New lens type

Discussion in 'Miscellaneous Equipment' started by johnnywalker, May 23, 2005.

  1. johnnywalker

    johnnywalker Subscriber

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    Anyone heard of anything like this before? From Radio Canada International.


    "A new lens that could revolutionize photography was announced by Canadian researchers in the province of Quebec on Sunday. The new lens is five times thinner than a sheet of paper. It can zoom in or out and focus with no moving parts. The lens can eliminate the thick glass used in optical lens, and has the potential to eliminate distortion caused by conventional zoom mechanisms. The inventor of the lens, Tigran Galstian of Laval University, said that the lens could dramatically increase the quality of photos taken by small cameras such as cellphone cameras. "Right now we're guessing what industry needs and we'd love to work with them on what they really want," he said."
     
  2. Loose Gravel

    Loose Gravel Member

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    Nope. Sounds impossible. I'll take two.
     
  3. livemoa

    livemoa Member

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    From, of all places, the website for Iran Daily


    Lens Makers Flat Out

    Optics researchers in Canada have made a liquid-crystal lens with a focal length that can be adjusted by applying a voltage. The lens, which is flat, could have applications in mobile phones, laser cavities and surveillance equipment, PhysicsWeb.org said.
    Vladimir Presnyakov and Tigran Galstian of the University of Laval in Quebec made their lens by adding a small amount of a light-sensitive monomer to a liquid crystal in a commercially available electro-optic cell and irradiating it with a laser beam.
    The laser caused the monomers to form a polymer network, and since the intensity of the laser beam varied with position, the density of the network also varied with position.
    This in turn influenced the orientation of the liquid crystal molecules in the cell and the refractive index at different positions. Therefore, by carefully controlling the intensity profile of the laser, it is possible for the cell to act as a lens.
    It is also possible to change the profile of the refractive index across the lens, and therefore the focal length of the lens, by applying a voltage. For instance, the Laval team was able to vary the focal length by a factor of five (from 1.6 to 8 meters) in a few milliseconds by increasing the applied voltage from 1.5 to 4.5 volts.
    Presnyakov and Galstian say that their device is a good alternative to other prototype liquid lenses because it has no moving parts. Furthermore, they claim that their lens is simpler, more robust and more cost-effective than other lenses.


    Sounds interesting. Liquid lenses have been around for a while, well ages actually, most have two on our face, but this sounds like a big jump.
     
  4. MattCarey

    MattCarey Member

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    I'll try to call up the Journal of Applied Physics article at work tomorrow.

    Without that, and with the two news stories I can find on google news:

    Sounds sort of like a fresnel lens. I worked with a team at Livermore who were working on applying fresnel lenses to inter-ocular lenses (i.e. cataract replacement lenses). This sounds much better, in that the index of refraction can be continuously varied across the lens.

    There are two parts to this lens
    1) the thin lens as-made. Single focal length. Very thin.
    2) variable focal length lens with applied voltage. Without more information, my guess is that this is not really ready yet. They may have demonstrated a 5x focal length variation, but with what drawbacks? I.e. as the zoom, what aberations are induced?
    3) the news articles are quoting focal lengths of 1.6 to 8 meters. They may be a ways away from a cell-phone digicam lens (with a focal length of 10mm).

    They are still left with some major drawbacks for a real lens
    1) They are talking about a single lens at the moment. How long ago did photography move towards multiple lenses for aberation correction? I am sure that this could be applied to multiple lens designs, but they seem to be targeting the cell-phone digital market. I think that the real advantage

    2) they are talking about a thin membrane. This is good for a small diameter lens. You are not going to replace the front element on a Nikon 80-200 f2.8 with it. Any flexing in the lens would kill any advantages. I would rather carry a big piece of glass that gets good results than a spider-web that blows in the wind.

    At the risk of being an incurable physics snob--they published in Journal of Applied Physics. Good journal, don't get me wrong. I would have expected this to be Applied Physics Letters if it was hot. Other journals (Science, Nature, other "Letters" type journals) if it was really hot. (Obscure snob statements over)

    By the way, of they don't have a patent disclosure out for inter-ocular lenses, they goofed.

    Matt
     
  5. Donald Qualls

    Donald Qualls Member

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    Actually, from the description, this isn't a Fresnel but a gradient index lens -- similar to the lineless bifocals that have been around for a couple decades (and which I understood were impossible to make precisely enough for photographic use at usable focal ratios -- and I believe were made only in optical plastic because of the difficulty of after-casting doping of optical glass), but with the addition of precision laser treatment to establish/tailor the gradient and electrically variable index, which could be used both for focus and for zoom. Stack two, a cm or so apart, and you have a no-moving-parts zoom (shorten the front focal length and shorten the negative focal length of the back unit to keep the focal plane at the film/sensor). Made with thicker optical quality plates instead of the very, very thin glass commonly used for displays, there's no reason this should flex in the wind like a "spider web" -- in fact, as an assembly, it could possibly be more robust than the heavy glass we use now, since a very robust titanium or aluminum protective housing plus the LC lens could still weigh less than the aluminum barrels and big chunks of glass we're used to.

    The only downsides I see here are that it may (for one reason or another) be impractical to manufacture in larger sizes suitable for film cameras, might require so many additional elements to correct aberrations as to give no improvement in lens size or weight, and likely (like most liquid crystal based technology) won't work at all well in extreme temperatures (LCD watches and calculators work very sluggishly if at all in significantly sub-freezing temperatures, and temporarily lose their polarizing effect a big above the human comfort zone -- both conditions in which we might want our cameras to work, at least occasionally).
     
  6. Murray@uptowngallery

    Murray@uptowngallery Member

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    I read the/an article on this in either Electronic Design or EDN. It was aimed at pretty small f.l. and format (like picture phones). I lost interest at that point. Limited use, at present anyway.

    Murray