header image
sub header image
header divider
build holography system header
Introduction

Overview

Optical Table

Environment

Laser

Beamsplitter

Mirrors/Lenses

Table Mounts

Optic Mounts

Plate Holder

Objects/Scenes

Hardcopy

Resources

Optical Table

The function of the optical table is to provide a vibration-free environment on its surface from ground vibrations and a substrate for the table mounts that support the components. I will cover more on vibrations later on this site. There are many commercially available optical tables but they are very expensive. Figure 2 shows a less expensive table that I've used in the past, but no longer.

The table in Figure 2 is 3 feet x 4 feet and is fine for making holograms up to 4 inches x 5 inches. You will need a table size of 4 feet x 6 feet for making 8 inch x 10 inch holograms. A 5 foot x 8 foot table is needed to make 12 inch x 16 inch holograms. I recommend that you decide up front what maximum size hologram you will want to make in the future and buy the appropriate table size. This will save you significant money in the long run.

optical table photo
Figure 2: Granite optical table showing cinder blocks (A), plywood (B),
inner tubes (C), and granite table (D).

The Table Legs

The following instructions apply to all table sizes even though the example is for a 3 feet x 4 feet table. The table will need to have four legs. Each leg is made from three cinder blocks, 8 inches on a side, stacked on top of each other, 3 blocks high. Their location under the table surface is important for providing the maximum dampening effect on ground vibrations.

The Plywood

On the top of each cinder block stack, place a circular piece of plywood 16 inches in diameter and 3/4 inches thick. These provide support for the inner tubes.

The Inner Tubes

On top of each piece of plywood, place two inflated inner tubes that have an approximate diameter of 15 inches when inflated. The inflation pressure or psi (pounds per square inch) cannot be measured with a tire gauge since the pressure is too low, but a good indication of proper inflation is being able to push your finger into the tube about 1 inch. If the tubes are over inflated, high frequency vibrations may be passed to the table surface from the ground. If the tubes are under inflated, low frequency vibrations may be passed. The proper inflation is not all that critical, so don't lose sleep over it. Valve extensions can be connected to each inner tube valve to allow periodic inflation or deflation, or you can do what I do: have someone lift the corner of the table while you remove the tube, adjust the air pressure with an air pump, and re-insert it. Make sure nothing falls off the table while doing this! Better yet, remove all components from the table before removing a tube.

The Granite ⁄ Marble Slab

The final step for the table is to place a granite or marble slab, polished on one side, on top of the inner tubes, polished side up. This slab acts as the table surface and should have dimensions of at least 3 feet x 4 feet, and be a minimum of 3/4 inches to 1 inch thick. A slab of marble or granite this size is very heavy (about 200 pounds) and will require two or more people to lift it. A heavy table is necessary to help dampen ground vibrations. Sometimes a slab that is slightly chipped, or a slightly smaller or larger remnant slab, can be found and purchased cheaper. Substitutions for the marble ⁄ granite slab are laboratory table tops or a piece of glass (at least 1/2 inch thick and edge-polished). I do not recommend using wood since it is flexible and not rigid (unless you are going to use a sand box system). I presently use a 5 foot x 8 foot x 1/2 inch thick glass table where I've created holograms up to 12 inches by 16 inches.

 

Revised 5/2/2017