Re: [tech-3d] holographic 3d

[lunazzi <lunazzi@xxxxxxxxxxxxxx>]

Peter Homer wrote:

> >The technique of projecting with mirrors is as old as 4000 years (the Incas and
> >the Olmecas). I did not think these new world civilisations were as old as this
> which is as old or older than anything in the old world and I thought the Olmecs were the oldest rather than the Incas

I do not know if they were older than the Incas, the interesting thing is that they disappeared before the Aztecs but left a very important influence on them. I do not know if Teotihuacan is considered precisely Olmec, but it seems to be, and was considered as a sacred city when it was found inhabited by the Aztecs.

> but perhaps that was just in Central rather than South America
> >http://www.geocities.com/Athens/Forum/3853/olm1e.html
> >
> I had a look at this site although I could not view the graphics properly with my my Netscaoe Navigator 2.02,

Maybe it is due to the version, because I use Netscape 4 now, although I started with 2.0
I verified by reading from a different terminal than I used for  editing, to avoid the direct lecture on the computer rather than through internet (is a typical error that sometimes arrives to me).

> I found it very interesting but was the original intention of the concave mirrors to project images or to focuss the suns rays to produce fire,as the name Tezcatlipoca ( smoking Mirror) suggests. Perhaps with a religious significance as the fire was taken directly from the sun,

This was already made by the Incas, precisely as you wrote, but using metal mirrors.

> I have seen some other illustrations of these types of mirrors made from polished pyrite or iron sulphide FeS2 which can form naturaly in balls or discs

I have some samples, but not in the form of balls or discs.

> consisting of radiating needle like crystals. Specular haematite can also form a miror like surface when polished,
>

I am trying a technician to made the polishing on them, using aluminum oxide.

I would like to put more information on my page, including the whole article, but for the moment I can mail you the article if you send me your postal address.

> >Projecting on lenses is also interesting, it renders a floating image.
> >The progress in this last years shoul be in increasing the field of view, wether
> >using paraboloidal mirrors more specific that the Olmecas ones (as Peter Homer
> >indicated)
>
> P.J.Homer

The serpent heads emerging in the Teotihuacan temples (pyramides) arises from mirrors (archeologist said), what shows clearly (at least to me) that mirrors were employed for imaging.  On the other hand, if they were merely to concentrate sun,  I can suppose that it did not needed so much polishing. Another interesting feature is that most Olmec mirrors has two different focal lenghts (along perpendicular directions) what makes them to not concentrate light in focus.

José


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