• Producing a Hologram
• Types of Lasers
• Still Holograms v. Stereograms

Types of Lasers Used

Holographers use two kinds of lasers to produce holograms: the continuous wave laser and the pulsed laser. The continuous wave laser emits a steady stream of laser light, whereas the pulsed laser emits laser light in bursts.

Continuous wave lasers are far more commonly used in standard holography. As discussed earlier, the recording of an interference pattern on the film forms a hologram. If the subject moves, even a microscopic amount, from one moment to the next, two different interference patterns will be recorded and the holographic image will be dim or may even not appear at all. An exposure with a continuous wave laser can take from less than a second to several minutes. During this time there can be no motion at all, including vibrations coming from the ground; therefore, the laser, optics, and subject must be placed on a vibration isolation table. Because it is absolutely critical that there is no motion at all, subjects that are holographed with continuous wave lasers must be ‘dead' or immobile objects that can be bolted or glued to the optical table surface.

Pulsed lasers, quite the opposite of continuous wave lasers, emit extremely quick bursts of very powerful laser light. Exposures can be made in ‘nanoseconds' (billionths of a second). No vibration table is needed and holograms can be made of people, animals, or even splashing water because no significant movement takes place in a nanosecond. The reason pulsed lasers are not used more is because they are significantly more expensive than the typical continuous wave laser.

Liti Holographics has a pulsed ruby rod laser and a full color continuous wave laser that was specially designed for us.

Want to learn more about holography, and how LitiGraphs are produced? Read more in the other Technology sections we've prepared: Producing a Hologram, Still Holograms v. Stereograms.

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