I have been reading about holography, and I think I understand the general concept, but one thing that has me completely lost is how computer generated holography works in practice.
I think I get the basic idea behind how CGHs work. If we were to take a 3D object, like a Utah teapot, we could emulate the behaviour of an actual laser beam bouncing off the teapot and interfering with itself, thus forming the hologram. Now, here's where I'm confused: I've read about printing holograms (as in, with a regular printer), recording actual holograms on CCDs, patterning a holographic plate with the fringes using an LCD, and even holographic displays. What I don't get at all is how this is even vaguely possible? Aren't the interference fringes which make up the hologram much smaller than wavelength of light? Even if we had LCDs with massive resolution, wouldn't the diffraction limit prevent the using of them to pattern the plate, in the same way that visible light photolithography is nearing its physical limitations in the microfabrication? Basically, I've never seen a straight forward explanation of how computer holograms are actually transferred to the physical recording medium. As far as I know, it is possible, because there are companies currently doing it (such as Zebra Imaging). However, reading over patents and other papers in the literature yielded no clear understanding of how this really works, most authors seems to gloss over the implementation, and often seemingly contradict themselves. It was my understanding that one needed an electron microscope to actually make out the fringes because they are so small. If this is the case, why does one not need an electron microscope to etch the fringes?