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Facts About Holograms

Holograms are a photographic emulsion, which records the optical information about a scene in a special way. Holograms capture a complete and realistic 3-D representation of a scene, including its shadow, texture and depth. The word "holography" itself reflects this definition: it's from the Greek "holos" and "graphein" meaning "complete writing."

History
- Hungarian physicist Dennis Gabor invented holography in 1947, and subsequently received the Nobel Prize for physics for his work in 1971. Holograms were an unexpected discovery made during the course of attempts to improve electron microscopes, and real advances were not really made in the field until the laser was developed in 1960. In 1962, in separate experiments, Soviet and U.S. scientists produced the first 3-D holographic images.
How Holograms Are Made
- As Professors Gerhard Ackermann and Jürgen Eichler of Berlin's University of Applied Sciences explain, holography uses the properties of light diffraction and interference to create a full reconstruction of an object. The laser beam directed at the subject is optically separated into two beams. The first, which is called the reference beam, is aimed at the film while the second, the object beam, is directed to fully illuminate the subject. The object beam reflects off the object, carrying with it information, including its shape, texture and size. The diffracted object beam then meets the reference beam at the point of the film at which an interference pattern is produced and recorded onto the light-sensitive emulsion.
Reflection and Transmission Holograms
- Reflection holograms are illuminated from the front, reflecting light to the viewer just like a photo or painting on a wall is viewed. Transmission holograms are illuminated from the rear, bending light passing through the hologram to the viewers' eyes in order to form an image.
Practical Applications
- Artists are utilizing holographic technology to produce 3-D works, and commercially, holograms are being used to enhance the design of some advertising materials. National governments have added holograms to official documents like passports, driver's licenses and currency to prevent counterfeiting. Banks and DVD makers are using holograms on their products for security purposes. Scientists are also working on ways to use holography to further develop data storage capacities, virtual reality communications capabilities and 3D television viewing.

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