Defects of vision. Correction of vision 1. Correction lens for near-sightedness: 1.1 =-+- Fmyopia = fmyopia P 4 Fmyopia - optical power of the lens, prescribed to correct near-sightedness or myopia (diopters), fmyopia - focal length of the lens, prescribed to correct near-sightedness or myopia (m), p = o far point of a healthy eye (m), q- desired image distance (m) Lera too strong Eye too long 2. Correction lens for far-sightedness: Fayperopia = fnyperopia Pa q Fhyperopia - optical power of the lens, prescribed to correct far-sightedness or hyperopia (diopters), fryperopia - focal length of the lens, prescribed to correct far-sightedness or hyperopia (m), Po = 25 cm is a far point of a healthy eye (m), q - desired image distance (m). Lens too weak Eye too short ) Hyperopia 3. Lens equation: 1 1.1 F=-=-+- f- lens focal length (m); F- lens optical power (D); p-distance from the object to the lens or object distance (m); q - distance from the image to the lens or image distance (m) 4. Laser vision correction has progressed rapidly in the last few years. It is the latest and by far the most successful in a series of procedures that correct vision by reshaping the cornea. As noted at the beginning of this section, the comea accounts for about two-thirds of the power of the eye. Thus, small adjustments of its curvature have the same effect as putting a lens in front of the eye. To a reasonable appraximation, the power of multiple lenses placed close together equals the sum of their powers. For example, a concave spectacle lens (for nearsightedness) having P--3.00 D has the same effect on vision as reducing the power of the eye itself by 3.00 D. So to correct the eye for nearsightedness, the comea is flattened to reduce its power. Similarly, to correct for farsightedness, the curvature of the comea is enhanced to increase the power of the eye - the same effect as the positive power spectacle lens used for farsightedness. Laser vision correction uses high intensity electromagnetic radiation to ablate (to remove material from the surface) and reshape the comeal surfaces. 2. Let us assume that a given hyperopic eye has a near point at 200 cm. The desired lens is to allow the eye to view objects at 25 cm. Find focal length and power of the lens required to fix this
Ray Optics
Optics is the study of light in the field of physics. It refers to the study and properties of light. Optical phenomena can be classified into three categories: ray optics, wave optics, and quantum optics. Geometrical optics, also known as ray optics, is an optics model that explains light propagation using rays. In an optical device, a ray is a direction along which light energy is transmitted from one point to another. Geometric optics assumes that waves (rays) move in straight lines before they reach a surface. When a ray collides with a surface, it can bounce back (reflect) or bend (refract), but it continues in a straight line. The laws of reflection and refraction are the fundamental laws of geometrical optics. Light is an electromagnetic wave with a wavelength that falls within the visible spectrum.
Converging Lens
Converging lens, also known as a convex lens, is thinner at the upper and lower edges and thicker at the center. The edges are curved outwards. This lens can converge a beam of parallel rays of light that is coming from outside and focus it on a point on the other side of the lens.
Plano-Convex Lens
To understand the topic well we will first break down the name of the topic, ‘Plano Convex lens’ into three separate words and look at them individually.
Lateral Magnification
In very simple terms, the same object can be viewed in enlarged versions of itself, which we call magnification. To rephrase, magnification is the ability to enlarge the image of an object without physically altering its dimensions and structure. This process is mainly done to get an even more detailed view of the object by scaling up the image. A lot of daily life examples for this can be the use of magnifying glasses, projectors, and microscopes in laboratories. This plays a vital role in the fields of research and development and to some extent even our daily lives; our daily activity of magnifying images and texts on our mobile screen for a better look is nothing other than magnification.
Let us assume that a given hyperopic eye has a near point at 200 cm. The desired lens is to allow the eye to view objects at 25 cm. Find focal length and power of the lens required to fix this problem.
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