I had time to sit down with Bill Beck of Barco to talk about speckle, which is inherently related to laser projection – which was a theme at the show for just about everybody! Beck has multiple patents in the area of speckle reduction, and was a founding member of the Laser Illuminated Projector Association (LIPA). We also caught up with him recently at the Infocomm Display Summit (Beck Explains LIPA Work and Barco Clearly Behind Laser).
Speckle is created because laser projectors produce coherent light, i.e. in a wave pattern. Speckle is the randomised pattern of light and dark spots that are created when these waves hit the screen out of synchronisation. Therefore, the solution is to make the light non-coherent – which is much easier said than done!
Beck said that one way to get around speckle is to add more light sources. Imagine a chequer board, with alternating light and dark squares. Now, imagine that each laser beam creates its own chequer board pattern. Adding lasers that can overlay the dark squares with light ones can theoretically eliminate speckle. This is known as angular diversity.
Another form is polarisation diversity. In this method, light is diffused across the imaging chip, depolarising it. Of course, to create 3D images the light must be polarised! Beck said that it took two years to solve speckle on silver screens because of this.
Finally, “the one that really does the trick” is specular diversity. This approach involves using multiple lasers (for the angular diversity), each with a slightly different wavelength; this makes the light source “more like a lamp.”
These are all very clever methods of reducing speckle. However, taken too far, emphasising speckle reduction can affect other factors such as contrast and brightness. It is all about balance.
There is one other not-so-clever method of getting rid of speckle, which is very quickly vibrating the screen itself. This has its own problems (noise being one of them), and no-one in the cinema industry really likes doing it. This is why Barco is working on methods inside the projector.
As we heard at Infocomm, LIPA launched its speckle measurement method in March. One interesting point that this has already shown is that 100% speckle reduction is now possible – even xenon projectors have been shown to exhibit some speckle.
In a separate area of the show, I saw the Barco Escape concept. Like the CJ Group’s ScreenX, this is an immersive form of cinema, with screens on three walls (to the right, left and in front of the audience) and surround sound. It was very easy to get caught up in the content – until a piece of action moved between screens. Then I found my immersion broken by the image distortion when going round the corner. This wasn’t a failure of Barco’s projectors, but of the way that three separate screens work together. It would be much more immersive, although less practical in most auditoriums, to have a single curved screen.
Barco did show a piece of content specifically made for Barco Escape: a short film called ‘Two-Legged Rat Bastards’, based on a short story by Daniel Wallace. Most of the film is set at a gambling table, and the premise worked excellently; one screen could be used to show each player, or different parts of the same person (eyes, hands and mouth, for example).
On the stand, Barco was demonstrating its lobby signage, under the ‘Cinema Barco’ label. The company was also proud to announce a new partnership with the Reel Cinemas multiplex in Dubai, which will be the first cinema in the world to use solely Barco laser projectors. Reel will install projectors in each of its 22 auditoriums.