The hologram projector is made up of two main systems. First, the holographic screen, in which water particles of the size of 10 microns are triggered, generated by the intersection of low power ultrasonic waves. These particles are large enough to absorb the light from a projector besieged in the back of the device, but small enough, at a certain speed, to pass unnoticed by the human eye. Secondly, there is the sensor system, an array of infrared emitters and sensors with a wide-angle lens that translates obstructions from the field of view of the sensors into interactions on an imaginary screen over the device.
To achieve a projection, a medium where the light is absorbed is necessary, it is not possible to create a projection in the air without an absorption medium (at least not safely). To be able to project an image floating in the air we first need to vitiate it with an absorption medium, in this case we use water particles with a size of 10 microns obtained by ultrasonic frequencies and that are completely harmless to the environment, they form a flat screen of less than 3mm thick. The particles of water shoot upwards from the device thanks to two air currents on the sides that form a vacuum screen of less than 3 mm in the middle, the speed is high enough for the particles to pass unnoticed by the human eye. If we just shoot the water particles out, we would have an effect similar to that of a sprinkler, in which the particles do not stay flat, but go out in all directions and our projection would shapeless. The air flow that surrounds the particle screen is controlled to create a laminar flow, this is obtained by dividing the air flow and regulating the speed, to keep a stable Reynolds number.
Only after a lot of tests on wind tunnel, we have been able to obtain the final design of Waiik, this has been thought to maintain the air flows that surround the screen of particles as laminar as possible, the final design of Waiik takes into account the Bernoulli principle and the Coanda, Venturi and Magnus effects, to create laminar flows tested in the simulator and in the wind tunnel. By keeping the air flows laminar, the particle screen remains laminar as well.
To create water particles of 10 microns is not a coincidence, after extensive research we could find a particle size that has the best properties to create projections in free space; this particle size is as large as to catch a good part of the light of a projector located at the back, and at the same time, it is not as big as to cause condensation. You can put your hand in the middle of the projection as long as you want and moisture will never form around you or in the room where Waiik is located.
To create the effect of a touch screen floating in the air we use an array of infrared sensors and emitters that measure less than 5 mm in thickness, each emitter is provided with a wide-angle lens, which allows us to detect that when an object crosses the area illuminated by infrared emitters, it is perceived by several sensors; solving the problem of stereoscopy for multiple cameras by numerical optimization, we can approximate the position where the user has carried out an interaction. By implementing tracking techniques, we can improve the interaction and discern between the gestures that the user carries out, resulting in an interaction similar to that of any Tablet, but in the middle of the air.