Many of the tutorials on our website assume the use of the Integraf Holography Diode Laser. If you're eager to use your own holography laser, the great news is that all our instructions still apply. You'll just want keep in mind the following considerations.
Integraf Holography Diode LaserThe Integraf holography diode laser has a wavelength of 650nm, single-mode stabilized frequency, coherence length of three feet (90cm), and an output of approximately 3.0 to 4.0 mW. The unique advantage of this laser is that does not need a separate beam spreader. Instead, this laser has an adjustable lens which naturally spreads out the beam. The result is a simpler, cleaner and brighter beam.
Not all lasers will work for making holograms. For red-sensitive PFG-03M and PFG-01 recording materials, you must use a laser with a wavelength between 632nm and 670nm. The laser must also have single-mode stabilized frequency, sufficient coherence length (of at least one foot or 30cm recommended), and sufficient output (at least 1.5 mW recommended). Most red Helium Neon (HeNe) lasers are appropriate for holography, while most laser pointers, on the other hand, do not work at all.
With your own laser, you may need to purchase a separate optical beam spreader. While a variety of lenses work, we recommend using a first-surface concave mirror (which can be found from optical suppliers for about $35). You will want a lens that spreads out the laser beam to cover the recording plate sufficiently when the lens is placed approximately 12 to 24 inches (30 to 60cm) from the plate.
Positioning Your Beam Spreader
If you're using your own laser and a separate beam spreader, these tips will help.
- Position your separate lens so the beam spreads out enough to cover the holographic plate.
- The distance from the separate lens to the holographic plate can vary depending on your laser and lens. Play it safe by keeping the distance within 1 to 2 feet (30cm-60cm).
- The distance between your laser and the lens does not really matter a whole lot. For practical purposes, keep it to less than 1 foot (30cm) away, preferably right next to the laser.
Depending on the output of your laser, the exposure time may differ from that described in the instructions and tutorials on our site. If your laser has an output greater than 3mW (the estimated effective output of the Integraf holography diode laser) you will need less exposure time. If your laser has less output than 3mW, you need more time.
For example, if your laser's output is 1.5mW, you need to expose twice as long as described in the instructions (20 seconds instead of 10 seconds)—watch out for vibration! If your laser has an output of 35mW, your exposure time is about 1/10th of that previously described (1 second instead of 10 seconds). Note that the published output of a HeNe laser is often not the actual output. You may need to experiment first.