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Want to build a hologram on a table,
Chladni vibration patterns
Here is a simple explanation to get you started. Physics gurus, please excuse the artistic license used here to make the process simple and accessible.To make a hologram you usually need a laser. This produces light waves that are all in-step with each other; this is known as "coherence". In essence, the waves leaving the laser are all the same size and are all in sync; this means that all of the peaks and troughs of the waves line up with each other.The first step is to pass the light beam through a "splitter". This is a half-silvered mirror that lets some of the light through and reflects the rest. The result is that you now have two light beams.One of these beams you shine directly at your target, which is a piece of photographic film or a light-sensitive sensor. This is called the reference beam.The other beam you shine at the object you want to turn into a hologram; this is the "object beam".Light reflected off the object is then also directed onto the photographic film or sensor.Now, although both beams of light - the reference and the object - were in-step when they left the laser, the object beam has travelled a different distance compared with the reference beam, because it has been reflected off the object along the way.This means that when they reach the photographic film, the two beams of light are now no-longer "in-step". In some places, some waves will arrive going up (to a peak) and meet other waves arriving going down. In these places they will cancel out, producing a dark spot. In other places, both waves will both be going upwards or downwards towards a peak or trough; here they add together and produce a bright spot. This is called interference and gives rise to a pattern of tiny "fringes" of light information on the photographic plate. These fringes correspond to the structure of the object's surface that reflected the object light beam.Now, when normal light, or another laser beam, falls on these patterns of fringes, they re-create a visual impression of the surface structure that produced them in the first place; this is the hologram.As I say, a very simple explanation to get you started. Perhaps the others here can embellish to add some meat on these bones.Chris
Quote from: Jolly on 15/12/2015 00:07:40Want to build a hologram on a table, Let me know how you get on. I want to make an holographic system for looking at Chladni vibration patterns. It looks as though I will need similar components to yours but lower power laser and hope for direct digital capture.
Quote from: Colin2B on 16/12/2015 10:49:51Chladni vibration patternsWhat are they?
Well how do you want to present them? Just as a hologram?
Quote from: Jolly on 16/12/2015 14:19:36Well how do you want to present them? Just as a hologram? No, as an interference pattern. Method of creation is very similar.
Not sure I entirely understand you mean you want to produce a hologram by creating an a lazer light interference pattern generated in a similar way?
actually generate a holographic image
Quote from: Jollyactually generate a holographic imageI take it that you are proposing to generate the holographic fringe pattern computationally, and then project this so that the human visual system sees the object that was generated by the computer?