Well, you're right, it would avoid cross talk. But, colour holograms are designed to be reconstructed with white light. Hey, Phil, got a white laser?!Joe Farina wrote:By the way, I wonder if it's possible to use a color reflection (not transmission) master, then make color copies. Maybe it would avoid crosstalk problems in the master? (But then again, my knowledge of copy configurations is extremely limited.)
Yes, you can reconstruct with three (or two) lasers, but there must be almost zero swelling. White light reconstruction allows a little "slop room", so that if your "633 fringes" have swollen to 650 ( a 2.6% swell), then your eye will see little difference since the cones overlap quite a bit. There'll be a slight shift of the image vis a vis the other colours, but at 2.6% shift, the eye/brain easily compensates. It's actually quite amazing how distorted an image has to become before the brain gives up, even random images become meaningful (which is why people see Jesus on a tortilla, but that's another story!). But, if you reconstruct the shifted red fringes with a laser, then the laser bandwidth is outside the 17nm "window" and it'd be dim at best. Of course, the same holds for all your other colours. In a single beam Denisyuk, there is always an angle at which the image comes out bright, since the replay colour shifts with angle. However, the three colours will shift by different amounts, so this technique may not work for colour.