrical surface. Distinguish its types: convex and concave.
Structure of glass bodies
The concave (diffusive lens) and convex (collective) consist of a wide and thin part. The scattering has a wide part at the edges and a thin one at the center, and the collective lens is the reverse.
We place such glass bodies in an environment where the refractive index is larger than the refractive index of the lenses mentioned above. Then the scattering lens will receive the properties of the collective lens - and vice versa.
The center of the sphere, part of which is the surface of the body, is called the center of curvature. If one of its surfaces is flat, then they say that it is in infinity.
A straight line connecting the centers of curvaturesurfaces that have a spherical shape are defined as the main optical axis. It is perpendicular to the surface of the lens at the points through which it passes. The point lying on the optical axis in the center is the optical center. Any straight line that can pass through such a center at right angles to the main axis is considered to be an indirect one.
Точка, где собираются все лучи, которые, в свою the queue, run parallel to the optical axis after exiting the lens, is called the focus. And the point where the continuations of the rays that are scattered are collected are called the imaginary focus of the scattering lens.
Расстояние от центра (имеется в виду оптический center) to the focus of the glass body, is the focal length. The plane that is drawn through the points in the focus and, in turn, runs perpendicular to the optical axis, is called the focal plane.
In order to make an image inthe scattering lens of some object, which gives the lens, it is necessary to build an image of its extreme points. It should be remembered that the rays that fall on the glass body will be parallel to the main optical axis when they exit and pass through the focus. And the rays that fell on the lens through the focus, after the output go parallel to the beam. If the beam hits the optical center, then after exiting it, it will move in the same direction, that is, it will not be refracted.
If we denote the distance from the object to the lens through b, and the distance from the image to the lens by v, with the focal length labeled V, then the following equality is valid:
1 / b + 1 / v = 1 / V.
Such an equation is considered a lens formula. It is necessary to determine the distance to the image when the object is placed differently with respect to the glass body.
If such a distance eventually comes outnegative, it means that the image of the object is on the same side of the lens as the object. Therefore, if this is a scattering lens, the value of the focal length in the last formula should be taken with a minus sign, since a negative value can not be avoided.
The value that is inverse to the focal length,Consider an optical force. It is measured in diopters. Knowing the dimensions of the image that the lens gives, and the size of the object, you can determine the linear magnification that the glass body gives. This increase is equal to the ratio of the height of the image to the height of the object itself.
Dispersing lens. Image building
The object is in infinity. Then the image of such an object will be in an imaginary focus. Its dimensions and parameters can only be assumed, since the exact value can not be achieved.
Предмет находится на небольшом расстоянии от glass body. For a scattering lens, wherever an object is located, its image will always be on the same side of the lens where the object itself is located. The image will be reduced, imaginary and direct.
