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Holographic Displays: Making Their Way into Everyday Devices

Holographic Displays: Making Their Way into Everyday Devices

Holographic displays use light refraction to create 3D images that can be viewed without special glasses. This makes them highly desirable for applications ranging from medicine to augmented reality.

Digital device development never stands still, and the next big thing in devices could be the integration of 3D holography. This area is attracting considerable interest from tech developers and researchers. Technical advances in control of electronic displays have taken the ease of operation to a whole new level and allowed safe, fast and easy updates.

Electronic display
Electronic display

Holographic displays

A holographic display uses coherent light, such as that created by laser, to create a three-dimensional (3D) image in space. The hologram seems to be based on principles seen in photography and, in essence, is a 3D photograph.

Photographs aim to capture an image through light that has passed through a lens and onto a sensor. Modern digital cameras typically contain a sensor known as charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS), which translates the captured light into a digital image.

Holograms differ from photographs in the image capture method. These aim to capture additional image data by using a laser and splitting the beam to illuminate the subject from two different angles. The light reflected off the subject is captured on a holographic plate, which is similar to an undeveloped strip of film. When light strikes an object with an irregular surface, it bounces off at a huge variety of angles, so different aspects of the object are disclosed when it’s viewed from different perspectives.

In a hologram, a beam of light passes through a so-called diffraction fringe, which bends the light so that it, too, emerges at a host of different angles. One way to produce holographic video is to create diffraction fringes from patterns displayed on an otherwise transparent screen. The problem with that approach is that the pixels of the diffraction pattern have to be as small as the wavelength of the light they’re bending, and most display technologies don’t happily shrink down that much. In another approach, holographic-video displays are created by adopting acousto-optic modulation, in which precisely engineered sound waves are sent through a piece of transparent material. The waves basically squeeze and stretch the material, changing its index of refraction.

Holographic technology projects 3D light images, and these projections may be used to display 3D images. The science of creating holograms is known as holography, and the secret behind this futuristic technology is light. The man who discovered the principles supporting holography was physicist and Nobel Prize (1971) winner Dennis Gabor. Dennis Gabor conducted several holography experiments that he called wave-front reconstruction. Early days of holographic technology may have been limited as Gabor resorted to using electrons to create imagery. However, modern holography seems to benefit from the use of lasers, which may have propelled Gabor’s underlying approach into a new era of innovation.

The early prototypes of tele-immersive displays require users to wear special goggles and ¬a head device that tracks the viewpoints of users looking at the screen. On the other end, the people that appear as 3D images are tracked with an array of seven ordinary video cameras, while two other video cameras capture real light patterns projected in each room to calculate distances. This enables the proper depth to be re-created on the screen. So, if a viewer moves his head to the right, he can see the corresponding images that would be seen if he were actually in the room with the person on the screen.

Images on the screen are split and polarised to create a different image for each eye. The goggles then combine these images so that the brain recognises only one 3D image. If that rate could be improved to 10 frames per second, it would create a seamless projected image that would be like looking through a window at another person. Scientists are developing new technologies (including the Internet, display technologies, haptic sensors and desktop supercomputers) to support this type of communication.

Holographic displays
Holographic display (Credit: http://bigthink.com)

Electronics with holography

Since its inception in the 1940s, holography seems to be gradually making its way toward integration with everyday devices and may potentially become a part of our daily lives. The potential applications of 3D digital holograms are enormous. In addition to arts and entertainment, various fields including biomedical imaging, scientific visualisation, engineering design and displays could benefit from this technology. For example, creating full-sized organs for 3D analysis by doctors could be helpful, but it remains a challenge owing to the limitation of hologram-generation techniques.

Researchers are looking to create flexible and elastic thin films that could be used on a whole range of surfaces, opening up the horizons of holographic applications. This achievement in holographic technology may grant electronic devices with advanced optical images and potentially many other uses.