Geometric optics // Analysis
A mirror is a regular surface, pulimentada a brilliant aspect and the reflection is not diffuse, they can be qualified according to his form in plane and curved, in turn the above mentioned can subdivide if the surface pulimentada finds in interior or exterior d the curve, in hollow and connected and according to the geometric way of the surface in ball, cylindrical, parabolic. The images support his size if the mirror is flat increase it if it is hollow and diminishes it if it is convex, also it is possible with a hollow mirror of such way of projecting images on a screen and in directing a beam of light, in a certain direction or concentrating it on a point.
A lens is a way trasparente limited by expensive two, of an almeno it is curved, the light that comes to her is refracted and turns aside, they can qualify, according to the effect, which they produce in the beams of the light, which affect on them in convergent and divergent, it are convergent those that an effect has, of flexionar the beams of light and tends to assemble them, they are divergent to which they produce the opposite effect, that is to say the one that separates the beams of light. A more daily example is the case of the magnifying glass, which is used to project and used in the correction of the astigmatism and myopia, for centuries one believed that the light was consisting of a jet of particles expressed by a luminous source, other bodies were seen because there are reflected some of the corpuscles that strike them, and to to come these particles to the eye, the sensation of seeing was taking place, this was explaining the reflection of the light in a mirror.
Formation of a rainbow by means of the geometric optics, source of image of mastery of Wikimedia Commons
Also we have another contribution, as of Isaac Newton he publishes in 1704 his optics and places the model corpuscular of the light on the ideas of Discardings, supposes that the light is formed by material corpuscles, which are thrown at big speed by the issuing bodies of light, dividing of this beginning also James Clerk Maxwell demonstrated, that the luminous waves are electromagnetic, of the type of the waves of radio, they do not need any way to propagate and the frequency of the luminous waves is much major than those of radio, and they impress the retina of the eye, giving him continuity it takes place for the first time in electromagnetic waves, in the shape of light from electrical alternate circuits and realizes with them reflection, refraction and interferences.
The action of an optical system the beams of light, which go out of an object meet again in some real point of the space, they form a real image of the object, but in other different points the images would form blurry.
¿ What do we know about the construction of images?
To know with accuracy where one finds the image of an object, the case happens for the action of one optical device, which must find the point, in which the beams of light are cut proveniente of him, after happening for the device, one of these beams, it is the one that comes to the optical device of form parallel to the principal axis and that turns aside in the direction of the focus of image, other would be in that not apart from the direction that was going, the effect mirror will be the one that affects in a perpendicular way, that is to say the one that continues ña direction, which happens for the center of curvature and in a lens, which happens for the optical center. Quite this theory causes at physical level Consists of the securing of free electrons of a metal when on this one a bundle of light affects, in case of an increase of the luminous intensity he did not suppose an increase of the kinetic energy of the expressed electrons this is what is named the photoelectric effect for the construction of image, because the light intergesticulates with the electrons of the matter, in discreet quantities that name all the that a form of energy, which this one is: And = h.v being v the frequency and h the constant of Planck whose value is h = 6,62. 10-34 J.s, thanks to this position the light propagates in the gap with a speed of 3.108 m/s mentioned by Einstein.
The principal elements, which form an optical system are the following ones:
principal Axis, it is the axis perpendicular to the plane of the mirror or glasses and that happens for his center.
Center of curvature, it is the center of the spherical surface, which forms his face.
Focus of image, it is the point where there concentrate the beams, which come in a way parallel to the principal axis after colliding with the mirror of the lens.
Focus I object, place in which an object has to be placed, so that the beams of light go out parallel to the principal axis, after happening for the mirror or lens.
optical Center, geometric center of the mirror or lens.
focal Distance, it is the distance, which exists between the focus and the optical element.
Inside the geometric optics, also phenomenon is observed as that of the electromagnetic waves, they differ between yes in his frequency and in his wavelength, but they all propagate in the gap at the same speed, because in the majority of I marry on an optical axis it serves as a homogeneous way and isótropo the trajectory of the light is rectilinear and his speed is constant, they are two different position under the same way but of different phenomena. As for the reflection it is the phenomenon for which the beam, in an incidental way it keeps on propagating for the way of incidence, this phenomenon allows to see not luminous objects and this one goes to depend on the case of the type of surface, smooth or irregular, the reflection will be to speculate, or diffuse, in her we have the contribution of the law of Snell, where the index of refraction 'n' from a way comes given by the following expression, where v is the speed of the light in this way, and 'c' that of the light in the gap:
n = c/v
The speed of the light in the materials depends on the index of refraction, and the index of refraction depends on the frequency of the light, the light to different frequencies travels at different speeds across the same material. This can cause distortion of electromagnetic waves that consist of multiple frequencies, so-called dispersion.
Reflection of the light, a bundle hits a mirror and is reflected, source of image of mastery of Wikimedia Commons
The use of prism as way of object capable of refracting, of reflecting and of decomposing the light in the colors of the rainbow, in accordance with the law of Snell, when the light goes on from the air to the glass of the prism diminishes his speed, turning his trajectory away and forming an angle with regard to the interface. As consequence, it is reflected or the light is refracted, the angle of incidence of the bundle of light and the indexes of refraction of the prism and the air determine the quantity of light that will be reflected, the quantity that will be refracted or if some of two things will happen exclusively.
Bibliography
Essentials of geometric optics for José Rodríguez García - 1997.
Manual of geometric optics for Adelina Felipe Marcet, César Albarrán Diego - 1998.
geometric Optics: exercises of graphic tracing of beams for Jaume Escofet Soteras, Jaume Escofet Soteras, Elisabet Pérez Cabré, Maria S. Millán and García Varela - 2005.