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Author Topic: Laser light sources Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 04-13-2013 06:21 PM                     quote: Carsten Kurz Hmm. I thought they wouldn't try going public with speckle still being visible. Does anybody actually know how they're getting rid of those speckles? I know there are "speckle reducers", but after shooting the spreaded beam onto a DMD, I guess that some of that speckle will return. Also, are the current prototypes single or triple DMD versions?  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 04-13-2013 06:44 PM                       Believe it or not, they use screen shakers in some of the demo's I've or heard about. It's either a brilliant or absurd idea depending on your point of view, but it does work.  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 04-13-2013 07:08 PM                     quote: Sam D. Chavez Believe it or not, they use screen shakers in some of the demo's I've or heard about. So, they're actually shaking the screen? Would be interesting to see how that works out with a 60ft / 18m screen . Afaik, a speckle reducer is noting more than a piece of "rough glass" with some "random" pattern that's rotated at high speed in front of the laser. So, practically you create noise to hide the noise. Obviously, such a filter reduces the intensity of your laser beam.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 04-13-2013 07:13 PM                     As far as I know, they are using lot's of different methods to reduce speckle. From jittering to a large number of laser emitters. Every measure reduces speckle a little bit more. And to my knowledge, the speckle in green is the most difficult to get rid of. Shaking a screen is actually not too difficult, at least a traditional screen under tension. - Carsten  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 04-13-2013 07:25 PM                     quote: Carsten Kurz Shaking a screen is actually not too difficult, at least a traditional screen under tension. Wouldn't that create noticeable ripples and some additional unwanted sound effects? Besides the additional wear and tear on your screen... I'm also curious as how much you would need to shake the screen of such a size to make an impact.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 04-14-2013 07:21 AM                     I think it only needs to vibrate fractions of mm. Of course, every screen would need it's own continuous tuning, depending on tension, room temperature, etc., I guess. If you overdo it, you could get interesting running waves or moire patterns... If you do it right, I guess even Moire could go away... - Carsten  |  IP: Logged

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