how is a hologram formed?
928192
Holograms are formed by shining laser light through a 3D object.  Unlike a photograph, not only is intensity of light recorded, but it's amplitude and phase.  When the appropriate light is shone onto the hologram, it diffracts some of the light until it is exactly the same as the light wave that came from the original object.  This is what causes the object to appear 3D.\n\nEarly holograms were only able to be viewed when laser light was shone onto them, but more recent ones can be viewed by white light.  The reason many holograms are on a reflective background is so that light is reflected through the image, allowing us to view the hologram.
353441
Refraction occurs when light enters two substances of diferent densities. It bends because the mass of the two substances are different ie, the spacing of particles are different.
339657
to date, the best description of gravity is given by general relativity.  general relativity was published in 1915.  however, physicists are trying to develop a more accurate quantum description of gravity because of the contradictions between general relativity and quantum physics.  both general relativity and quantum physics are supported by incredibly precise observations.\n\nhttp://en.wikipedia.org/wiki/General_relativity\n\nthis is really bizarre.  it is the holographic universe.  the name comes from the hologram, which is a two dimensional film that has information stored on it and will project a three dimensional image, if laser light is put thru it.  physicists can describe the universe with two sets of laws: one three dimensional set with gravity and one two dimensional set without gravity, and there is no way to tell them apart.  this second set essentially states that gravity is an illusion.  see "the illusion of gravity", scientific american, november 2005
838669
The absolute minimum you need is a laser, a beam splitter, two lenses, some mirrors, and a photographic plate. You will also need to develop the photo using conventional chemical means, which is no longer easy to have done. I'm sorry, but it just can't be done with any less than that.\n\nBut if you're still game, here's how.\n\nFirst set up the laser to go thru the beam splitter. (This is just a partially silvered mirror that reflects half the light while allowing the other half to pass straight thru.) One half of the beam will pass thru a lens (to broaden it out), and will fall directly on the photographic plate. The other half of the beam will pass thru another lens (to broaden it out) and illuminate the target object. The laser light reflected off the target must then ALSO be visible to the photographic plate. \n\nDarken the room, open the plate holder (so that the plate will be exposed) and turn on your laser. At this point both the direct and reflected laser light should be falling on the plate. When you've exposed it enough (how long? depends!) turn off the laser and cover the plate. Then you can have the plate developed.\n\nWhen it comes back from the developer, you'll be keenly disappointed. In order to view the image, you will need to shine a laser thru the plate again to make the image visible in 3-d.\n\nAdded edit: You must also make sure that the room is TOTALLY dark, and that the ONLY light falling on the plate is laser light, either direct or reflected. Also, even tiny vibrations are enough to ruin or partially ruin the effect, so keep everyone out of the house (including pets!), or do your hologram when everyone is asleep.
1127946
The image which is formed on the retina through the lens of the eye is very similar to a pin-hole camera, the image is reversed both horizontally and vertically. The lens of the eye is purely used to focus this images.
768599
Hi. Try this link for info on the holographic storage of a mind. : http://twm.co.nz/pribram.htm and here : http://www.acsa2000.net/bcngroup/jponkp/
1080725
shadow is formed through light.
899857
A solid that is formed by a chemical reaction.
1162679
There is one, that if you were to do it and found a way to publish the results, a lot of common people would be very interested.  It is the formation and collapse of a gravitational field.\n\nWere you to go to http://timebones.blogspot.com   and then to the November Archive, toward the bottom of that month you shall find "How to Form and Collapse a Gravitational Field".  What I have suggested has been done by myself, but I have never found anyone interested in the results.
45043
this question doesn't make sense (it's incoherent HAH! sorry.. corny joke.)\n\nlight from a light bulb is called incoherent light because it's made up of many different waves.  waves as you know have a property called phase, which tells you where along the wave-front you are at a given position and time.  incoherent light is a mixture of light waves with random phases.\n\ncoherent light on the other hand, is used to describe light where all of the waves have the same phase - so the waves peak and trough at exactly the same time and position.  coherent light is much more intense than incoherent light because all of the phase fronts add up constructively, and so you end up with a very large amplitude wave.\n\nso, if you "concentrate" UV light, by using a lens or some other sort of focusing device, it will be more intense than the spread-out light, but it won't be coherent.  the only way to get coherent light is at the source - for instance, an excimer laser can be tuned to emit in the ultraviolet, and the light will be coherent.  \n\nthere is no (known) way to convert incoherent light into coherent light, though that's not to say it's impossible - such a thing just hasn't been invented.
967866
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?!
560835
with travelling electrons.depending on their wavelength,colours are formed
1150116
It forms due to diffraction of light by the small water droplets in fog. It's formation is similar to formation of the rainbow.
126059
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
412947
You can tell the difference between a photo and a holograph by considering what a black and white photo is: it is a point-to-point recording of the intensity of light rays that make up an image. Every point records something, the intensity (i.e. the square of the amplitude of the electric field) of the light wave that illuminates that particular point. In a color photo, more information is recorded (in effect the image is recorded three times viewed through three different color filters), which allows a limited reconstruction of the wavelength of the light, and thus its color.\n\nHowever, the light which makes up a real scene is not only specified by its amplitude and wavelength, but also by its phase. In a photograph, the phase of the light from the original scene is lost. In a hologram, both the amplitude and the phase of the light (usually at one particular wavelength) are recorded. When reconstructed, the resulting light field is identical to that which emanated from the original scene, giving a perfect three-dimensional image (albeit, in most cases, a monochromatic one, though color holograms are possible).\n\nTo produce a recording of the phase of the light wave at each point in an image, holography uses a reference beam which is combined with the light from the scene or object (the object beam). Optical interference between the reference beam and the object beam, due to the superposition of the light waves, produces a series of intensity fringes that can be recorded on standard photographic film. These fringes form a type of diffraction grating on the film, which is called the hologram.\n\nOnce the film is processed, if illuminated once again with the reference beam, diffraction from the fringe pattern on the film reconstructs the original object beam in both intensity and phase (except for rainbow holograms where the depth information is encoded entirely in the zoneplate angle). Because both the phase and intensity are reproduced, the image "pops out"; the viewer can move her viewpoint and see the image rotate exactly as the original object would.\n\nBecause of the need for interference between the reference and object beams, holography typically uses a laser in production. The light from the laser is split into two beams, one forming the reference beam, and one illuminating the object to form the object beam. A laser is used because the coherence of the beams allows interference to take place, although early holograms were made before the invention of the laser, and used other (much less convenient) coherent light sources such as mercury-arc lamps.\n\nIn simple holograms the coherence length of the beam determines the maximum depth the image can have. A laser will typically have a coherence length of several meters, ample for a deep hologram. Also certain pen laser pointers have been used to make small holograms (see External links). The size of these holograms is not restricted by the coherence length of the laser pointers (which can exceed 1 m), but by their low power of below 5 mW.
419125
I think you mean diffraction of light.\n\nIf so then you need to consider light as an electromagnetic  wave form, not as a form of particles - small energy packets called photons. The light, you see, has duel nature - it acts in certain situations as a wave whereas in other situations it is observed to behaves as if it is made of tiny particles.\n\nNow in its electromagnetic wave form light behave very much like water waves. The water waves, for example, when emerge from a narrow openings spread out in form of arcs or semicircles into a wider region.\n\nLight too has this property. It tends to bend round sharp edges and spread into regions where it is not supposed to be. On the other hand if light were composed of particles a burst of particles would always follow a straight line trajectory.
87319
I would have to say hardware. there is a new Holographic Memory coming out. you can store 1 terabyte (TB) of data in a sugar-cube-sized crystal. A terabyte of data equals 1,000 gigabytes, 1 million megabytes or 1 trillion bytes.