Full-color holograms were once just an imaginary mode of communication between rebel princesses and venerated Jedi masters. Daniel Smalley, a graduate student at MIT, has made the technology a reality with a new method that creates displays that are vibrant, detailed, and inexpensive. The resolution of his prototype is equivalent to that of a standard TV. Able to refresh images 30 times a second, his invention can simulate the illusion of movement. The device relies upon a small chip that resembles a microscope slide that Smalley was able to fabricate for only $10 in the MIT labs.
A hologram functions by using a beam of light passing through a diffraction fringe. This bends the light so that it emerges at different angles. To produce a hologram, Smalley was able to take advantage of a technique known as called acousto-optic modulation. This method sends precisely engineered sound waves through a piece of transparent material. Utilizing the crystal of a material called lithium niobate, Smalley created microscopic channels known as waveguides just beneath the surface. Each waveguide sports a metal electrode that can produce an acoustic wave which manipulates the trapped light. A pixel corresponds with each waveguide through which beams of red, green, and blue travel. As they pass through the crystal, the material determines which hues are to be filtered out. Combination colors, such as purple, do not require a separate waveguide but instead rely on an acoustic-wave pattern.
“What’s most exciting about [the new chip] is that it’s a waveguide-based platform, which is a major departure from every other type of spatial light modulator used for holographic video right now.” says Smalley.
Smalley and his team were able to increase the resolution and number of pixels of previous technology by a factor of 500 times. The techniques could also aid 2D displays in becoming more energy efficient and improve their resolution. A leap forward in hologram technology, the researchers have the potential to revolutionize the optical electronics industry.