The nipkow how small could one be made

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The nipkow how small could one be made

Postby Harry Dalek » Mon Jan 31, 2011 8:20 pm

I was thinking about how you could get a tiny one to work ?

Disk the size of a jar lid perhaps .

Also about it wouldn't the light level used because it would be massive for a tiny nipkow be brighter than lighting a normal sized one since your directing light to a smaller area.

I was thinking it could be made from tin foil.... holes made via a pin prick mounted on a frame to rotate///and of cause a lenes.....need one of those with my eyes !

Is there a record for the smallest Nipkow ? i think every one wants a big one but lets talk Tiny !
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Postby gary » Mon Jan 31, 2011 8:55 pm

Well, the smallest I have made is one made out of a CD - it is very difficult to make them accurately (I used a .3mm drill - you only have to look at them and they break), but they give very clear, albeit, tiny pictures.

I suppose the smallest Nipkow disks would be those used in Confocal Microscopy, but I think they bear little resemblance to the Nipkow disks we know and love, having nested spirals and thousands of holes in the frame at any one time - goodness knows how they work.
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Postby Harry Dalek » Mon Jan 31, 2011 10:10 pm

Hi gary

Yes i expect it would be hard to make them accurate ,never tried cd size yet anyway only got to single record size .


I was thinking of some thing thin and not transparent when lights behind it perhaps even at this size thick black paper ,i like the idea of tinfoil but.

Yes i have seen those hobby drill bits at bunnings boy they charge for them i think i have seen them at jaycar electronics store as well.

i will have a google on that modern day Nipkow
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Postby gary » Mon Jan 31, 2011 10:28 pm

harry dalek wrote:Yes i have seen those hobby drill bits at bunnings boy they charge for them i think i have seen them at jaycar electronics store as well.


I think the smallest in those sets is 0.5mm - too big! I had to get them in special via hobbyco - yes expensive.
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Postby M3DVQ » Mon Jan 31, 2011 10:34 pm

This is where a laser on a CNC machine would be handy :)
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Postby kareno » Tue Feb 01, 2011 12:43 am

The thought occurred to me the other day: The metal foil on a CD is very thin - ideal disk material! I imagined a Nipkow disk made by just piercing the foil - no need to drill right through the acrylic.

It won't work of course - that foil layer is so thin it transmits significant amounts of light. Curses!
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Postby Dave Moll » Tue Feb 01, 2011 1:23 am

Some packs of CDs/DVDs come with a dummy (transparent) one on top of the stack. Perhaps one could apply an opaque layer (e.g. paint) to one side of it and make "pinholes" in just that layer. It might even work with a real disc if you pierce both the added layer and the foil.
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Postby gary » Tue Feb 01, 2011 6:56 am

It's not obvious to me how it would be any easier to pierce just the foil/opaque material accurately than it is the entire disk, in fact I can't think of a way it would be done.

Even if there was only foil to get through, as in the case of the suggestion of placing a piece of foil over a larger hole, it would require that the resultant flashing be removed somehow (in pin hole cameras it is usually done by repeatedly fine sanding and re-piercing - a laborious process when doing it 32 times.
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Postby gary » Tue Feb 01, 2011 7:02 am

M3DVQ wrote:This is where a laser on a CNC machine would be handy :)


Well I have the CNC machine, unfortunately the nanny state I live in precludes me obtaining a laser pointer never mind a laser capable of cutting material - although I am waiting for someone to give me an old DVD burner they no longer require ;-)
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Postby gary » Tue Feb 01, 2011 10:29 am

Of course if you make it a bead disk the positional accuracy is just as demanding but at least you can use a bigger drill.
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Postby DrZarkov » Tue Feb 01, 2011 5:31 pm

If there is a need to make it small, but fully functional with the NBTV standard, why not make a disc with say 4 or 6 aperture, and use a second disc with masks, like it was done with the 180 lines Nipkow-discs? That would avoid the need of microscopic pinholes.
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Postby Harry Dalek » Tue Feb 01, 2011 8:19 pm

Dave Moll wrote:Some packs of CDs/DVDs come with a dummy (transparent) one on top of the stack. Perhaps one could apply an opaque layer (e.g. paint) to one side of it and make "pinholes" in just that layer. It might even work with a real disc if you pierce both the added layer and the foil.


Hi Dave

In fact i think using one of those for a cd size experiment is pretty good it could work with my tin foil idea ...you could pin hole the foil and use the dummy cd as a backing...

Oh i am not sure if they are all like this but i took apart a broken dvd player and the motor driving the dvd was just a normal dc motor just have to push the above on it if it was made.
just an easy way to mount your nipkow just push it on and its locked .
Last edited by Harry Dalek on Tue Feb 01, 2011 9:32 pm, edited 3 times in total.
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Postby Harry Dalek » Tue Feb 01, 2011 8:28 pm

gary wrote:It's not obvious to me how it would be any easier to pierce just the foil/opaque material accurately than it is the entire disk, in fact I can't think of a way it would be done.


Hi Gary

when i made my first nipkow i used to put a large pin over a candle and heat it then i would pierce a record nothing to do with the above but it jogged my memory...think was easier than drilling as i recall...bit stinky but !
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Postby Harry Dalek » Tue Feb 01, 2011 9:06 pm

DrZarkov wrote:If there is a need to make it small, but fully functional with the NBTV standard, why not make a disc with say 4 or 6 aperture, and use a second disc with masks, like it was done with the 180 lines Nipkow-discs? That would avoid the need of microscopic pinholes.


Hi Doctor

I think small is better if you can make it ,it would be a nice challenge :wink:

I don't think i have heard of this one do you have any other info .


But i understand using a separate Vert Horiz scanning would give a larger raster on a small monitor disc or drums .

I don't think but there are free lunches in nbtv and i found you need a lot more light passing 2 of these ..

But still i do like a 2 motor idea .
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Postby gary » Tue Feb 01, 2011 10:44 pm

harry dalek wrote:when i made my first nipkow i used to put a large pin over a candle and heat it then i would pierce a record nothing to do with the above but it jogged my memory...think was easier than drilling as i recall...bit stinky but !


Yes it is a method , and yet I have never been able to do that accurately - and then there is always that swarf to remove...
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