deep hologram Denisyuk-How was it done?

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dave battin

deep hologram Denisyuk-How was it done?

Post by dave battin » Sun Jun 20, 2010 10:46 pm

BobH wrote:I have to say I see this same technique in Saxby's Second Edition on page 127, under "Reflection Master Holograms", and he references Hans Bjelkhagen from 1977 and Nils Abramson. :?

danny's method is totally different than the saxby book. This method has not been recorded in any book and this method was not really available (for hobbiest),to be done in the earlier days of holography, as long coherents is needed to do a deep image,and the polarising films are much better now (lower attenuation)....

a paper on this will be a good thing and holographers world wide will be saying "WHY didin't i think of that!" :doh:

Colin Kaminski

deep hologram Denisyuk-How was it done?

Post by Colin Kaminski » Mon Jun 21, 2010 2:21 am

I would still reference any litrature you can in the paper as this appears to be the next step in a long line of thought.

Danny Bee

deep hologram Denisyuk-How was it done?

Post by Danny Bee » Mon Jun 21, 2010 2:54 am

Colin Kaminski wrote:I would still reference any litrature you can in the paper as this appears to be the next step in a long line of thought.
very wise advice, yes I will do this

BobH

deep hologram Denisyuk-How was it done?

Post by BobH » Mon Jun 21, 2010 5:06 am

So you're saying there's more to it than using a polarizer instead of an ND filter, and sticking it to the plate instead of having it separated as in Saxby?

dave battin

deep hologram Denisyuk-How was it done?

Post by dave battin » Mon Jun 21, 2010 10:13 am

BobH wrote:So you're saying there's more to it than using a polarizer instead of an ND filter, and sticking it to the plate instead of having it separated as in Saxby?
yes and then use a 1/2 wave polariser to adjust the amount of light hitting the plate...............

BobH

deep hologram Denisyuk-How was it done?

Post by BobH » Tue Jun 22, 2010 4:22 am

Well that's a good idea. :clap: :clap: :clap:

JohnFP

deep hologram Denisyuk-How was it done?

Post by JohnFP » Tue Jul 06, 2010 1:26 pm

I like it. :clap: I implemented this technique in doing a Single Beam H1 to H2 copy.

http://www.holograms3d.com/Illustration ... erence.jpg

dave battin

deep hologram Denisyuk-How was it done?

Post by dave battin » Tue Jul 06, 2010 4:36 pm

JohnFP wrote:I like it. :clap: I implemented this technique in doing a Single Beam H1 to H2 copy.

http://www.holograms3d.com/Illustration ... erence.jpg

Hi john!

Thanks for this picture ,but i dont think its really the same set-up, and i see a potental problem with that VDBS you have pictured,as you will see the gradent across the beamsplitter, remember the beam is already expanded..................better to use density filters instead as Saxby recomends in his book.

JohnFP

deep hologram Denisyuk-How was it done?

Post by JohnFP » Wed Jul 07, 2010 10:11 am

Hey Dave, thanks for the suggestion. But I use what I have :wink: The hologram turned out quite well actually.

I didn't want to comment too much but since you asked....

Some things you find out from actually making the hologram that one may forget or oversee on paper or as I have it, in a drawing.

Stealing a little of an expanded beam off to the side, and considering the beam is gausian, surely yields a less then homogeneous spread of the beam. But ah ha, the variable attenuator I have compensates for this when I used the top of the attenuator.

To explain, the beam fell off in intensity from right to left (right having a little more power then the left side). The top of my attentuator, when oriented the correct way, falls off from left to right. So the light that actually went through was pretty hologeneous. Good enough for dispay work anyway.

I wasn't trying to take away from Danny's technique, I thought it was brilliant for a SBR. I was trying to justify that that technique really does have merrit with trying to represent something similar, not the same. It must be me, but I seem to feel something other then objective comments when you reply to my posts.

BobH

deep hologram Denisyuk-How was it done?

Post by BobH » Wed Jul 07, 2010 1:52 pm

I have to say I see no significant difference between what Danny did and what John did. Spatial beamsplitting, variable attenuation of one of the beams. Only the means for the variable attenuation is different, and there are trade-offs for both methods. John's approach, as he said, compensates for the nonuniformity of the beam being attenuated. Danny's reference beam attenuator results in variable polarization of the object beam, changing the "look" of the object regarding highlights. Not an issue if all you do is completely diffuse imagery, but still a limitation. Both are good ways to deal with the down-side of spatial beamsplitting.

By the way, once the beam is split, it's no longer a "Denisyuk" hologram. It's a "split-beam" system, regardless of the technique used to split the beam.

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