Laser focal point manipulation

[mfb]

No. That thread started with your quote of

Sure, the lens (better: use a mirror) would have to be larger than the image, the viewing angle would not be so good and there is no real point in it anyway... but it is possible.

which refers to the setup of post 8.

 

[Drakkith]

No. That thread started with your quote of which refers to the setup of post 8.

Ah, I see. I misread your post. My mistake.

 

[Andy Resnick]

hi Andy

for my own learning
could you please elaborate on that response ? :)

Dave

Sure- changing the propagating radiant field requires interaction with a material ("scattering"). Scattering without anything to 'scatter off of' is a violation of the conservation of momentum.

 

[Stanley514]

An example of a sreenless display from a sci-fi movie.

 

[Danger]

...a sci-fi movie.

Exactly the point. If you care to check out the gorgeous cartoon chick (Jessica Rabbit) from a neighbouring video, you'll note that she is fictional as well.

 

[Stanley514]

Some companies claim, they already started to develop cell phones with holographic displays.



http://news.yahoo.com/apple-patent-suggests-holographic-iphone-130008307.html

 

[Danger]

Some companies claim, they already started to develop cell phones with holographic displays.

I don't know whether that's even a real video or a fake one, but in either case that particular technology is nothing new. There have been virtual keyboards available for years which work by projecting the keys and then measuring where your fingers are in relation to them. The display in that case, as in yours, is not holographic, since it's not 3-D; that's just a hype term to use for a simple projected image. In both cases, it has to be projected onto the desk surface rather than into thin air.

 

[Stanley514]

For the two mirrors, you have quite a large possible viewing angle.

Sure, the lens (better: use a mirror) would have to be larger than the image, the viewing angle would not be so good and there is no real point in it anyway... but it is possible.

Yeah, in order to make it practical they need to achieve that image would be much larger than a mirrors and make it look like it floats in dozen of inches above mirrors. But I do not think it have to be 3d image, I would be satisfied with a 2d image.
I suggest you do not need to use a real physical object like a coin to generate image and everything could be gone with help of a lasers simply? Mirrors could work with lasers as well?

 

[Danger]

I would be satisfied with a 2d image.
I suggest you do not need to use a real physical object like a coin to generate image and everything could be gone with help of a lasers simply? Mirrors could work with lasers as well?

Okay, 2D is not as unreasonable as 3D; I merely mentioned that aspect since your phone clip says "holographic" when it clearly isn't.
I honestly can't see how you could use lasers instead of a physical object in the instance that you refer to. With that double parabolic mirror cavity "floating coin" effect, you would have to have your source in the exact same focal point of the device that the coin currently occupies. That means that the illusion would be of the projector with a red dot on it floating above the dish, not just the dot.

 

[mfb]

Yeah, in order to make it practical they need to achieve that image would be much larger than a mirrors and make it look like it floats in dozen of inches above mirrors. But I do not think it have to be 3d image, I would be satisfied with a 2d image.

That does not work. At least not in the way you describe it.

 

[Stanley514]

Then I have question to specialists in optics: What is maximal possible angle of defocusing and what is dependence between the focal length and angle of defocusing?

 

[Drakkith]

Then I have question to specialists in optics: What is maximal possible angle of defocusing and what is dependence between the focal length and angle of defocusing?

I believe it's about 180 degrees for a mirror, and a little less for a lens. There is no dependence between focal length and angle of defocusing. For a laser beam and a simple optical system, the larger the beam radius, the longer the lens/mirror focal length can be.