a copy of the Master...

[Thieu]

Hi all,

Just wanted to share some pics of two DCG holograms I made this weekend. They are the first ones made with a C315M I bought long ago but until now hadn't finished making a nice enclosure for. Even though exposure times are of course longer compared to the 405 and 445nm diodes, not having to worry about mode purity is definitely nice for a change.

One of the (reflection)holograms reconstructed so bright under laser illumination that I decided to see if it was possible to make an image plane copy of it. This was much easier than I thought, just a matter of rotating the plate twice to get the virtual image to reconstruct inside the new plate on top of it.

This is the original:

And this is the copy:

copy2.JPG (42.08 KiB) Viewed 2500 times

It's hard to see in the pics, but part of the image now floats in front of the hologram.

What I'm most happy about is that results were finally consistent. I made 3 holograms with the same parameters and all came out pretty much the same. Hope things will stay this way, it makes navigating the parameter landscape *a lot* easier...

[Tony]

It would be intesting to see how this looked under laser light and see how close you were to the masters wavelenght. If you were centered it should glow like crazy. Try tilting the plate back and forth and see were it is brightest. If your centered it will be brightest at the angle the object was shot at. However, if your goal was that it is an image plane then that goal was achieved.
I think it is great photographing the hologram while hand holding it. It showes the relative brightness.
The hologram is nice and clean, and it looks like you've encountered blue-ees and greenies which could mean many different things. The coating is a bit off, but that takes time. Looks like bubbles and dust.
Image plane holos (sorry Joe) are great. Dinesh told me the key is to place the image such the the focal point (in this case the face) is where you want it and makes the best artistic impact. The face for example should be (I am guessing) just behind the glass while the belly sticking out.
Overall your progress is great

[Thieu]

Unfortunately the master was pretty much lost due to some silly mistakes I made prior to sealing it. But indeed it was very bright under laser illumination. There was very little difference in brightness between the hologram and the object itself when held close to each other in the same beam. Actually this was what made me decide to give the copying a try. If you have a hologram that's as bright as an object, then it sure must be possible to make a hologram of it, was my reasoning.

Below is one of the other test plates that had some stability issues but the good parts, close to the plate, are similar to how they looked in the master. The real object is in my hand on the left for comparison.

laser illumination.jpg (25.97 KiB) Viewed 2453 times

Since I never intended to use the hologram as a master it was processed to be broadband (99% ipa only), so the angle wasn't that critical.

Thanks for your suggestions on things that can be improved. There's indeed quite some room for improvement as far as the coatings are concerned. The next batch will probably be mold coated again and I'll see if I can find a good duster. I believe the dust is mainly from the paper kitchen towels I use to dry the plates after cleaning them prior to coating. I have to admit that I haven't paid much attention to the artistic aspects so far, mainly because the technical difficulties were so overwhelming.