Printer ink is often of different colours and black printer ink is usually unable to produce saturated tones. This means different inks have to be produced, which is unnecessarily complex.

Greyscale can be imitated by halftone. Presumably, halftone using dots between one and about twelve microns, separated by the same order of distance would look like greyscale to the naked eye. But what happens if the dots and the separation are both between three hundred and eight hundred nanometres? I'm not good at this, so help me out please. Does it not mean that a surface covered in such a halftone pattern would look coloured rather than greyscale?

Having said this, paper has a rough surface. It's a mat of lumpy vegetable gunk on the whole, unless it's made of beetles, polythene or something. I imagine this would mess the spacing up somewhat and make the colour non- Lambertian. So, it's not enough just to fling precise globs of goo at a surface like Francis Bacon. That surface has to be even.

Well, to make a virtue out of a necessity, before you start doing that, coat the paper with a translucent white layer, very evenly, then throw the particles of ink with a precise force to embed them at different distances from the surface of the coating. This would afford different levels of saturation too, though the scattering introduced by the translucency would presumably also mess up the diffraction thing.

So, how to do the spacing and size? Use a printer head which consists of an adjustable grid of squares a total of twelve microns on a side with each square adjustable to within the limits of the visual spectrum along with the gaps, avoid viscosity problems by making the ink gaseous and hot, with a subliming point above the temperature at which paper catches fire (which is not four hundred and fifty one degrees F of course), and methinks one has a printer which can generate its own colour ink from black toner. No idea what kind of gas or coating to use though.
-- nineteenthly, Jul 19 2011

Colour Holography http://school.maths...sis03.htm#Heading32
One method for creating true-colour holograms. [Wrongfellow, Jul 19 2011]

Colour Holography 2 http://www.wired.co...plasmonic-holograph
Another way to do it - more high-tech, but perhaps less relevant to this idea. [Wrongfellow, Jul 19 2011]

I'm not sure about this - you talk about placing ink particles on the paper close enough to each other to create diffraction effects, and thus different colours, however the point about this method of creating colour is that ink isn't needed - all the colour is created by the structure of the surface. So, the iridescence on a butterfly's wing might be created by material all of the same colour. Another way to do this would be to not use ink at all, but instead use a laser to etch diffraction patterns in the surface of the paper.
-- hippo, Jul 19 2011


Ooh, i like that! In which case ink is entirely unnecessary and it's less fiddly.
-- nineteenthly, Jul 19 2011


//...use a laser to etch diffraction patterns...//

If you're doing this, why stop at colours? You can use it to print a hologram.
-- Wrongfellow, Jul 19 2011


That's horses for courses really though, because is it not a case of either realistic colour or a hologram?
-- nineteenthly, Jul 19 2011


Not if you don't restrict it to a monochromatic light source. (2 links for the price of 1!)
-- Wrongfellow, Jul 19 2011


I like this. It should work, using a shiny paper and an opaque ink - you'd basically create a diffraction mirror.

You'd have to be very accurate, though (I'm guessing you'd need accuracy down to a tenth of a wavelength, say 50nm), and the colour would depend on the angle you viewed it from.

An alternative approach would be to coat a reflective paper with a continuous layer of transparent, lacquer-like ink of precisely- controlled thickness. I inadvertently did this (on a silicon wafer substrate), and the intensity of the colours is absolutely astonishing.
-- MaxwellBuchanan, Jul 19 2011


Unfortunately the difference between my MBE machine and my printer is that only one of them has a USB port to connect it to my computer.
-- hippo, Jul 20 2011


I am left with the impression of a rapid prototyper which can produce medals, though i presume you're talking about some semiconductor producing thingy. There would presumably be iridescence. Maybe it would also be able to conterfeit banknotes?
-- nineteenthly, Jul 20 2011



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