I am trying to make like a "periscope" that i can use with a mobile camera. I have made a very quick prototype with two mirrors and it "works" but you can see the interior of the walls so it is not a good solution. It currently looks like this enter image description here

enter image description here

So as I said the problem is that you can see the "walls" on the interior of the periscope when i put the camera in there. Is there anyway I can adjust this or do I need to look at an optional solution?

What i want to achieve is to make the backcamera of the phone to be like a frontcamera and have it under the camera that is vertical. (just like my current model). Can I somehow adjust the periscope (build it better, add more mirrors, maybe add a magnifying glass?) or do I need to build something else completely in order to make it work flawlessly without interior walls etc being in the way making the quality bad.

Any tips, tricks, links is very much appreciated!

  • $\begingroup$ My initial thoughts are you should investigate refining the optical system within the periscope to focus the image from the first mirror onto the lens of the camera. $\endgroup$ – Fred Oct 20 '16 at 11:09
  • $\begingroup$ Look at this video: youtube.com/watch?v=wqb9w5S0dH0 it is a solution that works! but i want to build something where you dont see the mirror prefereably and build it like a tube. Do you think it is possible if i follow the video i just linked and try to build a "tube" around the mirrors? $\endgroup$ – Carlos Rodrigez Oct 20 '16 at 13:10

Ok let me draw some pictures you right now have the following situation:

enter image description here

If you add a convex lens to this setup you get:

enter image description here

Which does work. However you may want to add a concave lens after the convex lens so that you can more readily adjust the beam focus and shape giving you more freedom to shape your periscope.

  • $\begingroup$ Thanks alot for this jooja! So should the concave lens be placed right after the convex lens or should it be in the middle of the periscope? $\endgroup$ – Carlos Rodrigez Oct 20 '16 at 19:43
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    $\begingroup$ A side question, what did you use to make those nice looking illustrations? $\endgroup$ – fibonatic Oct 21 '16 at 0:44
  • $\begingroup$ @fibonatic illustrator $\endgroup$ – joojaa Oct 21 '16 at 4:30
  • $\begingroup$ @CarlosRodrigez you should draw the lines like i have drawn in the examples. You can quite freely place the lenses in the system in a way that could work, it all depends on your actual values of lenses and actual dimensions. For example both lenses could be after first the mirror, or they may need to be before first mirror and after the last one or something like that. $\endgroup$ – joojaa Oct 21 '16 at 10:34
  • $\begingroup$ Okok! imgur.com/a/CHNaK Is the small lense on the magnifying glass a convex lens? Could I use this one you think? $\endgroup$ – Carlos Rodrigez Oct 21 '16 at 13:11

The basic answer is that the field of view (FOV) of your camera is much wider than the FOV of the periscope. Unless you add a lens system between the periscope and the phone to limit the effective FOV of the camera, there is no way to avoid seeing the walls of the periscope. (Well, you could build a periscope large enough that the walls are outside the camera's FOV, but that would be ugly :-) )

  • $\begingroup$ I guess it is quite difficult to build a lens system at home so maybe i should create a bigger periscope. the only thing i would need to do is to increase the periscopes width (mirrors width) and then it would work? how wide of a mirror are we talking, 5cm? 10? But of course it would be better with a lens system. Would that be hard to make at home? Or is it easier than it sounds? Magnifying glass and that is it or is it much more complex? I appreciate the reply alot!! :) $\endgroup$ – Carlos Rodrigez Oct 20 '16 at 13:38
  • $\begingroup$ imgur.com/a/QX6Yb trying to understand the logic a bit here. So a mirror (45 degrees) first and then right after that a magnifying glass and then at the end another mirror. Or is it more complex then this? $\endgroup$ – Carlos Rodrigez Oct 20 '16 at 14:15
  • $\begingroup$ @Carlos you need 2 lenses one to straighten the beam and one to let it widen again. $\endgroup$ – joojaa Oct 20 '16 at 14:47
  • $\begingroup$ Okok. I will take a look into it. So if i want to make it the same way like the above image it would look like this: first mirror -> lens to straight -> lens to widen it again -> last mirror? $\endgroup$ – Carlos Rodrigez Oct 20 '16 at 15:12
  • $\begingroup$ After googling a bit it seems pretty complex to make this happen. I think I will probably make it with a wider mirror instead. I dunno how to make it look good though as of now but i will experiment a bit. I want to build in the mirror somehow so you can't see the wide mirror but yeah it is harder than it sounds probably. $\endgroup$ – Carlos Rodrigez Oct 20 '16 at 15:38

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