Two issues - losing an object beam and spots on plate

Starting point for beginners questions.
amtonio
Posts: 19
Joined: Wed Jan 09, 2019 8:58 am

Re: Two issues - losing an object beam and spots on plate

Post by amtonio »

In the upper reference scheme, the beam is incident at 56 degrees and I adjust the half wave lamina to cancel the reflection of the crystal (crystal, film, crystal), and the object beam polarizes it just like the reference beam using a polarizer, in the final hologram only the part of the reference light that has illuminated the object is visible, the illumination of the object beam does not appear
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jrburns47
Posts: 165
Joined: Mon Sep 14, 2015 2:48 pm
Location: Oyster Bay, NY

Re: Two issues - losing an object beam and spots on plate

Post by jrburns47 »

Are Holomark and amtonio two different people? If two different people, did Holomark have the same setup and solve the problem?
jrburns47
Posts: 165
Joined: Mon Sep 14, 2015 2:48 pm
Location: Oyster Bay, NY

Re: Two issues - losing an object beam and spots on plate

Post by jrburns47 »

Amtonio, judging from your description, and assuming that the solo horizontal object beam is the same as it was in the completely horizontal setup that worked, except the new location of the half wave plate, it seems that you need to rotate the solo horizontal object beam half wave plate to correctly match the polarization of the overhead reference/object beam that’s working. What kind of beamsplitter are you using?
amtonio
Posts: 19
Joined: Wed Jan 09, 2019 8:58 am

Re: Two issues - losing an object beam and spots on plate

Post by amtonio »

I have used a cube and a sheet and I have the same problem, the polarization of the object beam is the same as that of the reference beam
amtonio
Posts: 19
Joined: Wed Jan 09, 2019 8:58 am

Re: Two issues - losing an object beam and spots on plate

Post by amtonio »

I'm Antonio, Holomark had the same problem and I think I solve it, but I don't know how
amtonio
Posts: 19
Joined: Wed Jan 09, 2019 8:58 am

Re: Two issues - losing an object beam and spots on plate

Post by amtonio »

by illuminating the object a lot and perfectly adjusting the half-wave laminate to match the polarization with the reference beam, it is possible to see the illumination of the object very dimly in the hologram, is it possible that the object beam is not in the same plane as the reference beam, despite having the same polarization?
Din
Posts: 402
Joined: Thu Mar 12, 2015 4:47 pm

Re: Two issues - losing an object beam and spots on plate

Post by Din »

I think it could be motion. But, I think it's more likely that the light reflecting from the object is missing the plate. If your angles are correct as drawn, most of the light hitting the sides of the skull are reflecting away from the plate. I would look at just the object light (no reference) through the plate, or, better still, place a white card in the plate holder, block the reference, and look at the reflection of the object on the card. If there is little light hitting the white card from the sides, you need to change the position of the object, or the object light.
lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Two issues - losing an object beam and spots on plate

Post by lobaz »

Antonio, I assume your object is diffuse, i.e., it breaks polarization. I also assume that lengths of the object and the reference paths are approximately the same, i.e., within the coherence length of the laser you use. You can check the amount of object light hitting the plate as Dinesh suggested, but 99% it is the movement. If you have some spare optical components, try putting a beam splitter to the position of the object and make an interferometer. If you are not sure, check Practical Holography, Appendix 4, how to check fringe stability.
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