Table ideas

Simple answers are here! For Theory look in General Holography.
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jsfisher

Table ideas

Post by jsfisher » Mon Sep 20, 2010 9:05 pm

I finally got around to setting up an interferometer on my simple setup. Watching the fringes dance as they do, I can't figure out how I got any holograms to come out at all.

Time for a better table.

While searching around for all the variations on home-made holography tables, I came across one that wasn't the usually sand, concrete, and/or steel. In A new design for a holographic table (1986 J. Phys. E: Sci. Instrum. 19 643), the authors describe a table constructed with layers of rubberized coir (coconut fiber coated with latex) and thin plywood sandwiched between two steel plates.

The part I find most intriguing is that it doesn't weigh a ton. The only heavy parts in the coir design are the steel plates themselves, (about 120 lbs each for 3/16" mild steel). Yet, the authors seem to claim reasonable vibration isolation, especially at the very low end, 2-4 Hz.

I cannot find rubberized coir in very small quantities, but I think I can get similar acoustic dampening from mineral wool board, something like Roxul Rockboard 60 or Owens Corning 705. I'd use cinder blocks for legs and build the table in the layers shown in the code block.

Does anyone think this may have some potential, or am I just wasting my time? Better still, has it been tried before?

Code: Select all

================================  3/16" Steel plate
////////////////////////////////  2" Rockboard
--------------------------------  3/16" Masonite
////////////////////////////////  2" Rockboard
--------------------------------  3/16" Masonite
////////////////////////////////  2" Rockboard
================================  3/16" Steel plate

Jeffrey Weil

Table ideas

Post by Jeffrey Weil » Tue Sep 21, 2010 1:37 pm

Hey There,

To me that table sounds like a compromise to get it lightweight. But probably just like a small speaker might have some advanced design that will allow it to beat other small speakers it won't do well against a full size one.

Is there some problem with a heavy table in your intended place for it? If not, I wouldn't re-invent the wheel.

A self made concrete table can be poured in place, so your never moving heavy stuff, and if you ever want to get rid of it all you need is a small sledge hammer and some other simple tools to take it down to rubble. That rubble can also be carried out in small bunches to make it practical for one person to move it all.

Jeff Weil
NorthBeach Holography Inc.

Joe Farina

Table ideas

Post by Joe Farina » Tue Sep 21, 2010 1:57 pm

I recommend the smallest table possible. My table is quite small, yet it does everything I need. It's always best to keep beam paths as short as possible for split-beam work, for stability reasons. So if your table is of modest dimensions, it compels you to keep your layout compact, which is to your benefit. For single-beam Denisyuks, all that's needed is a small paving slab of stone or concrete.

Thieu

Table ideas

Post by Thieu » Tue Sep 21, 2010 3:03 pm

The rubberized coir is pretty one-of-a-kind stuff. I have a small 20x20 cm piece someone used for packing a laser. It's hard to describe how it feels, but it's certainly different than rockboard. I think it's really an essential part of the setup the article describes.

jsfisher

Table ideas

Post by jsfisher » Wed Sep 22, 2010 2:16 am

Jeffrey Weil wrote:Is there some problem with a heavy table in your intended place for it? If not, I wouldn't re-invent the wheel.
As a successful parent (meaning the kids, young and strong, have moved away), I'd prefer to avoid a heavy table. That said, my thoughts on are that if this works without the large mass, great, but if not, I can still add mass to it later to make it work better. No matter what, it can't be a complete failure, and it includes some grand experiments along the way.

I should mention that the authors of the original paper are from India, the home of the coir industry, not that that may have motivated their design choices. Also, there are only two citations to the paper (well, design note, actually), both by one of the authors. My hopes are not extraordinarily high for the design, but for me, this hobby is more about invention than the end product.

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