Holograms- with help from Jeff Spella

Everybody loves holograms, especially the really trippy ones. We've seen them since we were kids. W'eve maybe seen them on collectible cards and things like that. We've always liked looking at them, and wondering how the heck did that do that? Whatever the certain picture was doing, maybe changing pictures just by rotating the object its on. But what exactly are they besides flippin' awesome?

They way it works is fairly simple. Holograms are simply photographs that are three-dimensional. This makes them appear to have depth. Holograms work by making an image made up of two-dimensional pictures of the same object seen from different angles. Holography needs to use light of a single exact wavelength, therefore lasers have to be used. When viewing any object, the human eyes each receive a distinct image, from slightly offset reference points. The brain combines them into a three-dimensional image. The hologram produces the same effect artificially.

The way this works is in holography one beam, which is called the reference beam, comes directly from the laser being used. The other laser being used, called the object beam. This laser comes from the same laser but impinges on the object. This distorts it, before striking the photographic film. What is recorded on the film is the interference pattern produced by the two beams. After development, if the hologram is illuminated by a beam of light from the direction of the reference beam, the object beam is recreated, and the object "appears."

Now, there are many different types of holograms. The main two are transmission and reflection hologram. When it comes to transmission holograms, the light passes through a holographic plate. The coherent light from the laser is split to form an object beam and a reference beam. Another characteristic of transmission holograms is that the object beam and the reference beam come in from the same side of the holographic film plate during the exposure. This all creates the three-dimensional picture.

Relfection holograms can be seen in white light. A reflection hologram, the reference beam and the object beam illuminate a filmplate on opposite sides. As a consequence of this, the resolution of film emulsion must be very high. The recording of a reflection holograms needs ten to a hundred times as much power as for a transmission hologram. The result is that the exposure time will be long, and we need an optical arrangement which is multi-stabile.

Holography has so many uses. They also play a huge role in our lives. I mean, honestly, without holograms how would have Luke Skywalker known that Princess Leah needed rescuing if it weren't for the holographic message from R2-D2? How would have Tony Stark have built his IronMan suit? How would have the Halo Master Chief have had contact with Cortana? Nowadays, there is also holographic packaging, the use of holograms on credit cards and bank-notes has reduced the opportunity for forgery and particle physicists make holographic records of bubble-chambers from which accurate measurements can be made. Many museums have made holograms of valuable articles in their collections, both for insurance purposes and to check for deterioration.

I think that one day everthing we look at could be a holographic image. Instead of TV's we may just be watching a holographic image in our living room. Or maybe, we will use them to communicate, just like in the movies. I mean why not? It seems very probable. And instead of normal photographs we will look at holographs.

Overall, holograms are very interesting. They are used for so many different things and will become used more and more in the future. Everybody likes them, and it seems likely that soon they will become even more popular. Artists could use holography to express their creativity and are shown in galleries around the world. Which I find very cool. Holograms are the vision of the future.