“Help me, Obi-Wan Kenobi, you’re my only hope… Help me, Obi-Wan Kenobi, you’re my only hope…”

 

From the annals of “Star Trek” and “Star Wars” to the color shift designs on a credit card, holograms have existed in the “Twilight Zone” between science fiction and science reality since they were discovered. The idea of projecting the 3-D likeness of an object—or a person—into thin air through some transmitting device has led to all sorts of interesting story lines.

 

Flat holograms printed on foils are mass-produced for security and anti-counterfeiting purposes because it is next to impossible to copy them. These kinds of holograms are commonly used to authenticate thousands of credit cards.

But there is more to a hologram than smoke and mirrors or a science-fiction writer’s imagination. A long history of discovery precedes the current state of the art, beginning with Dennis Gabor, who came across the phenomenon while researching improvements in electron microscopes in 1947. The discoveries continue today in laboratories across the world in a race for what will become the future’s dominant 3-D imaging technology.

 

SIMILAR BUT DIFFERENT

In some ways, holograms are similar to lenticular imaging, the View-Master children’s toy and movies like “Avatar.” The common thread in all this is the 3-D element. Holography is also similar to photography in that an image is recorded and can later be reproduced. But those similarities soon end.

 

Lenticular imaging is a result of interlacing strips from two or more images that are precisely aligned with the different facets of a lenticular lens so that a different image, or the illusion of depth appears as the viewer’s perspective changes. With a View-Master, two images—one for each eye—are viewed simultaneously, creating a stereoscopic image, or one with the illusion of 3-D. 3-D movies like “Avatar” are also stereoscopic, using a camera system that records images from different perspectives, but can be viewed as 3-D only with special eyewear.

 

Holograms are created a little differently. Fundamentally, holograms are made using a few simple components that are arranged in a very exact and precise manner so that a whole (holo-) 3-D recording is made of an object at very high resolution.

 

Those components don’t necessarily include smoke, but do include mirrors —as well as lasers, lenses, prisms, special substrates and emulsions. For a glimpse into how complex a “few simple components” can be, consider these entries from Webster’s New World Dictionary:

 

The holographic recording process. (From Wikipedia)

• HOLOGRAM – n., a photographic plate containing the record of the interference pattern produced by means of holography.

 

• HOLOGRAPHY – n., a method of making three-dimensional photographs without a camera, by splitting a laser beam into two beams and recording on a photographic plate the minute interference patterns made by one beam going from the laser to the plate and the other beam going from the laser to the object to the plate: the virtual image can be reconstructed by shining laser light, white light, etc., through the developed film.

 

TRANSMISSION & REFLECTION

For a more comprehensive introduction to the physics behind holography, visit www.science.howstuffworks.com/hologram.htm/printable, where among other useful information is an explanation of the difference between two types of holograms that are prevalent: transmission holograms and reflection holograms. As their names suggest, transmission holograms are backlit and reflective holograms are frontlit. When light travels through a transmission hologram, a 3-D image is created; when light reflects off the surface of a reflection hologram, a 3-D image is created.

 

Some holograms must be viewed with a laser or monochromatic light source; others can be viewed with common white light.

 

Holograms are also sometimes classified as thick or thin, which loosely describes their perceived depth. Other descriptions include rainbow holograms, which appear to shift colors from red to green to violet, depending on the viewer’s distance from them. Embossed holograms are mass-produced from a negative impression of a holographic image and reprinted onto another substrate, such as foil. Holographic foils are a common printing substrate used for packaging, promotional items, anti-counterfeiting and brand recognition.

 

ELEMENTARY SCHOOL TO RESEARCH LAB

The techniques for producing holograms are pretty simple. In fact, Integraf LLC, a holographic film and supplies company based in Kirkland, Wash., posts directions on its website for making both transmission and reflective holograms as a grade-school science project (www.holokits.com/a-simple_holography.htm).

 

The holographic reconstruction process. (From Wikipedia)

But the authors, Dr. T.H Jeong, Alec Jeong, et al, emphasize it is a simple and inexpensive method for introducing the concepts and techniques to elementary school students. “Once interested, students will be induced to learn all the fundamental principles of optics and photonics: reflection, refraction, interference, diffraction, polarization, coherence, and scattering,” say the authors.

 

In other words, holography moves quickly from child’s play into the world of high-tech.

Just how high tech?

 

The “hologram” of Princess Leia in the first “Star Wars” movie is just theatrical smoke and mirrors, as are the many other holograms in the movies and TV. Until recently the process of creating just one hologram has been cumbersome and slow due to the enormous volume of information being recorded. But that’s improving. 

 

A November 2010 report by Katherine Bourzac in MIT’s “Technology Review,” describes the development of a full-color holographic display system that refreshes every two seconds. The research was done by Nasser Peyghambarian and colleagues at the University of Arizona collaborating with Oceanside, Calif.-based Nitto Denko Technical Corporation. A description of the work was published in the journal Nature. 

 

According to the report, a light-responsive polymer composite and faster laser speeds are key to the technology. While it’s still much slower than the 25 frames per second that human beings are used to seeing when they watch TV, the researchers in Arizona and California expect to overcome that barrier. When that happens, the result may be a 3-D imaging display technology that could compete with other 3-D—as well as 2-D—technologies. Medical and military applications head the waiting list of potential users of such advanced holographic technology, but applications could easily extend into the dynamic digital signage and display advertising markets.

 

Also on the front line of advanced holographic technology is Austin, Texas-based Zebra Imaging. The company holds more than 30 patents related to holographic imaging technology and is actively providing solutions for military imaging needs, as well as a number of medical clients and corporations in the private sector. Among the company’s product offerings are high-resolution 3-D architectural and topographical prints in which images seem to project about a foot above the substrate when lit with a monochromatic light source.

 

Similar to other 3-D imaging technologies, the future points toward an increasingly larger role for holography in all types of imaging markets. It may soon graduate from being a fantasy in a futuristic science-fiction movie to the real technology we’ll use to watch the movies of the future. But in the meantime, there are a number of present-day applications everywhere you look.