NTNUJAVA Virtual Physics LaboratoryEnjoy the fun of physics with simulations! Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/
September 27, 2020, 07:48:01 am

To live close to great minds is the best kind of education. ..."John Buchan (1875~1940 Scotticsh historian, Governor General of Canada)"

 Pages: [1]   Go Down
 Author Topic: To form a real 3D image  (Read 32210 times) 0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
Lok
Newbie

Offline

Posts: 3

 « Embed this message on: February 19, 2006, 01:39:54 pm »

Hello!! I am the new member here~
I've got some problems to solve

The following diagram is a system to form an aerial 3D image but i don't know what name it is. I can understand why the image can be 3D but I don't know why it can be observed without screen.
At the place where I saw that gave it a name "Reflective hologram". However, in holography theory, the "3 dimensional imgae formation" is just on a single surface film. The "3D image" that we observing is just a combination by lot of layers. It's not like the following, this is real 3D image.

Anybody knows that?? Plx help me~~~~~thx a lot
 Logged
Fu-Kwun Hwang
Hero Member

Offline

Posts: 3085

 « Embed this message Reply #1 on: February 20, 2006, 10:55:24 am » posted from:Taipei,T'ai-pei,Taiwan

Please check out the following applet Mirage! you can see it but you can not touch it!
 Logged
Lok
Newbie

Offline

Posts: 3

 « Embed this message Reply #2 on: February 20, 2006, 08:41:15 pm »

I can understand the ray diagram and why the image can be 3D but I don't understand why the image can be observed without screen. When we form a real image just by convex lens or concave mirror, the image can't be observed, unless we sit on the image point. At least, we won't see something aerial like this toy.

For the java, I have some confusions, when the distance between mirror and the object is 0, the image should be formed on the focus. For the red line, do the different ray paths exsist?
If the ray paths like the java showing, when there is not the upper mirror, the rays go away, so how can the image be formed at focus??

There is on thing I can sure, the total image must be formed by lot of views of images. thus it is a combination of mutliimage. From this, I made an assumption that when mor than 1 image are overlapping, we may observe it without screen. Is that possible??

I have made an assumption that is because of interference of muti-foucsing point but my lecturer said that is not true, I have no idea, no direction to analysis that now.............

 Logged
Fu-Kwun Hwang
Hero Member

Offline

Posts: 3085

 « Embed this message Reply #3 on: February 21, 2006, 08:58:59 am » posted from:Taipei,T'ai-pei,Taiwan

The only way we can see something is that light must be able to enter our eye. And our mind will try to interpreted where is the image. The above two light paths you shown will not be able to enter our eye at the same time. Althought there can be many light paths emitted from the object. Only those paths which will be able to enter our eye can be used to interpreted where the object is. The light paths shown on the original documents will not be able to enter to your eye at the same time, so I create the simulation to show how the image could be formed. The red and blue light paths represents light emitted from two different points of the object. When those light enter our eye , our mind interpreted it is coming from the top of the mirage.
 Logged
Lok
Newbie

Offline

Posts: 3

 « Embed this message Reply #4 on: February 21, 2006, 03:54:36 pm »

Thank you very much!!!!!!!!!!!
When I'm studying this case I even forgot the most most basic knowledge..........................

"The only way we can see something is that light must be able to enter our eye. And our mind will try to interpreted where is the image. "

Let me conclude somthing
We can see the image without screen in this case because the system reflect light rays in almost all directions then enter our eyes. For the other case(e.g real image by concave mirror/convex lens) light rays are going in the same direction, in the condition that screen is absent, we can't see the image unless we sit on the area that dirtributing light rays or the image point.

Right??

One more question, we're going to apply this technique on projector to form a real 3D image but it seems to be somebody done that already
http://www.io2technology.com/index
http://www.fogscreen.com/
Although those products are projecting 2D aerial image, I think the theory used in those products are close to my case. We must make our project faster..................
 Logged
Fu-Kwun Hwang
Hero Member

Offline

Posts: 3085

 « Embed this message Reply #5 on: February 21, 2006, 04:36:07 pm » posted from:Taipei,T'ai-pei,Taiwan

Yes. Light need to enter our eye for us to see any object.
Normally, we do not see the path of ray when we use a laser pointer.
The light path shown in the movie(e.g. Star War) for laser rays are not real, especially in the space. Nothing can reflect those light.

The sun is always shining even in the evening. But we did not see the sun light at night because those light go away from us. Only when some of those light hit ths surface of moon and reflected back to our eys so that we can see the moon.
:-)
 Logged
gunman23
Newbie

Offline

Posts: 1

 « Embed this message Reply #6 on: May 13, 2009, 05:23:28 pm » posted from:Singapore,,Singapore

my physics teacher says that the retina is the screen for this image...but im still confused as well
 Logged
desertrose3
Newbie

Offline

Posts: 11

Physics <3

 « Embed this message Reply #7 on: January 19, 2012, 04:56:31 am » posted from:Lahore,Punjab,Pakistan

Sometimes you need to review the basics as well, it happens with me all the time : )

The link isn't working for me? It takes me to the main page of the forums.
 Logged
Fu-Kwun Hwang
Hero Member

Offline

Posts: 3085

 « Embed this message Reply #8 on: January 19, 2012, 07:34:15 am » posted from:LONDON,ENGLAND,UNITED KINGDOM

The link should work fine now. (It has been modified). Please check it again!
 Logged
desertrose3
Newbie

Offline

Posts: 11

Physics <3

 « Embed this message Reply #9 on: January 20, 2012, 06:03:09 am » posted from:Lahore,Punjab,Pakistan

Thank you! It's working now.
 Logged
 Pages: [1]   Go Up
To live close to great minds is the best kind of education. ..."John Buchan (1875~1940 Scotticsh historian, Governor General of Canada)"