It's getting on to Summer time and with that comes the Sun. I wanted to make a lens or perhaps an array of lenses to focus the Sun's radiation in to one smaller concentrated point which could almost instantly com bust wood. Thanks!

PS I won't light my house on fire. ;3

  • Lenses or convex mirrors can be used to focus the suns' radiation as they have something called a "focal point" by design. Now I wouldn't really describe it as a life hack, as you would be using those things to do exactly what the'yre meant to do. The fact it will result in fire is just the natural result of this. cfr this article
    – Laurent S.
    Commented Jun 29, 2015 at 9:48
  • I'm not sure how you could make a lens as a "hack" as I think you would need specialised equipment to make them. The largest lens I can think of that you may be able to find and repurpose are something of an antique. When television screens were very small large magnifiers were available to effectively increase the screen size. I think Newtonain telescope reflectors are the largest light gathering device you're likely to find with commercial ones of 12" diamater available. You could also try mirroring the surface of a satellite dish with foil and use a lens to tighten the focus.
    – Dave
    Commented Jun 29, 2015 at 11:18
  • greenpowerscience on youtube has a video where they use a transparent plastic sheet supported on a tall frame with a puddle of water in it. It works really well! You can also get big fresnel lenses out of old projection TVs. Commented Mar 11, 2017 at 1:16

1 Answer 1


It sounds like what you want is something to concentrate light, not necessarily magnify anything.

For the former, you can simply use multiple mirrors. You can use normal flat mirrors (for example, by having a bunch of pairs of mirrors that all reflect incident sunlight toward a specific point), but focusing light is easier if you also have convex mirrors (with focal points of one or more meters).

I won't give you a design, because there are a literally infinite number that'd work well, and because you'd need a diagram to implement it (and I'm terrible at diagrams). But this is the general principle.

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