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Literally seeing a real image?

  1. Dec 12, 2006 #1
    Normally we see a virtue image after light from the object reflects off a mirror. We then trace back to behind the mirror to a point where the virtue image came from.

    A real image is seen when light from the object projecting the image reflects off a screen or mirror and we see it with our eyes. We know where the image came from and it sits on the screen or mirror.

    With the real image scenario, what happens if I try to see the light projecting the image directly? In other words replace the screen or mirror with my own eyes. What do I see? One thing is that a second pair of eyes looking at my eyes will see the image reflected off my eyes although faintly.
     
  2. jcsd
  3. Dec 12, 2006 #2

    Danger

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    Can you clarify the question a bit? Are you talking about looking into a projector beam? If that's the case, you'll pretty much just be temporarily blinded.
     
  4. Dec 12, 2006 #3

    russ_watters

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    Objects reflect light in all directions at once (typically). So you'll see the exact same thing whether you are 10 feet in front of a mirror or 10 feet behind where it was (minus seeing yourself, of course). But the path the photons take to get to your eye will be different.

    It is simple enough to visualize if you draw a diagram of where the rays go.
     
  5. Dec 12, 2006 #4
    Just because the concept is called 'real' doesn't mean it actually is an image of you in reality. The Physics Classroom has a thorough tutorial on The Reflection and the Ray Model of Light.
     
  6. Dec 12, 2006 #5
    Yeah that's what I mean. What about a very low intensity projector?
     
  7. Dec 12, 2006 #6

    I am asking whether I can see the light before it reflects off an object or screen. i.e. Seeing a ver low intensity projector directly.
     
  8. Dec 12, 2006 #7
    The link doesn't work.
     
  9. Dec 12, 2006 #8

    Integral

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    Why don't you just pick up an magnifing glass and look through it? Look at a distant object while the lens is greater then the focal length from your eye.
     
  10. Dec 12, 2006 #9

    jtbell

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    Set up a converging lens and an object such that a sharp real image is produced on a screen. Get behind the screen, with the screen between you and the lens, fairly close to your eye but not so close that you can't focus on the back of the screen (say, to read something printed there).

    Now, remove the screen. You should see an inverted image of the object, floating in the air between you and the lens. Actually, if the image is large, you'll see only part of it, the part that's framed by the circle of the lens. By moving your head around, you can see different parts of the image.

    If you move your head towards the former location of the screen, the image apparently gets bigger (because you're getting closer to it), but at some point you get too close and can't focus on it with your eyes any more, so it becomes blurry. When your eye reaches the actual image location, it's as if you were smacking the (enlarged or reduced) object itself right into your eye, except less painful. :biggrin:
     
  11. Dec 12, 2006 #10

    Danger

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    Fascinating, jt. Would each eye receive the same image, or would parallax hold true to produce a 3-d picture?
     
  12. Dec 12, 2006 #11

    russ_watters

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    Why not just find a projector, turn it off, and look through the lens?
     
  13. Dec 12, 2006 #12

    Integral

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    Because the lamp will blind you?
     
  14. Dec 12, 2006 #13

    Integral

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    I don't think so. The image you are viewing is created by the single lens, so you only have that perspective to work with.

    Using paralax you can locate the image in space.
     
  15. Dec 12, 2006 #14

    russ_watters

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    Um, I don't think it will. Perhaps you should should reread what I wrote... :wink:
     
  16. Dec 12, 2006 #15

    Danger

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    I was wondering about that the other way around. Projectors (at least the ones that I've seen) are light-tight. How could you see into one?
     
  17. Dec 12, 2006 #16

    I want to try to see it for myself but don't seem to have the equipment.
     
  18. Dec 12, 2006 #17

    I did that and I saw an inverted image which looked smaller than it really is.

    Is that pretty much the same thing as jtbell was talking about? But I don't feel as if the image is hitting my eyes.
     
    Last edited: Dec 12, 2006
  19. Dec 12, 2006 #18

    Danger

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    At the risk of sounding facetious... if it isn't hitting your eye, you can't see it.
     
  20. Dec 12, 2006 #19

    russ_watters

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    Sorry, I left out a word there. That should be overhead projector.
     
  21. Dec 12, 2006 #20
    What kind of projectors are you talking about?
     
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