lens - a transparent body, which is limited by two spherical surfaces.The main property is the ability of the lens to give subjects the image.They can be imaginary and real, inverted and straight decrease and increase.The linear dimensions of the image changes depending on the location of objects.
Increased lens - the ratio of the linear dimensions of the image and the object.The magnification factor (K) can be expressed as: K = u / v, where u is the distance from the lens to the object, and v - distance from the lens to the image.The magnification factor is a measure of how the linear dimensions of the object larger or smaller image size.
In science, there are such things as collecting lens and diverging.The first column in the middle and thinner at the edge, at the second - just the opposite.The lenses are characterized by a focal distance (from the optical center to the focal point: from the diverging lens, it is negative, while collecting - positive), and the optical power which is measured in diopters.Focal length of one diopter is 1 meter.Optical power is dependent on the radii of curvature of the spherical surfaces of the lens, and the material (its refractive index), from which it is made.It is the reciprocal of the focal length.
collecting lens is distinguished from scattering:
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collects light.
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edges thinner than the middle.
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It is a collection of a large number of expanding to the middle of the lens (not the edges) of triangular prisms.
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focus lens (ie, the point of intersection of rays after refraction, located on the main optical axis), is a real (not imaginary), as the rays crossed themselves, and not their extensions.
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ability to collect the rays falling on the surface at one point, which is located on the other side of the lens.
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collecting lens may be directed to the subject by any party, and the rays will be collected at the same time, as this lens has two focus.On the optical axis of the front and rear focal points are located on both sides of the focal length of the main points of the lens.
lens materials
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quartz glass.It features high heat resistance and UV bandwidth.Also, it is inert to many chemicals;
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silicon.This material combines a high dispersion with a large absolute value of the refractive index in the range of infrared radiation, fully opaque in the visible spectrum;
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organic polymers.With casting it is possible to create inexpensive aspheric lenses, which are used in recent times.Soft contact lenses are used in ophthalmology, are made of materials having biphasic nature.Silicone-gidrolievye linzyblagodarya high oxygen permeability and a combination of hydrophilic properties can be continuously used for a month;
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other materials.
Types of lenses
collecting lenses are divided into 3 types:
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biconcave;
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plano-convex;
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concave-convex.
Spread lenses are also divided into 3 types:
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biconcave;
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plano-concave;
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convex-concave.
lenses can be simple, and can be combined from several - to build some kind of complex optical systems.A lens system located at a certain distance, the axes of which coincide called centered.
Application lenses
They are necessary for the manufacture of telescopes, microscopes, binoculars, cameras, projectors, optical sights, etc.The lenses are used extensively in ophthalmology as needed to persons with vision deficiencies such as myopia and hyperopia.Furthermore, a single condensing lens is used as a magnifying glass.
