Home Optical Table

[holorefugee]

and you'll see why particle board and carpet are not very good choices for building materials.

Can you expand on this? In what way are they bad to use? In several DIY table descriptions they suggest particle boards and carpets underneath a stiffer and heavier top. What options do you suggest?

I have used both, particle board is not very humidity tolerant even though it is a good dampening coefficient. It also has a short life. Carpet tends to not be useful at all as far as I can tell. It is pretty good at dampening high frequencies but so poor at low frequencies that it is not worth the space.

[John Klayer]

I made a table consisting of soda cans and two steel plates.

[erose]

[/quote]I have used both, particle board is not very humidity tolerant even though it is a good dampening coefficient. It also has a short life. Carpet tends to not be useful at all as far as I can tell. It is pretty good at dampening high frequencies but so poor at low frequencies that it is not worth the space.[/quote]

Carpet is a throwback to the early big sand tables. I kinda think the carpet was originally as much to protect between the hard concrete blocks and the inner tubes as anything. It also, to some extent, helped the big sand tables self-level when built on uneven floors.

[holorefugee]

I would agree with that Eric.

[profdc9]

I once made an optical table at home from parts from the hardware store.

1. Construct a square frame from 2-by-4 wood the size of the table.
2. Find a piece of sheet metal (preferably 1/16 thick or greater). Using caulk adhesive, attach the sheet metal to the square frame. Use set-in sheet metal screws (with the cone-shaped top) to secure it onto the frame once the caulk is dry.
3. Buy a bag of concrete, mix it up, and pour it into the inverted wooden frame.
4. Attach a sheet of plywood to the bottom.
5. Place on your favorite vibration isolated surface (old tire, in a sandbox covered with plastic sheeting, hang from stout bungee cords, etc.)

You can use magnetic bases or pucks you buy at the hardware store on the sheet metal to hold your components. Something like

http://www.acehardware.com/product/inde ... 4565775503

I actually built a white-light interferometer at home on a board like this. It was stable if I didn't touch the board.

Dan

[Arturo]

Hi,

just for the record, and since I have often asked about tables, I finally got around to build my 'table', and the results (yes, I know, no interferometer yet) have proven great: given that I live in a fifth floor downtown Madrid with lots of traffic around I have managed to get nice holograms with 7 minutes exposure (litiholo plates).

I am using an inner tube, a granite slab and 2 iron slabs for a total surface of 80x80 cm and weight of about 140 kg. You can see some photos here:

http://www.flickr.com/photos/theotocopu ... 737682907/

Cheers, and thanks to everyone who ever advised me about this topic!

[holomaker]

years back i made my portable table 4' x 3' x 3.5", it was made from a solid core door cut in half and then glued together. Very solid and only a wood top used with gravity bases. The laser was mounted off table and the table held my 10" collimating mirror on a metal frame.

This hologram was shot on that table





http://www.myspace.com/davebattin/videos

[Colin Kaminski]

The idea of particle board and carpet have to do with damping coefficients. The big problem in stiff tables is the lowest resonance frequency. This is the whole table moving at once and can be hard to damp out. It is easier to do this with commercial legs. The opposite strategy is to make the table not ring at all and this is a sand table. Time has show us that both work but there is a strong preference for very heavy stiff tables with commercial legs mounted to a foundation.

The larger table you need the harder this is. A 1' table is quite easy to make a 4x8 foot table is much harder.

[Johnfp]

I have not read this thread in a while, but the beauty of DCG is you do not need to create transmission masters if you don't want. DCG is efficient enough to make reflection masters, then a contact or proximity copy for your image planed holograms. Both of those holograms can be SBR's.

The reason I insist not taking all the trouble making a interferomically stable table is....there is enough hurdles to overcome learning DCG. To me it's kind of like building and airplane to drive down the highway.

I do agree with BobH and you really dont need the paving stone, I like the idea of a small 18" square paving stone so you can have a little forgiveness in your set up. By far the best is to lay your plate in your object. But you may want to buidl three little stands (out of nails) that support the plate right over your object if your object does not have surfaces that can accomidate setting the plate right on it.

Again, my emphasis here is if you truely want to make DCG reflection holograms, forget all that stuff about tables. WAY, WAY, WAY overkill. You will have enough to worry about with emulsion concentrations, plate coating, controlling your exposure variables and processing.

[holomaker]

The simplicity of a denisyuk set up is really the easiest setup a beginner, so its kinda nice to have to only worrie about the DCG process (as stated previous), even off topic here the mirror needed to expand the beam can be mounted anywhere regardless of vibrations! In my earlier setups I actually have the mirror (1/2"dia CCmirror) attached to an overhead pipe, i noticed when doing an exposuer,to my dismay my wife was directly overhead and started doing the dishes, i could see the expanded beam vibrating slightly as she was walking about, But in the end the hologram came out a bright as usual!