Why is the human eye curved?

Sexl Physik 7, textbook

? Answer to the initial question The human eye The cornea, the aqueous humor, the lens of the eye and the vitreous humor together form a refractive system through which a sharp image is thrown onto the retina. The lens of the eye can be curved more or less by the ciliary muscle, which changes the focal length by about 4mm. If the lens is the flattest, an incident parallel bundle of rays is combined on the retina. If it is most curved, light rays emanating from an object about 10 cm in front of the eye can be collected on the retina. The ability of the eye lens to focus on a distance range from about 10 cm (near point) to infinity by changing the refractive power is called accommodation. In front of the eye lens is the colored iris, which acts as a diaphragm and regulates the amount of incident light. The brighter our surroundings, the more the opening of the iris, the pupil, becomes smaller. This keeps harmful light intensities away from the retina. The optical correction of eye defects using cut glass lenses was probably first achieved in Italy at the end of the 13th century. At that time, cut crystals (beryl) were used, from which the name glasses is derived. Today, besides glass lenses, plastic lenses are often used for glasses. An alternative are small lenses (“adhesive shells”) that float directly on the cornea. The refractive power of glasses is given in diopters. The refractive power D of a lens is the reciprocal of the focal length measured in meters when the lens is surrounded by a medium with n = 1. D = 1 / f… unit of measurement 1 diopter (dpt) = 1m −1 For converging lenses D is positive, for diverging lenses it is negative. The unit of refractive power is a diopter (dpt). A pair of glasses with D = −2dpt is therefore a diverging lens with a focal length of f = 0.5m. Investigate, consider, research: The eye 61.1 W 1 How big is the human eye? What do the cornea or lens contribute to the refractive power? 61.2 S 1 With the help of a biology teacher, dissect a fresh fish eye and look at your surroundings through the fish's eye lens. What do you notice? Fish eyes cannot accommodate. How do fish manage to see clearly at different distances? 61.3 S 2 What do we know about the visual sense organs of animals and about their eyesight? Gather information about different animal species and think about the connections between the behavior of the animals and their visual perception. 61.4 S 1 What are the most important eye defects and diseases? 61.5 In photo technology, strongly curved lenses are used in extremely wide-angle lenses (fisheye lenses). They allow viewing angles of up to 180 °. Wide-angle lenses have a shorter focal length than normal lenses and cover a larger area. 61.6 Numerous optical illusions are based on the fact that we cannot fall back on our experience for certain situations. 61.1 Red-green blind people cannot distinguish between blue and purple or green and yellow. Goethe made a watercolor according to the instructions of a person concerned. Cornea iris ciliary muscle vitreous lens yellow spot pupil blind spot retina optic nerve optical axis choroid muscle attachment aqueous humor 61.2. The structure of the human eye. The ciliary muscle is a sphincter muscle that is used to suspend the lens and for accommodation. The “yellow spot” is the place with the greatest density of photoreceptor cells, the “blind spot” is the exit point of the optic nerve. 61.3 What is the meaning of the numbers on the lens? What do the camera and the eye have in common? L R Eye base 61.4 The spatial perception when seeing is based on the fact that a three-dimensional object is seen with both eyes simultaneously at different angles to the background due to the interpupillary distance (base). The different images created on the retina of both eyes are then processed in the brain to create a spatial impression. 61 | ELECTROMAGNETIC WAVES For testing purposes only - property of the publisher öbv

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