A Fresnel Lens cooker that Heats from Below
by Bruce Joseph
(Tucson, AZ (USA))
Fresnel cooker from the side
I recently modified my Fresnel lens "grill" to heat from below. This allows more conventional cooking than the old version, and is more practical to use.
Instead of the lens being mounted on straight arms that pivot at the focal line, this new version uses arms with a 90 degree elbow, and a mirror placed at a 45 degree angle at the elbow. The arms still pivot at the focal line.
Because of some losses added by the mirror, this cooker is slightly less efficient than the original. The first thing I cooked, was a 1/3 pound lamb burger. It took about 8 minutes (as opposed to 6 on the "grill.") It will also ignite a 2"X4" in under 10 seconds, where the old grill can do it in about 5.
Still, this grill should allow me to steam veggies, and cook in pots and pans, and possibly even be the heat source for a solar oven, which the old version simply could not do.
Greetings again Bruce,
Thank you for sharing this with our site visitors, this is great...you really did some nice and practical revisions of your Fresnel lens cooker.
We look forward to hearing more from you when you wish.