Display Technology

A holographic display, science

without the fi ction

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isplays are a big part of our lives - we rely on our phones, work from our laptops and computer screens, binge Netflix shows on our smart TVs. The technology has come a long way from the bulky Cathode-Ray Tube television sets to slim augmented reality smart glasses that we wear on our heads. Realising that we can put displays in every corner of our human existence, the big question is “What’s the next wave in display technology?” True 3D display, where a viewer cannot distinguish between the real and the virtual, has always been the ultimate goal and the term “Holographic Display” is often mentioned in this context. Let us look at the origins of holography to put into perspective where we are now.

Historical account

The science of holography dates back to 1947 when Denis Gabor, a hungarian-born physicist-engineer introduced the concept to enhance the image in electron microscopes. His method was ingenious, as it imaged the object using a physical process of diffraction and interference. Unlike photography, which captures the intensity of the object, but disregards the phase, holography preserved the complete pattern, including the 3D nature of the object.

Holography was perfected within the academic labs and better processes and materials to record holograms were developed. Researchers realized that holographic patterns can function in the same way as “classical” optical elements - lenses and mirrors. These earned the

name Holographic Optical Elements (HOEs). The HOE windshield combiner of the Head-Up-Display acts as a big lens, without the associated size and weight. Holograms also found applications in security materials. They are challenging to produce and require specialized equipment, which makes them difficult to forge. All of these applications spun out of the single stroke of insight of Denis Gabor, and the wide applications of the idea earned him the Nobel Prize in Physics in 1971.

A concept of Computer-Generated Holography emerged in the late 1960s. Instead of recording holograms on film or gelatine, one can compute and display the holograms dynamically on devices known as Spatial Light Modulators (SLMs).

Computational challenge In generating CGH, the task is to numerically answer the question, “what pattern has to be displayed on an SLM so that the modulated laser beam diffracts into a 3D shape we desire?”. This in itself is a challenging undertaking, which, back in the 1990s needed a supercomputer. It is complicated still, as SLMs are only capable of displaying some small number of phase states. Doing it in a naive way gives rise to noise, which degrades image quality and ruins the viewing experience. VividQ has bridged the gap by developing a novel set of algorithms to answer this question and do it effectively, achieving high image quality in real time. Our complete software pipeline takes a 3D representation of data and handles the steps from hologram computation all the way to the integration

20 May 2020

Components in Electronics

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