1. As travelers move through the walkway, they activate invisible light beams that produce sounds ranging from frogs to flute music. 2. A terahertz beam is a tightly focused, invisible beam that is created through the use of a laser. 3. Light-emitting diodes transmit the message on an invisible infrared beam in the same way a TV remote control works. 4. Switching to a computer-controlled laser, Seedor trained an invisible beam of cool ultraviolet light on the exposed soft underlayers. 5. Controllers carry a laser that allows them to point an invisible beam on the target. |