I have a plastic tube that has a wall thickness of around 3 to 4 mm and it is transparent. I am trying to build a ring for the top of the cylinder that just illuminates the sides of the tube, but nothing inside of the tube.

For more context, I am trying to light up the sides of the tube as shown below. I don't want the rat inside to be illuminated by the light as much as the sides of the tube will be illuminated.

enter image description here

I'm thinking of using LED light pins, but I am unsure of whether that will just illuminate the side of the tube or the whole thing. Any help?

  • \$\begingroup\$ Maybe cap on top with light entering at centre. Cap overhangs edges and is grooved to cause light emission. Portion over cylinder is opaqued. What is the purpose? \$\endgroup\$ – Russell McMahon Jul 23 '15 at 16:25
  • \$\begingroup\$ Search on total internal reflection. Note that this can also translate t5o total non entry of light. \$\endgroup\$ – Russell McMahon Jul 23 '15 at 16:26
  • \$\begingroup\$ What does it mean to "light up the sides of a transparent cylinder"? By definition, any light striking the sides will be either passed through or reflected. Where do you actually want the light to end up? In any case, this has nothing whatsoever to do with electronics, and you'll probably get a better response on Engineering.SE. \$\endgroup\$ – Dave Tweed Jul 23 '15 at 16:32
  • \$\begingroup\$ Is it really a cylinder or is it a tube? A cylinder is solid and can't contain a rat (or not a live one - not for very long). A tube is hollow and can contain a rat. \$\endgroup\$ – Majenko Jul 23 '15 at 21:12
  • \$\begingroup\$ @Majenko It's a tube \$\endgroup\$ – Shrey Jul 23 '15 at 21:23

You are asking about Edge lighting or Edge Lit. As a tube, it just means you have to make/fabricate a round ring of lighting. See How to make whole top side of project box glow uniformly? for a good primer on lighting plexiglas or acrylic sheets, everything applies. Including that the sides will not be highly lit, if they are smooth/clear. It would look like this, unless you go with opaque tube (meaning you won't see whatever is inside the tube):

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