HIMNL9
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That's 1000 Watts / 1,000,000mm = 0.001 Watts/mm or 1mW/mm..
Jerry
..... not if you use an 1 square meter magnifying lens ..... :eg:

(J/K, sorry, can't resist


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.....
That's 1000 Watts / 1,000,000mm = 0.001 Watts/mm or 1mW/mm..
Jerry
and less if you use a 1 square meter Concave Lens.......... not if you use an 1 square meter magnifying lens ..... :eg:.....
(J/K, sorry, can't resist:crackup: :crackup: :crackup
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Power is not what burns. You need an optical density high enough to do "work" on a given substance. The optical density needed depends on a lot of things though. Lasers are used to induce chemical reactions all the time. Consider sunlight in the same way. Less than 5mw per square cm does nothing to a leaf on the pavement. However, compressing the light from one square cm in area down to one tenth of a mm, will do "work" on the leaf. The burning areas may not be large enough to burn with enough oxygen to start a full flame, but however you look at it, its still burning. Burning can look like lots of things.