Lasers

Lasers

The first step in producing holograms for ourselves is acquiring a suitable light source. We already stated that a Helium-Neon (HeNe) laser fills the bill. However the laser you purchase must meet certain specifications in order for it to be capable of producing holograms. The most important specification is that it operates in TEMoo Mode. The majority of HeNe lasers operate in TEMoo Mode so this isn't a problem.

The next consideration is power output. The power of the laser is directly related to exposure time. Shooting a hologram with a 1 milliwatt laser will require a longer exposure time than shooting the same scene with a 2 milliwatt laser. For beginners, either a 1 or 2 milliwatt laser is suitable. A 1.25 milliwatt HeNe laser suitable for holography complete with power supply is available from Images Co. for $99.00, see suppliers source.

Laser Safety

Never look directly into the beam of a laser. An unspread beam from a small .5 milliwatt laser is well above the ANSI standard for eye safety.

Where to Shoot

The next step is determining where you can set-up the equipment to shoot. The area must be quiet (no vibrations) and dark (no light). There are green safe-lites available that do not fog (expose) the red sensitive holographic film. Using this safelight saves you from having to work in complete darkness. To start out I recommend setting up the holographic equipment directly on the floor to reduce vibration. A concrete floor in your basement is perfect, but a bathroom or bedroom floor may be ok too.

Isolation Table

Holograms are very sensitive to vibrations. Vibrations so subtle they can't be felt can prevent a hologram from forming. Because of this, holographers always use an isolation table. The isolation table, as its name implies, is designed to isolate and dampen as much vibration as possible. The table we will use is cheap, simple and portable.

The table consists of three components; a small piece of carpet, a small 12-18 inch diameter inner tube, and a metal plate, see figure 4. The carpet should be large enough so that the inner tube can lay on it without hanging over the edge. The inner tube has just enough air for it to be filled but still remain very soft. In other words you could squeeze the sides of it together easily. The top metal plate is our working area and should be about the same size as the carpet. The metal should be thick enough so that it doesn't flex when components are placed on it. The plate I use is 3/16" thick. If you cannot get a metal plate you can substitute 3/4" or thicker plywood, with a thin sheet of metal adhered to the top (working) side.

Figure 4

Figure 4

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