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How Holograms Work

        Science | Optics

Workspace Requirements
You can create your own holography table using inner tubes and sand to dampen vibration.
You can create your own holography table using inner tubes and sand to dampen vibration.

Getting a good image requires a suitable work space. In some ways, the requirements for this space are more stringent than the requirements for your equipment. The darker the room is, the better. A good option for adding a little light to the room without affecting the finished hologram is a safelight, like the ones used in darkrooms. Since darkroom safelights are often red and holography often uses red light, there are green and blue-green safelights made specifically for holography.

Holography also requires a working surface that can keep the equipment absolutely still -- it can't vibrate when you walk across the room or when cars drive by outside. Holography labs and professional studios often use specially designed tables that have honeycomb-shaped support layers resting on pneumatic legs. These are under the table's top surface, and they dampen vibration. You can make your own holography table by placing inflated inner tubes on a low table, then placing a box full of a thick layer of sand on top of it. The sand and the inner tubes will play the role of the professional table's honeycombs and pneumatic supports. If you don't have enough space for such a large table, you can improvise using cups of sand or sugar to hold each piece of equipment, but these won't be as steady as a larger setup.

To make clear holograms, you need to reduce vibration in the air as well. Heating and air conditioning systems can blow the air around, and so can the movement of your body, your breath and even the dissipation of your body heat. For these reasons, you'll need to turn the heating and cooling system off and wait for a few minutes after setting up your equipment to make the hologram.

These precautions sound a little like photography advice taken to the extreme -- when you take pictures with a camera, you have to keep your lens clean, control light levels and hold the camera absolutely still. This is because making a hologram is a lot like taking a picture with a microscopic level of detail. We'll look at how holograms are like photographs in the next section.