Can someone make me understand what is holography and the holographic technology briefly?
Can someone make me understand what is holography and the holographic technology briefly?
26-30, M
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Ahmed010 · 31-35, M
Its very complicated technology based on interference between electromagnetic light beams for example laser beams to create an image..for example if we want to simulate you in 3d image we use laser splitter to make 2 laser beams one directed toward you to make like a photo of you on aboard then the other beam directed toward the board the interference between two beams create acomplete image of you .
SomeMichGuy · M
Holography is the recording of images in holographs, a special type of photograph.
[u]Traditional images[/u]
Traditional photographs made using glass plates or flexible "film" used special emulsions which were light-sensitive (photo-reactive) in this way: when the lense system focused light from the scene [either emitted by or reflected from it], that light would induce a chemical change to "expose" the emulsion.
The exposing is a photon-by-photon process, and it relates to intensity in this way: more intense light of ANY wavelength/frequency has more photons than less intense light. So the exposure is either greater or lesser depending upon how many photons hit the reactive emulsion during the time of the exposure. [Too short, not a good pic--too dark. Too long, also not good--too bright/washed out. Thus, you used a light meter--hand-held or incorporated into your camera--to set the exposure time, given the film "speed", a measure of how quickly it could make an image, i.e., its sensitivity; the higher the speed, the more sensitive the film.]
Then process the film to get a negative image (real light areas of the scene are recorded as dark areas on the negative, and vice versa), and make prints from the negative.
All of that was to capture light, the photons from the scene.
[u]Digital Images[/u]
In digital systems, something similar happens, but instead of a photo-reactive chemical changing to record a photon's presence, photons hit a special semiconductor and release charges. These are isolated into different physical places and quickly "read out", with the number of charges found at a given place corresponding to the brightness there. (This is the Charge-Coupled Device, or CCD.)
So, again, single-photon events are recorded.
[u]Wave/particle duality[/u]
For tiny particles like the photon, a cornerstone of modern physics is that they exhibit wave-particle duality: in some interactions, they seem to behave like particles,while in others, they seem to behave like waves.
In [b]both[/b] of the traditional film and digital photography instances, [b]the photon interacts like a particle[/b].
But what about it looking like a [b]wave[/b]?
[u]Holograph[/u]
The holograph gives you the wavelike alternative to recording an image!
In order to do this, it was easiest at first to use a laser beam because of its special properties.
A single laser beam is split, with one part of it being used as the "reference" beam, and the other part going to the scene to be holographically recorded. The beam hits the scene and bounces off of it, and the light is collected and then re-combined with the other part, the reference beam.
THEY ARE COMBINED AT A GLASS PLATE OR FILM (just like for normal photography) but now you are recording an [b]interference pattern[/b] from the two different beams interfering when they recombine. (Interference looks like light and dark rings, etc.; you can do a quick image search and see examples.)
So we go back to the particle-like recording, but we are not recording the image directly, but a wave property, interference pattern based in part on the image and in part on the reference beam.
You develop the film or plate as usual, and now you have a modern art type design.
How do you recover the image? [u]Illuminate the plate with a laser of the same frequency, at the same angle as the reference beam![/u]
The interference pattern records an image which is 3D (you can move your head and see objects move just as in real life) and which is recorded all over the film/plate (you can break a plate in half and have 2 images, albeit at half intensity).
[u]Traditional images[/u]
Traditional photographs made using glass plates or flexible "film" used special emulsions which were light-sensitive (photo-reactive) in this way: when the lense system focused light from the scene [either emitted by or reflected from it], that light would induce a chemical change to "expose" the emulsion.
The exposing is a photon-by-photon process, and it relates to intensity in this way: more intense light of ANY wavelength/frequency has more photons than less intense light. So the exposure is either greater or lesser depending upon how many photons hit the reactive emulsion during the time of the exposure. [Too short, not a good pic--too dark. Too long, also not good--too bright/washed out. Thus, you used a light meter--hand-held or incorporated into your camera--to set the exposure time, given the film "speed", a measure of how quickly it could make an image, i.e., its sensitivity; the higher the speed, the more sensitive the film.]
Then process the film to get a negative image (real light areas of the scene are recorded as dark areas on the negative, and vice versa), and make prints from the negative.
All of that was to capture light, the photons from the scene.
[u]Digital Images[/u]
In digital systems, something similar happens, but instead of a photo-reactive chemical changing to record a photon's presence, photons hit a special semiconductor and release charges. These are isolated into different physical places and quickly "read out", with the number of charges found at a given place corresponding to the brightness there. (This is the Charge-Coupled Device, or CCD.)
So, again, single-photon events are recorded.
[u]Wave/particle duality[/u]
For tiny particles like the photon, a cornerstone of modern physics is that they exhibit wave-particle duality: in some interactions, they seem to behave like particles,while in others, they seem to behave like waves.
In [b]both[/b] of the traditional film and digital photography instances, [b]the photon interacts like a particle[/b].
But what about it looking like a [b]wave[/b]?
[u]Holograph[/u]
The holograph gives you the wavelike alternative to recording an image!
In order to do this, it was easiest at first to use a laser beam because of its special properties.
A single laser beam is split, with one part of it being used as the "reference" beam, and the other part going to the scene to be holographically recorded. The beam hits the scene and bounces off of it, and the light is collected and then re-combined with the other part, the reference beam.
THEY ARE COMBINED AT A GLASS PLATE OR FILM (just like for normal photography) but now you are recording an [b]interference pattern[/b] from the two different beams interfering when they recombine. (Interference looks like light and dark rings, etc.; you can do a quick image search and see examples.)
So we go back to the particle-like recording, but we are not recording the image directly, but a wave property, interference pattern based in part on the image and in part on the reference beam.
You develop the film or plate as usual, and now you have a modern art type design.
How do you recover the image? [u]Illuminate the plate with a laser of the same frequency, at the same angle as the reference beam![/u]
The interference pattern records an image which is 3D (you can move your head and see objects move just as in real life) and which is recorded all over the film/plate (you can break a plate in half and have 2 images, albeit at half intensity).
l0stwithin · 26-30, M
Watch Star Trek. That will answer all your questions.