As per the diagram shown, my inside window looks out on a shared hallway, not the outside. Using mirrors or optics, I would like to be able to see the tree and sun from inside. I can't alter the shared hallway, and I would like the solution to take up as little room inside my own space as possible. I'd also prefer the image plane be vertical, as if it were a window. How might the image be transferred?

  • $\begingroup$ Start by getting some pictures through your window at different angles. That will provide what you have to work with. From there you'd have to figure out where you want to be standing to see what you photographed, and draw your line of sight and the line you photographed from as the constraints for your optics. $\endgroup$
    – Abel
    Commented Nov 17, 2023 at 13:08
  • 1
    $\begingroup$ web cam + large flatscreen monitor? $\endgroup$
    – Dave Tweed
    Commented Nov 18, 2023 at 21:20

1 Answer 1


The simplest solution would be to use a periscope. You need to be aware of a few points - mostly that light travels in straight lines and that when reflected on a mirror the angle of reflection is equal to the angle of incidence (hence a 45° mirror will turn the light by 90°).

enter image description here

Figure 1. Getting closer to the aperture increases the field of view.

A viewer at B will have a wider field of view than a viewer at A. In your case the closest you can get to the window will be the height difference between your eyeballs and the centre of the window + a bit!

enter image description here

Figure 2. The periscope.

Here you could optimise the mirrors to give a good view from one position - your desk, perhaps. As you move about the room the view will change. Changing your eye-level will cause an image shift. Moving left or right might be OK if the windows are wider than your mirrors.

Other considerations:

  • The top mirror may cause some loss of overall daylight in the room.
  • Overhead mirrors pose a life-threatening hazard. I don't know if you can get laminated or safety mirrors but I suspect there must be some form of safety glass used in sliding wardrobe door mirrors.

I suggest that you make a scale mockup from a cardboard box and a couple of pocket mirrors to get a feel for it. You could use a laser pointer to check your field of view from any position (the head position in Figure 2), sweep it up and down, left and right, and see the results. Then do a drawing to figure out the smallest mirror sizes that will do the job.


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