Two issues - losing an object beam and spots on plate

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Holomark
Posts: 121
Joined: Wed Jan 07, 2015 3:01 pm

Two issues - losing an object beam and spots on plate

Post by Holomark » Mon Jun 10, 2013 9:52 pm

I am currently experiencing two problems in my rinkydink lab.
First, I am having problems with object beams not showing on hologram (are lit by split off object beam does not appear lit on hologram). While I have intermittently had this problem I have solved it by adding mirrors, but I just not sure which problem to fix in current setup??-there are many likely culprits)
I am trying to do a split beam reflection hologram with overhead reference/object beam on plate and front of object and two object beams on sides of object.
The two side beams illuminate the side of object, the hologram is as if those two beams were not present. This is the result:
skull for depth.JPG
hologram - what happened to side lights
skull for depth.JPG (23.76 KiB) Viewed 5701 times
First thought is a polarization issue... so I bought some polarized sunglasses and...well, it looks ok to me. I first put the glasses in object beam between last mirror and object at normal (as if wearing and looking at beam); then I compared to turning glasses 90 degrees (perpendicular to ground) (normal had only faint shadow while perp blocked most of the light). Then I compared this to the reference beam (also lighting front of object) The result was the essentially the same... Pictures
object 1 normal.JPG
object normal
object 1 normal.JPG (27.41 KiB) Viewed 5701 times
object 1 perp.JPG
Object 1 perp
object 1 perp.JPG (27.36 KiB) Viewed 5701 times
OPL Normal.JPG
OPL normal
OPL Normal.JPG (26.28 KiB) Viewed 5701 times
OPL perp.JPG
OPL perp
OPL perp.JPG (29.51 KiB) Viewed 5701 times
So I wonder does it matter that the reference beam goes up over the object and back down to plate/object while object beams stay paralled (almost) to table?
Does the difference in pathlength make a difference? (Using Compass 315 and pathlength is less than 10 inches different)
Does it make a difference that I turn reference beam upwards by with my diverging lense? (not going through center of lense)
Does it make a difference the relative intensity of object and reference beams?

Issue #2. There is a spot in the center of plate (and smaller spots near bottom) Don't know if I burnt (overexposed) center, or if it is a plate issue.

Ed Wesly
Posts: 512
Joined: Wed Jan 07, 2015 2:16 pm

Two issues - losing an object beam and spots on plate

Post by Ed Wesly » Tue Jun 11, 2013 10:51 am

#1 killer of holograms is movement. Seems to me that the side lighting mirrors are to blame, batten down the hatches on them.

With the 315, path length matching shouldn't be an issue. Since the object probably scrambles polarization, that becomes a moot point; but check if the object light is indeed polarized by looking at the object and rotating the polarizing filter.

Tap the mirror mounts with your finger and listen closely for any sounds other than the impact; that might tell you if they are loose.

Good luck!
"We're the flowers in the dustbin" Sex Pistols

Jeffrey Weil

Two issues - losing an object beam and spots on plate

Post by Jeffrey Weil » Tue Jun 11, 2013 1:53 pm

Ed Wesly wrote:#1 killer of holograms is movement.
I don't have much problems with motion anymore. I find the #1 killer of holograms is forgetting to load a plate before going through all the time of settling and exposure.

With motion I'll still get something on the plate. With no plate....nothing.

142laser
Posts: 452
Joined: Wed Jan 07, 2015 10:14 am
Location: Tampa, FL

Two issues - losing an object beam and spots on plate

Post by 142laser » Wed Jun 12, 2013 12:10 pm

That is funny Jeff but think of all the money you can save on plates! :) Phil

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 » Sat Nov 02, 2019 5:29 pm

Hi. I am new to the forum and it is the first time I participate. How did you solve the first problem of the object beams? I have the same problem and with the same configuration and I am desperate, it is not a problem of polarization or movement. hraciss for your help

John Klayer
Posts: 272
Joined: Thu Jan 08, 2015 2:28 am

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

Post by John Klayer » Tue Nov 05, 2019 10:39 am

What's hraciss mean?

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 » Wed Nov 06, 2019 7:47 am

Hi. I am from Spain and use a translator. I wanted to put thanks but I wrote it wrong

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 » Sat Nov 09, 2019 1:00 pm

It is difficult to judge, but as Ed pointed out: the most likely reason is movement. It can be either movement of an optical component, which can be tracked by careful inspection of the setup. The other thing that can move is air - split beam setups are very sensitive to air currents.

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 » Sat Nov 09, 2019 4:03 pm

thanks for the reply. if I make a configuration of two horizontal beams it works perfectly, but if the reference is vertical and the horizontal object beam, adjusting the polarization then it does not work it is as if the object beam did not exist

jrburns47
Posts: 154
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 » Sat Nov 09, 2019 4:06 pm

A perspective diagram or photo(s) of your problem setup vs. your setup that works would be helpful.

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