At one point, those who wanted to invest in a 3D hologram projector would have had to acquire a complicated piece of equipment that would have been difficult to maintain as a result of its reliance on a rotating disk. Now, however, semiconductors are used to generate light that a small lens can focus onto a substrate in order to display an image that appears to have depth as well as height.
Unlike resistors or traditional conductors, a semiconductor is made from some sort of mineral that resists the flow of electricity as its temperature goes up. When the temperature drops, it starts to conduct electricity. Various chemical agents can be added to a semiconductor chip in order to make it more or less resistant to the flow of electricity. Once engineers have struck just the right balance, they’re able to produce a chip that generates a sufficient amount of light to be used in a 3D hologram projector.
Beams produced by these chips can normally be rotated in one of several different directions. While you generally need a number of chips to generate a complete image, the human eye won’t perceive it as being made up of different blocks. As a result, modern hologram projectors are capable of producing images that move back and forth freely without the appearance of individual sectors that ruin the illusion. Best of all, it doesn’t require the use of any moving parts since the beam gets aimed electronically.
Researchers continue to develop new types of projectors, but it’s likely that any future equipment will still function on similar principles.