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Polymer 'Muscle' Changes How we Look at Color
New Scientist is reporting that in the not-so-distant future computer monitors, and televisions may utilize a color changing polymer that responds to a current instead of existing techniques. From the article: "Aschwanden and colleagues built arrays of 10 pixels, each 80 micrometers across. The pixels consist of a piece of polymer covered with ridges tipped with gold. When white light is shone at the polymer from one side it reflects out of the screen and is also split into different wavelengths by this 'diffraction grating'. However, a slit above the polymer ensures that only one wavelength of light escapes, giving the pixel its color. The pieces of polymer also contract in response to current, like simple muscles. As they do so, the fan of light-waves is moved, changing the color that is fed through the slits above and out of the screen. Cutting the current causes the muscle to return to its original state."
I like the idea of reducing our current RGB model to a "true pixel" technology, because it will make displays smaller, sharper and more. But as far as I understand our vision system is itself based on a sort of RGB sensor and the human eye is not really capable of seeing e.g. orange, which is why the whole RGB (and CMY) display technology works in the first place. There are some high range displays (at least in research facilities) giving you a larger dynamic per color than the 256 scales of traditional 24 bit images, so the lack of "true colors" mentioned in the article might be solved by conventional technology.
But what about the use for data transfer over fiber? One of the nice things about fiber is that you can send several "colors" in parallel which will not disturb each other, something impossible with copper. Up till now they use laser diodes with a fixed wavelength, so the number of diodes determines how many parallel signals you can send.
Now there is a technology that can create any wavelength. Combined with matching optics, could one not use one of those polymer displays to create multiple wavelength signals and send them through one fiber, in theory allowing an indefinite number of signals? Still limited by the number of pixels on the display and the accuracy of the sensors on the other side, but much easier than to arrange several thousand laser diodes.
[Just speculating, no real clue about optics.]
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For certain applications. It's my understanding that usually the synthetic muscle stuff isn't particularly speedy in changing shape. My first question is how many flips per second can you get? Are we aiming for TVs or variable paintings? My second question is about power requirements. 300 volts, sure, but are we talking amps or microamps?
Neat, as most science is, but possibly not terribly useful.
So we have a "pixel" that can be truely any color. Does it mean "any" color, as in Hue, or can it truely be of anything (ie. full spectrum output; Image of fluorescent light would have spiky spectrum, etc.). If the former, instead of RGB we can simply transmit HSV (Hue-Saturation-Value(Brightness)), but if it's a continuous spectrum...
Instead of transmitting just RGB values from 0-255 (24 bits) per pixel, instead you have to somehow convey the entire spectrum. At what resolution do you get? Instead of three values (R, G and B) do you get 400 (one per nanometer, from 300 to 700 nm?) - or 4000? What kind of format do spectrograms use?
Anyway, consider transmitting data from a spectrogram - times some standard monitor resolution - for multiple frames per second. That's a lot of uncompressed data.
...Sweet! That's almost as good as the camera on my cell phone!
It reflects white light. It works like a glass prism. Do you see people working with prisms getting microwaved to death or skin cancer from UV? There's your answer.
At the time you put it on a real product, it makes no difference (maybe outside the price) if you have an array of leds or a device capable of emiting any frequency. You receiver won't be able to read on a perfectly sharp spectrum, and light will scatter on the fiber, adding noise to the frequencies close to the ones you are using.
At nature, you never have infinite precision, so anything you do can be discretized.
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Instead of transmitting just RGB values from 0-255 (24 bits) per pixel, instead you have to somehow convey the entire spectrum.
.red, blue or green.
It's just a tunable filter with a default value. That default value could be. .
The filter is "tweaked" by sending it another value, say, one between 1 and 255.
KFG
Cutting the current causes the muscle to return to its original state.
Depending on what you're watching, that's a lot like regular TV.
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The ability to generate any visible light frequency would not only extend the gamut to the full human range (unlike other schemes, like the 6-color Iridori system presented at SIGGRAPH 2004), but it would also allow tetrachromats to enjoy television and computers much better (this issue was discussed previously on slashdot).
Of course, as the article suggests, they will still have to use multiple emitters per pixel, as it can only generate colors on the edge of the CIE Color Space (warning, you can't see what colors they are, because your monitor cannot display anything outside the RGB Triangle). And of course tetrachromats are rare but have been found.
This is definitely an interesting technology, but I still think that display technology really has a long way to go before it can be used for general purpose things such as books and the like. The one thing that bugs myself about monitors/lcd's is that they always require a backlight or some active light source to function -- which IMHO really can bug the crap out of your eyes. What if they could invent a technology that didn't require a light source to be seen, but just reflected whatever existing light.. like a normal surface. Not only would this sort of thing definitely bring down the strain factor, but it would seem like you're reading a book or paper or something. Just a thought.
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I'm *assuming* you've experienced a prism. White light into an infinite gradient of spectrum.* Keeping your position still and moving the prism sweeps the colors across your vision. The "muscle" in their prototype is doing essentially the same thing. The "slits" act like filters. Kind of like what's in present displays. Each filter is essentially going to see the gradient for it's particular color (the intensity should be equal for all pixels). A color LCD essentially sees variable intensity (controlled by the twist) which adds up to a particular color.
Wikipedia has a good section on color.
*Not strictly true for some kinds of light sources, but let's keep this simple.
You probably do not need a continuously variable spectrum for each pixel. A simple set of red, green, and blue primaries cannot reproduce the stimulus of all the spectral colours, yet they give a good enough representation of most scenes. This works because the eye-brain system transmits brightness, colour, motion detection, and other signals as firing rates in nerves. The nerves will typically have a significant background firing rate even for zero signal, so the system has to continuously try to calibrate itself, and work out what the zero and scale signals are. This is why we can look at printed images with a typical contrast ratio of 100:1 and a white point as set by the ambient light, and recognize a scene without worrying that the blacks look grey or the whites look coloured. Many illusions depend on fooling this feedback process. For example, if you look at a slowly moving object for some time and the look at a still scene, it may seem to rotate in the opposide direction because your motion sensors have adapted. Well, the same happens with your sense of colour contrast - that will adapt to compensate for the variations due to intensity. If you look at a dimmer version of an image, the colour difference signals are weaker but colours you see will look much the same (until you get down to mesopic light levels, and the adaption system begins to pack up altogether). If you are looking at an image in a darkened room, and the colours are 10% desaturated, you will probably not notice unless there is some other stimulus (such as a red power LED on your monitor) to act as an independent reference. It many seem that a three-component display can only get at about half the colour space within the spectral locus, but under typical viewing conditions, we are poor judges of colour contrast. If you want to make an image look more colourful, make it brighter. Get a slide projector and move it close to the screen so the image is small but really bright - you know the colours have stayed the same and only the intensity has changed, but you will probably find the colours a lot more satisfying.
There are other reasons for wanting to go for more primaries. You eye does not have uniform colour sensitivity: it will detect colours differently in the centre and in the periphery. The brain tries to remove this variation, as it is part of the eye not part of the image. You do not see this variation directly, but you can get to see it if you look at a large white patch on a screen where the left and right halves have different spectra. If you have an RGB projector with broad spectral primaries, this will give you a similar stimulus to a general reflection scene in the central and the peripheral vision, but you will not be able to get the saturated colors. If you have narrow band primaries, you will be able to get the deep reds, peacock blues, and violets you cannot get with the broad primaries, but you may have strange side-effects because your central and peripheral vision no longer match. make a projector with six primaries, and you could get the best of both.
But, is the extra effort really worth it? It is a bit like 3D - twice as much technology giving you a bit of extra stimulus that can startle, but can also detract from the nett visual experience. I would love one of these variable filters as a research tool, but I don't expect fully spectral displays any time soon.