• Question: We saw a 2D image on a CD case and a 2D image on a mist screen. But where was the Hologram, a 3D image that changes as you walk around it?

    Asked by Terry Froggatt on 6 Jan 2015.
    • Photo: Fiona Dickinson

      Fiona Dickinson answered on 6 Jan 2015:

      You are right in that there was no ‘hologram’ as we traditionally understand it (like the image used on bank notes or DVDs) good holograms are truly amazing, but are not practical, for (as far as I know) so far they have only been able to be used for ‘still’ images. The image takes quite a long time to scan so we can’t yet project a live image. We will improve on this technology I am sure, but at the moment the cheats of 2D projection onto a cd case or a mist are the best we have.

    • Photo: Joe Myerscough

      Joe Myerscough answered on 6 Jan 2015:

      An excellent point Terry! We’re still a long way away from a Princess Leia style 3D image that floats in mid-air that you can walk around…. but a lot of people are trying.

      To create a true hologram you would need to find a way of generating light particles in mid-air. Quite tricky.

      One option is to trick the brain into thinking that light is coming from somewhere it isn’t…. this is how the CD case hologram works. Light is generated by the mobile phone but the reflection off the CD case makes it appear like it is coming from the empty space behind.

      Or you can put a particle into the air (fog or water) and bounce light off it… which is what we did with the mist screen.

      The final option is to actually excite the air particles themselves, by which I mean get them to release a photon (a light particle) by some other technique. A company called Holoxica in Edinburgh are doing some of the most exciting work in this field and you can see a video of their latest prototype here… http://vimeo.com/62616968

      People have also tried to think their way around the problem… literally.

      If you go back to the 2008 Christmas Lectures which Prof Chris Bishop of Microsoft Research presented you can see a device which has a spinning screen in the middle of it and then projects a different image onto the screen depending on it’s position. Because it’s spinning really fast, it creates a 360 degree image that you can walk around. Depending where you stand you see the spinning screen in a different position and therefore a different image. Clever stuff, but it requires a large noisy unit to work. You can watch the lecture here…. http://www.richannel.org/christmas-lectures-2008-chris-bishop–chips-with-everything (the device is about 29 minutes in).

      The final thing you should look at is this project from the University of North Carolina…. https://www.youtube.com/watch?v=ecMOX8_GeRY
      They use an XBox Kinect to track the position of your eyes and then update the image on the screens in front of you so as you move from side to side, you can look around a live 3D image of a room. If we’d had more time in the lectures I would have loved to have talked about this as it uses technology that you may well have at home to do something really cool.

    • Photo: Tim Stephens

      Tim Stephens answered on 6 Jan 2015:

      A real hologram contains extra information that a photograph doesn’t capture: photos capture the brightness of the light that’s reflected from the subject, whereas holograms capture the brightness and the timing of how the light is reflected. Scientists call this timing information the phase of the light and it helps to tell you how far away the light has come from.

      Unfortunately, the only way to capture this information on film is to use a laser as the light source for the hologram, and then use a laser to illuminate it when you want to view it. This isn’t really possible when you want to show the result on TV (although as the camera moves around a hologram, you ought to be able to see the image moving).

      As far as I know, there isn’t a way to make real moving image holograms yet because the LCDs (or whatever one uses to make a moving picture) are not capable of recording/reproducing the fine detail that you get in a hologram image.