Holograms have some very interesting properties that make them different from 2-dimensional images. One of these properties that we periodically get asked about is what happens if a hologram is cut in half, or even shattered into a million pieces? One aspect of this question is based on the fact that every part of the hologram contains information about the whole scene, but there’s also an element of urban legend that holograms are just magic, and because most people have never gotten to make a hologram, much less break one into a million pieces, it has just become accepted that holograms somehow replicate themselves by some sort of physics voodoo. Well, let’s find out.
I’ve got the LitiHolo Hologram Kit set up here, and to demonstrate this I’m using just some ordinary dice that I’ve set up for the hologram that we’re going to make. Now for the first part of our demonstration, I’ve taken a picture of this exact same setup, and I’ve got some scissors here. I’ll cut this picture into 3 pieces right between the dice, and you can see that if I only had one piece from the picture I would only know what number was on the die from that piece. Here I’ve got a 2, but I would have no idea from just this piece of the picture that there was a 1 to the left and a 3 to the right. This is, of course, what you expected. But what about a hologram?
I’ve already got the laser set up and my dice are in postion for the hologram I want. I’ll drop in the paper shutter to block the laser light while I get out one of the Instant Hologram Film plates and put it into position. When it’s all set, I’ll remove the shutter and the hologram image will start exposing. This process takes about 2-5 minutes typically. Once the time is up, I should have a nice hologram, and I’ll just move the real dice out of the way so that you can see the holographic image that has been recorded, as if the dice are still there. Now I’ll take the hologram plate, and I’m going to peel the hologram film off the glass. I’ve got my scissors here again and I’ll do same thing I did before, and cut the hologram into sections. I’ll take one of those sections and put it back onto the glass in the about the same spot, and I’ll put it back into the setup for viewing. As you look through this piece, you can see the die with the 2 on it, but here’s the crazy part: as I get closer and look around inside this piece, I can also see the die to the left with a 1 AND the die on the right with the 3! I can actually see all of the dice from the original hologram just in this one piece – 1, 2, 3!
The reason this works is because unlike ordinary pictures, which only capture one perspective of a scene through a camera lens, a hologram is a type of “lens-less photography” that captures a multitude of a perspectives of the captured scene. So when you cut the hologram in half, it’s not that the hologram is replicating itself into each piece, but rather the half you have is like a smaller window onto the whole scene, and you can look around inside that piece and still get perspectives that show the whole scene instead of just half. This is like looking through a key hole, and you can still see the whole room on the other side of the door. Each piece of the hologram captures a unique perspective of the whole scene.
Very cool!