Holographic controls could be used by drivers to dial the phone.
A solution to both problems -- virtual controls that seem to float on air -- combine holographic and wave-sensor technologies. Engineers at HoloTouch Inc., Darien, Conn. (www.holotouch.com), use transmission or reflection holograms to make images of controls. (Transmission and reflection refer to how holographic images are made and projected). Their position can be adjusted to meet applications' needs.
A wave-source sensor, which could be infrared or acoustic, detects when a finger or other object enters the space that seems to be occupied by one of the holographic buttons and sends a signal to the actual equipment the buttons are meant to control. Tunable emitter/detectors let engineers adjust the activation area. If the image is of several buttons, the detector can be designed to scan the entire holographic image employing software analogous to that for programming a computer screen for interaction with a mouse. The software determines exactly which button is being "pushed."
Holographic controls could be useful in dirty environments, places where workers need to keep their hands clean or in consumer applications where repeated use and durability are issues. They would also benefit people without the strength or agility to manage regular controls.