Craptastic VRP-M H2: The Butterfly Farmers

Justin W · Post by **Justin W** » Thu Nov 01, 2007 11:08 pm

Another mediocre reflection copy from transmission master, rendered into an amorphous green blob by my webcam....
The master was great. It was my first hologram shot with a spatially-filtered and collimated reference beam, and the quality showed. The master was exposed to 65ujoules/cm^2 with a beam ratio of 3.2:1. Very bright and clear.
Then things went to hell. Nothing I tried as far as replaying my master for copying gave me the quality that the beam from my one spatial filter did.... Turns out flaws in an H1 reconstruction beam cause ripples that make an H2 appear immersed in liquid or something... So..... I was/is/still am/shall remain stuck because I needed that spatial filter to kick me a nice reference beam for my H2 and replay my H1. I placed a beamsplitter cube in the output of my spatial filter. Several optical surfaces there, so of course things weren't perfect, but i was able to get a clean replay beam and a *cough* reasonable reference beam for H2....

And wound up with an almost bright, almost clear hologram. The image is a little grainy, and my guess is that it is showing me the surfaces of my beamsplitter and a couple mirrors. I left it diverging, as I didn't have the room or the line-of-sight to get it to my collimator (nor would it have been the proper focal length). i moved mirrors around till i had something like 1:1, and exposed to 80ujoules per.

So I reckon a spatial filter is like a bad habit you just can't kick... if you have one, you need two.

Anyway, that's my latest effort there...

JohnFP · Post by **JohnFP** » Fri Nov 02, 2007 9:25 am

Justin,

I made this H1 transmission to H2 reflection hologram (Exceptionally bright and clean)

http://www.holograms3d.com/PhotoGal/Mic ... ghtEle.JPG

With this set up, which only uses one spatial filter.

http://www.holograms3d.com/PhotoGal/Mic ... G_2764.JPG

Object beam is red and illuminates the H1, which is on the right, barely visible in the plateholder.
Reference beam is blue and illuminates H2 on the left.

Colin Kaminski · Post by **Colin Kaminski** » Fri Nov 02, 2007 1:14 pm

So I reckon a spatial filter is like a bad habit you just can't kick... if you have one, you need two.

I thought this once too, and a few years back Lon chastised me and said that I would need more. Lately I want 5 as 4 is just not quite enough.

Justin W · Post by **Justin W** » Fri Nov 02, 2007 7:48 pm

'Lo again all!

John - thanks for the tips, my friend. I'm not entirely certain I understand what I'm seeing there in the diagram you provided, but I get the impression you are expanding/cleaning a rather healthy beam with the spatial filter, then arranging for a portion of it to fall on your collimator (for H1 replay), while the rest is mirrored down from a flat mirror to provide H2 reference?

I think I'm confused how this would work, as any H1/H2 work I've done involved my H1 replay and H2 reference doing something of the "guns at dawn" thing, arriving at the two plates from opposite sides....

However.. despite my inability to grasp the specifics of what you show there, I can dig your basic point - there's ultimately a lot of beam there to work with, and a little creative geometry goes a long way!

Think outside the box, tow the line, break the paradigms, and other catchy corporate buzzwords! My thinking is folded uncomfortably into an 18"x36" box of sand, and it seems I need to squint my eyes, cock my head to the side, and take a harder look at what i've got to work with... Honestly! Shame on me! I have a spatial filter, I have a collimator, I have a stable laser, and an apparently endless list of excuses for not getting dazzling results from the gear I've got

Just one more mirror and I'll have it!

Anyhow, apologies for the lengthy rant, and in the spirit of continuing to waste everyones' time with nearly unviewable photos of my work, I'll attach another blurry pic of the same gram in a durn purty red - Sugary Sweet! I love this color.

JohnFP · Post by **JohnFP** » Sun Nov 04, 2007 6:12 pm

John - thanks for the tips, my friend. I'm not entirely certain I understand what I'm seeing there in the diagram you provided, but I get the impression you are expanding/cleaning a rather healthy beam with the spatial filter, then arranging for a portion of it to fall on your collimator (for H1 replay), while the rest is mirrored down from a flat mirror to provide H2 reference?

I think I'm confused how this would work, as any H1/H2 work I've done involved my H1 replay and H2 reference doing something of the "guns at dawn" thing, arriving at the two plates from opposite sides....

Justin, aren't beams (red-object and blue-reference) hitting the H2 from opposite sides? The H2 is the plate on the left that has the red obect coming in from the right and the blue reference coming in from the left. The blue reference beam is hitting that H2 at and angle and of course the H1 is parallel to the H2. The H1 is getting illuminated with the red object beam which is also hitting it at the replay angle.

Looking at the 18" paving stone, this overhead set up seems to take up only about 36" long and about 18" wide.

Scroll down to the elephant section

http://www.holograms3d.com/PhotoGal/PhotoGal.htm

maybe the last two with the white card will help. The first is lookign at the reference beam hitting the white card and the second is the object beam hitting the card. You can even make out the elephant in the latter (upside down of course).

Again, I have to thank Michael for the use of his master.

Justin W · Post by **Justin W** » Mon Nov 05, 2007 1:07 pm

Yes!
Thank you, John. I see it now. Your diagram is clear but my thinking is not. Indeed you show a beam arrangement that works in ways I am accustomed to.

Mmmm...overhead beams. Yessir. Yessir indeedy. 18"x36" sounds like a lot more room when using maybe just one more of the dimensions this universe so accomodatingly supplied... Time to hoist the mainsail. And by mainsail I mean of course telescope primary. Maybe I can plant a tripod in my sandbox or something... Like I say - restricted thinking. Yep, time to track down a specialist who can perform that operation to remove my head from my... ah, whatever

So. Yes. The single-spatial-filter arrangement you showed there makes a lot more sense when I Iook at it with both my eyes pointed in the same direction

John - I very much appreciate your patience in the matter of walking me through this.

Colin Kaminski · Post by **Colin Kaminski** » Mon Nov 05, 2007 4:04 pm

Remember when you leave a plane that your polarization can rotate. See Kaveh's Thesis for a great explaination and ways to use this to your advantage.

Justin W · Post by **Justin W** » Wed Nov 07, 2007 4:48 am

Colin - I would love to have a look at that, as I am only recently learning of polarization and the necessity for tending it, and would love to feel like I know a bit more about the subject...

I'm not gonna ask that you dig it up for me; I imagine said endevour could potentially be time-consuming. Maybe you could just point me in the right direction? Sounds like a great read.

Cheers.

JohnFP · Post by **JohnFP** » Thu Nov 08, 2007 4:27 pm

Yes Kaveh, your thesis is great reading. Is it possible to put it on The Holographer web page so that other may enjoy it also?