Watch Focused Sunlight Melt Steel, Rock, and Anything Else

very interesting!

OK, now we have bought solar heating to a new level. Can we tune the focus of the mirrors (with tracking) to heat a house or hot water that can then radiate throughout a house. This device looks like it has massive potential. Heating, cutting, trash disposal, even hot enough to use with hazardous goods in the environment like PCB. Wow.

It seems like it might be a great way to turn regolith into building material (especially if you configure it as a 3d Printer.)

This is a replication of the experiments of Boettcher who experimented 300 years ago with a solar furnace in his attempt to make the first European porcelain.

He was successful in 1706 with red to brown-colored early pieces and 1708 with the first white pieces.

He had considerable help from Tschirnhaus an expert in chemistry and materials.

They conducted series of experiments with any combination of natural materials that could be done pretty fast with a parabolic mirror 2.4m diameter made from bronze.

They had to construct a high temperature (1500°C) furnace with good temperature distribution to start fabrication (manufacture at that time).

They had to construct crushing and grinding and sieving equipment to get the right grain-distribution from the raw materials.

The king of Saxony supported them as the imports from China were awfully expensive at that time. And the secrets of manufacture were not available.

It took only 8 years for these secrets to leak to Austria and France - both started their own very profitable business.

RHABE

2 Square meters of sunlight= about 2 kw of energy on a clear day.Impressive if focused on a small area, but it cannot boil much water or do much work because of conversion losses.A typical old satellite receiver dish,10 ft diameter has approximately 9 square meters of area,which would give about 18 kw output if everything was perfect, but we know this is not possible yet...but one day....maybe..with improvements in gas (NH3 or similar?) turbine alternator and electrical/chemical storage technology,who knows.

Hang on to that antiquated eyesore, it may prove useful someday.

The sun? Excuse me, but I didn't see the sun anywhere near that thing.

You lot are so gullible.

The video was made at the Solar Furnace facility in France. It did look odd. The sunlight was coming from above and was being focused by a very short focal-ratio optic. (I would have thought it was a fresnel lens, but one of the guys in the video called it a mirror). I (turkey-dinnered) googled info on the Solar Furnace facility and did not see how they could be focusing the light as shown in the video, given the layout of the facility. Nevertheless, considering the size of the Solar Furnace facility, it is far easier to believe that somehow they were using lenses / mirrors to focus sunlight than to believe they were converting it to electrical power, then re-converting the electrical power for an intense arc lamp. Focused sunlight can reach a temperature close to the surface temperature of the sun, roughly 6000 kelvin, which would melt steel, rock, etc.

It is impressive, but I do not think you can focus sunlight to such a (zero area) focus that they show. It is going to be at least the size of a penny , I think. the sun is about half a degree across. So the focus cannot be a point.

Whatever they have done, that amount of precision is incredible. Must have cost a fortune to achieve it.

The lens/mirror doing the focusing appears to have an effective focal length of about a meter, near as I can tell from the video. It also has an extremely fast f/ratio, on the order of around 0.6.

For a fast optical system like this with a diffraction-limited design, the formula for the image size, S, of an object is:

S = 2*f*tan(Φ/2) where f is the focal length and Φ is the angular diameter of the object being imaged. The sun has an angular diameter of 0.5 degrees, and f is perhaps 1000 mm.

So the image diameter, S, will be around 8.73 mm. If the system is not diffraction-limited (which is likely, since that would be very hard to do with a fast f/0.6 system) the image size will be somewhat larger.

If you watch carefully you'll see that the smallest width of the imaging cone is not a point. It's hard to tell if the image size is 8.73 mm, but it is clearly not a 'point'.

"So the focus cannot be a point."

Perhaps not with the lens they''re using, but I have read about specially designed lenses that do. Interestingly, the claim of the lab that produced the lens was the focal point reached a temp of 50,000 degrees. I wonder what they used to measure that or if it was just a calculated temperature.

The flat Fresnel reflector/lens in the now obsolete overhead projectors makes a an intense focal point for sunlight.

I'd love to tell you about a solar collector in my yard (a dish)

but sure as hell lynch would probably make a degrading remark about it

Stub