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HD platters..


themos
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..are flatter than 3 nanometers or so. That's better than λ/100.

They should make perfect optical flats.

But what about their use as primaries, in segmented form? Anybody heard of a project involving them. I read that they boast 95% reflectivity which is not bad. It should be easy to deform them precisely, through the central hole. So anybody thinking what I'm thinking?

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That is soooo scary! I only the other day discussed this with a friend of mine! Using alu HD platters (mind out that they aren't glass!).

I was thinking of having a crack at a primary made from platters, perhaps hexagonally cut?

Great minds and all.....

Cheers

Jamie

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So where can we get lots and lots of old HDD's from cheap? The principle will work using them as found, and mounting them side by side (maths is fun!)

The central hole in each wont matter but they would need to be mounted on a suitable surface with correct geometry for ie parabolic. 30 discs would give a pretty decent size mirror?

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It should be easy to deform them precisely, through the central hole.

I think this may be the failing in your plan I'm afraid. How would you do this, and what shape would you get out? (parabola/sphere?).

As for making a segmented mirror -- the segments need to be off-axis parts of the whole mirror shape, so deforming through the centre wouldn't work unfortunately (unless you have a spherical primary mirror).

Testing what they could do as a small optical flat would be interesting though...

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I think this may be the failing in your plan I'm afraid. How would you do this, and what shape would you get out? (parabola/sphere?).

As for making a segmented mirror -- the segments need to be off-axis parts of the whole mirror shape, so deforming through the centre wouldn't work unfortunately (unless you have a spherical primary mirror).

Testing what they could do as a small optical flat would be interesting though...

A piezo adaptive mirror setup might work- but you'd be straying off budget a bit!

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As we are going for monster aperture, we would have to consider a spherical primary, possibly a Klevtsov Cassegrain design?

Klevtsov?Cassegrain telescope - Wikipedia, the free encyclopedia

Interesting :BangHead: That would certainly reduce the otherwise great length of the tube. AND there would certainly be a large number of adjustments involved. As I see it, x and y on each segment plus the centre to alter the curvature. The finished thing could be really awesome ;) Edited by Gina
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Even if you can't deform them to optical accuracy, you could still try for a solar cooker by nailing them (flat) onto a correctly shaped wooden base.

All you'd need then would be some sun :BangHead:

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Even if you can't deform them to optical accuracy, you could still try for a solar cooker by nailing them (flat) onto a correctly shaped wooden base.

All you'd need then would be some sun :BangHead:

Well thats doomed to failure then!

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  • 6 years later...

what you want to get hold of is some old IBM HDD 3370 14" Diameter 1/8th inch thick Platters seven of the devils... these where used in mainframe computers,also many others in various large sizes look on good old fleabay under mainframe disk platters if you want the large ones

one example https://www.ebay.com/itm/LH502-HARD-DRIVE-PLATTERS-OLD-BIG-COMPUTER-MAINFRAME-DISKS-VINTAGE-1980s-3-lbs/122944035909?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D47300%26meid%3Dc7013092194f4639a95681928d41b491%26pid%3D100005%26rk%3D3%26rkt%3D3%26sd%3D232473079057%26itm%3D122944035909&_trksid=p2047675.c100005.m1851

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