Applications of Virtual objects

[rishurboi]

I've heard virtual objects are used in cinema halls I'm not sure of what that means, can someone explain this to me please?

And btw by virtual object i mean when diverging rays from real object passes through a convex lens, the rays will converging and if you'll place a plane mirror infront of the the lens, a virtual object will form at the non-reflecting side of mirror. (Image below)

all I'm asking is what are some application of this in real life.

 

[sophiecentaur]

I've heard virtual objects are used in cinema halls I'm not sure of what that means, can someone explain this to me please?

And btw by virtual object i mean when diverging rays from real object passes through a convex lens, the rays will converging and if you'll place a plane mirror infront of the the lens, a virtual object will form at the non-reflecting side of mirror. (Image below)

all I'm asking is what are some application of this in real life.

I suggest you search Google, using terms like "the difference between real and virtual images". You will get a massive range of hits and, between them, you should get an answer to your question (be careful not. However:.....

In cinemas, the image you see is Real because it's been projected on a solid screen and, as it's a set of points in space with different brightnesses it can actually be treated as a secondary object; the light from each part of that 'object' can be seen by everyone in the hall. You'd need to tell us where you "heard" an example of virtual images.

When you see your face in a mirror, THAT's a virtual image. Light rays arrive at your eye in the same way as they would if your face were where it 'appears to be' in the mirror. When you wear eye glasses, the rays enter your eye from a place that's not where the object is but as if it's nearer (or further, depending) away from you - that's a virtual mage.

Otoh, real images are actually not often seen in everyday life. They are formed by the rays from the points on an object are focused at an array of actual 'real' points, corresponding to the points of the original image. In a telescope, the large objective lens gathers the light arriving from a distant object and focuses them in a plane inside the scope. The real image is there but it's very hard to see because it's very small and you have to get y our eye in just the right place. You need another lens (the eyepiece lens) to turn the intermediate real image into a virtual image that's in a position way out in front of the scope (even infinity if it suits you) and which is easy to see.
If you have a concave shaving mirror then you can see a virtual image of your face when standing close up. But if you step back from the mirror, the image of your face goes distorted and, a bit further still and you will see an upside down image of your face which appears to be out in the room. It is real because the light rays come from a real position and go directly to you eye.

You can do the same sort of thing with the concave face of a shiny spoon. Move a pencil about, close in and you'll get a real inverted image of the tip, right in front of the spoon.

 

[Andy Resnick]

I've heard virtual objects are used in cinema halls I'm not sure of what that means, can someone explain this to me please?
[...]
all I'm asking is what are some application of this in real life.

Not sure about cinema, but eyepieces (telescopes, microscopes, riflescopes, etc) and heads-up displays all use virtual images; placing the virtual image at +infinity allows your eye to view the image in its relaxed configuration, avoiding eyestrain.

 

[sophiecentaur]

Not sure about cinema, but eyepieces (telescopes, microscopes, riflescopes, etc) and heads-up displays all use virtual images; placing the virtual image at +infinity allows your eye to view the image in its relaxed configuration, avoiding eyestrain.

Tbh, I can't think of examples where we actually look at a real image. The normal layout of optics is to present a final image virtually so you can look at it easily. Any real image I can think of will be in an inconvenient place and hard to locate and latch onto with your eyes (certainly not both eyes).

There may be some examples of small scale optics like lenticular screens where a virtual image is (could be) used, rather than the usual direct projection system onto a painted screen. This may be what the OP's sources was referring to??

 

[Andy Resnick]

Tbh, I can't think of examples where we actually look at a real image. The normal layout of optics is to present a final image virtually so you can look at it easily. Any real image I can think of will be in an inconvenient place and hard to locate and latch onto with your eyes (certainly not both eyes).

There may be some examples of small scale optics like lenticular screens where a virtual image is (could be) used, rather than the usual direct projection system onto a painted screen. This may be what the OP's sources was referring to??

Not sure what you mean- projectors, for example, project a real image onto a surface.

 

[sophiecentaur]

Not sure what you mean- projectors, for example, project a real image onto a surface.

Yes. A real image appears on a solid screen but I think the lenticular screen will be basically a lens / reflector which, on a small scale, will produce a virtual image that's not necessarily in the exact plane of the backing. Wouldn't that, strictly speaking, be virtual? The source of info that the OP got may have been a bit 'clever clogs' about the actual meaning of virtual here. I guess it's possible that the screen forms a real image in front of its surface of course . . . . .

 

[nasu]

What is a lenticular screen? It used to be just a white wall.

 

[sophiecentaur]

What is a lenticular screen? It used to be just a white wall.

If you use a 'white wall" the majority of the light is reflected back the way it came and the viewing angle is very limited. This is despite attempts at matt paint finish (which is also less reflective all over). A lenticular screen refracts / reflects the light over a wide angle and produces a much more uniform field of satisfactory view. Granny in the corner can see as good an image as Dad in the front middle seat. (It's far from being just nonsense.)

 

[nasu]

Who said it's nonsense? I asked because I never heard about it and not to challange you.

 

[sophiecentaur]

Who said it's nonsense? I asked because I never heard about it and not to challange you.

Sorry. I didn't feel "challenged". Perhaps you are too young to remember when 'everyone' had a 35mm slide projector and mostly found that a white wall is really bad as a projection screen. Manufacturers made a big thing of fancy screen surfaces. These days, people do use (Electronic) video projectors but the circs are different as they're seldom used in the home and it's mainly only tekkies who set them up. TVs are big and brighter for home viewing. So the weekly struggle to erect a screen in your living room to show your mates your latest batch of slides is a thing of the past.