Collimating mirrors

[BobH]

I hear what you're saying, Keveh, but consider this: If pitching the hologram over in the plateholder didn't compensate for the aberrations present in the reference beam I described, how do we get such a well focused real image focused in space? If the arerrations are doubled (as you suggest), or even present, we'd see the image blurred because the information forming it from one side of the plate would be focused to a different position than the information comming from the other side of the plate.

If you made a mask with an aperture in it, let's say 10% the area of the hologram, and move it around on the hologram, the location of the real image would depend on the location of the aperture on the hologram plate. That's not been my experience, using an 18" diameter f/4.5 parabolic mirror off axis pretty much as extreme as in my sketch.

All of the image swings I see in transfers come from the unmatched conjugate beams used for the H-2, which are always lit by diverging beams and seldom made with converging beams by home holographers. It takes a big mirror and lots of table space for conventional "analog" holography of sculpture.

I've modified the sketch to indicate which sides of each beam are Diverging or Converging when the center is collimated. You can see how they match.