how does a hologram work?
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A hologram is essentially a three-dimesional photograph. However, it takes much more work to make a hologram than it does for an ordinary two-dimensional photograph. To learn how holograms are made, we first need to learn a little about lasers. \n\nInterference is what holograms are all about. A hologram is basically a reproduction of the "interference pattern" of laser light that's been shined on something. Let's say we had a coffee cup and we shone some laser light on it. However, we didn't shine all of the light on the cup. Some we diverted directly onto the photographic paper (the reference beam). The rest of the laser light (the object beam) shines on the cup, and is then reflected onto the paper. So we have light straight from the laser source and light that's been reflected from the cup. These two beams interfere with each other, causing a specific pattern of bright and dark spots where there has been constructive and destructive interference, spots where the waves added and subtracted. \n \n\nIt's the interference pattern that the photographic film records, unlike a regular photograph, which records the amount of light from a specific point (see the module on pinhole cameras for more information). Also, unlike the photograph, each point of the hologram contains all of the information from the object. So we could destroy almost all of our hologram and still reconstruct the image from a small piece. Try to do that with your regular photograph! \n\nTo see the hologram, we have to shine light that's just like the reference beam onto the photographic film after it's been developed. To see the hologram made from a laser, we need to use a similar laser. Now do you see why it's so hard to duplicate a hologram?!
1091417
Fascinating question! The surface of the vibrating object would alternately cause reflected light to red shift and blue shift, but that's about as far as my thinking can go. Would the shifts cancel each other, rendering the object invisible?
915429
We only see the light reflected off of an object.  Google the invisibility cloak that scientists have comeup with.  It works by refracting and redirecting light .
52788
A Prism bends the light and separates it to the different colors, usually seen as rainbow colors or primary colors that all other colors come from the blending of these colors in one way or another.  An optical instrument gathers light bends it and projects it to your eye on the correct focal lengnth through the ocular lens or eyepiece.  It is the focusing of the instument that puts the color right again and projects the image to your eye.  You do not look through an optical instrument it is actually projecting an image to your eye the way a projector projects a movie to a screen.
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It is possible, using nonlinear optical processes, to exactly reverse the propagation direction and phase variation of a beam of light. The reversed beam is called a conjugate beam, and thus the technique is known as optical phase conjugation (also called time reversal, wavefront reversal and retroreflection).\n\nOne can interpret this nonlinear optical interaction as being analogous to a real-time holographic process. In this case, the interacting beams simultaneously interact in a nonlinear optical material to form a dynamic hologram (two of the three input beams), or real-time diffraction pattern, in the material. The third incident beam diffracts off this dynamic hologram, and, in the process, reads out the phase-conjugate wave. In effect, all three incident beams interact (essentially) simultaneously to form several real-time holograms, resulting in a set of diffracted output waves that phase up as the "time-reversed" beam. In the language of nonlinear optics, the interacting beams result in a nonlinear polarization within the material, which coherently radiates to form the phase-conjugate wave.\n\nThe most common way of producing optical phase conjugation is to use a four-wave mixing technique, though it is also possible to use processes such as stimulated Brillouin scattering. A device producing the phase conjugation effect is known as a phase conjugate mirror (PCM).
145631
The 'How Stuff Works' website has a really good explanation.  You can find it at http://home.howstuffworks.com/question420.htm
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A common garden variety TV screen is a Cathode Ray Tube- the screen itself is a phosphor coated glass surface attached to the vacuum bottle and electron gun assembly that makes up the rest of it. In operation the electrons from the gun at the rear of the thing are electromagnetically accelerated to the phosphor screen, and scanned by electromagnetic deflection back and forth over the phosphor, making little dots of light that cumulatively make the "picture"- each dot is a "picture element" or pixel the whole accumulation makes a recognizable image. and if you like I can explain how the thing work in color, too.
740646
Phase-only optical filter for use in an optical correlation system - Patent 4588260  \n... with zero phase does not reconstruct the correct structure, where as ... would be to construct such a filter by means of a computer generated hologram. ...www.freepatentsonline.com/4588260.html \nHolographic fingerprint device - Patent 6061463  \n... hologram, also affixed to the substrate but at a position along the ... slightly different angle than the one used to construct the hologram (and thus ...www.freepatentsonline.com/6061463.html
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Not all lenses do that, just convex lenses.  Know anyone that wears glasses?\nYou'll lear how lenses and prisms work when you take physics 2.\n\n-jose-
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It works on photo electricprinciple.\n\nBasic is a light source and a reflective surface(mirror).\n\nCircuit either stay normaly open or shute but when the beam is broken it provides a signal which in turn operates a system, say bell or a motor, that can open a door.
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ok here is the thing\nif you are trying to calculate the thickness of a piece of paper you will need some equpment. Even though there is a lot of room for human error you still can get a fair estimate. \n\nwhat you need is 2 extrememly smooth glass plates and a lineat light source say a laser pointer. \n\nput one glass plate on a table place your paper on the side of the glass and put the other glass plate on the top of the two so that you will get a wedge between the two glasses. \n\nnow point the laser pointer perpendicular to the bottom glass plate and place a screen for reflections. you will get multiple reflections. (btw you need to know the frequency of the light emitted from the pointer.)\n\nthis is the set up\nfor calculations do a little search on air wedge interference \n\ni dont think you will need refractive indexes since you are using the same glass\nwith a little algebra you can figure it out
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The how of refraction is that light travels at different speed in different media, and always takes the minimum time of flight path.\n\nFor example, if you consider a plate of glass with a beam of light hitting it at an angle, like so:\n\n   &#92;&#92;&#92;       Air\n--------------\n    |||      Glass\n\nThe light will bend to travel at a sharper angle as it passes into the glass.  Where exactly it lands ends up being the point that has minimum travel time.  If you were to consider a plane inside the glass parallel to the surface of the glass and calculate, based on the speed in air and the speed in glass, the time it would take the light from the specified source to hit various points on this plane, you'd find the point it actually hits is the one that has the shortest time of flight.  This idea for determining the "why" of refraction originated with the mathematician Fermat, who found that the "principle of least action" applied to many things in physics.   This idea is very similar to the idea of geodesics in modern gravitational theories.\n\nThere are various other ways to calculate this, such as classical methods using Huygen's principle which analyzes the main wavefront into many small wavelets, and considers the action at many points as the incident wavefront meets with material of a different propagation velocity.  The net action of the changes on each wavelet creates a change in direction for the entire wavefront.  \n\nAlso, you can use Feynman's method of considering light taking all possible routes, with the observed route being the phase interference sum of all of these possible routes.  The phase interacts to cancel out all things we *don't* see happen, but, from a quantum mechanical point of view, these non-happening paths are still is a sense real, just very improbable.  So, in that case, the change in path is a result of a Huygen's like phase velocity change, and a phase summation over all possibilities which reinforces the "classical" behaviour.
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Magnifying mirrors are concaved inward and work by focusing the light on a point such that the image is larger than the original object.\n\nhttp://physics.bu.edu/py106/notes/Spherical.html
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A white light hologram is not aluminum foil.  It's a very high quality photograph.  The way the picture was taken is what makes it holographic.  The main thing for any hologram is that a LASER hits the photographic film and another copy of the same LASER hits the object you're photographing before going to the same film.  For a white light hologram they use a slit to eliminate vertical parallax.
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No.\n\nA true hologram (not just a 3D illusion) is a proper recording of the wavefront of an image. It is not taken using a lens, and it can be viewed from any angle. This is why it is so convincing - as you move your head you see the image exactly as it would have been from the new viewpoint. It is also why it cannot be projected - it makes no sense at all physically.\n\nThe other problem is that a hologram records the wavefront using the principle of interference. Basically, the object is lit using a source of monchromatic coherent light and so is the film. The light from object then leaves an interference pattern on the film. When this is lit using the same light source again, it recreates exactly the light pattern that was originally falling on the film.\n\nThis is very hard to extend to full colour light, and very hard to use for real scenes.
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A hologram is a 3d image of an object.  If you look at one you may try to reach out and touch it but nothing is there.\n\nWe don't actually see objects, we see the light that is reflected from them.  If that light is bent somehow the image will change and the appearance of the object will be different than the case of no interference.  We try to extrapolate what was actually there based on the light that reaches our eyes (and the extrapolation is distorted if the light gets bent).\n\nIn short, the mirage is a real image, but it is not a real object.
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Inside a copier there is a special drum. The drum acts a lot like a balloon -- you can charge it with a form of static electricity. \n\nInside the copier there is also a very fine black powder known as toner. The drum, charged with static electricity, can attract the toner particles. \nThere are three things about the drum and the toner that let a copier perform its magic: \nThe drum can be selectively charged, so that only parts of it attract toner. In a copier, you make an "image" -- in static electricity -- on the surface of the drum. Where the original sheet of paper is black, you create static electricity on the drum. Where it is white you do not. What you want is for the white areas of the original sheet of paper to NOT attract toner. The way this selectivity is accomplished in a copier is with light -- this is why it's called a photocopier! \n\nSomehow the toner has to get onto the drum and then onto a sheet of paper. The drum selectively attracts toner. Then the sheet of paper gets charged with static electricity and it pulls the toner off the drum. \n\nThe toner is heat sensitive, so the loose toner particles are attached (fused) to the paper with heat as soon as they come off the drum. \nThe drum, or belt, is made out of photoconductive material. Here are the actual steps involved in making a photocopy: \nThe surface of the drum is charged. \n\nAn intense beam of light moves across the paper that you have placed on the copier's glass surface. Light is reflected from white areas of the paper and strikes the drum below. \n\nWherever a photon of light hits, electrons are emitted from the photoconductive atoms in the drum and neutralize the positive charges above. Dark areas on the original (such as pictures or text) do not reflect light onto the drum, leaving regions of positive charges on the drum's surface. \n\nNegatively charged, dry, black pigment called toner is then spread over the surface of the drum, and the pigment particles adhere to the positive charges that remain. \n\nA positively charged sheet of paper then passes over the surface of the drum, attracting the beads of toner away from it. \n\nThe paper is then heated and pressed to fuse the image formed by the toner to the paper's surface.