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A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescope design was originally used in spyglasses and astronomical telescopes but is also used for long-focus camera lenses .
A real image occurs at points where rays actually converge, whereas a virtual image occurs at points that rays appear to be diverging from. Real images can be produced by concave mirrors and converging lenses, only if the object is placed further away from the mirror/lens than the focal point, and this real image is inverted. As the object ...
For the diverging lens, forward extension of converging rays toward the lens will meet the converging point, so the point is a virtual object. For a (refracting) lens, the real image of an object is formed on the opposite side of the lens while the virtual image is formed on the same side as the object. For a (reflecting) mirror, the real image ...
In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. [1] Refraction of light is the most commonly observed phenomenon, but other waves such as sound waves and water waves also experience refraction. How much a wave ...
The refracting telescope which uses lenses to form an image. [27] The reflecting telescope which uses an arrangement of mirrors to form an image. [28] The catadioptric telescope which uses mirrors combined with lenses to form an image. A Fresnel imager is a proposed ultra-lightweight design for a space telescope that uses a Fresnel lens to ...
An Achromatic telescope uses an achromatic lens to correct for this. An achromatic lens is a compound lenses made with two types of glass with different dispersion. One element, a concave lens made out of Flint glass, has relatively high dispersion, while the other, a convex element made of Crown glass, has a lower dispersion. The crown lens is ...
There are structural problems involved in manufacturing and manipulating large-aperture lenses. Since a lens can only be held in place by its edge, the center of a large lens will sag due to gravity, distorting the image it produces. The largest practical lens size in a refracting telescope is around 1 meter. [17]
That is, given a specific image, to determine a surface whose refracted or reflected light forms this image. In the discrete version of this problem, the surface is divided into several micro-surfaces which are assumed smooth, i.e. the light reflected/refracted by each micro-surface forms a Gaussian caustic.