Last edited: 26 March 2017
A Better Focus Co., Inc. designs and manufactures concentrating solar dishes that can be used for solar cooking, water disinfection, and even steam generation. This is a long-focus dish, app. 4' in diameter, utilizing reflective film to focus to a 3-4" diameter hot spot at a distance of 10-15 feet away. Cooking surfaces (pots, pans, ovens) are mounted to a separate pole.
Theory of Operation[edit | edit source]
Reflective film is stretched over a 4' diameter dish that has a small raised surface at the face on the circumference, creating a cavity inside. A vacuum is pulled inside the dish with a small hand pump, deforming the film to a concave shape that focuses sunlight to a variable spot of intense heat. Vacuum holds for a minimum of two hours before requiring a few pumps to hold a given focus.
The dish requires small adjustments as the sun moves every 5 minutes or so. Automatic tracking is planned for summer of 2017.
Safety[edit | edit source]
While it is true that long focal length parabolic reflectors such as this one can cause burns or fires if the focal point is directed incorrectly, this model includes a feature in that air escapes slowly from the disk causing it to lose its parabolic shape over 1-2 hours. Its designer states that there is little danger coming in contact with the beam except within a foot or so of the focal point. The provided cover should always be placed over the dish reflective surface when not in use. A pair of sunglasses is provided with each shipment, and are strongly recommended for all observers who look at the focused light on cooking surfaces.