4 April 2009, 11:28 PM
If you’ve missed it, here are parts one, two, and three of our adventures with a 4’x3′ fresnel lens, along with a gallery of all the pictures.
Our lens arrived with a corner chipped off, so the lens company sent us a second one for free (which also had its corner chipped off on arrival, but we didn’t get a third for free). I’ve been holding off writing this post because I was hoping to title it “Episode IV: A New Lens,” but we still haven’t built the frame for the second lens or the frame for the mirrors that will reflect light from both lenses onto a single point. So, instead of waiting for that to happen, I’m posting the results I’ve already got.
The same SAFETY NOTES as before apply, as always. In lieu of new safety warnings (we haven’t had any new dangers come up!), I’ve got a few tips for anyone trying to duplicate this. Some tips for fellow lensers, followed by more pictures of results →
22 February 2009, 6:06 PM
If you missed it, here’s part 1 and part 2 of our adventures with a 4’x3′ fresnel lens. As always, I’ve got a gallery of all the raw pictures, and this is a summary of the good ones.
The same SAFETY NOTES as before apply, with the addition that you shouldn’t eat any food you cooked in the same skillet in which you just cooked non-edible things (plastics, coins, etc). Also, we’ve upgraded our welding goggles, from a shade 5 filter to a shade 12, which is actually good enough that you can stare at stuff in the focal point. It’s not quite good enough to stare directly at the sun, but it’s darn close, and rumor has it that you can watch sunspots through this thing if you don’t look at them too long.
Last time, I left you with a picture of popcorn getting ready to be lensed. More results with more pictures →
13 February 2009, 12:23 AM
In case you missed it, here’s part 1 of our adventures with the 3’x4′ fresnel lens.
Oh, man. I have lots more pictures. The same SAFETY NOTE as last time applies again, but with a few more additions. You should probably wash your hands after you’re done handling stuff in the lens. In particular, when you heat copper up until it turns black, you’ve probably made copper (II) oxide, which is a somewhat nasty irritant. I also make no guarantees about how many carcinogens we’ve made/touched/breathed, although so far I still feel healthy (no cancer in the past week!). Speaking of health hazards, if you use a frying pan to hold stuff, make sure it doesn’t have a Teflon non-stick coating! That coating will burn away and become a huge safety hazard (it’s mainly fluorine, and most fluorine compounds are toxic, volatile, and several other kinds of nasty; quite a few fluorine compounds were used as chemical weapons and precursors to sarin nerve gas, so avoid it at all costs). We got a cast-iron skillet, which is reasonably safe and inert, and it doesn’t melt until we break 1800K, which is very unlikely with our current setup.
Anyway, on to the results. with more pictures, of course. →
31 January 2009, 1:05 AM
A couple weeks ago, Dustin got a whole bunch of people to each contribute a few dollars, and we bought a four foot by three foot fresnel lens. It arrived earlier this week, and we’ve been spending our lunch hours out in the sun playing with it.
Explanation of the lens and safety note, followed by more pictures →
