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Holographic Technology – Is this the real 3D?

April 28, 2016, Written by 0 comment

Holographic technology has been around for quite some time but there are still challenges with the engineering side of building a true 3D display. This is because the diffraction of light requires features similar to the wavelength of light (less than a micron).

What is holographic technology?

Holograms are a three-dimensional image that records the light scattered from an object and then presents it in a way that appears three-dimensional. Allowing you to look around an object, viewing it in a slightly different perspective to real life.

Various different types of holograms have been made over the years, these holograms being transmission holograms and rainbow holograms.

Transmission holograms

This is when light coming from a laser is split to form an object beam and a reference beam, the light from the illuminated object and the reference beam form an interference pattern on some film, the pattern which is the hologram, contains information about the object which can be viewed as a three-dimensional image.

Basically, this allows light to be shined through them and the image to be viewed from the side

Rainbow holograms

Rainbow holograms can be viewed in white light (can be viewed in daylight). They are made by a  double holographic process where an ordinary hologram such as transmission hologram is used as the object and a second object is made through a slit. A horizontal slit limits the vertical perspective of the first image so that there is no vertical parallax in the resultant rainbow hologram. This slit process removes the coherence requirement on the viewing light so that full advantage can be taken of the image brightness obtained from ordinary room light while maintaining the three-dimensional character of the image as the viewers eye is moved horizontally. If the viewers eye is moved vertically, no parallax is seen and the image colour sweeps through the rainbow spectrum from blue to red, hence the name: “rainbow hologram”.

How do holograms work?

A laser beam is split into two identical beams which are then redirected by the use of mirrors. The illumination beam or object beam is then directed at the object. Some of the light is reflected off the object onto the recording medium.

The second beam, known as the reference beam, is directed onto the recording medium. This way, it doesn’t conflict with any imagery that comes from the object beam and coordinates with it to create a more precise image in the hologram location.

The two beams intersect and interfere with each other. The interference pattern is what is imprinted on the recording medium to recreate a virtual image for our eyes to see.

The recording medium, where the lights converge, can be made up of various materials. One of the most common used with hologram creation is photographic film, with an added amount of light-reactive grains. This enables the resolution to be higher for the two beams, making the image look much more realistic than using the silver halide material from the 1960s.

The future of holography

New holographic technology is being developed that projects 3D images from another location in real time. The images are also static like today’s current holograms, but they are refreshed every two seconds, creating a strobe-like effect of movement. The researchers hope to improve the technology over the next few years to bring higher resolution and faster image streaming.

It was also announced that a group of researchers from Hewlett Packard Laboratories had developed glasses-free, multiperspective, 3D display technology for mobile devices.

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