Improvement on my project

Post a reply

:D :) ;) :( :o :shock: :? 8-) :lol: :x :P :oops: :cry: :evil: :twisted: :roll: :!: :?: :idea: :arrow: :| :mrgreen: :geek: :ugeek:

BBCode is ON
[img] is OFF
[flash] is OFF
[url] is ON
Smilies are ON

Topic review

Expand view Topic review: Improvement on my project

Re: Improvement on my project

by Zeta » Fri May 25, 2018 11:34 pm

I use clear epoxy for sealing my hologram.

I use this one 3$. It has extra working time 20min but not very clear and have super small bubbles in it and little yellow.

1pack can seal 2 and a half 7x9 plate
A4A76108-8287-4936-A847-F2A232378537.jpeg (186.74 KiB) Viewed 5238 times

Re: Improvement on my project

by pluto » Fri May 25, 2018 1:15 pm

Nice work, what were your final steps for sealing the hologram?

Re: Improvement on my project

by Zeta » Fri May 25, 2018 5:33 am

Finally done
S__26419227.jpg (1.14 MiB) Viewed 5247 times

S__26419228.jpg (926.96 KiB) Viewed 5247 times

S__26419229.jpg (745.63 KiB) Viewed 5247 times


Re: Improvement on my project

by Zeta » Sat May 12, 2018 2:11 am

My expanded beam diameter is around 14” a size of A4 paper, laser is 50mw

Smaller test but same setup
my casio watch
30min exp 30min dark
I did not put the tape around the edge
0557867F-D2CE-4403-B22A-3CB2B6357970.jpeg (1.8 MiB) Viewed 5195 times

Re: Improvement on my project

by pluto » Fri May 11, 2018 5:02 pm

The black plastic isn't ideal for holograms. A silver/metal camera would probably show up a lot better.

Also you'll always have those lines unless you use a first-surface mirror. Not sure why your professor would mind you using better equipment, but I highly recommend it. Having two reflections from your mirror could be causing other issues as well, as I imagine they would form a secondary interference pattern?

Play with the exposure time as well, look at this graph of exposure vs diffraction efficiency:


The diffraction efficiency does go back up when you expose 3-4 times longer than required, but you start getting burn-in. I believe DCG is intentionally exposed at these sorts of lengths to produce HOEs, but it's not ideal for display holography.

What is the area of your expanded beam? And what is the power of your laser?

Re: Improvement on my project

by Zeta » Fri May 11, 2018 11:43 am

I still using normal mirror because I have to make a set of work and I have done 5 good plate with normal mirror if I change now my prof. will question me about the different in this set of work.

This one is sharp but still dim
It is a black plastic camera
2hr. Exp 17hr. Dark
8F6708FB-E49D-401D-AAEB-AF137F3F2565.jpeg (1.88 MiB) Viewed 5230 times

The problem of my last camera is everything is black and not shiny (black metal and black leather) so it doesn’t reflect laser back to the plate but the little shiny thing on left and right is bright and sharp

Re: Improvement on my project

by pluto » Thu May 10, 2018 7:46 pm

90 minute exposure without vibration is going to be tough... you can see how the lens part is clearer because it's in good contact with the glass, and thus more stable.

Definitely keep going with the first surface mirror. I still recommend making smaller holograms... early on you want to create as many holograms as possible (while taking notes) and get a good feel for how different variables affect the result.

I'm maybe 100 exposures in, and I'm finally now starting to get a hang of it... but I'm probably a slow learner :)

Re: Improvement on my project

by Zeta » Thu May 10, 2018 2:34 am

It is my plate holder that not stable, so now I just put the plate on top of the object

This one using front surface mirror
No strip line on my plate
But not really bright and sharp but can see a detail in deeper part
1hr 30min exp 30 min dark

Thin one use normall mirror
Sharper but only part that close to the plate deeper part is super dim
1hr 30min exp 17hr dark
AD2FDABB-AF87-4CB1-8F94-2BA9021EAA50.jpeg (179.84 KiB) Viewed 5296 times
Object is nikonos
96038AD6-E09D-49EB-8016-1783435AEF0E.jpeg (24.83 KiB) Viewed 5296 times

Re: Improvement on my project

by lobaz » Tue May 08, 2018 1:20 pm

Zeta wrote:Nothing on the plate
The most likely reason is bad stability. I would proceed in following steps:

1. Repeat some setup that was OK. Probably small plate, simple object (coins) in contact with the plate, short exposure time.

If you succeed, proceed step by step:

2. Small plate, short exposure time, simple object (coins) that is not in direct contact with the plate.

3. Small plate, short exposure time, "advanced object" that is not in direct contact with the plate.

4. Small plate, long exposure time, "advanced object" that is not in direct contact with the plate.
You can move the laser farther from the hologram to make the exposure time longer, use a ND filter or so.

5. Large plate, long exposure time, "advanced object" that is not in direct contact with the plate.

Debugging what went wrong is a painful process. Start with something that works and proceed slowly.

Re: Improvement on my project

by Zeta » Tue May 08, 2018 10:34 am

Update new problem

Nothing on the plate

Just shiny yellow and red and little purple
64F76397-4CB9-4230-ABA4-D19E8A70E32F.jpeg (107.79 KiB) Viewed 5317 times
No more mirror
AABE3FA2-7B96-4FF5-B889-3C8A9E660924.jpeg (432.69 KiB) Viewed 5317 times
Still no
I overdry and burn the middle of the plate
003BA765-7A69-4D71-8234-0864AD4247C1.jpeg (108.15 KiB) Viewed 5317 times
More visible in video

I feel like my improvement is going backwards :(